Lyme borreliosis is a tick-borne disease caused by the Borrelia burgdorferi sensu lato complex. Bio-Rad Laboratories has developed a fully automated multiplex bead-based assay for the detection of IgM and IgG antibodies to B. burgdorferi. The BioPlex 2200 Lyme Total assay exhibits an improved rate of seropositivity in patients with early Lyme infection. Asymptomatic subjects from endemic and nonendemic origins demonstrated a seroreactivity rate of approximately 4% that was similar to other commercial assays evaluated in this study. Coupled to this result was the observation that the Lyme Total assay retained a high first-tier specificity of 96% while demonstrating a relatively high sensitivity of 91% among a well-characterized CDC Premarketing Lyme serum panel. The Lyme Total assay also performs well under a modified two-tier algorithm (sensitivity, 84.4 to 88.9%; specificity, 98.4 to 99.5%). Furthermore, the new assay is able to readily detect early Lyme infection in patient samples from outside North America.

Limited treatment options contribute to high morbidity/mortality rates with carbapenem-resistant, Gram-negative bacterial infections. New approaches for carbapenemase-producing organism (CPO) detection may help inform clinician decision-making on patient treatment and infection control. BD Phoenix CPO detect (CPO detect) detects and classifies carbapenemases in Enterobacterales, Acinetobacter baumannii, and Pseudomonas aeruginosa during susceptibility testing. The clinical performance of CPO detect is reported here. Enterobacterales, Acinetobacter baumannii, and Pseudomonas aeruginosa isolates were evaluated across three sites using CPO detect and a composite reference method (RM); the latter was comprised of the modified carbapenem inactivation method and a MIC screen for ertapenem, imipenem, and meropenem. Multiplex PCR testing was also utilized for Ambler class determination. Positive and negative percentages of agreement (PPA and NPA, respectively) between CPO detect and the RM were determined. The PPA and NPA for Enterobacterales were 98.5% (confidence intervals, 96.6%, 99.4%) and 97.2% (95.8%, 98.2%), respectively. The A. baumannii PPA and NPA, respectively, were 97.1% (90.2%, 99.2%) and 97.1% (89.9%, 99.2%). The P. aeruginosa PPA and NPA, respectively, were 95.9% (88.6%, 98.6%) and 92.3% (86.7%, 95.6%). The PPA values for carbapenemase class designations for all organisms combined and Enterobacterales alone, respectively, were 95.3% (90.2%, 97.8%) and 94.6% (88.8%, 97.5%) for class A, 94.0% (88.7%, 96.6%) and 96.4% (90.0%, 98.8%) for class B, and 95.0% (90.1%, 97.6%) and 99.0% (94.4%, 99.8%) for class D carbapenemases. NPA values for all organisms and Enterobacterales alone ranged from 98.5% to 100%. CPO detect provided accurate detection and classification of CPOs for the majority of isolates of Enterobacterales, Acinetobacter baumannii, and Pseudomonas aeruginosa tested.

MALDI-TOF mass spectrometry (MS) identification of pathogenic filamentous fungi is often impaired by difficulties in harvesting hyphae embedded in the medium and long extraction protocols. The ID Fungi Plate (IDFP) is a novel culture method developed to address such difficulties and improve the identification of filamentous fungi by MALDI-TOF MS. We cultured 64 strains and 11 clinical samples on IDFP, Sabouraud agar-chloramphenicol (SAB), and ChromID Candida agar (CAN2). We then compared the three media for growth, ease of harvest, amount of material picked, and MALDI-TOF identification scores after either rapid direct transfer (DT) or a long ethanol-acetonitrile (EA) extraction protocol. Antifungal susceptibility testing and microscopic morphology after subculture on SAB and IDFP were also compared for ten molds. Growth rates and morphological aspects were similar for the three media. With IDFP, harvesting of fungal material for the extraction procedure was rapid and easy in 92.4% of cases, whereas it was tedious on SAB or CAN2 in 65.2% and 80.3% of cases, respectively. The proportion of scores above 1.7 (defined as acceptable identification) were comparable for both extraction protocols using IDFP (P = 0.256). Moreover, rates of acceptable identification after DT performed on IDFP (93.9%) were significantly higher than those obtained after EA extraction with SAB (69.7%) or CAN2 (71.2%) (P = <0.001 and P = 0.001, respectively). Morphological aspects and antifungal susceptibility testing were similar between IDFP and SAB. IDFP is a culture plate that facilitates and improves the identification of filamentous fungi, allowing accurate routine identification of molds with MALDI-TOF-MS using a rapid-extraction protocol.

