ty A comprehensive evaluation of a typical plant telomeric G-quadruplex (G4) DNA reveals the dynamics of G4 formation, rearrangement, and unfolding [Plant Biology] By feedproxy.google.com Published On :: 2020-04-17T00:06:05-07:00 Telomeres are specific nucleoprotein structures that are located at the ends of linear eukaryotic chromosomes and play crucial roles in genomic stability. Telomere DNA consists of simple repeats of a short G-rich sequence: TTAGGG in mammals and TTTAGGG in most plants. In recent years, the mammalian telomeric G-rich repeats have been shown to form G-quadruplex (G4) structures, which are crucial for modulating telomere functions. Surprisingly, even though plant telomeres are essential for plant growth, development, and environmental adaptions, only few reports exist on plant telomeric G4 DNA (pTG4). Here, using bulk and single-molecule assays, including CD spectroscopy, and single-molecule FRET approaches, we comprehensively characterized the structure and dynamics of a typical plant telomeric sequence, d[GGG(TTTAGGG)3]. We found that this sequence can fold into mixed G4s in potassium, including parallel and antiparallel structures. We also directly detected intermediate dynamic transitions, including G-hairpin, parallel G-triplex, and antiparallel G-triplex structures. Moreover, we observed that pTG4 is unfolded by the AtRecQ2 helicase but not by AtRecQ3. The results of our work shed light on our understanding about the existence, topological structures, stability, intermediates, unwinding, and functions of pTG4. Full Article
ty Spectral and photochemical diversity of tandem cysteine cyanobacterial phytochromes [Plant Biology] By feedproxy.google.com Published On :: 2020-05-08T03:41:14-07:00 The atypical trichromatic cyanobacterial phytochrome NpTP1 from Nostoc punctiforme ATCC 29133 is a linear tetrapyrrole (bilin)-binding photoreceptor protein that possesses tandem-cysteine residues responsible for shifting its light-sensing maximum to the violet spectral region. Using bioinformatics and phylogenetic analyses, here we established that tandem-cysteine cyanobacterial phytochromes (TCCPs) compose a well-supported monophyletic phytochrome lineage distinct from prototypical red/far-red cyanobacterial phytochromes. To investigate the light-sensing diversity of this family, we compared the spectroscopic properties of NpTP1 (here renamed NpTCCP) with those of three phylogenetically diverged TCCPs identified in the draft genomes of Tolypothrix sp. PCC7910, Scytonema sp. PCC10023, and Gloeocapsa sp. PCC7513. Recombinant photosensory core modules of ToTCCP, ScTCCP, and GlTCCP exhibited violet-blue–absorbing dark-states consistent with dual thioether-linked phycocyanobilin (PCB) chromophores. Photoexcitation generated singly-linked photoproduct mixtures with variable ratios of yellow-orange and red-absorbing species. The photoproduct ratio was strongly influenced by pH and by mutagenesis of TCCP- and phytochrome-specific signature residues. Our experiments support the conclusion that both photoproduct species possess protonated 15E bilin chromophores, but differ in the ionization state of the noncanonical “second” cysteine sulfhydryl group. We found that the ionization state of this and other residues influences subsequent conformational change and downstream signal transmission. We also show that tandem-cysteine phytochromes present in eukaryotes possess similar amino acid substitutions within their chromophore-binding pocket, which tune their spectral properties in an analogous fashion. Taken together, our findings provide a roadmap for tailoring the wavelength specificity of plant phytochromes to optimize plant performance in diverse natural and artificial light environments. Full Article
ty Repression of sphingosine kinase (SK)-interacting protein (SKIP) in acute myeloid leukemia diminishes SK activity and its re-expression restores SK function [Molecular Bases of Disease] By feedproxy.google.com Published On :: 2020-04-17T00:06:05-07:00 Previous studies have shown that sphingosine kinase interacting protein (SKIP) inhibits sphingosine kinase (SK) function in fibroblasts. SK phosphorylates sphingosine producing the potent signaling molecule sphingosine-1-phosphate (S1P). SKIP gene (SPHKAP) expression is silenced by hypermethylation of its promoter in acute myeloid leukemia (AML). However, why SKIP activity is silenced in primary AML cells is unclear. Here, we investigated the consequences of SKIP down-regulation in AML primary cells and the effects of SKIP re-expression in leukemic cell lines. Using targeted ultra-HPLC-tandem MS (UPLC-MS/MS), we measured sphingolipids (including S1P and ceramides) in AML and control cells. Primary AML cells had significantly lower SK activity and intracellular S1P concentrations than control cells, and SKIP-transfected leukemia cell lines exhibited increased SK activity. These findings show that SKIP re-expression enhances SK activity in leukemia cells. Furthermore, other bioactive sphingolipids such as ceramide were also down-regulated in primary AML cells. Of note, SKIP re-expression in leukemia cells increased ceramide levels 2-fold, inactivated the key signaling protein extracellular signal-regulated kinase, and increased apoptosis following serum deprivation or chemotherapy. These results indicate that SKIP down-regulation in AML reduces SK activity and ceramide levels, an effect that ultimately inhibits apoptosis in leukemia cells. The findings of our study contrast with previous results indicating that SKIP inhibits SK function in fibroblasts and therefore challenge the notion that SKIP always inhibits SK activity. Full Article
ty N{alpha}-Acetylation of the virulence factor EsxA is required for mycobacterial cytosolic translocation and virulence [Molecular Bases of Disease] By feedproxy.google.com Published On :: 2020-04-24T06:08:45-07:00 The Mycobacterium tuberculosis virulence factor EsxA and its chaperone EsxB are secreted as a heterodimer (EsxA:B) and are crucial for mycobacterial escape from phagosomes and cytosolic translocation. Current findings support the idea that for EsxA to interact with host membranes, EsxA must dissociate from EsxB at low pH. However, the molecular mechanism by which the EsxA:B heterodimer separates is not clear. In the present study, using liposome-leakage and cytotoxicity assays, LC-MS/MS–based proteomics, and CCF-4 FRET analysis, we obtained evidence that the Nα-acetylation of the Thr-2 residue on EsxA, a post-translational modification that is present in mycobacteria but absent in Escherichia coli, is required for the EsxA:B separation. Substitutions at Thr-2 that precluded Nα-acetylation inhibited the heterodimer separation and hence prevented EsxA from interacting with the host membrane, resulting in attenuated mycobacterial cytosolic translocation and virulence. Molecular dynamics simulations revealed that at low pH, the Nα-acetylated Thr-2 makes direct and frequent “bind-and-release” contacts with EsxB, which generates a force that pulls EsxB away from EsxA. In summary, our findings provide evidence that the Nα-acetylation at Thr-2 of EsxA facilitates dissociation of the EsxA:B heterodimer required for EsxA membrane permeabilization and mycobacterial cytosolic translocation and virulence. Full Article
ty Mechanistic insights explain the transforming potential of the T507K substitution in the protein-tyrosine phosphatase SHP2 [Signal Transduction] By feedproxy.google.com Published On :: 2020-05-01T00:06:09-07:00 The protein-tyrosine phosphatase SHP2 is an allosteric enzyme critical for cellular events downstream of growth factor receptors. Mutations in the SHP2 gene have been linked to many different types of human diseases, including developmental disorders, leukemia, and solid tumors. Unlike most SHP2-activating mutations, the T507K substitution in SHP2 is unique in that it exhibits oncogenic Ras-like transforming activity. However, the biochemical basis of how the SHP2/T507K variant elicits transformation remains unclear. By combining kinetic and biophysical methods, X-ray crystallography, and molecular modeling, as well as using cell biology approaches, here we uncovered that the T507K substitution alters both SHP2 substrate specificity and its allosteric regulatory mechanism. We found that although SHP2/T507K exists in the closed, autoinhibited conformation similar to the WT enzyme, the interactions between its N-SH2 and protein-tyrosine phosphatase domains are weakened such that SHP2/T507K possesses a higher affinity for the scaffolding protein Grb2-associated binding protein 1 (Gab1). We also discovered that the T507K substitution alters the structure of the SHP2 active site, resulting in a change in SHP2 substrate preference for Sprouty1, a known negative regulator of Ras signaling and a potential tumor suppressor. Our results suggest that SHP2/T507K's shift in substrate specificity coupled with its preferential association of SHP2/T507K with Gab1 enable the mutant SHP2 to more efficiently dephosphorylate Sprouty1 at pTyr-53. This dephosphorylation hyperactivates Ras signaling, which is likely responsible for SHP2/T507K's Ras-like transforming activity. Full Article
ty Modification of a PE/PPE substrate pair reroutes an Esx substrate pair from the mycobacterial ESX-1 type VII secretion system to the ESX-5 system [Molecular Bases of Disease] By feedproxy.google.com Published On :: 2020-05-01T00:06:09-07:00 Bacterial type VII secretion systems secrete a wide range of extracellular proteins that play important roles in bacterial viability and in interactions of pathogenic mycobacteria with their hosts. Mycobacterial type VII secretion systems consist of five subtypes, ESX-1–5, and have four substrate classes, namely, Esx, PE, PPE, and Esp proteins. At least some of these substrates are secreted as heterodimers. Each ESX system mediates the secretion of a specific set of Esx, PE, and PPE proteins, raising the question of how these substrates are recognized in a system-specific fashion. For the PE/PPE heterodimers, it has been shown that they interact with their cognate EspG chaperone and that this chaperone determines the designated secretion pathway. However, both structural and pulldown analyses have suggested that EspG cannot interact with the Esx proteins. Therefore, the determining factor for system specificity of the Esx proteins remains unknown. Here, we investigated the secretion specificity of the ESX-1 substrate pair EsxB_1/EsxA_1 in Mycobacterium marinum. Although this substrate pair was hardly secreted when homologously expressed, it was secreted when co-expressed together with the PE35/PPE68_1 pair, indicating that this pair could stimulate secretion of the EsxB_1/EsxA_1 pair. Surprisingly, co-expression of EsxB_1/EsxA_1 with a modified PE35/PPE68_1 version that carried the EspG5 chaperone-binding domain, previously shown to redirect this substrate pair to the ESX-5 system, also resulted in redirection and co-secretion of the Esx pair via ESX-5. Our results suggest a secretion model in which PE35/PPE68_1 determines the system-specific secretion of EsxB_1/EsxA_1. Full Article
ty A neuroglobin-based high-affinity ligand trap reverses carbon monoxide-induced mitochondrial poisoning [Molecular Biophysics] By feedproxy.google.com Published On :: 2020-05-08T03:41:14-07:00 Carbon monoxide (CO) remains the most common cause of human poisoning. The consequences of CO poisoning include cardiac dysfunction, brain injury, and death. CO causes toxicity by binding to hemoglobin and by inhibiting mitochondrial cytochrome c oxidase (CcO), thereby decreasing oxygen delivery and inhibiting oxidative phosphorylation. We have recently developed a CO antidote based on human neuroglobin (Ngb-H64Q-CCC). This molecule enhances clearance of CO from red blood cells in vitro and in vivo. Herein, we tested whether Ngb-H64Q-CCC can also scavenge CO from CcO and attenuate CO-induced inhibition of mitochondrial respiration. Heart tissue from mice exposed to 3% CO exhibited a 42 ± 19% reduction in tissue respiration rate and a 33 ± 38% reduction in CcO activity compared with unexposed mice. Intravenous infusion of Ngb-H64Q-CCC restored respiration rates to that of control mice correlating with higher electron transport chain CcO activity in Ngb-H64Q-CCC–treated compared with PBS-treated, CO-poisoned mice. Further, using a Clark-type oxygen electrode, we measured isolated rat liver mitochondrial respiration in the presence and absence of saturating solutions of CO (160 μm) and nitric oxide (100 μm). Both CO and NO inhibited respiration, and treatment with Ngb-H64Q-CCC (100 and 50 μm, respectively) significantly reversed this inhibition. These results suggest that Ngb-H64Q-CCC mitigates CO toxicity by scavenging CO from carboxyhemoglobin, improving systemic oxygen delivery and reversing the inhibitory effects of CO on mitochondria. We conclude that Ngb-H64Q-CCC or other CO scavengers demonstrate potential as antidotes that reverse the clinical and molecular effects of CO poisoning. Full Article
