The synthesis of cholesterol requires more than 20 enzymes, many of which are intricately regulated. Post-translational control of these enzymes provides a rapid means for modifying flux through the pathway. So far, several enzymes have been shown to be rapidly degraded through the ubiquitin–proteasome pathway in response to cholesterol and other sterol intermediates. Additionally, several enzymes have their activity altered through phosphorylation mechanisms. Most work has focused on the two rate-limiting enzymes: 3-hydroxy-3-methylglutaryl CoA reductase and squalene monooxygenase. Here, we review current literature in the area to define some common themes in the regulation of the entire cholesterol synthesis pathway. We highlight the rich variety of inputs controlling each enzyme, discuss the interplay that exists between regulatory mechanisms, and summarize findings that reveal an intricately coordinated network of regulation along the cholesterol synthesis pathway. We provide a roadmap for future research into the post-translational control of cholesterol synthesis, and no doubt the road ahead will reveal further twists and turns for this fascinating pathway crucial for human health and disease.

The development of a chronic, low-grade inflammation originating from adipose tissue in obese subjects is widely recognized to induce insulin resistance, leading to the development of type 2 diabetes. The adipose tissue microenvironment drives specific metabolic reprogramming of adipose tissue macrophages, contributing to the induction of tissue inflammation. Uncoupling protein 2 (UCP2), a mitochondrial anion carrier, is thought to separately modulate inflammatory and metabolic processes in macrophages and is up-regulated in macrophages in the context of obesity and diabetes. Here, we investigate the role of UCP2 in macrophage activation in the context of obesity-induced adipose tissue inflammation and insulin resistance. Using a myeloid-specific knockout of UCP2 (Ucp2ΔLysM), we found that UCP2 deficiency significantly increases glycolysis and oxidative respiration, both unstimulated and after inflammatory conditions. Strikingly, fatty acid loading abolished the metabolic differences between Ucp2ΔLysM macrophages and their floxed controls. Furthermore, Ucp2ΔLysM macrophages show attenuated pro-inflammatory responses toward Toll-like receptor-2 and -4 stimulation. To test the relevance of macrophage-specific Ucp2 deletion in vivo, Ucp2ΔLysM and Ucp2fl/fl mice were rendered obese and insulin resistant through high-fat feeding. Although no differences in adipose tissue inflammation or insulin resistance was found between the two genotypes, adipose tissue macrophages isolated from diet-induced obese Ucp2ΔLysM mice showed decreased TNFα secretion after ex vivo lipopolysaccharide stimulation compared with their Ucp2fl/fl littermates. Together, these results demonstrate that although UCP2 regulates both metabolism and the inflammatory response of macrophages, its activity is not crucial in shaping macrophage activation in the adipose tissue during obesity-induced insulin resistance.

Poly(ADP-ribose) polymerase (PARP) superfamily members covalently link either a single ADP-ribose (ADPR) or a chain of ADPR units to proteins using NAD as the source of ADPR. Although the well-known poly(ADP-ribosylating) (PARylating) PARPs primarily function in the DNA damage response, many noncanonical mono(ADP-ribosylating) (MARylating) PARPs are associated with cellular antiviral responses. We recently demonstrated robust up-regulation of several PARPs following infection with murine hepatitis virus (MHV), a model coronavirus. Here we show that SARS-CoV-2 infection strikingly up-regulates MARylating PARPs and induces the expression of genes encoding enzymes for salvage NAD synthesis from nicotinamide (NAM) and nicotinamide riboside (NR), while down-regulating other NAD biosynthetic pathways. We show that overexpression of PARP10 is sufficient to depress cellular NAD and that the activities of the transcriptionally induced enzymes PARP7, PARP10, PARP12 and PARP14 are limited by cellular NAD and can be enhanced by pharmacological activation of NAD synthesis. We further demonstrate that infection with MHV induces a severe attack on host cell NAD+ and NADP+. Finally, we show that NAMPT activation, NAM, and NR dramatically decrease the replication of an MHV that is sensitive to PARP activity. These data suggest that the antiviral activities of noncanonical PARP isozyme activities are limited by the availability of NAD and that nutritional and pharmacological interventions to enhance NAD levels may boost innate immunity to coronaviruses.

COP27: Navigating a difficult road to Sharm El-Sheikh Expert comment NCapeling 6 July 2022

Against a backdrop of rising urgency, COP27 in Egypt will bring all aspects of climate action into the spotlight – but especially the role of the host country.

As COP26 drew to a close in Glasgow, Egyptian officials announced their priorities for COP27, emphasizing climate finance and climate adaptation – a new approach given previous COPs mainly focused on mitigation, reducing emissions to limit climate damage.

This was followed by the COP27 presidency outlining its vision at MENA Climate Week 2022 to achieve ‘substantive and equal progress’ on all aspects of the negotiations, and Egypt emphasizing its intention to focus on implementing existing carbon reduction targets rather than pushing for further carbon cuts.

Egypt argues it is hosting COP27 on behalf of African nations and that, while it is promoting the interests of the developing world, it will be an impartial arbiter. However it is also useful to consider its priorities from the Egyptian government’s perspective.

Agenda drivers

Egypt has long prioritized climate finance and adaptation because it remains in need of technical and financial support to adapt, especially in agriculture and tourism.

It plans to expand its access to climate funding and investment, an area in which Egypt has been relatively successful as it currently receives 27 per cent of all multilateral climate finance in the MENA region and has issued the region’s first sovereign green bonds.

With public debt currently 94 per cent of GDP, Egyptian officials have also called for debt relief for Egypt and other developing countries.

Egypt’s Climate Change Strategy reflects this approach, aiming to enhance Egypt’s rank on the Climate Change Performance Index in order to ‘attract more investments and acquire more climate funding’.