Human herpesvirus 6 (HHV-6) is an important cause of meningitis and meningoencephalitis. As testing for HHV-6 in cerebrospinal fluid (CSF) is more readily available using the FilmArray Meningitis/Encephalitis panel (FA-ME; BioFire Diagnostics, Salt Lake City, UT), we aimed to determine the clinical significance of detecting HHV-6 in order to identify true infections and to ensure appropriate antiviral initiation. Chart review on 25 patients positive for HHV-6 by FA-ME was performed to determine clinical presentation, comorbidity, treatment, and outcome. The presence of chromosomally integrated HHV-6 (ciHHV-6) DNA was also investigated. Of 1,005 children tested by FA-ME, HHV-6 was detected in 25 (2.5%). Five patients were diagnosed with either HHV-6 meningitis or meningoencephalitis based on HHV-6 detection in CSF, clinical presentation, and radiographic findings. Detection of HHV-6 by FA-ME led to discontinuation of acyclovir within 12.0 h in all 12 patients empirically treated with acyclovir. Six of the 12 patients were started on ganciclovir therapy within 6.8 h; 4 of these were treated specifically for HHV-6 infection, whereas therapy was discontinued in the remaining 2 patients. CSF parameters were not generally predictive of HHV-6 positivity. The presence of ciHHV-6 was confirmed in 3 of 18 patients who could be tested. Five of the 25 patients included in the study were diagnosed with HHV-6 meningitis/meningoencephalitis. FA-ME results led to discontinuation of empirical antiviral treatment in 12 patients and appropriate initiation of ganciclovir in 4 patients. In our institution, detection of HHV-6 using FA-ME led to faster establishment of disease etiology and optimization of antimicrobial therapy.

On 31 December 2019, the World Health Organization was informed of a cluster of cases of pneumonia of unknown etiology in Wuhan, China. Subsequent investigations identified a novel coronavirus, now named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), from the affected patients. Highly sensitive and specific laboratory diagnostics are important for controlling the rapidly evolving SARS-CoV-2-associated coronavirus disease 2019 (COVID-19) epidemic. In this study, we developed and compared the performance of three novel real-time reverse transcription-PCR (RT-PCR) assays targeting the RNA-dependent RNA polymerase (RdRp)/helicase (Hel), spike (S), and nucleocapsid (N) genes of SARS-CoV-2 with that of the reported RdRp-P2 assay, which is used in >30 European laboratories. Among the three novel assays, the COVID-19-RdRp/Hel assay had the lowest limit of detection in vitro (1.8 50% tissue culture infective doses [TCID₅₀]/ml with genomic RNA and 11.2 RNA copies/reaction with in vitro RNA transcripts). Among 273 specimens from 15 patients with laboratory-confirmed COVID-19 in Hong Kong, 77 (28.2%) were positive by both the COVID-19-RdRp/Hel and RdRp-P2 assays. The COVID-19-RdRp/Hel assay was positive for an additional 42 RdRp-P2-negative specimens (119/273 [43.6%] versus 77/273 [28.2%]; P < 0.001), including 29/120 (24.2%) respiratory tract specimens and 13/153 (8.5%) non-respiratory tract specimens. The mean viral load of these specimens was 3.21 x 10⁴ RNA copies/ml (range, 2.21 x 10² to 4.71 x 10⁵ RNA copies/ml). The COVID-19-RdRp/Hel assay did not cross-react with other human-pathogenic coronaviruses and respiratory pathogens in cell culture and clinical specimens, whereas the RdRp-P2 assay cross-reacted with SARS-CoV in cell culture. The highly sensitive and specific COVID-19-RdRp/Hel assay may help to improve the laboratory diagnosis of COVID-19.

The new decade of the 21^st century (2020) started with the emergence of a novel coronavirus known as SARS-CoV-2 that caused an epidemic of coronavirus disease (COVID-19) in Wuhan, China. It is the third highly pathogenic and transmissible coronavirus after severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV) emerged in humans. The source of origin, transmission to humans, and mechanisms associated with the pathogenicity of SARS-CoV-2 are not yet clear, however, its resemblance to SARS-CoV and several other bat coronaviruses was recently confirmed through genome sequencing-related studies. The development of therapeutic strategies is necessary in order to prevent further epidemics and cure infections. In this review, we summarize current information about the emergence, origin, diversity, and epidemiology of three pathogenic coronaviruses with a specific focus on the current outbreak in Wuhan, China. Furthermore, we discuss the clinical features and potential therapeutic options that may be effective against SARS-CoV-2.