ty Brain manganese and the balance between essential roles and neurotoxicity [Molecular Bases of Disease] By feedproxy.google.com Published On :: 2020-05-08T03:41:14-07:00 Manganese (Mn) is an essential micronutrient required for the normal development of many organs, including the brain. Although its roles as a cofactor in several enzymes and in maintaining optimal physiology are well-known, the overall biological functions of Mn are rather poorly understood. Alterations in body Mn status are associated with altered neuronal physiology and cognition in humans, and either overexposure or (more rarely) insufficiency can cause neurological dysfunction. The resultant balancing act can be viewed as a hormetic U-shaped relationship for biological Mn status and optimal brain health, with changes in the brain leading to physiological effects throughout the body and vice versa. This review discusses Mn homeostasis, biomarkers, molecular mechanisms of cellular transport, and neuropathological changes associated with disruptions of Mn homeostasis, especially in its excess, and identifies gaps in our understanding of the molecular and biochemical mechanisms underlying Mn homeostasis and neurotoxicity. Full Article
ty POSTPONED: The Development of Libyan Armed Groups since 2014: Community Dynamics and Economic Interests By feedproxy.google.com Published On :: Wed, 04 Mar 2020 14:15:01 +0000 Invitation Only Research Event 18 March 2020 - 9:00am to 10:30am Chatham House | 10 St James's Square | London | SW1Y 4LE Event participants Abdul Rahman Alageli, Associate Fellow, MENA Programme, Chatham HouseEmaddedin Badi, Non-Resident Scholar, Middle East InstituteTim Eaton, Senior Research Fellow, MENA Programme Chatham HouseValerie Stocker, Independent Researcher Since the overthrow of the regime of Muammar Gaddafi in 2011, Libya’s multitude of armed groups have followed a range of paths. While many of these have gradually demobilized, others have remained active, and others have expanded their influence. In the west and south of the country, armed groups have used their state affiliation to co-opt the state and professionals from the state security apparatus into their ranks.In the east, the Libyan Arab Armed Forces projects a nationalist narrative yet is ultimately subservient to its leader, Field Marshal Khalifa Haftar. Prevailing policy narratives presuppose that the interests of armed actors are distinct from those of the communities they claim to represent. Given the degree to which most armed groups are embedded in local society, however, successful engagement will need to address the fears, grievances and desires of the surrounding communities, even while the development of armed groups’ capacities dilutes their accountability to those communities.This roundtable will discuss the findings of a forthcoming Chatham House research paper, ‘The Development of Libyan Armed Groups Since 2014: Community Dynamics and Economic Interests’, which presents insights from over 200 interviews of armed actors and members of local communities and posits how international policymakers might seek to curtail the continued expansion of the conflict economy.PLEASE NOTE THIS EVENT IS POSTPONED UNTIL FURTHER NOTICE. Event attributes Chatham House Rule Department/project Middle East and North Africa Programme, Countering Conflict Economies in MENA, Libya’s Conflict Economy Georgia Cooke Project Manager, Middle East and North Africa Programme +44 (0)20 7957 5740 Email Full Article
ty The Development of Libyan Armed Groups Since 2014: Community Dynamics and Economic Interests By feedproxy.google.com Published On :: Mon, 16 Mar 2020 17:25:16 +0000 17 March 2020 This paper explores armed group–community relations in Libya and the sources of revenue that have allowed armed groups to grow in power and influence. It draws out the implications for policy and identifies options for mitigating conflict dynamics. Read online Download PDF Tim Eaton Senior Research Fellow, Middle East and North Africa Programme @el_khawaga LinkedIn Abdul Rahman Alageli Associate Fellow, Middle East and North Africa Programme @abdulrahmanlyf Emadeddin Badi Policy Leader Fellow, School of Transnational Governance, European University Institute Mohamed Eljarh Co-founder and CEO, Libya Outlook Valerie Stocker Researcher Amru_24-2_13.jpg Fighters of the UN-backed Government of National Accord patrol in Ain Zara suburb in Tripoli, February 2020. Photo: Amru Salahuddien SummaryLibya’s multitude of armed groups have followed a range of paths since the emergence of a national governance split in 2014. Many have gradually demobilized, others have remained active, and others have expanded their influence. However, the evolution of the Libyan security sector in this period remains relatively understudied. Prior to 2011, Libya’s internal sovereignty – including the monopoly on force and sole agency in international relations – had been personally vested in the figure of Muammar Gaddafi. After his death, these elements of sovereignty reverted to local communities, which created armed organizations to fill that central gap. National military and intelligence institutions that were intended to protect the Libyan state have remained weak, with their coherence undermined further by the post-2014 governance crisis and ongoing conflict. As a result, the most effective armed groups have remained localized in nature; the exception is the Libyan Arab Armed Forces (LAAF), which has combined and amalgamated locally legitimate forces under a central command.In the west and south of the country, the result of these trends resembles a kind of inversion of security sector reform (SSR) and disarmament, demobilization and reintegration (DDR): the armed groups have used their state affiliation to co-opt the state and professionals from the state security apparatus into their ranks; and have continued to arm, mobilize and integrate themselves into the state’s security apparatus without becoming subservient to it. In the eastern region, the LAAF projects a nationalist narrative yet is ultimately subservient to its leader, Field Marshal Khalifa Haftar. The LAAF has co-opted social organizations to dominate political and economic decision-making.The LAAF has established a monopoly over the control of heavy weapons and the flow of arms in eastern Libya, and has built alliances with armed groups in the east. Armed groups in the south have been persuaded to join the LAAF’s newly established command structure. The LAAF’s offensive on the capital, which started in April 2019, represents a serious challenge to armed groups aligned with the Tripoli-based Government of National Accord (GNA). The fallout from the war will be a challenge to the GNA or any future government, as groups taking part in the war will expect to be rewarded. SSR is thus crucial in the short term: if the GNA offers financial and technical expertise and resources, plus legal cover, to armed groups under its leadership, it will increase the incentive for armed groups to be receptive to its plans for reform.Prevailing policy narratives presuppose that the interests of armed actors are distinct from those of the communities they claim to represent. Given the degree to which most armed groups are embedded in local society, however, successful engagement will necessarily rely on addressing the fears, grievances and desires of the surrounding communities. Yet the development of armed groups’ capacities, along with their increasing access to autonomous means of generating revenue, has steadily diluted their accountability to local communities. This process is likely to be accelerated by the ongoing violence around Tripoli.Communities’ relationship to armed groups varies across different areas of the country, reflecting the social, political, economic and security environment:Despite their clear preference for a more formal, state-controlled security sector, Tripoli’s residents broadly accept the need for the presence of armed groups to provide security. The known engagement of the capital’s four main armed groups in criminal activity is a trade-off that many residents seem able to tolerate, providing that overt violence remains low. Nonetheless, there is a widespread view that the greed of Tripoli’s armed groups has played a role in stoking the current conflict.In the east, many residents appear to accept (or even welcome) the LAAF’s expansion beyond the security realm, provided that it undertakes these roles effectively. That said, such is the extent of LAAF control that opposition to the alliance comes at a high price.In the south, armed groups draw heavily on social legitimacy, acting as guardians of tribal zones of influence and defenders of their respective communities against outside threats, while also at times stoking local conflicts. Social protections continue to hold sway, meaning that accountability within communities is also limited.To varying extents since 2014, Libya’s armed groups have developed networks that enmesh political and business stakeholders in revenue-generation models:Armed groups in Tripoli have compensated for reduced financial receipts from state budgets by cultivating unofficial and illicit sources of income. They have also focused on infiltrating state institutions to ensure access to state budgets and contracts dispersed in the capital.In the east of the country, the LAAF has developed a long-term strategy to dominate the security, political and economic spheres through the establishment of a quasi-legal basis for receiving funds from Libya’s rival state authorities. It has supplemented this with extensive intervention in the private sector. External patronage supports military operations, but also helps to keep this financial system, based on unsecured debt, afloat.In the south, limited access to funds from the central state has spurred armed groups to become actively involved in the economy. This has translated into the taxation of movement and the imposition of protection fees, particularly on informal (and often illicit) activity.Without real commitment from international policymakers to enforcing the arms embargo and protecting the economy from being weaponized, Libya will be consigned to sustained conflict, further fragmentation and potential economic collapse. Given the likely absence of a political settlement in the short term, international policymakers should seek to curtail the continued expansion of the conflict economy by reducing armed groups’ engagement in economic life.In order to reduce illicit activities, international policymakers should develop their capacity to identify and target chokepoints along illicit supply chains, with a focus on restraining activities and actors in closest proximity to violence. Targeted sanctions against rent maximizers (both armed and unarmed) is likely to be the most effective strategy. More effective investigation and restraint of conflict economy actors will require systemic efforts to improve transparency and enhance the institutional capacity of anti-corruption authorities. International policymakers should also support the development of tailored alternative livelihoods that render conflict economy activities less attractive. Department/project Middle East and North Africa Programme, Chaos States, Countering Conflict Economies in MENA, Libya’s Conflict Economy Full Article
ty Webinar: Can the Justice and Development Party Still Absorb Popular Anger in Morocco? By feedproxy.google.com Published On :: Tue, 31 Mar 2020 13:50:01 +0000 Webinar Research Event 8 April 2020 - 1:00pm to 2:00pm Event participants Mohammed Masbah, Director, Moroccan Institute for Policy Analysis; Associate Fellow, MENA Programme, Chatham HouseModerator: Lina Khatib, Director, MENA Programme, Chatham House Ever since independence, the Moroccan monarchy has used political parties to legitimize the country’s authoritarian political process and structure, and to absorb social and political anger. The palace puts successive governments and other elected institutions, such as local and regional councils, at the frontline of public blame, and replaces them once they fail this function.In a recent article, MENA Programme Associate Fellow, Mohammed Masbah, examines how the Moroccan monarchy has used this strategy with the ruling Justice and Development Party (PJD) so that the palace remains the centre of political power, while the PJD – and other political parties before it– takes responsibility for coping with the mounting socio-economic crisis.In this webinar, part of the Chatham House project on The Future of the State in the Middle East and North Africa, the article’s author will discuss the risks this approach presents for the long-term stability of Morocco and what reforms are needed to increase citizens’ dwindling confidence in the political process.You can express your interest in attending by following this link. You will receive a Zoom confirmation email should your registration be successful. Department/project Middle East and North Africa Programme, The Future of the State in the Middle East Full Article