Limiting the mitigation scope and the focus on finance also echoes Egypt’s own reluctance to make carbon reduction commitments. The Egyptian nationally determined contribution (NDC) – its 2030 pledge under the Paris Agreement – does not include any quantifiable emission reduction targets.

Egypt is one of only a few countries which failed to submit an updated NDC in 2021 and its upcoming update will not include an economy-wide carbon reduction target.

Egypt has also never published a long-term strategy and has no decarbonization plans despite independent estimates it should cut rising emissions by one-quarter by 2030, and by two-thirds by 2050 to be aligned with the Paris Agreement. This partly explains why observers rate Egypt’s climate action as highly insufficient.

Furthermore, Egypt’s championing of ‘moving from pledges to implementation’ without having quantifiable carbon reduction pledges of its own effectively exempts it from both pledging and implementation.

As a developing country, Egypt’s negotiating position is supported by UNFCCC provisions which recognize differentiated responsibilities and respective capabilities of nations.

Its proposal to focus COP27 on the implementation of climate action and finance pledges is important in consolidating progress. But not pushing for more emission reductions at this critical moment risks derailing global decarbonization momentum and undermining global climate action.

According to optimistic estimates, if current climate pledges were implemented the world would still remain on track for 2°C of warming by the end of the century, with far worse impacts than if warming was curbed at 1.5°C.

Under a 2°C scenario, 37 per cent of the global population could regularly be exposed to extreme heat waves compared to 14 per cent in a 1.5°C warmer world, with developing countries expected to be worst-affected.

A 2°C trajectory also runs the risk of tipping points such as the melting of ice sheets in Antarctica and Greenland, triggering runaway climate change. Time to change the warming trajectory is running out as the latest IPCC assessment warns the window of opportunity is now ‘brief and rapidly closing’, and the UN Secretary General recently called for faster carbon cuts by the end of 2022 to avoid a ‘climate catastrophe’.

A different energy transition

Egypt opted not to join any of the voluntary sectoral coalitions at COP26 on reducing methane, clean energy transition, transition to zero-emissions vehicles, or moving beyond oil and gas.

This position is explained by its growing role as an exporter and advocate for fossil gas in the energy transition. Egypt is the second-largest producer of natural gas in Africa and is emerging as a fossil gas hub for the eastern Mediterranean, which is shaping its domestic energy policy.

Its 59GW electricity generation capacity is almost double the peak demand and is dominated by gas-powered electricity generation, which currently represents 42 per cent of all Africa’s gas generation.

Egypt’s climate policy is also shaped by fossil gas, and its national Climate Change Strategy encourages the expansion of gas use by promoting a transition to compressed natural gas for vehicles, the expansion of its domestic natural gas network – despite having universal access to electricity – and shifting to a gas-fuelled shipping sector.

Egypt also voiced support for other African countries to extract and deploy fossil gas and oil resources, making it one of the protagonists of the ‘great fossil gas pushback’. These advocates defend the right of developing countries to deploy fossil gas as a ‘transition fuel’ and champion its necessity to solve energy poverty.

But their position is not shared by all African and developing countries, and is rejected by some civil society groups, who argue it risks locking in greenhouse gases and local emissions for decades as well as delaying future development of low carbon energy systems.

Egypt’s huge spare generation capacity has contributed to a slowdown in renewable energy projects over the past two years. With renewables representing just 6GW, Egypt is expected to miss its renewable energy target for 2022, set at 20 per cent of generating capacity.

Engaging Egypt better

But these positions are more malleable than they seem, and Egypt is open to dialogue – not just on refining the COP27 agenda but also on reviewing its own climate priorities and leveraging its energy sector for a more ambitious transition.

Review: Decolonization and its discontents The World Today mhiggins.drupal 1 August 2022

Jenna Marshall on a lively if flawed argument to find a way forward in a debate that has descended ‘into acrimony’.

Against Decolonization: Taking African Agency Seriously
Olufemi Taiwo, Hurst, £14.99

Decolonization was once heralded as a moment of potential and possibility for the formerly imperial world to chart a new way forward no longer tied to the apparatus of empire.

It marked a period of transition to nation states – and an expansion of a rights-based international community that would dispense with the morally bankrupt regime of racism, dispossession and subjugation that characterized colonialism.  
 

The descent of the decolonization debate

Half a century later, the debate surrounding decolonization has descended into acrimony. Some factions cast the issue of decolonization as a sustained attack on British and western culture writ large; other disparate voices coalesce around related social justice issues such as inequality, climate change and education. 

Decolonization has become ubiquitous in the public domain – and its ubiquity is the problem. In Against Decolonization, Olufemi Taiwo renounces a concept he conceives as having been emptied of serious study and analytical purchase; one incapable of addressing the complexities of modern global politics and more importantly, Africa’s place in it. 

Although the book attacks the inexhaustible ways in which the ‘trope of decolonization’ has been deployed, Taiwo is less bothered by the purported failures of scholars he deems ‘decolonizers’ and focuses his attention instead on the political landscape of African countries, past and present. 

Central to the book’s argument are two distinct scholarly strands on decolonization. The first, legal focus, centres on the political and economic forces of state-building. The second essays an ‘ideology’ of decolonization that rests on ‘forcing an ex-colony to forswear on pain of being forever under the yoke of colonization any and every cultural, political, intellectual, social and linguistic artefact, idea, process, institution and practice that retains even the slightest whiff of the colonial past’. 

Whether one should characterize the latter as simply a field of study or a potential set of policy arrangements remains unclear – yet what is certain is that it is too nebulous, too elastic, too open-ended to offer any substantive model or mechanism to understand postcolonial Africa. 
 

Correcting Eurocentric narcissism

 The decolonization research agenda in Africa came to prominence during the Cold War period of national liberation struggles.