The QIAstat-Dx Respiratory Panel (QIAstat-Dx RP) is a multiplex in vitro diagnostic test for the qualitative detection of 20 pathogens directly from nasopharyngeal swab (NPS) specimens. The assay is performed using a simple sample-to-answer platform with results available in approximately 69 min. The pathogens identified are adenovirus, coronavirus 229E, coronavirus HKU1, coronavirus NL63, coronavirus OC43, human metapneumovirus A and B, influenza A, influenza A H1, influenza A H3, influenza A H1N1/2009, influenza B, parainfluenza virus 1, parainfluenza virus 2, parainfluenza virus 3, parainfluenza virus 4, rhinovirus/enterovirus, respiratory syncytial virus A and B, Bordetella pertussis, Chlamydophila pneumoniae, and Mycoplasma pneumoniae. This multicenter evaluation provides data obtained from 1,994 prospectively collected and 310 retrospectively collected (archived) NPS specimens with performance compared to that of the BioFire FilmArray Respiratory Panel, version 1.7. The overall percent agreement between QIAstat-Dx RP and the comparator testing was 99.5%. In the prospective cohort, the QIAstat-Dx RP demonstrated a positive percent agreement of 94.0% or greater for the detection of all but four analytes: coronaviruses 229E, NL63, and OC43 and rhinovirus/enterovirus. The test also demonstrated a negative percent agreement of ≥97.9% for all analytes. The QIAstat-Dx RP is a robust and accurate assay for rapid, comprehensive testing for respiratory pathogens.

The IR Biotyper is a new automated typing system based on Fourier-transform infrared (FT-IR) spectroscopy that gives results within 4 h. We aimed (i) to use the IR Biotyper to retrospectively analyze an outbreak of extended-spectrum beta-lactamase-producing Klebsiella pneumoniae (ESBL-KP) in a neonatal intensive care unit and to compare results to BOX-PCR and whole-genome sequencing (WGS) results as the gold standard and (ii) to assess how the cutoff values used to define clusters affect the discriminatory power of the IR Biotyper. The sample consisted of 18 isolates from 14 patients. Specimens were analyzed in the IR Biotyper using the default analysis settings, and spectra were analyzed using OPUS 7.5 software. The software contains a feature that automatically proposes a cutoff value to define clusters; the cutoff value defines up to which distance the spectra are considered to be in the same cluster. Based on FT-IR, the outbreak represented 1 dominant clone, 1 secondary clone, and several unrelated clones. FT-IR results, using the cutoff value generated by the accompanying software after 4 replicates, were concordant with WGS for all but 1 isolate. BOX-PCR was underdiscriminatory compared to the other two methods. Using the cutoff value generated after 12 replicates, the results of FT-IR and WGS were completely concordant. The IR Biotyper can achieve the same typeability and discriminatory power as genome-based methods. However, to attain this high performance requires either previous, strain-dependent knowledge about the optimal technical parameters to be used or validation by a second method.

Transcription of a chromatin template involves the concerted interaction of many different proteins and protein complexes. Analyses of specific factors showed that these interactions change during stress and upon developmental switches. However, how the binding of multiple factors at any given locus is coordinated has been technically challenging to investigate. Here we used Epi-Decoder in yeast to systematically decode, at one transcribed locus, the chromatin binding changes of hundreds of proteins in parallel upon perturbation of transcription. By taking advantage of improved Epi-Decoder libraries, we observed broad rewiring of local chromatin proteomes following chemical inhibition of RNA polymerase. Rapid reduction of RNA polymerase II binding was accompanied by reduced binding of many other core transcription proteins and gain of chromatin remodelers. In quiescent cells, where strong transcriptional repression is induced by physiological signals, eviction of the core transcriptional machinery was accompanied by the appearance of quiescent cell–specific repressors and rewiring of the interactions of protein-folding factors and metabolic enzymes. These results show that Epi-Decoder provides a powerful strategy for capturing the temporal binding dynamics of multiple chromatin proteins under varying conditions and cell states. The systematic and comprehensive delineation of dynamic local chromatin proteomes will greatly aid in uncovering protein–protein relationships and protein functions at the chromatin template.