ty Can Protest Movements in the MENA Region Turn COVID-19 Into an Opportunity for Change? By feedproxy.google.com Published On :: Tue, 28 Apr 2020 14:07:38 +0000 29 April 2020 Dr Georges Fahmi Associate Fellow, Middle East and North Africa Programme @GeorgesFahmi The COVID-19 pandemic will not in itself result in political change in the MENA region, that depends on the ability of both governments and protest movements to capitalize on this moment. After all, crises do not change the world - people do. 2020-04-28-covid-19-protest-movement-mena.jpg An aerial view shows the Lebanese capital Beirut's Martyrs Square that was until recent months the gathering place of anti-government demonstrators, almost deserted during the novel coronavirus crisis, on 26 March 2020. Photo by -/AFP via Getty Images. COVID-19 has offered regimes in the region the opportunity to end popular protest. The squares of Algiers, Baghdad, and Beirut – all packed with protesters over the past few months – are now empty due to the pandemic, and political gatherings have also been suspended. In Algeria, Iraq and Lebanon, COVID-19 has achieved what snipers, pro-regime propaganda, and even the economic crisis, could not.Moreover, political regimes have taken advantage of the crisis to expand their control over the political sphere by arresting their opponents, such as in Algeria where the authorities have cracked down on a number of active voices of the Hirak movement. Similarly, in Lebanon, security forces have used the pandemic as an excuse to crush sit-ins held in Martyr’s Square in Beirut and Nour Square in Tripoli.However, despite the challenges that the pandemic has brought, it also offers opportunities for protest movements in the region. While the crisis has put an end to popular mobilization in the streets, it has created new forms of activism in the shape of solidarity initiatives to help those affected by its consequences.In Iraq, for example, protest groups have directed their work towards awareness-raising and sharing essential food to help mitigate the problem of food shortages and rising prices across the country. In Algeria, Hirak activists have run online campaigns to raise awareness about the virus and have encouraged people to stay at home. Others have been cleaning and disinfecting public spaces. These initiatives increase the legitimacy of the protest movement, and if coupled with political messages, could offer these movements an important chance to expand their base of popular support.Exposes economic vulnerabilityEconomic grievances, corruption and poor provision of public services have been among the main concerns of this recent wave of protests. This pandemic only further exposes the levels of economic vulnerability in the region. COVID-19 is laying bare the socio-economic inequalities in MENA countries; this is particularly evident in the numbers of people engaged in the informal economy with no access to social security, including health insurance and pensions.Informal employment, approximately calculated by the share of the labour force not contributing to social security, is estimated to amount to 65.5% of total employment in Lebanon, 64.4% in Iraq, and 63.3% in Algeria. The crisis has underscored the vulnerability of this large percentage of the labour force who have been unable to afford the economic repercussions of following state orders to stay at home.The situation has also called attention to the vital need for efficient public services and healthcare systems. According to the fifth wave of the Arab Barometer, 74.4% of people in Lebanon are dissatisfied with their country’s healthcare services, as are 67.8% of people in Algeria and 66.5% in Iraq.Meanwhile, 66.2% of people in Lebanon believe it is necessary to pay a bribe in order to receive better healthcare, as do 56.2% of people in Iraq and 55.9% in Algeria. The COVID-19 crisis has highlighted the need for more government investment in public healthcare systems to render them more efficient and less corrupt, strengthening the protesters’ case for the need for radical socio-economic reforms.On the geopolitical level, the crisis puts into question the stability-focused approach of Western powers towards the region. For years, Western powers have directed their aid towards security forces in the interests of combating terrorism but COVID-19 has proved itself to be a much more lethal challenge to both the region and the West.Facing this new challenge requires international actors to reconsider their approach to include supporting health and education initiatives, as well as freedom of expression and transparency. As argued by Western policymakers themselves, it was China’s lack of transparency and slow response that enabled the proliferation of the virus, when it could have been contained in Wuhan back in December 2019.This crisis therefore offers regional protest movements the opportunity to capitalize on this moment and push back against the policies of Western powers that have invested in regional stability only to the extent of combating Islamic jihad. But crises do not change the world, people do. The COVID-19 pandemic will not in itself result in political change in the MENA region. Rather, it brings opportunities and risks that, when exploited, will allow political actors to advance their own agendas. While the crisis has put an end to popular mobilization and allowed regimes to tighten their grip over the political sphere, behind these challenges lie real opportunities for protest movements.The current situation represents a possibility for them to expand their popular base through solidarity initiatives and has exposed more widely the importance of addressing socio-economic inequalities. Finally, it offers the chance to challenge the stability-focused approach of Western powers towards the region which until now has predominantly focused on combating terrorism. Full Article
ty Biosynthesis of depsipeptides with a 3-hydroxybenzoate moiety and selective anticancer activities involves a chorismatase [Metabolism] By feedproxy.google.com Published On :: 2020-04-17T00:06:05-07:00 Neoantimycins are anticancer compounds of 15-membered ring antimycin-type depsipeptides. They are biosynthesized by a hybrid multimodular protein complex of nonribosomal peptide synthetase (NRPS) and polyketide synthase (PKS), typically from the starting precursor 3-formamidosalicylate. Examining fermentation extracts of Streptomyces conglobatus, here we discovered four new neoantimycin analogs, unantimycins B–E, in which 3-formamidosalicylates are replaced by an unusual 3-hydroxybenzoate (3-HBA) moiety. Unantimycins B–E exhibited levels of anticancer activities similar to those of the chemotherapeutic drug cisplatin in human lung cancer, colorectal cancer, and melanoma cells. Notably, they mostly displayed no significant toxicity toward noncancerous cells, unlike the serious toxicities generally reported for antimycin-type natural products. Using site-directed mutagenesis and heterologous expression, we found that unantimycin productions are correlated with the activity of a chorismatase homolog, the nat-hyg5 gene, from a type I PKS gene cluster. Biochemical analysis confirmed that the catalytic activity of Nat-hyg5 generates 3-HBA from chorismate. Finally, we achieved selective production of unantimycins B and C by engineering a chassis host. On the basis of these findings, we propose that unantimycin biosynthesis is directed by the neoantimycin-producing NRPS–PKS complex and initiated with the starter unit of 3-HBA. The elucidation of the biosynthetic unantimycin pathway reported here paves the way to improve the yield of these compounds for evaluation in oncotherapeutic applications. Full Article
ty Substrate recognition and ATPase activity of the E. coli cysteine/cystine ABC transporter YecSC-FliY [Microbiology] By feedproxy.google.com Published On :: 2020-04-17T00:06:05-07:00 Sulfur is essential for biological processes such as amino acid biogenesis, iron–sulfur cluster formation, and redox homeostasis. To acquire sulfur-containing compounds from the environment, bacteria have evolved high-affinity uptake systems, predominant among which is the ABC transporter family. Theses membrane-embedded enzymes use the energy of ATP hydrolysis for transmembrane transport of a wide range of biomolecules against concentration gradients. Three distinct bacterial ABC import systems of sulfur-containing compounds have been identified, but the molecular details of their transport mechanism remain poorly characterized. Here we provide results from a biochemical analysis of the purified Escherichia coli YecSC-FliY cysteine/cystine import system. We found that the substrate-binding protein FliY binds l-cystine, l-cysteine, and d-cysteine with micromolar affinities. However, binding of the l- and d-enantiomers induced different conformational changes of FliY, where the l- enantiomer–substrate-binding protein complex interacted more efficiently with the YecSC transporter. YecSC had low basal ATPase activity that was moderately stimulated by apo FliY, more strongly by d-cysteine–bound FliY, and maximally by l-cysteine– or l-cystine–bound FliY. However, at high FliY concentrations, YecSC reached maximal ATPase rates independent of the presence or nature of the substrate. These results suggest that FliY exists in a conformational equilibrium between an open, unliganded form that does not bind to the YecSC transporter and closed, unliganded and closed, liganded forms that bind this transporter with variable affinities but equally stimulate its ATPase activity. These findings differ from previous observations for similar ABC transporters, highlighting the extent of mechanistic diversity in this large protein family. Full Article
ty Modification of a PE/PPE substrate pair reroutes an Esx substrate pair from the mycobacterial ESX-1 type VII secretion system to the ESX-5 system [Molecular Bases of Disease] By feedproxy.google.com Published On :: 2020-05-01T00:06:09-07:00 Bacterial type VII secretion systems secrete a wide range of extracellular proteins that play important roles in bacterial viability and in interactions of pathogenic mycobacteria with their hosts. Mycobacterial type VII secretion systems consist of five subtypes, ESX-1–5, and have four substrate classes, namely, Esx, PE, PPE, and Esp proteins. At least some of these substrates are secreted as heterodimers. Each ESX system mediates the secretion of a specific set of Esx, PE, and PPE proteins, raising the question of how these substrates are recognized in a system-specific fashion. For the PE/PPE heterodimers, it has been shown that they interact with their cognate EspG chaperone and that this chaperone determines the designated secretion pathway. However, both structural and pulldown analyses have suggested that EspG cannot interact with the Esx proteins. Therefore, the determining factor for system specificity of the Esx proteins remains unknown. Here, we investigated the secretion specificity of the ESX-1 substrate pair EsxB_1/EsxA_1 in Mycobacterium marinum. Although this substrate pair was hardly secreted when homologously expressed, it was secreted when co-expressed together with the PE35/PPE68_1 pair, indicating that this pair could stimulate secretion of the EsxB_1/EsxA_1 pair. Surprisingly, co-expression of EsxB_1/EsxA_1 with a modified PE35/PPE68_1 version that carried the EspG5 chaperone-binding domain, previously shown to redirect this substrate pair to the ESX-5 system, also resulted in redirection and co-secretion of the Esx pair via ESX-5. Our results suggest a secretion model in which PE35/PPE68_1 determines the system-specific secretion of EsxB_1/EsxA_1. Full Article
ty The major subunit of widespread competence pili exhibits a novel and conserved type IV pilin fold [Protein Structure and Folding] By feedproxy.google.com Published On :: 2020-05-08T03:41:14-07:00 Type IV filaments (T4F), which are helical assemblies of type IV pilins, constitute a superfamily of filamentous nanomachines virtually ubiquitous in prokaryotes that mediate a wide variety of functions. The competence (Com) pilus is a widespread T4F, mediating DNA uptake (the first step in natural transformation) in bacteria with one membrane (monoderms), an important mechanism of horizontal gene transfer. Here, we report the results of genomic, phylogenetic, and structural analyses of ComGC, the major pilin subunit of Com pili. By performing a global comparative analysis, we show that Com pili genes are virtually ubiquitous in Bacilli, a major monoderm class of Firmicutes. This also revealed that ComGC displays extensive sequence conservation, defining a monophyletic group among type IV pilins. We further report ComGC solution structures from two naturally competent human pathogens, Streptococcus sanguinis (ComGCSS) and Streptococcus pneumoniae (ComGCSP), revealing that this pilin displays extensive structural conservation. Strikingly, ComGCSS and ComGCSP exhibit a novel type IV pilin fold that is purely helical. Results from homology modeling analyses suggest that the unusual structure of ComGC is compatible with helical filament assembly. Because ComGC displays such a widespread distribution, these results have implications for hundreds of monoderm species. Full Article