The intellectual project that followed centred on dismantling Eurocentrism as colonial subjugation through its promotion of the West as the crucible of legitimate and scientific knowledge. Since then, scholars have argued that decolonization itself has become compromised by its enduringly Eurocentric gaze at the expense of the agency of African thinkers, creatives and statesmen and women. 

Taiwo seeks to correct this narcissism – and the omissions left in its wake – by introducing lesser-known Africans and pan-African scholars and cultural figures. These voices, he hopes, will illuminate issues often ignored by ‘decolonizers’ and spark a ‘renewed interest in an appreciation of the many different ways in which African thinkers have responded to the colonial experience’.
 

The decolonization of language

Taiwo challenges the decolonization of language as an oversold promise.

Romanticizing an imagined, pristine African pre-colonial past, he says, ultimately leads to nativism and atavism. As a case in point, Taiwo highlights bureaucratic instances of ‘language policy planning’ to deploy African languages in places such as Niger, Mali, Cameroon, Senegal and Nigeria that were hindered by multilingualism, education and high rates of illiteracy.

The author goes on to confront the abstract language of decolonization, which, he says, allows western scholars to unproblematically engage with the concept without any serious consideration of their own complicity in upholding systems of exclusion. It entrenches their own institutional power within the academy, amplifies their perspectives at the expense of others, and limits the possibilities for understanding the problems of world politics with deleterious effects on policy.

It is a serious claim, but there are issues to be addressed: Taiwo assumes there is coherence among scholars of decolonization, which is not the case. 

When Taiwo approaches how to foster political systems that cater to the needs of their citizens he dismantles the binary of ‘West as modern’ v ‘Africa as traditional’. Chieftaincies as traditional African governance, he points out, were the product of colonial anthropology, not Africans themselves. From the Fanti Confederation of 1871 to the Egba United Government in what is now Nigeria, Taiwo demonstrates that there has been a sustained tradition towards demands for democratic values. 

As he concedes an intellectual neglect of African philosophers that underlies the design and operations of Africa’s political institutions, Taiwo’s initial dismissal of the significance of cultural decolonization deserves another look. How should political and economic drives toward self-determination be advanced in the absence of knowledge shaped and mediated through African lived experiences?

In this respect, the tale of two decolonizations – the legal alongside the ideological – suggest an unhelpful, if not false, binary.
 

The problem of reconciling modernity and colonialism

What resonates throughout the book is the idea that Europe cannot profess to hold an exclusive intellectual claim to modernity. Its universal aspirations are open to all of humanity, allowing those who have historically been marginalized to be worldmakers. 

The idea that modernity and colonialism are irreconcilable is problematic. For instance, Taiwo argues that the curtailment of capitalism in Africa by restricting the growth of the middle classes while limiting competition between African capitalists and the metropole is the consequence of colonialism.

Yet the celebrated cultural anthropologist Sidney Mintz established an understanding that the matter for debate is not whether non-westerners were part of the modern system, but how and to what degree they were included and able to actualise its ideals. 

The emerging capitalist world economy needed non-western lands and labour, and so they were conscripted to this end. Recent abolitionist and black radical scholarship has built on this argument to maintain that capitalism not only requires inequality for it to function but that race – as a mechanism for producing ‘difference’ – enshrines it.

Acknowledging the unacknowledged

In the end, Taiwo communicates a palpable frustration at the state of academic discourses on contemporary Africa under the guise of emancipatory and radical scholarship. He offers an alternative approach whereby African students might rid themselves of a faddism that is ‘at best unsatisfactory’ and at worst produces ‘confusion, obscurantism, if not outright distortion and falsification’.

Yet out of this irritation, Taiwo’s greatest contribution in Against Decolonization might be to urge an acknowledgement of how and to what degree decolonization has become subdued and its political possibilities curtailed. He ultimately urges us to reconsider the purpose of the decolonization academic movement as an ethics to abide by rather than a social theory of the postcolonial world. 

This requires those ‘decolonizers’ on whose careers the term is built to adopt greater intellectual humility – to resist the posture of the anarchist radical scholar armed for the ‘good fight’. Instead, they should apply a scholarly curiosity to genuinely engage with those already on the battlefield, so to speak; those ‘doing the work’ in practice, but who have been unacknowledged until now.

Towards just transition in Africa: Continental coordination on green financing and job creation 6 October 2022 — 7:00AM TO 3:30PM Anonymous (not verified) 8 September 2022 Addis Ababa and online

At this hybrid conference in Addis Ababa, speakers take stock of preparations ahead of the ‘African COP27’ in November and discuss the key priorities for streamlining continental cooperation on policy approaches to just transition.

At this hybrid conference in Addis Ababa, speakers will take stock of policy efforts and preparations ahead of the ‘African COP27’ in November and discuss the key priorities for streamlining continental cooperation on policy approaches to just transition.

Global climate policies towards a ‘just transition’ under the Paris Agreement should align with and support African states’ national sustainable development priorities – in particular, the need for decent and fair job creation, as well as resilient and sustainable land, environment and ecosystem management policies.

They must also be cognizant of African nations’ urgent requirements for sustainable and accessible energy to underpin economic development. Achieving green growth requires innovative and more accessible financing models, especially as wealthy nations’ financial pledges have fallen short. It also requires clarity and cooperation to unlock investment in both renewable and transitional energy.

African countries face collective climate and employment-related challenges. However, policymaking often remains regionally siloed according to differing political, energy sector and ecological realities. There is a need for transformational strategic thinking and context-specific action from African governments, civil society, businesses and financiers, in their green financing demands and national implementation plans.

At this hybrid conference in Addis Ababa, speakers will take stock of policy efforts and preparations ahead of the ‘African COP27’ in November and discuss the key priorities for streamlining continental cooperation on policy approaches to just transition, job creation and green financing.

This event is the third in a series on Towards just transition: Connecting green financing and sustainable job creation in Africa, supported by the Chatham House Sustainability Accelerator.