Retrospective lineage tracing harnesses naturally occurring mutations in cells to elucidate single cell development. Common single-cell phylogenetic fate mapping methods have utilized highly mutable microsatellite loci found within the human genome. Such methods were limited by the introduction of in vitro noise through polymerase slippage inherent in DNA amplification, which we characterized to be approximately 10–100x higher than the in vivo replication mutation rate. Here, we present RETrace, a method for simultaneously capturing both microsatellites and methylation-informative cytosines to characterize both lineage and cell type, respectively, from the same single cell. An important unique feature of RETrace was the introduction of linear amplification of microsatellites in order to reduce in vitro amplification noise. We further coupled microsatellite capture with single-cell reduced representation bisulfite sequencing (scRRBS), to measure the CpG methylation status on the same cell for cell type inference. When compared to existing retrospective lineage tracing methods, RETrace achieved higher accuracy (88% triplet accuracy from an ex vivo HCT116 tree) at a higher cell division resolution (lowering the required number of cell division difference between single cells by approximately 100 divisions). Simultaneously, RETrace demonstrated the ability to capture on average 150,000 unique CpGs per single cell in order to accurately determine cell type. We further formulated additional developments that would allow high-resolution mapping on microsatellite-stable cells or tissues with RETrace. Overall, we present RETrace as a foundation for multi-omics lineage mapping and cell typing of single cells.

Recent progress has been made in identifying genomic regions implicated in trait evolution on a microevolutionary scale in many species, but whether these are relevant over macroevolutionary time remains unclear. Here, we directly address this fundamental question using bird beak shape, a key evolutionary innovation linked to patterns of resource use, divergence, and speciation, as a model trait. We integrate class-wide geometric-morphometric analyses with evolutionary sequence analyses of 10,322 protein-coding genes as well as 229,001 genomic regions spanning 72 species. We identify 1434 protein-coding genes and 39,806 noncoding regions for which molecular rates were significantly related to rates of bill shape evolution. We show that homologs of the identified protein-coding genes as well as genes in close proximity to the identified noncoding regions are involved in craniofacial embryo development in mammals. They are associated with embryonic stem cell pathways, including BMP and Wnt signaling, both of which have repeatedly been implicated in the morphological development of avian beaks. This suggests that identifying genotype-phenotype association on a genome-wide scale over macroevolutionary time is feasible. Although the coding and noncoding gene sets are associated with similar pathways, the actual genes are highly distinct, with significantly reduced overlap between them and bill-related phenotype associations specific to noncoding loci. Evidence for signatures of recent diversifying selection on our identified noncoding loci in Darwin finch populations further suggests that regulatory rather than coding changes are major drivers of morphological diversification over macroevolutionary times.

Cohesin is a ring-shaped multiprotein complex that is crucial for 3D genome organization and transcriptional regulation during differentiation and development. It also confers sister chromatid cohesion and facilitates DNA damage repair. Besides its core subunits SMC3, SMC1A, and RAD21, cohesin in somatic cells contains one of two orthologous STAG subunits, STAG1 or STAG2. How these variable subunits affect the function of the cohesin complex is still unclear. STAG1- and STAG2-cohesin were initially proposed to organize cohesion at telomeres and centromeres, respectively. Here, we uncover redundant and specific roles of STAG1 and STAG2 in gene regulation and chromatin looping using HCT116 cells with an auxin-inducible degron (AID) tag fused to either STAG1 or STAG2. Following rapid depletion of either subunit, we perform high-resolution Hi-C, gene expression, and sequential ChIP studies to show that STAG1 and STAG2 do not co-occupy individual binding sites and have distinct ways by which they affect looping and gene expression. These findings are further supported by single-molecule localizations via direct stochastic optical reconstruction microscopy (dSTORM) super-resolution imaging. Since somatic and congenital mutations of the STAG subunits are associated with cancer (STAG2) and intellectual disability syndromes with congenital abnormalities (STAG1 and STAG2), we verified STAG1-/STAG2-dependencies using human neural stem cells, hence highlighting their importance in particular disease contexts.