ty Asia-Pacific security is about more than just China and the US By feedproxy.google.com Published On :: Fri, 09 Oct 2015 14:22:43 +0000 21 September 2015 20150924AsiaPacific.jpg Photo: Jacob Parakilas/Chatham House. Seeing geo-strategic rivalry between the US and China as the sole variable in Asia-Pacific security risks becoming a self-fulfilling prophecy, according to a forthcoming Chatham House paper. As Xi Jinping’s visit to the US approaches, The Asia-Pacific Power Balance: Beyond the US–China Narrative, warns against deploying Cold War-type narratives that pit the two countries against each other. Such narratives not only misunderstand the complexity of the region and the growing influence of India, Japan and Indonesia, but also risk increasing the likelihood of conflict and of missing vital opportunities for future cooperation. The paper, by John Nilsson-Wright, Tim Summers and Xenia Wickett argues that by focusing too heavily on the US and China, policymakers risk narrowing the aperture through which they evaluate policy choices regarding major regional challenges. Some of the key findings include the following:MilitaryDespite rapidly rising defence spending across Asia, the relative importance of traditional military means is declining relative to instruments such as development assistance and cyber offence.The militaries of Japan and India are becoming – in very different ways – more versatile and potentially expanding their remits. In the future, there will be a larger number of more capable military powers in the region, including South Korea and Vietnam.Current perceptions that the main dynamic is China’s rising military capabilities outstripping others in the region, therefore, need to be tempered. India’s defence spending, for example, as a percentage of GDP has surpassed China’s for the past several decades.EconomicsAlthough China has the world’s second-largest economy and – despite recent problems – is growing faster than most major economies, its growth rate is in secular decline. China has gone from near-constant double-digit growth over the past four decades to 7.4 per cent in 2014 and could dip below 7 per cent this year.Whilst India’s economy remains notably smaller than those of China, the US and Japan, it will surpass China’s growth rate this year and has a lot of potential.If the Trans-Pacific Partnership (TPP) is successfully negotiated, the potential for integration and growth between the United States, Japan and the other 10 TPP members may reduce their current trade dependence on China.DemographyThe demography of Asia is another reason to look beyond the US-China nexus, as China faces the challenge of an aging society, while countries such as India have the advantage of a younger population and decades of demographic dividend ahead of them.Likewise populations across much of Southeast Asia, such as the Philippines and Indonesia are growing rapidly and expanding their middle classes. Editor's notes Read the report The Asia-Pacific Power Balance: Beyond the US–China Narrative from Chatham House.For all enquiries, including requests to speak with the authors of this paper, please contact the press office. Contacts Press Office +44 (0)20 7957 5739 Email Full Article
ty Centre on Global Health Security collaborates with the Gates Foundation at the Munich Security Conference By feedproxy.google.com Published On :: Mon, 22 Feb 2016 11:03:22 +0000 22 February 2016 Support from the Bill & Melinda Gates Foundation has enabled Chatham House to develop a global health security track at the Munich Security Conference (MSC). 2016-02-22-MSC-Niblett.jpg The primary objectives of this three-year partnership are to integrate consideration of global health security challenges into the MSC agenda, highlight the threats from infectious diseases and stimulate discussion of the importance of investment in global health, particularly in low- and middle-income countries. At the 2016 MSC, the Chatham House Centre on Global Health Security facilitated a roundtable on civilian access to health care during conflict and a panel session entitled 'The Plot Sickens – The Health-Security Nexus'. This marked the first time health security had been featured in the main conference, and highlights the growing significance of health security to broader global stability and security. Chatham House produced, with support from the Gates Foundation, a short film including insights from UN Secretary-General Ban Ki-moon and Melinda Gates to introduce themes that were discussed as key security threats on the health-security nexus.Initiated in 2015, the collaboration will continue with a Chatham House roundtable and a plenary session at the MSC’s Core Group Meeting in Addis Ababa in April, and further contributions to the 2017 MSC agenda. Full Article
ty Oxford University Press to publish International Affairs By feedproxy.google.com Published On :: Fri, 11 Mar 2016 09:55:35 +0000 11 March 2016 Chatham House has signed an agreement with Oxford University Press (OUP) to publish International Affairs from 2017. International Affairs, the institute’s peer-reviewed journal, has published high-quality, policy relevant articles for over 90 years and its global readership includes many of the world’s pre-eminent academic thinkers, policy-makers and practitioners. From January, when its current contract to publish with Wiley-Blackwell ends, OUP will assume responsibility to publish, distribute and market the journal to new and existing readers and audiences.Vanessa Lacey, senior publisher for Oxford Journals, commented on the acquisition: 'We are thrilled to have been chosen by Chatham House to publish their prestigious journal International Affairs from 2017. International Affairs is a critically important, ‘must read’ journal of relevance to international relations academics and policy-makers alike. We look forward to partnering with Chatham House and International Affairs’ exceptional editorial team to reinforce its position as a global leader in its field.'Robin Niblett, director of Chatham House, said: 'Chatham House is delighted to have teamed up with OUP, the world’s leading university press, to publish International Affairs. In terms of shared values, reputation and vision, OUP is an ideal partner for International Affairs and Chatham House. This is an exciting opportunity to develop further the journal’s digital outreach and its engagement with new audiences around the world.'Andrew Dorman, commissioning editor of International Affairs also commented: 'The IA team is really pleased to be working in partnership with OUP to produce the journal. We share a common vision to publish cutting edge articles from across the discipline, which influence both the academic and practitioner communities in all parts of the world.'OUP adds International Affairs, the foremost UK international relations journal and one of the top ten internationally, to a growing portfolio of respected international relations-related journals. Full Article
ty Chatham House appoints Adam Ward as deputy director By feedproxy.google.com Published On :: Mon, 16 Jan 2017 14:54:55 +0000 17 January 2017 Chatham House is pleased to announce that Adam Ward will join the institute in a new role as deputy director. 2017-01-17-AdamWard2.jpg Adam Ward takes up the position of deputy director on 10 April 2017 and will join Chatham House from the International Institute of Strategic Studies (IISS) in London, where he has served as director of studies since 2009.As deputy director, Adam will oversee and coordinate Chatham House's multiple areas of research, help manage the institute's relationships with key external constituencies, ensure the delivery of high-quality publications and deputize for the institute’s director, Dr Robin Niblett.This is a new position, created after a period of sustained growth for Chatham House, especially in research and policy outputs. The appointment also coincides with the opening this spring of new working and meeting space for the institute in Ames House, the building adjacent to Chatham House on Duke of York Street in the St James's area of central London.At IISS, publishers of the renowned annual Military Balance and other high-quality publications and organizers of influential annual security summits, including the Shangri-La Dialogue, Adam was responsible for the oversight of its worldwide research activities, which are also conducted from IISS offices in the Middle East, Asia and the US. Adam led the establishment of the office in Washington and was previously a senior fellow for East Asia.Dr Robin Niblett, director of Chatham House, said:‘I am delighted that Adam Ward will shortly be joining Chatham House. At a time of great uncertainty and risk in international affairs, his experience in leading research at the prestigious IISS and knowledge of how research institutes can develop and communicate their ideas on public policy will be of enormous value. His wide-ranging expertise on geopolitics and the foreign policies of China and the United States will also help the institute develop integrated projects that reflect the changing balance of world power. I very much look forward to working with him.’Adam Ward said:‘I am excited to take up this opportunity to join Chatham House's executive leadership and to work with Robin Niblett and his senior management team. Chatham House has a well-deserved reputation for rigour and excellence in its research and for providing insights and solutions across a comprehensive range of international challenges. Chatham House's capacity for inter-disciplinary research is one of its distinctive strengths, and I look forward to ensuring its ideas are brought to bear on an ever more complex policy environment.’ Editor's notes About Chatham HouseChatham House, the Royal Institute of International Affairs, is an independent policy institute based in London. Its mission is to help build a sustainably secure, prosperous and just world. Founded in 1920, Chatham House engages governments, the private sector, civil society and its members in open debate and confidential discussion on the most significant developments in international affairs. Each year, the institute runs more than 300 private and public events – conferences, workshops and roundtables – in London and internationally with partners. Its convening power attracts world leaders and the best analysts in their respective fields from across the globe.About Adam WardAs director of studies of the IISS, Adam Ward has since 2009 led the execution of the Institute’s worldwide research activities, including setting priorities, raising funds and the management of a research staff distributed across four international offices. Between 2009 and 2014 he organized the annual series of IISS Global Strategic Review conferences. He represents the institute internationally among its audiences in government, the expert community and business.Adam was previously, from 2006, executive director of the IISS office in Washington DC, where he led the relocation of the office to larger premises, an expansion in its staff, the development of a busy events programme and research activities and acted as the institute’s principal liaison with US government agencies and the Washington-based diplomatic and academic community. Prior to this, he served from 2001 simultaneously as the IISS senior fellow for East Asian security and editor of Strategic Comments, a series of analytical briefing papers on global topics.He began his career in 1997 as an analyst and editor at the consulting firm Oxford Analytica, focusing on the Asia-Pacific region. He holds a bachelor’s degree in German and Politics and an MA in International Relations, both from the University of Warwick, and also studied for one academic year at the University of Salzburg in Austria. Full Article