Reflections at 100: Empire and decolonization Audio MVieira 1 November 2022

How did leading academics and policymakers think about and impact imperialism and decolonization from the 1920s to 1970s?

This episode of Reflections at 100, marking the centenary of International Affairs, looks at how empire and decolonization have been discussed in the journal.

Isabel and Krisztina speak to Meera Sabaratnam about how thinkers and policymakers from the 1920s to 1970s understood both empire and then decolonization. Meera highlights four tensions present within the discussions, and how these may impact the international order today.

Inderjeet Parmar delves deeper into the influence of Chatham House at the time and situates these discussions in the broader think-tank and global context.

Reflections at 100 is a mini-series accompanying the journal’s centenary Archive Collections. The collections bring together articles from our archive which speak to the past, present, and future of current affairs issues. In each podcast episode we speak to editors and contributors to the collection and explore what the research tells us about policymaking today. 

Explore the Archive Collection, free to access until mid-November 2022, including Meera’s introduction: 100 years of empire and decolonization.

International Affairs was started at Chatham House in 1922 to communicate research to members who could not attend in person. Over the past 100 years it has transformed into a journal that publishes academically rigorous and policy relevant research. It is published for Chatham House by Oxford University Press. Read the latest issue here. 

Sudan’s gold boom: Connections to conflict and transnational impacts 7 December 2022 — 2:00PM TO 3:30PM Anonymous (not verified) 24 November 2022 Online

At this event, experts will discuss Sudan’s gold sector, its connections to conflict, and transnational impacts. 

At this webinar panellists will discuss Sudan’s gold sector, its connections to conflict, and transnational impacts.

Sudan is one of the largest gold producers on the continent, with the industry constituting Sudan’s foremost source of hard currency since the secession of South Sudan in 2011 and resulting loss of oilfields.

The gold rush that has ensued has had important implications for domestic and transnational conflict dynamics. Military actors and armed groups have sought control of gold-producing areas in the peripheries and to capitalize on the flow of labour migrants, against a wider backdrop of conflict partly stemming from contestation for control between central and local actors.

International interests are prominent, including increased Russian involvement in the sector, while gold smuggling has also interlaced with mercenary activity in neighbouring CAR, Chad and Libya.
 
At this event, panellists will discuss Sudan’s gold trade, its connections to conflict, and transnational impacts, including the international politics of Sudan’s gold extraction and role of armed groups. It will also explore the environmental and socio-economic dimensions of gold in Sudan’s border areas. 
 
This roundtable is an output of the Cross-Border Conflict: Evidence, Policy and Trends (XCEPT) research programme, funded by UK Aid from the UK government.
 

Africa in 2023: Continuing political and economic volatility Expert comment NCapeling 6 January 2023

Despite few African trade and financial links with Russia and Ukraine, the war in Ukraine will cause civil strife in Africa due to food and energy inflation.

Africa’s economy was recovering from the COVID-19 pandemic in 2022 when a range of internal and external shocks struck such as adverse weather conditions, a devastating locust invasion, and the Russian invasion of Ukraine – all of which worsened already rapidly-rising rates of inflation and borrowing costs.

Although the direct trade and financial linkages of Africa with Russia and Ukraine are small, the war has damaged the continent’s economies through higher commodity prices, higher food, fuel, and headline inflation.

The main impact is on the increasing likelihood of civil strife because of food and energy-fuelled inflation amid an environment of heightened political instability.

Key African economies such as South Africa and Nigeria were already stuck with low growth and many African governments have seen their debt burdens increase – some such as Ethiopia and Ghana now have dollar debt trading at distressed levels – and more countries will follow in 2023.

On average the public sector debt-to-GDP ratio of African countries stood at above 60 per cent in 2022. The era of Chinese state-backed big loans and mega-projects which started 20 years ago in Angola after the end of its civil war may be coming to an end but Chinese private sector investments on the continent will continue through its Belt and Road Initiative and dual circulation model of development.

Great and middle powers building influence

Geopolitical competition in Africa has intensified in 2022, particularly among great powers such as China, Russia, the US, and the EU but also by middle powers such as Turkey, Japan, and the Gulf states.

The sixth AU-EU summit held in Brussels in February 2022 agreed on the principles for a new partnership, although the Russian invasion of Ukraine which followed disrupted these ambitions. Japan’s pledge of $30 billion in aid for Africa at TICAD 8 in August 2022 was clearly made due to the $40 billion pledged at the China–Africa summit in November 2021.

The US also launched a new strategy to strengthen its partnership and held a second US-Africa Leaders’ summit in Washington in December, the first since 2014. Russia’s ambition has been curtailed by its invasion of Ukraine, postponing its second summit with African states to 2023.

The imposition of international sanctions complicated its trade and investments, and military support such as that provided by Russian paramilitary group Wagner focused on Mali, Libya and the Central African Republic (CAR) has been curtailed.

The strategic importance of Africa has resulted in all the UN P5 members calling on the G20 to make the African Union (AU) its 21st member in 2023 under India’s presidency.

International competition to secure Africa’s critical and strategic minerals and energy products intensified in 2022 and, in the energy sector, European countries are seeking to diversify away from Russian oil and gas with alternative supplies, such as those from Africa.

Western mining companies and commodity traders are also increasingly seeking alternative supplies from Africa. Decarbonization is becoming a driver of resource nationalism and geopolitical competition in certain African mining markets, home to large deposits of critical ‘transition minerals’ such as copper, cobalt, graphite, lithium, or nickel.

COP27 was hosted in Egypt in November and gave African leaders an opportunity to shape climate discussions by pushing priority areas such as loss and damage, stranded assets, access to climate finance, adaptation, and desertification. Climate adaptation in Africa is a key condition to preserving economic growth and maintaining social cohesion.

The Horn of Africa, particularly Somalia, is suffering from one of the worst droughts in memory. The geopolitical and geoeconomic ramifications of the war in Ukraine has directly impacted the African continent by contributing to food and cooking oil inflation and humanitarian aid delivery.