Pre-eclampsia (PE)-induced fetal programming predisposes offspring to health hazards in adult life. Here, we tested the hypothesis that pre-eclamptic fetal programming elicits sexually dimorphic inflammatory and cardiovascular complications to endotoxemia in adult rat offspring. PE was induced by oral administration of L-NAME (50 mg/kg per day for seven consecutive days) starting from day 14 of conception. Cardiovascular studies were performed in conscious adult male and female offspring preinstrumented with femoral indwelling catheters. Compared with non-PE male counterparts, intravenous administration of lipopolysaccharide (LPS, 5 mg/kg) to PE male offspring caused significantly greater 1) falls in blood pressure, 2) increases in heart rate, 3) rises in arterial dP/dtmax, a correlate of left ventricular contractility, and 4) decreases in time- and frequency-domain indices of heart rate variability (HRV). By contrast, the hypotensive and tachycardic actions of LPS in female offspring were independent of the pre-eclamptic state and no clear changes in HRV or dP/dtmax were noted. Measurement of arterial baroreflex activity by vasoactive method revealed no sex specificity in baroreflex dysfunction induced by LPS. Immunohistochemical studies showed increased protein expression of toll-like receptor 4 in heart as well as in brainstem neuronal pools of the nucleus of solitary tract and rostral ventrolateral medulla in endotoxic PE male, but not female, offspring. Enhanced myocardial, but not neuronal, expression of monocyte chemoattractant protein-1 was also demonstrated in LPS-treated male offspring. Together, pre-eclamptic fetal programming aggravates endotoxic manifestations of hypotension and autonomic dysfunction in male offspring via exacerbating myocardial and neuromedullary inflammatory pathways.

Transient receptor potential (TRP) melastatin 8 (TRPM8) is a temperature-sensing ion channel mainly expressed in primary sensory neurons (A-fibers and C-fibers in the dorsal root ganglion). In this report, we characterized KPR-5714 (N-[(R)-3,3-difluoro-4-hydroxy-1-(2H-1,2,3-triazol-2-yl)butan-2-yl]-3-fluoro-2-[5-(4-fluorophenyl)-1H-pyrazol-3-yl]benzamide), a novel and selective TRPM8 antagonist, to assess its therapeutic potential against frequent urination in rat models with overactive bladder (OAB). In calcium influx assays with HEK293T cells transiently expressing various TRP channels, KPR-5714 showed a potent TRPM8 antagonistic effect and high selectivity against other TRP channels. Intravenously administered KPR-5714 inhibited the hyperactivity of mechanosensitive C-fibers of bladder afferents and dose-dependently increased the intercontraction interval shortened by intravesical instillation of acetic acid in anesthetized rats. Furthermore, we examined the effects of KPR-5714 on voiding behavior in conscious rats with cerebral infarction and in those exposed to cold in metabolic cage experiments. Cerebral infarction and cold exposure induced a significant decrease in the mean voided volume and increase in voiding frequency in rats. Orally administered KPR-5714 dose-dependently increased the mean voided volume and decreased voiding frequency without affecting total voided volume in these models. This study demonstrates that KPR-5714 improves OAB in three different models by inhibiting exaggerated activity of mechanosensitive bladder C-fibers and suggests that KPR-5714 may provide a new and useful approach to the treatment of OAB.

Glucagon-like peptide-2 (GLP-2) agonists have therapeutic potential in clinical indications in which the integrity or absorptive function of the intestinal mucosa is compromised, such as in short bowel syndrome (SBS). Native hGLP-2, a 33–amino acid peptide secreted from the small intestine, contributes to nutritional absorption but has a very short half-life because of enzymatic cleavage and renal clearance and thus is of limited therapeutic value. The GLP-2 analog teduglutide (Revestive/Gattex; Shire Inc.) has been approved for use in SBS since 2012 but has a once-daily injection regimen. Pharmacokinetic (PK) and pharmacodynamic studies confirm that apraglutide, a novel GLP-2 analog, has very low clearance, long elimination half-life, and high plasma protein binding compared with GLP-2 analogs teduglutide and glepaglutide. Apraglutide and teduglutide retain potency and selectivity at the GLP-2 receptor comparable to native hGLP-2, whereas glepaglutide was less potent and less selective. In rat intravenous PK studies, hGLP-2, teduglutide, glepaglutide, and apraglutide had clearances of 25, 9.9, 2.8, and 0.27 ml/kg per minute, respectively, and elimination half-lives of 6.4, 19, 16, and 159 minutes, respectively. The unique PK profile of apraglutide administered via intravenous and subcutaneous routes was confirmed in monkey and minipig and translated into significantly greater in vivo pharmacodynamic activity, measured as small intestinal growth in rats. Apraglutide showed greater intestinotrophic activity than the other peptides when administered at less-frequent dosing intervals because of its prolonged half-life. We postulate that apraglutide offers several advantages over existing GLP-2 analogs and is an excellent candidate for the treatment of gastrointestinal diseases, such as SBS.