ty Chatham House appoints Rob Yates as the new head of the Centre on Global Health Security By feedproxy.google.com Published On :: Thu, 27 Jun 2019 09:35:01 +0000 27 June 2019 Chatham House is pleased to announce that Rob Yates has been appointed as head of the Centre on Global Health Security. Yates.jpg He brings decades of experience as a health economist working in international development and health and is an internationally recognized expert on universal health coverage (UHC) and progressive health financing, operating at the highest political levels.For the past five years, Rob has led the Centre’s work on Universal Health Coverage (UHC) as director of its UHC Policy Forum, which works on the political economy of UHC reform processes and advises political leaders and government ministries on how to plan, finance and implement national UHC reforms.He has also worked closely with The Elders on presenting policy options on universal health reforms to heads of state across the world. Before leading the UHC Policy Forum at Chatham House, Rob was a senior health economist at the World Health Organization from 2011 to 2014, after moving from the UK Department for International Development (DFID), where he was a senior health economist. Prior to that, Rob was the deputy head of the Integrated UN Office in the Democratic Republic of Congo. He also spent five years working for the government of Uganda as a senior health economist, on secondment from DFID during the early 2000s.'I am delighted to welcome Rob Yates as the head of the Centre on Global Health Security. He will bring a wealth of experience to the role at a time of risk but also great opportunity in the sector,' said Dr Robin Niblett, director of Chatham House. 'Rob will continue to work on his own area of expertise – universal health coverage – while ensuring the Centre continues to address other major global health challenges that manifest themselves as foreign policy and international affairs problems.'Rob replaces David Heymann, who retires from the role as the Centre marks its 10th anniversary but will remain involved in several of the Centre’s projects.'I would also like to pay tribute to David Heymann, who launched the Centre on Global Health Security in 2009 to examine key global health challenges in international affairs and world politics,' Niblett added. 'Without David the Centre would not have had the impact that it has and I am truly grateful for his hard work and achievements over the last 10 years.'Yates takes up his post this week.'I am honoured to become the new head of the Centre on Global Health Security and build on the successes delivered by David Heymann and the team over the last decade,' he said. 'My priority as the new head will be to ensure that our research and activities have a real impact in accelerating progress towards the Sustainable Development Goals by focusing on improving health security and health coverage in countries across the world. Engaging in issues related to the political economy of health and health care reforms will be critical in achieving this impact.' Full Article
ty Collective Defence and Common Security: Twin Pillars of the Atlantic Alliance By feedproxy.google.com Published On :: Tue, 10 Jun 2014 09:04:44 +0000 10 June 2014 Robin Niblett Director and Chief Executive, Chatham House @RobinNiblett Martin Butora, Ivo Daalder, Camille Grand, Ana Palacio, Roland Paris, Volker Perthes, Nathalie Tocci, Sinan Ülgen and Marcin Zaborowski 20140609NATOFoghRasmussenHagel.jpg NATO Secretary-General Anders Fogh Rasmussen, right, greets US Defense Secretary Chuck Hagel, center, before the start of their joint meeting at North Atlantic Council (NATO) on June 2 2014 in Brussels. Photo by Pablo Martinez Monsivais - Pool/Getty Images. Dr Robin Niblett, director of Chatham House, is chair of the NATO Group of Policy Experts, tasked with providing NATO Secretary-General Anders Fogh Rasmussen and the North Atlantic Council with ideas on how to strengthen the Alliance's transatlantic bond ahead of September's NATO summit in Wales. The group's report Collective Defence and Common Security: Twin Pillars of the Atlantic Alliance was published on 10 June for discussion at a NATO conference in Brussels on the transatlantic bond. Executive Summary Key points from the Policy Experts report to NATO Secretary-General Anders Fogh Rasmussen, released at the Conference on Strengthening the Transatlantic Bond in Brussels on 10 June 2014:Transatlantic security cannot be taken for granted. Following its withdrawal from Afghanistan, NATO needs to reaffirm its value around the twin objectives of collective defence and common security. Upholding peace and stability in Europe The commitment under NATO’s Article V to treat an attack against one as an attack against all must be credible, and NATO members should take concrete steps together to make it so. Tallinn should be as secure as Toronto. There can be no return to a ‘strategic partnership’ between NATO and Russia so long as Russia’s actions threaten European security.European governments bear particular responsibility for ensuring their own territorial security. They must invest in the necessary R&D, equipment and deployable capabilities. No amount of ‘smarter’ defence will compensate for a failure to reverse falling defence spending.NATO needs to develop effective responses to the ‘non-linear’ forms of aggression seen during the crisis in Ukraine. But the EU should take the lead in helping its members and neighbours embed good governance practices that will lessen their vulnerability to external destabilization. European countries should reduce their dependence on Russian energy. Russia’s main strength should no longer be Europe’s main vulnerability. NATO’s door should remain open to all European democracies that share the values of the Alliance. However, existing members must be ready, willing and able to extend the full benefits of Alliance membership to them, including those in Article V. Confronting international insecurity NATO should not turn inwards after 2014. Much of the Middle East, and North Africa face a decade of turmoil which will pose direct threats to NATO members. In Asia, unresolved territorial disputes and historical animosities are driving dramatic rises in defence spending. It must be remembered that the Pacific Ocean is the western flank of NATO. In this context, it should not be left to the United States and a handful of others to deploy hard power beyond NATO’s borders. An over-reliance on US power projection will erode the foundations of the transatlantic bond over time. NATO and the EU must also cooperate closely to deliver their comprehensive range of capabilities to manage international crises, from market access and development assistance to military intervention and post-conflict civilian support. Completion of the Transatlantic Trade and Investment Partnership (TTIP) will strengthen the transatlantic community strategically as well as economically.NATO needs to differentiate its approach to working with its international partners. In particular, it should develop long-term cooperative arrangements with the small number of countries in Europe and beyond which have contributed actively alongside NATO to international security in recent years. The NATO–Russia Council should continue to operate at ambassadorial and higher levels. This will help the two sides coordinate responses to international crises and potentially rebuild trust on European security. NATO publics are increasingly sceptical about the value of any form of external intervention. Political leaders need to communicate better the deterioration of the security situation in Europe; the importance of international security to their nations' welfare and prosperity; and the need to protect the core values that underpin the Alliance, especially democratic governance, open economies and the rule of law. Chatham House press release: Director of Chatham House to Chair New NATO Group of Policy Experts NATO press release: NATO Secretary General to attend conference on Strengthening the Transatlantic Bond Related documents Report: Collective Defence and Common Security: Twin Pillars of the Atlantic Alliancepdf | 153.13 KB Executive Summary: Collective Defence and Common Security: Twin Pillars of the Atlantic Alliancepdf | 22.1 KB Full Article
ty Transatlantic Strategy Group on the Future of US Global Leadership: Transatlantic Security Policy Towards a Changing Middle East By feedproxy.google.com Published On :: Thu, 05 Mar 2015 11:45:02 +0000 Invitation Only Research Event 6 February 2015 - 8:45am to 4:30pm Residence of the British Ambassador to France, Paris Meeting Summarypdf | 95.65 KB With the Middle East in chaos and the future of many states increasingly uncertain, there is a large amount of attention as to how policy-makers in Europe and the US should respond. In particular, many in Europe are unsure of long-term US policy in light of competing American priorities, budgetary constraints and a public adverse to committing further resources abroad. In this context, it is important that European and American policy-makers understand each other’s positions.At this all-day event, a group of experts will discuss how US policy towards the Middle East is changing, what this means for Europe and, subsequently, how Europe should respond. Attendance at this event is by invitation only.The workshop is held as part of the Transatlantic Strategy Group on the Future of US Global Leadership run jointly with the German Marshall Fund of the United States. Over the course of a year, this group will discuss how US policy is changing on key issues and the implications for Europe. This project is supported by the Fritz Thyssen Foundation, with support for this event provided by the Delegation of Strategic Affairs of the French Ministry of Defence and the British Embassy in Paris. Event attributes External event Department/project US and the Americas Programme Full Article
ty Why We Need a Transatlantic Charter for Data Security and Mobility By feedproxy.google.com Published On :: Tue, 27 Jun 2017 09:59:17 +0000 28 June 2017 Dr Christopher Smart @csmart Former Associate Fellow, US and the Americas Programme Setting common guidelines for data flows is crucial both to protect the goods and services that already depend on big data and to support the next generation of productivity gains and business opportunities. 2017-06-23-TsystemsData.jpg Data centre for T-Systems, a subsidiary of Deutsche Telekom. Photo by: Thomas Trutschel/Photothek/Getty Images While trade and tax remain at the heart of the difficult economic conversations between Europe and the US, a new issue has emerged as a potential source of even greater friction: data.Growth in the traditional global trade in goods and services has levelled off, but cross-border data flows continue to expand rapidly and the challenges of developing policies that protect privacy, security and innovation are already tremendous. For example, data analytics are driving dramatic productivity gains in industry, particularly for large and complex installations whose safety and efficiency will increasingly depend on flows of those data across jurisdictions. Meanwhile, ‘fintech’ (financial technology) start-ups and large banks alike are testing new modes of accumulating, analysing and deploying customer data to provide less expensive services and manage the risk profile of their businesses.The rules that govern the collection, transmission and storage of data are perhaps one of the more surprising controversies in the transatlantic relationship. Similar liberal democracies with similar geostrategic interests might be expected to approach the handling of personal, corporate and government data in more or less the same way. And yet the US and its key European partners have struck different balances in the trade-offs between national security and citizens’ rights, between freedom of expression and personal privacy, and between free enterprise and market regulation.While the US debate on the use of data has often been framed around the trade-off between national security and personal privacy, Europeans often face an even more complex set of concerns that include worries that their digital and technology firms lag behind dominant US competitors. The political and regulatory uncertainty helps neither side, and leaves transatlantic companies struggling to comply with uncertain and conflicting rules in different jurisdictions.This makes more determined efforts by US and European policymakers to agree basic principles that will guide the usage and protection of personal and commercial data all the more important. While common regulations or even greater alignment among regulators seem out of reach, a ‘Transatlantic Charter for Data Security and Mobility’ would provide a set of principles for more specific rules amid political landscapes and technological developments that are evolving rapidly. It could also provide the basis for firms, whether in manufacturing or financial services or health care, to draft their own voluntary standards on how they protect data even as they develop new algorithms that improve productivity, safety and customer