Thoughout 2022 the AU was undergoing intensive reform and it struggled to respond to the growing number of security crises across the continent. Hotspots in 2023 will be in the western Sahel and Lake Chad Basin, eastern DRC, and northern Mozambique, all of them crossing state borders.

In Mozambique, a 2019 peace deal assisted by the United Nations (UN) will see the last ex-guerrillas from Renamo demobilized in 2023 to reintegrate into civilian life – some having been recruited in 1978.

In eastern Congo, M23 – one of around 120 armed groups – resumed its conflict against the central government. After lying dormant for several years, it took up arms again in 2021 and has been leading an offensive in eastern DRC against the Congolese army.

According to the UN, Rwanda has been supporting M23, and Kenya’s parliament approved in November the deployment of about 900 soldiers to the DRC as part of a joint military force from the East African Community (EAC) bloc – DRC joined the EAC in March.

In the Horn of Africa, Ethiopia saw an uneasy ceasefire agreed between the federal government and the Tigray People’s Liberation Front (TPLF).

Islamist militant groups in Africa further expanded their territorial reach in 2022, particularly in the western Sahel where al-Qaeda and Islamic State affiliates are competing for influence and continued to make inroads.

The drawdown and exit of western forces from Mali, both the French Operation Barkane and international contributions for the UN’s MINUSMA mission there, adds new dimensions to regional security challenges.

Mali’s decision in May to withdraw from the G5 Sahel has also eroded the regional security architecture. Jihadist activity may spread further into coastal states which has resulted in international partners such as France and the UK redesigning their security assistance strategies for the region.

Coups on the increase again

Since 2020, there have been successful military coups in Burkina Faso (twice), Chad, Guinea, Mali (twice), and Sudan, and failed ones in the CAR, Djibouti, Guinea-Bissau, Madagascar, Niger, and possibly Gambia and São Tomé and Príncipe.

Three national elections illustrate the state of African democracy in 2022. In Angola’s August elections, the ruling MPLA lost its absolute majority with the opposition UNITA winning the majority in Luanda for the first time.

Independent Thinking: China in Africa, conflicts in 2023 Audio NCapeling 13 January 2023

Episode ten discusses Africa and the complex role China plays on the continent, and how the world should be responding to the major conflicts of 2023.

The first episode of 2023 examines Africa and the complex role China plays on the continent as a new Chatham House report highlights 22 African countries suffering from debt distress with Beijing a key creditor to many of them.

China’s new foreign minister Qin Gang is also touring several African states this week and next, with visits planned to Ethiopia, Angola, Gabon, and the headquarters of the African Union (AU).

This week Chatham House also hosted Dr Comfort Ero, president of the International Crisis Group, to discuss ten conflicts to watch in 2023. The panel examines some of the key conflicts mentioned and how the world is responding to them.

Joining Bronwen Maddox on the podcast this week from Chatham House are Dr Alex Vines, director of the Africa programme, Creon Butler, director of the Global Economy and Finance programme, Dr Yu Jie, senior fellow on the Asia-Pacific programme, and Armida van Rij, research fellow with the International Security programme.

About Independent Thinking

A weekly podcast hosted by Chatham House director Bronwen Maddox, in conversation with leading policymakers, journalists, and Chatham House experts providing insight on the latest international issues.

Africa Aware: Supply chains, land contestation, conflict Audio NCapeling 30 March 2023

This episode examines relations between Ethiopia and Sudan as part of an XCEPT project mini-series.

The war in northern Ethiopia since November 2020, and subsequent conquest of disputed farmlands in Al-Fashaga by the Sudanese army on the Ethiopia-Sudan border, has brought into focus the importance of agricultural commodities such as sesame as a potential driver of land contestation and conflict. 

The panel discusses the interrelation of commodity and conflict supply chains, land contestation, and boundary disputes in the Horn of Africa, with a particular focus on the regions of Wolkait/Western Tigray in northwest Ethiopia and Al Fashaga in eastern Sudan.

This podcast was produced with support from the Cross-Border Conflict Evidence, Policy and Trends (XCEPT) project, funded by UK Aid from the UK government.

Purpose: The ⁶⁸Ga-PSMA PET/CT is a commonly used imaging modality in prostate cancers. However, few studies have compared the diagnostic efficiency between ⁶⁸Ga-PSMA and ¹⁸F-FDG PET/CT and evaluated whether a heterogeneous metabolic phenotype (especially PSMA-FDG+ lesions) exists in patients with castration-resistant prostate cancer (CRPC). We determined the added value of ¹⁸F-FDG PET/CT compared to ⁶⁸Ga-PSMA PET/CT in CRPC patients and identified CRPC patients who may benefit from additional ¹⁸F-FDG PET/CT. Methods: Data of 56 patients with CRPC who underwent both ⁶⁸Ga-PSMA and ¹⁸F-FDG PET/CT from May 2018 to February 2021 were retrospectively analysed. Patients were classified into two groups with or without PSMA-FDG+ lesions. The differences in patient characteristics between the two groups and predictors of patients who having at least one PSMA-FDG+ lesion were analysed. Results: Although both the detection rate (75.0% vs. 51.8%, P = 0.004) and positive lesion number (135 vs. 95) of ⁶⁸Ga-PSMA PET/CT were higher than ¹⁸F-FDG PET/CT, there were still 13/56 (23.2%) patients with at least one PSMA-FDG+ lesion. The prostate-specific antigen (PSA) and Gleason score were both higher in the patients with PSMA-FDG+ lesions than in those without PSMA-FDG+ lesions (P = 0.04 and P<0.001, respectively). Multivariate regression analysis showed that the Gleason score (≥8) and PSA (≥7.9 ng/mL) were associated with the detection rate of patients who had PSMA-FDG+ lesions (P = 0.01 and P = 0.04, respectively). The incidences of having PSMA-FDG+ lesions in low-probability (Gleason score<8 and PSA<7.9 ng/mL), medium-probability (Gleason score≥8 and PSA<7.9 ng/mL or Gleason score<8 and PSA≥7.9 ng/mL), and high-probability (Gleason score≥8 and PSA≥7.9 ng/mL) groups were 0%, 21.7%, and 61.5%, respectively (P<0.001). Conclusion: Gleason score and PSA are significant predictors for PSMA-FDG+ lesions, and CRPC patients with high Gleason score and PSA may benefit from additional ¹⁸F-FDG PET/CT.