Abicipar pegol (abicipar) is a novel DARPin therapeutic and highly potent vascular endothelial growth factor (VEGF) inhibitor intended for the treatment of neovascular age-related macular degeneration (nAMD). Here we develop a translational pharmacokinetic/pharmacodynamic (PK/PD) model for abicipar to guide dosing regimens in the clinic. The model incorporated abicipar-VEGF binding kinetics, VEGF expression levels, and VEGF turnover rates to describe the ocular and systemic PK data collected from the vitreous, aqueous humor (AH), choroid, retina, and serum of rabbits after a 1-mg abicipar intravitreal (IVT) dose. The model was translated to humans using human-specific mechanistic parameters and refitted to human serum and AH concentrations from patients with diabetic macular edema and nAMD. The model was then used to simulate 8-, 12- (quarterly), and 16-week dosing intervals in the clinic. Simulations of 2 mg abicipar IVT at 8-week or quarterly dosing in humans indicates minimum steady-state vitreal concentrations are maintained above both in vitro IC₅₀ and in vivo human IC₅₀ values. The model predicted virtually complete VEGF inhibition for the 8-week and quarterly dosing schedule during the 52-week treatment period. In the 16-week schedule, clinically significant VEGF inhibition was maintained during the 52-week period. The model quantitatively described abicipar-VEGF target engagement leading to rapid reduction of VEGF and a long duration of VEGF inhibition demonstrating the clinical feasibility of up to a 16-week dosing interval. Abicipar is predicted to reduce IVT dosing compared with other anti-VEGF therapies with the potential to lessen patient treatment burden.

Decreased release of palmitic acid methyl ester (PAME), a vasodilator, from perivascular adipose tissue (PVAT) might contribute to hypertension pathogenesis. However, the PAME biosynthetic pathway remains unclear. In this study, we hypothesized that PAME is biosynthesized from palmitic acid (PA) via human catechol-O-methyltransferase (COMT) catalysis and that decreased PAME biosynthesis plays a role in hypertension pathogenesis. We compared PAME biosynthesis between age-matched normotensive Wistar Kyoto (WKY) rats and hypertensive spontaneously hypertensive rats (SHRs) and investigated the effects of losartan treatment on PAME biosynthesis. Computational molecular modeling indicated that PA binds well at the active site of COMT. Furthermore, in in vitro enzymatic assays in the presence of COMT and S-5'-adenosyl-L-methionine (AdoMet), the stable isotope [¹³C₁₆]-PA was methylated to form [¹³C₁₆]-PAME in incubation medium or the Krebs–Henseleit solution containing 3T3-L1 adipocytes or rat PVAT. The adipocytes and PVATs expressed membrane-bound (MB)-COMT and soluble (S)-COMT proteins. [¹³C₁₆]-PA methylation to form [¹³C₁₆]-PAME in 3T3-L1 adipocytes and rat PVAT was blocked by various COMT inhibitors, such as S-(5'-adenosyl)-L-homocysteine, adenosine-2',3'-dialdehyde, and tolcapone. MB- and S-COMT levels in PVATs of established SHRs were significantly lower than those in PVATs of age-matched normotensive WKY rats, with decreased [¹³C₁₆]-PA methylation to form [¹³C₁₆]-PAME. This decrease was reversed by losartan, an angiotensin II (Ang II) type 1 receptor antagonist. Therefore, PAME biosynthesis in rat PVAT is dependent on AdoMet, catalyzed by COMT, and decreased in SHRs, further supporting the role of PVAT/PAME in hypertension pathogenesis. Moreover, the antihypertensive effect of losartan might be due partly to its increased PAME biosynthesis.