satisfaction.Embarrassing leaks, careful denials and endless lawsuits will continue to shape the awkward efforts of policymakers to find common ground around issues like cyberespionage, defence of common networks and the sharing of personal data with law enforcement. Cyberattacks with the aim of disrupting government operations or influencing election campaigns will add still further pressures. These will all serve as a noisy backdrop to a related but separate debate over how commercial firms should exploit the opportunities of global networks and ‘big data’ analytics while protecting national interests and privacy.Yet, setting common guidelines for commercial data transmission and storage remains crucial both to protect the goods and services that already depend on sophisticated data-gathering and analysis, and to support the next generation of productivity gains and business opportunities.Global firms yearn for clarity and predictability as they organize themselves to make the most of the data revolution. Neither is likely to become a reality soon. The EU’s new General Data Protection Regulation will take effect in 2018, but its implementation will inevitably be coloured by the fact that American firms currently dominate the information technology business. Last year’s ‘Privacy Shield’ agreement between the US and the EU renews the permission for firms with transatlantic business interests to transfer data, subject to compliance with basic standards of protection, but the agreement remains vulnerable to European court challenges. Britain’s decision to leave the EU adds a further complication, as it establishes its own set of data protection rules that may not easily align with either European or US requirements. Meanwhile, the World Trade Organization continues to debate new rules for digital trade, even as markets like China, Russia and Brazil make up their own.If this ‘Transatlantic Charter for Data Security and Mobility’ were adopted bilaterally, say as part of the annual reviews of the US–EU Privacy Shield agreement, it could form the basis for broader cooperation on these issues, helping to drive progress in the G7 and G20 and ultimately perhaps in trade agreements under the WTO. It would hardly secure complete alignment on these questions, but it could help establish the framework for a debate that all too often lurches to extremes and risks damaging a fundamental alliance for global stability – along with a fundamental driver of 21st-century economic progress.To comment on this article, please contact Chatham House Feedback Full Article
ty Supporting the US Economy by Improving the Mobility of High-skilled Labour Across the Atlantic By feedproxy.google.com Published On :: Wed, 20 Sep 2017 10:33:17 +0000 27 September 2017 US policymakers should give special consideration to a more open immigration policy for highly skilled professionals from the EU. This would ultimately benefit the US economy. Read online Download PDF Marianne Schneider-Petsinger Senior Research Fellow, US and the Americas Programme @mpetsinger 2017-09-25-labour-mobility-us-economy.jpg Businessman on bicycle passing skyline of La Defense business district in Paris, France. Photo: Getty Images. SummaryThe United States and the European Union are deeply integrated economically in terms of movement of goods, services and capital across the Atlantic, but this is not matched by the mobility of labour. Freer movement of high-skilled workers across the Atlantic has a potentially critical role to play in maintaining and strengthening the bilateral economic relationship.Both the US and EU seek to attract high-skilled labour through the use of temporary visa programmes. Various routes are available for highly skilled workers from the EU to temporarily work in the US (for instance, through the H-1B visa for foreign nationals in ‘specialty occupations’, as well as other visa categories for treaty traders and investors, intra-company transferees, and international students seeking work authorization in the US before or after graduation). The main ways for highly skilled workers from the US to temporarily work in EU member states are through EU-wide schemes that apply in 25 out of the 28 member states (for holders of EU Blue Cards or intra-company transferees); or via member states’ parallel national schemes.The experiences of US and EU employers and workers under the US H-1B programme and the EU’s Blue Card scheme differ greatly. The EU Blue Card scheme avoids many of the drawbacks of the H-1B visa. It does not have an annual cap on the number of visas issued. It also grants greater autonomy to the worker by not requiring the employer to sponsor long-term residence, by providing greater flexibility to switch employment, and by having a longer grace period for visa-holders to find new employment after dismissal.The US visa system hampers America’s economic growth. Restrictive policies such as an annual limit on the number of H-1B visas issued, and the associated uncertainty for employees and employers, hinder the ability of US companies to expand and innovate. The complex and costly visa application process is a particular burden for small and medium-sized enterprises. Problems around the timely availability of visas frustrate investors both from the US and from abroad (including from the EU). European firms face difficulties in acquiring visas for intra-company transferees, and not all EU member states have access to the treaty trader and treaty investor visa categories. At times, this impedes foreign direct investment and restricts US job creation. In addition, current policies hinder the economy’s retention of EU and other graduates of US universities. This is of particular concern given that skilled graduates have a critical role to play in addressing the US’s growing shortage of workers in the science, technology, engineering and mathematics (STEM) fields.Given the comparability of US and EU wages and labour markets, US concerns about foreign workers ‘stealing’ their jobs or depressing wages generally do not apply to EU citizens. On the contrary, a more open immigration policy for high-skilled workers – in particular for EU citizens – would benefit the US economy.Efforts to reform visa systems for high-skilled labour are under way in both the US and EU. In order to facilitate the movement of highly skilled workers across the Atlantic, this research paper recommends (1) creating a special visa for highly skilled EU citizens to work temporarily in the US; (2) extending the availability of treaty trader and investor visas to all EU member states; and (3) increasing efforts to eliminate fraud and abuse in the H-1B system. These measures could potentially help to create more investment, jobs and economic growth in the US. Department/project International Security Programme, US and the Americas Programme Full Article
ty Biosecurity: Preparing for the Aftermath of Global Health Crises By feedproxy.google.com Published On :: Thu, 09 Jan 2020 14:16:59 +0000 9 January 2020 Professor David R Harper CBE Senior Consulting Fellow, Global Health Programme @DavidRossHarper Benjamin Wakefield Research Associate, Global Health Programme @BCWakefield LinkedIn The Ebola outbreak in the Democratic Republic of the Congo is a reminder that the security of samples taken during global health emergencies is a vital part of safeguarding biosecurity. 2020-01-09-DRC.jpg A nurse prepares a vaccine against Ebola in Goma in August 2019. Photo: Getty Images. The world’s second-largest Ebola outbreak is ongoing in the Democratic Republic of the Congo (DRC) and experts from around the world have been parachuted in to support the country’s operation to stamp out the outbreak. The signs are encouraging, but we need to remain cautious.In such emergencies, little thought is usually given to what happens to the body-fluid samples taken during the course of the outbreak after the crisis is over. What gets left behind has considerable implications for global biosecurity.Having unsecured samples poses the obvious risk of accidental exposures to people who might come into contact with them, but what of the risk of malicious use? Bioterrorists would have ready access to materials that have the characteristics essential to their purpose: the potential to cause disease that is transmissible from person to person, the capacity to result in high fatality rates and, importantly, the ability to cause panic and social disruption at the very mention of them.Comparisons can be drawn with the significant international impact of the anthrax attacks in the US in 2001. Not only was there a direct effect in the US with five deaths and a further 17 people infected, but there was a paralysis of public health systems in other countries involved in the testing of countless samples from the so-called ‘white-powder incidents’ that followed.Many laboratory tests were done purely on a precautionary basis to eliminate any possibility of a risk, no matter how remote. However, the UK was also hit when a hoaxer sent envelopes of white powder labelled as anthrax to 15 MPs.The threat of the pathogen alone resulted in widespread fear, the deployment of officers trained in response to chemical, biological, radiological and nuclear incidents and the evacuation of a hospital emergency department.We learned from the 2014–16 West Africa Ebola outbreaks that during the emergency, the future biosecurity implications of the many thousands of samples taken from people were given very little consideration. It is impossible to be sure where they all are and whether they have been secured.It is widely recognized that the systems needed at the time for tracking and monitoring resources, including those necessary for samples, were weak or absent, and this has to be addressed urgently along with other capacity-building initiatives.In Sierra Leone, for example, the remaining biosecurity risk is only being addressed after the fact. To help achieve this, the government of Canada is in the process of providing a secure biobank in the Sierra Leonean capital of Freetown. The aim is to provide the proper means of storage for these hazardous samples and to allow them to remain in-country, with Sierra Leonean ownership.However, it is already more three years since the emergency was declared over by the then director-general of the World Health Organization (WHO), Margaret Chan, and the biobank and its associated laboratory are yet to be fully operational.There are many understandable reasons for this delay, including the critical issue of how best to ensure the sustainability of any new facility. But what is clear is that these solutions take time to implement and must be planned for in advance.The difficulties of responding to an outbreak in a conflict zone have been well documented, and the frequent violence in DRC has undoubtedly caused delays in controlling the outbreak. According to figures from WHO, during 2019 approximately 390 attacks on health facilities in DRC killed 11 and injured 83 healthcare workers and patients.Not only does the conflict inhibit the response, but it could also increase the risk posed by unsecured samples. There are two main potential concerns.First is the risk of accidental release during an attack on a health facility, under which circumstances sample containers may be compromised or destroyed. Second is that the samples may be stolen for malicious use or to sell them to a third-party for malicious use. It is very important in all outbreaks to ensure the necessary measures are in place to secure samples; in conflict-affected areas, this is particularly challenging.The sooner the samples in the DRC are secured, the sooner this risk to global biosecurity is reduced. And preparations for the next emergency must be made without further delay.The following steps need to be taken:Affected countries must ‘own’ the problem, with clear national government commitment to take the required actions.Funding partners must coordinate their actions and work closely with the countries to find the best solutions.If samples are to be kept in-country, secure biobanks must be established to contain them.Sustainable infrastructure must be built for samples to be kept secure into the future.An international agreement should be reached on the best approach to take to prepare for the aftermath of global health emergencies. Full Article