Visual Abstract

Researchers use dynamic PET imaging with target-selective tracer molecules to probe molecular processes. Kinetic models have been developed to describe these processes. The models are typically fitted to the measured PET data with the assumption that the brain is in a steady-state condition for the duration of the scan. The end results are quantitative parameters that characterize the molecular processes. The most common kinetic modeling endpoints are estimates of volume of distribution or the binding potential of a tracer. If the steady state is violated during the scanning period, the standard kinetic models may not apply. To address this issue, time-variant kinetic models have been developed for the characterization of dynamic PET data acquired while significant changes (e.g., short-lived neurotransmitter changes) are occurring in brain processes. These models are intended to extract a transient signal from data. This work in the PET field dates back at least to the 1990s. As interest has grown in imaging nonsteady events, development and refinement of time-variant models has accelerated. These new models, which we classify as belonging to the first, second, or third generation according to their innovation, have used the latest progress in mathematics, image processing, artificial intelligence, and statistics to improve the sensitivity and performance of the earliest practical time-variant models to detect and describe nonsteady phenomena. This review provides a detailed overview of the history of time-variant models in PET. It puts key advancements in the field into historical and scientific context. The sum total of the methods is an ongoing attempt to better understand the nature and implications of neurotransmitter fluctuations and other brief neurochemical phenomena.

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Sophos X-Ops unveils five-year investigation tracking China-based groups targeting perimeter devices

Felicia Grasso
Dec 1, 2020; 19:1986-1996
Research

Wenhe Zhu
Dec 29, 2020; 0:RA120.002353v1-mcp.RA120.002353
Research

Toma Keser
Dec 29, 2020; 0:RA120.002433v1-mcp.RA120.002433
Research

Kyle Swovick
Dec 28, 2020; 0:RA120.002301v1-mcp.RA120.002301
Research

Ji Eun Kim
Dec 20, 2020; 0:RA120.002159v1-mcp.RA120.002159
Research

Zilu Ye
Dec 28, 2020; 0:R120.002204v1-mcp.R120.002204
Review

Peter Lasch
Dec 1, 2020; 19:2125-2138
Technological Innovation and Resources

Julia Knöckel
Dec 22, 2020; 0:RA120.002432v1-mcp.RA120.002432
Research

Nadine Prust
Dec 17, 2020; 0:RA120.002232v1-mcp.RA120.002232
Research

Xinting Zhang
Dec 8, 2020; 0:RA120.002306v1-mcp.RA120.002306
Research

Laura F Fielden
Nov 11, 2020; 0:RA120.002370v1-mcp.RA120.002370
Research

Johannes Griss
Dec 1, 2020; 19:2115-2124
Technological Innovation and Resources

Philipp Emanuel Geyer
Dec 17, 2020; 0:RA120.002359v1-mcp.RA120.002359
Research

Adult progenitor cell populations typically exist in a quiescent state within a controlled niche environment. However, various stresses or forms of damage can disrupt this state, which often leads to dysfunction and aging. We built a glucocorticoid (GC)-induced liver damage model of mice, found that GC stress induced liver damage, leading to consequences for progenitor cells expansion. However, the mechanisms by which niche factors cause progenitor cells proliferation are largely unknown. We demonstrate that, within the liver progenitor cells niche, Galectin-3 (Gal-3) is responsible for driving a subset of progenitor cells to break quiescence. We show that GC stress causes aging of the niche, which induces the up-regulation of Gal-3. The increased Gal-3 population increasingly interacts with the progenitor cell marker CD133, which triggers focal adhesion kinase (FAK)/AMP-activated kinase (AMPK) signaling. This results in the loss of quiescence and leads to the eventual stemness exhaustion of progenitor cells. Conversely, blocking Gal-3 with the inhibitor TD139 prevents the loss of stemness and improves liver function. These experiments identify a stress-dependent change in progenitor cell niche that directly influence liver progenitor cell quiescence and function.

The extracellular matrix encompasses a reservoir of bioactive macromolecules that modulates a cornucopia of biological functions. A prominent body of work posits matrix constituents as master regulators of autophagy and angiogenesis and provides molecular insight into how these two processes are coordinated. Here, we review current understanding of the molecular mechanisms underlying hyaluronan and HAS2 regulation and the role of soluble proteoglycan in affecting autophagy and angiogenesis. Specifically, we assess the role of proteoglycan-evoked autophagy in regulating angiogenesis via the HAS2-hyaluronan axis and ATG9A, a novel HAS2 binding partner. We discuss extracellular hyaluronan biology and the post-transcriptional and post-translational modifications that regulate its main synthesizer, HAS2. We highlight the emerging group of proteoglycans that utilize outside-in signaling to modulate autophagy and angiogenesis in cancer microenvironments and thoroughly review the most up-to-date understanding of endorepellin signaling in vascular endothelia, providing insight into the temporal complexities involved.