Monica L. Salgado-Lucio, Danelia Ramirez-Ramirez, Coral Y. Jorge-Cruz, Ana L. Roa-Espitia, and Enrique O. Hernandez-Gonzalez

Actin polymerization is a crucial process during sperm capacitation. We have recently described the participation of FAK during actin polymerization in guinea pig spermatozoa. However, the mechanism by which FAK mediates these processes is unknown. Our previous data have shown that MAPK1 (hereafter referred to as ERK2) is activated during the first minutes of capacitation, and inhibition of ERK2 blocked actin polymerization and the acrosome reaction. In this current study, we found that FAK is involved in ERK2 activation – as FAK was phosphorylated at tyrosine residue 925 and bound to Grb2 – and that inhibition of FAK results in a significant decrease of ERK2 activation. We also confirmed the presence of Rho guanine nucleotide exchange factor 2 (ARHGEF2, hereafter referred to as GEF-H1), which is able to associate with RhoA during capacitation. RhoA activation and its participation in actin polymerization were also analyzed. Inhibition of FAK or ERK1/2 impeded GEF-H1 phosphorylation, RhoA activation, and the association between GEF-H1 and RhoA. Finally, we observed the presence of fibronectin on the sperm surface, its role in sperm–sperm interaction as well as participation of β-integrin in the activation of ERK2. Our results show that the signaling pathway downstream of fibronectin, via integrin, FAK, Grb2, MEK1/2, ERK2, GEF-H1 and RhoA regulates the actin polymerization associated with spermatozoa capacitation.

The first Biograph Vision PET/CT system (Siemens Healthineers) was installed at the University Medical Center Groningen. Improved performance of this system could allow for a reduction in activity administration or scan duration. This study evaluated the effects of reduced scan duration in oncologic ¹⁸F-FDG PET imaging on quantitative and subjective imaging parameters and its influence on clinical image interpretation. Methods: Patients referred for a clinical PET/CT scan were enrolled in this study, received a weight-based ¹⁸F-FDG injected activity, and underwent list-mode PET acquisition at 180 s per bed position (s/bp). Acquired PET data were reconstructed using the vendor-recommended clinical reconstruction protocol (hereafter referred to as "clinical"), using the clinical protocol with additional 2-mm gaussian filtering (hereafter referred to as "clinical+G2"), and—in conformance with European Association of Nuclear Medicine Research Ltd. (EARL) specifications—using different scan durations per bed position (180, 120, 60, 30, and 10 s). Reconstructed images were quantitatively assessed for comparison of SUVs and noise. In addition, clinically reconstructed images were qualitatively evaluated by 3 nuclear medicine physicians. Results: In total, 30 oncologic patients (22 men, 8 women; age: 48–88 y [range], 67 ± 9.6 y [mean ± SD]) received a single weight-based (3 MBq/kg) ¹⁸F-FDG injected activity (weight: 45–123 kg [range], 81 ± 15 kg [mean ± SD]; activity: 135–380 MBq [range], 241 ± 47.3 MBq [mean ± SD]). Significant differences in lesion SUV_max were found between the 180-s/bp images and the 30- and 10-s/bp images reconstructed using the clinical protocols, whereas no differences were found in lesion SUV_peak. EARL-compliant images did not show differences in lesion SUV_max or SUV_peak between scan durations. Quantitative parameters showed minimal deviation (~5%) in the 60-s/bp images. Therefore, further subjective image quality assessment was conducted using the 60-s/bp images. Qualitative assessment revealed the influence of personal preference on physicians’ willingness to adopt the 60-s/bp images in clinical practice. Although quantitative PET parameters differed minimally, an increase in noise was observed. Conclusion: With the Biograph Vision PET/CT system for oncologic ¹⁸F-FDG imaging, scan duration or activity administration could be reduced by a factor of 3 or more with the use of the clinical+G2 or the EARL-compliant reconstruction protocol.