ty China's 2020: Economic Transition, Sustainability and the Coronavirus By feedproxy.google.com Published On :: Tue, 04 Feb 2020 21:15:01 +0000 Corporate Members Event 10 March 2020 - 12:15pm to 2:00pm Chatham House | 10 St James's Square | London | SW1Y 4LE Event participants Dr Yu Jie, Senior Research Fellow on China, Asia-Pacific Programme, Chatham HouseDavid Lubin, Associate Fellow, Global Economy and Finance Programme, Chatham House; Managing Director and Head of Emerging Markets Economics, CitiJinny Yan, Managing Director and Chief China Economist, ICBC StandardChair: Creon Butler, Director, Global Economy and Finance Programme, Chatham House Read all our analysis on the Coronavirus ResponseThe coronavirus outbreak comes at a difficult time for China’s ruling party. A tumultuous 2019 saw the country fighting an economic slowdown coupled with an increasingly hostile international environment. As authorities take assertive steps to contain the virus, the emergency has - at least temporarily - disrupted global trade and supply chains, depressed asset prices and forced multinational businesses to make consequential decisions with limited information. Against this backdrop, panellists reflect on the country’s nascent economic transition from 2020 onward. What has been China’s progress towards a sustainable innovation-led economy so far? To what extent is the ruling party addressing growing concerns over job losses, wealth inequality and a lack of social mobility? And how are foreign investors responding to these developments in China? Members Events Team Email Full Article
ty Webinar: Coronavirus Crisis – Implications for an Evolving Cybersecurity Landscape By feedproxy.google.com Published On :: Thu, 23 Apr 2020 11:25:01 +0000 Corporate Members Event Webinar 7 May 2020 - 1:00pm to 2:00pm Event participants Neil Walsh, Chief, Cybercrime and Anti-Money Laundering Department, UN Office of Drugs and CrimeLisa Quest, Head, Public Sector, UK & Ireland, Oliver WymanChair: Joyce Hakmeh, Senior Research Fellow, International Security Programme; Co-Editor, Journal of Cyber Policy, Chatham HouseFurther speakers to be announced. The COVID-19 pandemic is having a profound impact on the cybersecurity landscape - both amplifying already-existing cyber threats and creating new vulnerabilities for state and non-state actors. The crisis has highlighted the importance of protecting key national and international infrastructures, with the World Health Organization, US Department of Health and Human Services and hospitals across Europe suffering cyber-attacks, undermining their ability to tackle the coronavirus outbreak. Changing patterns of work resulting from widespread lockdowns are also creating new vulnerabilities for organizations with many employees now working from home and using personal devices to work remotely.In light of these developments, the panellists will discuss the evolving cyber threats resulting from the pandemic. How are they impacting ongoing conversations around cybersecurity? How can governments, private sector and civil society organizations work together to effectively mitigate and respond to them? And what could the implications of such cooperation be beyond the crisis? This event is part of a fortnightly series of 'Business in Focus' webinars reflecting on the impact of COVID-19 on areas of particular professional interest for our corporate members and giving circles.Not a corporate member? Find out more. Full Article
ty The histone H4 basic patch regulates SAGA-mediated H2B deubiquitination and histone acetylation [DNA and Chromosomes] By feedproxy.google.com Published On :: 2020-05-08T03:41:14-07:00 Histone H2B monoubiquitylation (H2Bub1) has central functions in multiple DNA-templated processes, including gene transcription, DNA repair, and replication. H2Bub1 also is required for the trans-histone regulation of H3K4 and H3K79 methylation. Although previous studies have elucidated the basic mechanisms that establish and remove H2Bub1, we have only an incomplete understanding of how H2Bub1 is regulated. We report here that the histone H4 basic patch regulates H2Bub1. Yeast cells with arginine-to-alanine mutations in the H4 basic patch (H42RA) exhibited a significant loss of global H2Bub1. H42RA mutant yeast strains also displayed chemotoxin sensitivities similar to, but less severe than, strains containing a complete loss of H2Bub1. We found that the H4 basic patch regulates H2Bub1 levels independently of interactions with chromatin remodelers and separately from its regulation of H3K79 methylation. To measure H2B ubiquitylation and deubiquitination kinetics in vivo, we used a rapid and reversible optogenetic tool, the light-inducible nuclear exporter, to control the subcellular location of the H2Bub1 E3 ligase, Bre1. The ability of Bre1 to ubiquitylate H2B was unaffected in the H42RA mutant. In contrast, H2Bub1 deubiquitination by SAGA-associated Ubp8, but not by Ubp10, increased in the H42RA mutant. Consistent with a function for the H4 basic patch in regulating SAGA deubiquitinase activity, we also detected increased SAGA-mediated histone acetylation in H4 basic patch mutants. Our findings uncover that the H4 basic patch has a regulatory function in SAGA-mediated histone modifications. Full Article
ty Strongly anisotropic type II blow up at an isolated point By www.ams.org Published On :: Tue, 10 Mar 2020 10:59 EDT Charles Collot, Frank Merle and Pierre Raphaël J. Amer. Math. Soc. 33 (2020), 527-607. Abstract, references and article information Full Article
ty Rigid continuation paths I. Quasilinear average complexity for solving polynomial systems By www.ams.org Published On :: Tue, 10 Mar 2020 10:59 EDT Pierre Lairez J. Amer. Math. Soc. 33 (2019), 487-526. Abstract, references and article information Full Article
ty Weak functoriality of Cohen-Macaulay algebras By www.ams.org Published On :: Tue, 10 Mar 2020 10:59 EDT Yves André J. Amer. Math. Soc. 33 (2020), 363-380. Abstract, references and article information Full Article
ty A PP2A Phosphatase High Density Interaction Network Identifies a Novel Striatin-interacting Phosphatase and Kinase Complex Linked to the Cerebral Cavernous Malformation 3 (CCM3) Protein By feedproxy.google.com Published On :: 2009-01-01 Marilyn GoudreaultJan 1, 2009; 8:157-171Research Full Article
ty Lysine Acetylation Is a Highly Abundant and Evolutionarily Conserved Modification in Escherichia Coli By feedproxy.google.com Published On :: 2009-02-01 Junmei ZhangFeb 1, 2009; 8:215-225Research Full Article
ty Lysine Propionylation and Butyrylation Are Novel Post-translational Modifications in Histones By feedproxy.google.com Published On :: 2007-05-01 Yue ChenMay 1, 2007; 6:812-819Research Full Article
ty Phosphoproteome Analysis of E. coli Reveals Evolutionary Conservation of Bacterial Ser/Thr/Tyr Phosphorylation By feedproxy.google.com Published On :: 2008-02-01 Boris MacekFeb 1, 2008; 7:299-307Research Full Article
ty Large Scale Screening for Novel Rab Effectors Reveals Unexpected Broad Rab Binding Specificity By feedproxy.google.com Published On :: 2008-06-01 Mitsunori FukudaJun 1, 2008; 7:1031-1042Research Full Article
ty Time-resolved Mass Spectrometry of Tyrosine Phosphorylation Sites in the Epidermal Growth Factor Receptor Signaling Network Reveals Dynamic Modules By feedproxy.google.com Published On :: 2005-09-01 Yi ZhangSep 1, 2005; 4:1240-1250Research Full Article
ty A Proteome-wide, Quantitative Survey of In Vivo Ubiquitylation Sites Reveals Widespread Regulatory Roles By feedproxy.google.com Published On :: 2011-10-01 Sebastian A. WagnerOct 1, 2011; 10:M111.013284-M111.013284Research Full Article
ty A Tandem Affinity Tag for Two-step Purification under Fully Denaturing Conditions: Application in Ubiquitin Profiling and Protein Complex Identification Combined with in vivoCross-Linking By feedproxy.google.com Published On :: 2006-04-01 Christian TagwerkerApr 1, 2006; 5:737-748Research Full Article
ty The cytochrome P450 enzyme CYP24A1 increases proliferation of mutant KRAS-dependent lung adenocarcinoma independent of its catalytic activity [Cell Biology] By feedproxy.google.com Published On :: 2020-05-01T00:06:09-07:00 We previously reported that overexpression of cytochrome P450 family 24 subfamily A member 1 (CYP24A1) increases lung cancer cell proliferation by activating RAS signaling and that CYP24A1 knockdown inhibits tumor growth. However, the mechanism of CYP24A1-mediated cancer cell proliferation remains unclear. Here, we conducted cell synchronization and biochemical experiments in lung adenocarcinoma cells, revealing a link between CYP24A1 and anaphase-promoting complex (APC), a key cell cycle regulator. We demonstrate that CYP24A1 expression is cell cycle–dependent; it was higher in the G2-M phase and diminished upon G1 entry. CYP24A1 has a functional destruction box (D-box) motif that allows binding with two APC adaptors, CDC20-homologue 1 (CDH1) and cell division cycle 20 (CDC20). Unlike other APC substrates, however, CYP24A1 acted as a pseudo-substrate, inhibiting CDH1 activity and promoting mitotic progression. Conversely, overexpression of a CYP24A1 D-box mutant compromised CDH1 binding, allowing CDH1 hyperactivation, thereby hastening degradation of its substrates cyclin B1 and CDC20, and accumulation of the CDC20 substrate p21, prolonging mitotic exit. These activities also occurred with a CYP24A1 isoform 2 lacking the catalytic cysteine (Cys-462), suggesting that CYP24A1's oncogenic potential is independent of its catalytic activity. CYP24A1 degradation reduced clonogenic survival of mutant KRAS-driven lung cancer cells, and calcitriol treatment increased CYP24A1 levels and tumor burden in Lsl-KRASG12D mice. These results disclose a catalytic activity-independent growth-promoting role of CYP24A1 in mutant KRAS-driven lung cancer. This suggests that CYP24A1 could be therapeutically targeted in lung cancers in which its expression is high. Full Article
ty SUMOylation of the transcription factor ZFHX3 at Lys-2806 requires SAE1, UBC9, and PIAS2 and enhances its stability and function in cell proliferation [Protein Synthesis and Degradation] By feedproxy.google.com Published On :: 2020-05-08T03:41:14-07:00 SUMOylation is a posttranslational modification (PTM) at a lysine residue and is crucial for the proper functions of many proteins, particularly of transcription factors, in various biological processes. Zinc finger homeobox 3 (ZFHX3), also known as AT motif-binding factor 1 (ATBF1), is a large transcription factor that is active in multiple pathological processes, including atrial fibrillation and carcinogenesis, and in circadian regulation and development. We have previously demonstrated that ZFHX3 is SUMOylated at three or more lysine residues. Here, we investigated which enzymes regulate ZFHX3 SUMOylation and whether SUMOylation modulates ZFHX3 stability and function. We found that SUMO1, SUMO2, and SUMO3 each are conjugated to ZFHX3. Multiple lysine residues in ZFHX3 were SUMOylated, but Lys-2806 was the major SUMOylation site, and we also found that it is highly conserved among ZFHX3 orthologs from different animal species. Using molecular analyses, we identified the enzymes that mediate ZFHX3 SUMOylation; these included SUMO1-activating enzyme subunit 1 (SAE1), an E1-activating enzyme; SUMO-conjugating enzyme UBC9 (UBC9), an E2-conjugating enzyme; and protein inhibitor of activated STAT2 (PIAS2), an E3 ligase. Multiple analyses established that both SUMO-specific peptidase 1 (SENP1) and SENP2 deSUMOylate ZFHX3. SUMOylation at Lys-2806 enhanced ZFHX3 stability by interfering with its ubiquitination and proteasomal degradation. Functionally, Lys-2806 SUMOylation enabled ZFHX3-mediated cell proliferation and xenograft tumor growth of the MDA-MB-231 breast cancer cell line. These findings reveal the enzymes involved in, and the functional consequences of, ZFHX3 SUMOylation, insights that may help shed light on ZFHX3's roles in various cellular and pathophysiological processes. Full Article
ty {gamma}-Hydroxybutyrate does not mediate glucose inhibition of glucagon secretion [Signal Transduction] By feedproxy.google.com Published On :: 2020-04-17T00:06:05-07:00 Hypersecretion of glucagon from pancreatic α-cells strongly contributes to diabetic hyperglycemia. Moreover, failure of α-cells to increase glucagon secretion in response to falling blood glucose concentrations compromises the defense against hypoglycemia, a common complication in diabetes therapy. However, the mechanisms underlying glucose regulation of glucagon secretion are poorly understood and likely involve both α-cell–intrinsic and intraislet paracrine signaling. Among paracrine factors, glucose-stimulated release of the GABA metabolite γ-hydroxybutyric acid (GHB) from pancreatic β-cells might mediate glucose suppression of glucagon release via GHB receptors on α-cells. However, the direct effects of GHB on α-cell signaling and glucagon release have not been investigated. Here, we found that GHB (4–10 μm) lacked effects on the cytoplasmic concentrations of the secretion-regulating messengers Ca2+ and cAMP in mouse α-cells. Glucagon secretion from perifused mouse islets was also unaffected by GHB at both 1 and 7 mm glucose. The GHB receptor agonist 3-chloropropanoic acid and the antagonist NCS-382 had no effects on glucagon secretion and did not affect stimulation of secretion induced by a drop in glucose from 7 to 1 mm. Inhibition of endogenous GHB formation with the GABA transaminase inhibitor vigabatrin also failed to influence glucagon secretion at 1 mm glucose and did not prevent the suppressive effect of 7 mm glucose. In human islets, GHB tended to stimulate glucagon secretion at 1 mm glucose, an effect mimicked by 3-chloropropanoic acid. We conclude that GHB does not mediate the inhibitory effect of glucose on glucagon secretion. Full Article