Autophagy plays critical roles in the maintenance of endothelial cells in response to cellular stress caused by blood flow. There is growing evidence that both cell adhesion and cell detachment can modulate autophagy, but the mechanisms responsible for this regulation remain unclear. Immunoglobulin and proline-rich receptor-1 (IGPR-1) is a cell adhesion molecule that regulates angiogenesis and endothelial barrier function. In this study, using various biochemical and cellular assays, we demonstrate that IGPR-1 is activated by autophagy-inducing stimuli, such as amino acid starvation, nutrient deprivation, rapamycin, and lipopolysaccharide. Manipulating the IκB kinase β activity coupled with in vivo and in vitro kinase assays demonstrated that IκB kinase β is a key serine/threonine kinase activated by autophagy stimuli and that it catalyzes phosphorylation of IGPR-1 at Ser220. The subsequent activation of IGPR-1, in turn, stimulates phosphorylation of AMP-activated protein kinase, which leads to phosphorylation of the major pro-autophagy proteins ULK1 and Beclin-1 (BECN1), increased LC3-II levels, and accumulation of LC3 punctum. Thus, our data demonstrate that IGPR-1 is activated by autophagy-inducing stimuli and in response regulates autophagy, connecting cell adhesion to autophagy. These findings may have important significance for autophagy-driven pathologies such cardiovascular diseases and cancer and suggest that IGPR-1 may serve as a promising therapeutic target.

Elevated levels of fasting insulin release and insufficient glucose-stimulated insulin secretion (GSIS) are hallmarks of diabetes. Studies have established cross-talk between integrin signaling and insulin activity, but more details of how integrin-dependent signaling impacts the pathophysiology of diabetes are needed. Here, we dissected integrin-dependent signaling pathways involved in the regulation of insulin secretion in β-cells and studied their link to the still debated autocrine regulation of insulin secretion by insulin/insulin-like growth factor (IGF) 2–AKT signaling. We observed for the first time a cooperation between different AKT isoforms and focal adhesion kinase (FAK)–dependent adhesion signaling, which either controlled GSIS or prevented insulin secretion under fasting conditions. Indeed, β-cells form integrin-containing adhesions, which provide anchorage to the pancreatic extracellular matrix and are the origin of intracellular signaling via FAK and paxillin. Under low-glucose conditions, β-cells adopt a starved adhesion phenotype consisting of actin stress fibers and large peripheral focal adhesion. In contrast, glucose stimulation induces cell spreading, actin remodeling, and point-like adhesions that contain phospho-FAK and phosphopaxillin, located in small protrusions. Rat primary β-cells and mouse insulinomas showed an adhesion remodeling during GSIS resulting from autocrine insulin/IGF2 and AKT1 signaling. However, under starving conditions, the maintenance of stress fibers and the large adhesion phenotype required autocrine IGF2-IGF1 receptor signaling mediated by AKT2 and elevated FAK-kinase activity and ROCK-RhoA levels but low levels of paxillin phosphorylation. This starved adhesion phenotype prevented excessive insulin granule release to maintain low insulin secretion during fasting. Thus, deregulation of the IGF2 and adhesion-mediated signaling may explain dysfunctions observed in diabetes.

Transient receptor potential vanilloid 1 (TRPV1) channel is a multimodal receptor that is responsible for nociceptive, thermal, and mechanical sensations. However, which biomolecular partners specifically interact with TRPV1 remains to be elucidated. Here, we used cDNA library screening of genes from mouse dorsal root ganglia combined with patch-clamp electrophysiology to identify the voltage-gated potassium channel auxiliary subunit Kvβ1 physically interacting with TRPV1 channel and regulating its function. The interaction was validated in situ using endogenous dorsal root ganglia neurons, as well as a recombinant expression model in HEK 293T cells. The presence of Kvβ1 enhanced the expression stability of TRPV1 channels on the plasma membrane and the nociceptive current density. Surprisingly, Kvβ1 interaction also shifted the temperature threshold for TRPV1 thermal activation. Using site-specific mapping, we further revealed that Kvβ1 interacted with the membrane-distal domain and membrane-proximal domain of TRPV1 to regulate its membrane expression and temperature-activation threshold, respectively. Our data therefore suggest that Kvβ1 is a key element in the TRPV1 signaling complex and exerts dual regulatory effects in a site-specific manner.

Tuberculosis (TB), caused by the infection of Mycobacterium tuberculosis (MTB), is one of the leading causes of death worldwide, especially in children. However, the mechanisms by which MTB infects its cellular host, activates an immune response, and triggers inflammation remain unknown. Mitochondria play important roles in the initiation and activation of the nucleotide-binding oligomerization domain-like receptor with a pyrin domain 3 (NLRP3) inflammasome, where mitochondria-associated endoplasmic reticulum membranes (MAMs) may serve as the platform for inflammasome assembly and activation. Additionally, mitofusin 2 (MFN2) is implicated in the formation of MAMs, but, the roles of mitochondria and MFN2 in MTB infection have not been elucidated. Using mircroarry profiling of TB patients and in vitro MTB stimulation of macrophages, we observed an up-regulation of MFN2 in the peripheral blood mononuclear cells of active TB patients. Furthermore, we found that MTB stimulation by MTB-specific antigen ESAT-6 or lysate of MTB promoted MFN2 interaction with NLRP3 inflammasomes, resulting in the assembly and activation of the inflammasome and, subsequently, IL-1β secretion. These findings suggest that MFN2 and mitochondria play important role in the pathogen-host interaction during MTB infection.

Protein quality control is maintained by a number of integrated cellular pathways that monitor the folding and functionality of the cellular proteome. Defects in these pathways lead to the accumulation of misfolded or faulty proteins that may become insoluble and aggregate over time. Protein aggregates significantly contribute to the development of a number of human diseases such as amyotrophic lateral sclerosis, Huntington's disease, and Alzheimer's disease. In vitro, imaging-based, cellular studies have defined key biomolecular components that recognize and clear aggregates; however, no unifying method is available to quantify cellular aggregates, limiting our ability to reproducibly and accurately quantify these structures. Here we describe an ImageJ macro called AggreCount to identify and measure protein aggregates in cells. AggreCount is designed to be intuitive, easy to use, and customizable for different types of aggregates observed in cells. Minimal experience in coding is required to utilize the script. Based on a user-defined image, AggreCount will report a number of metrics: (i) total number of cellular aggregates, (ii) percentage of cells with aggregates, (iii) aggregates per cell, (iv) area of aggregates, and (v) localization of aggregates (cytosol, perinuclear, or nuclear). A data table of aggregate information on a per cell basis, as well as a summary table, is provided for further data analysis. We demonstrate the versatility of AggreCount by analyzing a number of different cellular aggregates including aggresomes, stress granules, and inclusion bodies caused by huntingtin polyglutamine expansion.

Mutations in the GUCY2D gene coding for the dimeric human retinal membrane guanylyl cyclase (RetGC) isozyme RetGC1 cause various forms of blindness, ranging from rod dysfunction to rod and cone degeneration. We tested how the mutations causing recessive congenital stationary night blindness (CSNB), recessive Leber's congenital amaurosis (LCA1), and dominant cone–rod dystrophy-6 (CORD6) affected RetGC1 activity and regulation by RetGC-activating proteins (GCAPs) and retinal degeneration-3 protein (RD3). CSNB mutations R666W, R761W, and L911F, as well as LCA1 mutations R768W and G982VfsX39, disabled RetGC1 activation by human GCAP1, -2, and -3. The R666W and R761W substitutions compromised binding of GCAP1 with RetGC1 in HEK293 cells. In contrast, G982VfsX39 and L911F RetGC1 retained the ability to bind GCAP1 in cyto but failed to effectively bind RD3. R768W RetGC1 did not bind either GCAP1 or RD3. The co-expression of GUCY2D allelic combinations linked to CSNB did not restore RetGC1 activity in vitro. The CORD6 mutation R838S in the RetGC1 dimerization domain strongly dominated the Ca2+ sensitivity of cyclase regulation by GCAP1 in RetGC1 heterodimer produced by co-expression of WT and the R838S subunits. It required higher Ca2+ concentrations to decelerate GCAP-activated RetGC1 heterodimer—6-fold higher than WT and 2-fold higher than the Ser838-harboring homodimer. The heterodimer was also more resistant than homodimers to inhibition by RD3. The observed biochemical changes can explain the dominant CORD6 blindness and recessive LCA1 blindness, both of which affect rods and cones, but they cannot explain the selective loss of rod function in recessive CSNB.

Post-transcriptional modifications of pre-mRNAs expand the diversity of proteomes in higher eukaryotes. In the brain, these modifications diversify the functional output of many critical neuronal signal molecules. In this study, we identified a brain-specific A-to-I RNA editing that changed glutamine to arginine (Q/R) at exon 20 and an alternative splicing of exon 4 in Tmem63b, which encodes a ubiquitously expressed osmosensitive cation channel. The channel isoforms lacking exon 4 occurred in ∼80% of Tmem63b mRNAs in the brain but were not detected in other tissues, suggesting a brain-specific splicing. We found that the Q/R editing was catalyzed by Adar2 (Adarb1) and required an editing site complementary sequence located in the proximal 5' end of intron 20. Moreover, the Q/R editing was almost exclusively identified in the splicing isoform lacking exon 4, indicating a coupling between the editing and the splicing. Elimination of the Q/R editing in brain-specific Adar2 knockout mice did not affect the splicing efficiency of exon 4. Furthermore, transfection with the splicing isoform containing exon 4 suppressed the Q/R editing in primary cultured cerebellar granule neurons. Thus, our study revealed a coupling between an RNA editing and a distant alternative splicing in the Tmem63b pre-mRNA, in which the splicing plays a dominant role. Finally, physiological analysis showed that the splicing and the editing coordinately regulate Ca2+ permeability and osmosensitivity of channel proteins, which may contribute to their functions in the brain.

Type I and III interferons induce expression of the “myxovirus resistance proteins” MxA in human cells and its ortholog Mx1 in murine cells. Human MxA forms cytoplasmic structures, whereas murine Mx1 forms nuclear bodies. Whereas both HuMxA and MuMx1 are antiviral toward influenza A virus (FLUAV) (an orthomyxovirus), only HuMxA is considered antiviral toward vesicular stomatitis virus (VSV) (a rhabdovirus). We previously reported that the cytoplasmic human GFP-MxA structures were phase-separated membraneless organelles (“biomolecular condensates”). In the present study, we investigated whether nuclear murine Mx1 structures might also represent phase-separated biomolecular condensates. The transient expression of murine GFP-Mx1 in human Huh7 hepatoma, human Mich-2H6 melanoma, and murine NIH 3T3 cells led to the appearance of Mx1 nuclear bodies. These GFP-MuMx1 nuclear bodies were rapidly disassembled by exposing cells to 1,6-hexanediol (5%, w/v), or to hypotonic buffer (40–50 mosm), consistent with properties of membraneless phase-separated condensates. Fluorescence recovery after photobleaching (FRAP) assays revealed that the GFP-MuMx1 nuclear bodies upon photobleaching showed a slow partial recovery (mobile fraction: ∼18%) suggestive of a gel-like consistency. Surprisingly, expression of GFP-MuMx1 in Huh7 cells also led to the appearance of GFP-MuMx1 in 20–30% of transfected cells in a novel cytoplasmic giantin-based intermediate filament meshwork and in cytoplasmic bodies. Remarkably, Huh7 cells with cytoplasmic murine GFP-MuMx1 filaments, but not those with only nuclear bodies, showed antiviral activity toward VSV. Thus, GFP-MuMx1 nuclear bodies comprised phase-separated condensates. Unexpectedly, GFP-MuMx1 in Huh7 cells also associated with cytoplasmic giantin-based intermediate filaments, and such cells showed antiviral activity toward VSV.