ty ABC transporters control ATP release through cholesterol-dependent volume-regulated anion channel activity [Signal Transduction] By feedproxy.google.com Published On :: 2020-04-17T00:06:05-07:00 Purinergic signaling by extracellular ATP regulates a variety of cellular events and is implicated in both normal physiology and pathophysiology. Several molecules have been associated with the release of ATP and other small molecules, but their precise contributions have been difficult to assess because of their complexity and heterogeneity. Here, we report on the results of a gain-of-function screen for modulators of hypotonicity-induced ATP release using HEK-293 cells and murine cerebellar granule neurons, along with bioluminescence, calcium FLIPR, and short hairpin RNA–based gene-silencing assays. This screen utilized the most extensive genome-wide ORF collection to date, covering 90% of human, nonredundant, protein-encoding genes. We identified two ABCG1 (ABC subfamily G member 1) variants, which regulate cellular cholesterol, as modulators of hypotonicity-induced ATP release. We found that cholesterol levels control volume-regulated anion channel–dependent ATP release. These findings reveal novel mechanisms for the regulation of ATP release and volume-regulated anion channel activity and provide critical links among cellular status, cholesterol, and purinergic signaling. Full Article
ty Noncatalytic Bruton's tyrosine kinase activates PLC{gamma}2 variants mediating ibrutinib resistance in human chronic lymphocytic leukemia cells [Membrane Biology] By feedproxy.google.com Published On :: 2020-04-24T06:08:45-07:00 Treatment of patients with chronic lymphocytic leukemia (CLL) with inhibitors of Bruton's tyrosine kinase (BTK), such as ibrutinib, is limited by primary or secondary resistance to this drug. Examinations of CLL patients with late relapses while on ibrutinib, which inhibits BTK's catalytic activity, revealed several mutations in BTK, most frequently resulting in the C481S substitution, and disclosed many mutations in PLCG2, encoding phospholipase C-γ2 (PLCγ2). The PLCγ2 variants typically do not exhibit constitutive activity in cell-free systems, leading to the suggestion that in intact cells they are hypersensitive to Rac family small GTPases or to the upstream kinases spleen-associated tyrosine kinase (SYK) and Lck/Yes-related novel tyrosine kinase (LYN). The sensitivity of the PLCγ2 variants to BTK itself has remained unknown. Here, using genetically-modified DT40 B lymphocytes, along with various biochemical assays, including analysis of PLCγ2-mediated inositol phosphate formation, inositol phospholipid assessments, fluorescence recovery after photobleaching (FRAP) static laser microscopy, and determination of intracellular calcium ([Ca2+]i), we show that various CLL-specific PLCγ2 variants such as PLCγ2S707Y are hyper-responsive to activated BTK, even in the absence of BTK's catalytic activity and independently of enhanced PLCγ2 phospholipid substrate supply. At high levels of B-cell receptor (BCR) activation, which may occur in individual CLL patients, catalytically-inactive BTK restored the ability of the BCR to mediate increases in [Ca2+]i. Because catalytically-inactive BTK is insensitive to active-site BTK inhibitors, the mechanism involving the noncatalytic BTK uncovered here may contribute to preexisting reduced sensitivity or even primary resistance of CLL to these drugs. Full Article
ty Reduction of protein phosphatase 2A (PP2A) complexity reveals cellular functions and dephosphorylation motifs of the PP2A/B'{delta} holoenzyme [Enzymology] By feedproxy.google.com Published On :: 2020-04-24T06:08:45-07:00 Protein phosphatase 2A (PP2A) is a large enzyme family responsible for most cellular Ser/Thr dephosphorylation events. PP2A substrate specificity, localization, and regulation by second messengers rely on more than a dozen regulatory subunits (including B/R2, B'/R5, and B″/R3), which form the PP2A heterotrimeric holoenzyme by associating with a dimer comprising scaffolding (A) and catalytic (C) subunits. Because of partial redundancy and high endogenous expression of PP2A holoenzymes, traditional approaches of overexpressing, knocking down, or knocking out PP2A regulatory subunits have yielded only limited insights into their biological roles and substrates. To this end, here we sought to reduce the complexity of cellular PP2A holoenzymes. We used tetracycline-inducible expression of pairs of scaffolding and regulatory subunits with complementary charge-reversal substitutions in their interaction interfaces. For each of the three regulatory subunit families, we engineered A/B charge–swap variants that could bind to one another, but not to endogenous A and B subunits. Because endogenous Aα was targeted by a co-induced shRNA, endogenous B subunits were rapidly degraded, resulting in expression of predominantly a single PP2A heterotrimer composed of the A/B charge–swap pair and the endogenous catalytic subunit. Using B'δ/PPP2R5D, we show that PP2A complexity reduction, but not PP2A overexpression, reveals a role of this holoenzyme in suppression of extracellular signal–regulated kinase signaling and protein kinase A substrate dephosphorylation. When combined with global phosphoproteomics, the PP2A/B'δ reduction approach identified consensus dephosphorylation motifs in its substrates and suggested that residues surrounding the phosphorylation site play roles in PP2A substrate specificity. Full Article
ty G{alpha}q splice variants mediate phototransduction, rhodopsin synthesis, and retinal integrity in Drosophila [Signal Transduction] By feedproxy.google.com Published On :: 2020-04-24T06:08:45-07:00 Heterotrimeric G proteins mediate a variety of signaling processes by coupling G protein–coupled receptors to intracellular effector molecules. In Drosophila, the Gαq gene encodes several Gαq splice variants, with the Gαq1 isoform protein playing a major role in fly phototransduction. However, Gαq1 null mutant flies still exhibit a residual light response, indicating that other Gαq splice variants or additional Gq α subunits are involved in phototransduction. Here, we isolated a mutant fly with no detectable light responses, decreased rhodopsin (Rh) levels, and rapid retinal degeneration. Using electrophysiological and genetic studies, biochemical assays, immunoblotting, real-time RT-PCR, and EM analysis, we found that mutations in the Gαq gene disrupt light responses and demonstrate that the Gαq3 isoform protein is responsible for the residual light response in Gαq1 null mutants. Moreover, we report that Gαq3 mediates rhodopsin synthesis. Depletion of all Gαq splice variants led to rapid light-dependent retinal degeneration, due to the formation stable Rh1-arrestin 2 (Arr2) complexes. Our findings clarify essential roles of several different Gαq splice variants in phototransduction and retinal integrity in Drosophila and reveal that Gαq3 functions in rhodopsin synthesis. Full Article
ty Mechanistic insights explain the transforming potential of the T507K substitution in the protein-tyrosine phosphatase SHP2 [Signal Transduction] By feedproxy.google.com Published On :: 2020-05-01T00:06:09-07:00 The protein-tyrosine phosphatase SHP2 is an allosteric enzyme critical for cellular events downstream of growth factor receptors. Mutations in the SHP2 gene have been linked to many different types of human diseases, including developmental disorders, leukemia, and solid tumors. Unlike most SHP2-activating mutations, the T507K substitution in SHP2 is unique in that it exhibits oncogenic Ras-like transforming activity. However, the biochemical basis of how the SHP2/T507K variant elicits transformation remains unclear. By combining kinetic and biophysical methods, X-ray crystallography, and molecular modeling, as well as using cell biology approaches, here we uncovered that the T507K substitution alters both SHP2 substrate specificity and its allosteric regulatory mechanism. We found that although SHP2/T507K exists in the closed, autoinhibited conformation similar to the WT enzyme, the interactions between its N-SH2 and protein-tyrosine phosphatase domains are weakened such that SHP2/T507K possesses a higher affinity for the scaffolding protein Grb2-associated binding protein 1 (Gab1). We also discovered that the T507K substitution alters the structure of the SHP2 active site, resulting in a change in SHP2 substrate preference for Sprouty1, a known negative regulator of Ras signaling and a potential tumor suppressor. Our results suggest that SHP2/T507K's shift in substrate specificity coupled with its preferential association of SHP2/T507K with Gab1 enable the mutant SHP2 to more efficiently dephosphorylate Sprouty1 at pTyr-53. This dephosphorylation hyperactivates Ras signaling, which is likely responsible for SHP2/T507K's Ras-like transforming activity. Full Article
ty The focal adhesion protein kindlin-2 controls mitotic spindle assembly by inhibiting histone deacetylase 6 and maintaining {alpha}-tubulin acetylation [Signal Transduction] By feedproxy.google.com Published On :: 2020-05-01T00:06:09-07:00 Kindlins are focal adhesion proteins that regulate integrin activation and outside-in signaling. The kindlin family consists of three members, kindlin-1, -2, and -3. Kindlin-2 is widely expressed in multiple cell types, except those from the hematopoietic lineage. A previous study has reported that the Drosophila Fit1 protein (an ortholog of kindlin-2) prevents abnormal spindle assembly; however, the mechanism remains unknown. Here, we show that kindlin-2 maintains spindle integrity in mitotic human cells. The human neuroblastoma SH-SY5Y cell line expresses only kindlin-2, and we found that when SH-SY5Y cells are depleted of kindlin-2, they exhibit pronounced spindle abnormalities and delayed mitosis. Of note, acetylation of α-tubulin, which maintains microtubule flexibility and stability, was diminished in the kindlin-2–depleted cells. Mechanistically, we found that kindlin-2 maintains α-tubulin acetylation by inhibiting the microtubule-associated deacetylase histone deacetylase 6 (HDAC6) via a signaling pathway involving AKT Ser/Thr kinase (AKT)/glycogen synthase kinase 3β (GSK3β) or paxillin. We also provide evidence that prolonged hypoxia down-regulates kindlin-2 expression, leading to spindle abnormalities not only in the SH-SY5Y cell line, but also cell lines derived from colon and breast tissues. The findings of our study highlight that kindlin-2 regulates mitotic spindle assembly and that this process is perturbed in cancer cells in a hypoxic environment. Full Article
ty Small-molecule agonists of the RET receptor tyrosine kinase activate biased trophic signals that are influenced by the presence of GFRa1 co-receptors [Neurobiology] By feedproxy.google.com Published On :: 2020-05-08T03:41:14-07:00 Glial cell line–derived neurotrophic factor (GDNF) is a growth factor that regulates the health and function of neurons and other cells. GDNF binds to GDNF family receptor α1 (GFRa1), and the resulting complex activates the RET receptor tyrosine kinase and subsequent downstream signals. This feature restricts GDNF activity to systems in which GFRa1 and RET are both present, a scenario that may constrain GDNF breadth of action. Furthermore, this co-dependence precludes the use of GDNF as a tool to study a putative functional cross-talk between GFRa1 and RET. Here, using biochemical techniques, terminal deoxynucleotidyl transferase dUTP nick end labeling staining, and immunohistochemistry in murine cells, tissues, or retinal organotypic cultures, we report that a naphthoquinone/quinolinedione family of small molecules (Q compounds) acts as RET agonists. We found that, like GDNF, signaling through the parental compound Q121 is GFRa1-dependent. Structural modifications of Q121 generated analogs that activated RET irrespective of GFRa1 expression. We used these analogs to examine RET–GFRa1 interactions and show that GFRa1 can influence RET-mediated signaling and enhance or diminish AKT Ser/Thr kinase or extracellular signal-regulated kinase signaling in a biased manner. In a genetic mutant model of retinitis pigmentosa, a lead compound, Q525, afforded sustained RET activation and prevented photoreceptor neuron loss in the retina. This work uncovers key components of the dynamic relationships between RET and its GFRa co-receptor and provides RET agonist scaffolds for drug development. Full Article