Brain-infiltrating leukocytes contribute to multiple sclerosis (MS) and autoimmune encephalomyelitis and likely play a role in traumatic brain injury, seizure, and stroke. Brain-infiltrating leukocytes are also primary targets for MS disease-modifying therapies. However, no method exists for noninvasively visualizing these cells in a living organism. 1-(2'-deoxy-2'-¹⁸F-fluoroarabinofuranosyl) cytosine (¹⁸F-FAC) is a PET radiotracer that measures deoxyribonucleoside salvage and accumulates preferentially in immune cells. We hypothesized that ¹⁸F-FAC PET could noninvasively image brain-infiltrating leukocytes. Methods: Healthy mice were imaged with ¹⁸F-FAC PET to quantify if this radiotracer crosses the blood–brain barrier (BBB). Experimental autoimmune encephalomyelitis (EAE) is a mouse disease model with brain-infiltrating leukocytes. To determine whether ¹⁸F-FAC accumulates in brain-infiltrating leukocytes, EAE mice were analyzed with ¹⁸F-FAC PET, digital autoradiography, and immunohistochemistry, and deoxyribonucleoside salvage activity in brain-infiltrating leukocytes was analyzed ex vivo. Fingolimod-treated EAE mice were imaged with ¹⁸F-FAC PET to assess if this approach can monitor the effect of an immunomodulatory drug on brain-infiltrating leukocytes. PET scans of individuals injected with 2-chloro-2'-deoxy-2'-¹⁸F-fluoro-9-β-d-arabinofuranosyl-adenine (¹⁸F-CFA), a PET radiotracer that measures deoxyribonucleoside salvage in humans, were analyzed to evaluate whether ¹⁸F-CFA crosses the human BBB. Results: ¹⁸F-FAC accumulates in the healthy mouse brain at levels similar to ¹⁸F-FAC in the blood (2.54 ± 0.2 and 3.04 ± 0.3 percentage injected dose per gram, respectively) indicating that ¹⁸F-FAC crosses the BBB. EAE mice accumulate ¹⁸F-FAC in the brain at 180% of the levels of control mice. Brain ¹⁸F-FAC accumulation localizes to periventricular regions with significant leukocyte infiltration, and deoxyribonucleoside salvage activity is present at similar levels in brain-infiltrating T and innate immune cells. These data suggest that ¹⁸F-FAC accumulates in brain-infiltrating leukocytes in this model. Fingolimod-treated EAE mice accumulate ¹⁸F-FAC in the brain at 37% lower levels than control-treated EAE mice, demonstrating that ¹⁸F-FAC PET can monitor therapeutic interventions in this mouse model. ¹⁸F-CFA accumulates in the human brain at 15% of blood levels (0.08 ± 0.01 and 0.54 ± 0.07 SUV, respectively), indicating that ¹⁸F-CFA does not cross the BBB in humans. Conclusion: ¹⁸F-FAC PET can visualize brain-infiltrating leukocytes in a mouse MS model and can monitor the response of these cells to an immunomodulatory drug. Translating this strategy into humans will require exploring additional radiotracers.

C-X-C motif chemokine receptor 4 (CXCR4) is expressed on the surface of various cell types involved in atherosclerosis, with a particularly rich receptor expression on macrophages and T cells. First pilot studies with ⁶⁸Ga-pentixafor, a novel CXCR4-directed PET tracer, have shown promise to noninvasively image inflammation within atherosclerotic plaques. The aim of this retrospective study was to investigate the performance of ⁶⁸Ga-pentixafor PET/CT for imaging atherosclerosis in comparison to ¹⁸F-FDG PET/CT. Methods: Ninety-two patients (37 women and 55 men; mean age, 62 ± 10 y) underwent ⁶⁸Ga-pentixafor and ¹⁸F-FDG PET/CT for staging of oncologic diseases. In these subjects, lesions in the walls of large arteries were identified using morphologic and PET criteria for atherosclerosis (n = 652). Tracer uptake was measured and adjusted for vascular lumen (background) signal by calculation of target-to-background ratios (TBRs) by 2 investigators masked to the other PET scan. On a lesion-to-lesion and patient basis, the TBRs of both PET tracers were compared and additionally correlated to the degree of arterial calcification as quantified in CT. Results: On a lesion-to-lesion basis, ⁶⁸Ga-pentixafor and ¹⁸F-FDG uptake showed a weak correlation (r = 0.28; P < 0.01). ⁶⁸Ga-pentixafor PET identified more lesions (n = 290; TBR ≥ 1.6, P < 0.01) and demonstrated higher uptake than ¹⁸F-FDG PET (1.8 ± 0.5 vs. 1.4 ± 0.4; P < 0.01). The degree of plaque calcification correlated negatively with both ⁶⁸Ga-pentixafor and ¹⁸F-FDG uptake (r = –0.38 vs. –0.31, both P < 0.00001). Conclusion: CXCR4-directed imaging of the arterial wall with ⁶⁸Ga-pentixafor PET/CT identified more lesions than ¹⁸F-FDG PET/CT, with only a weak correlation between tracers. Further studies to elucidate the underlying biologic mechanisms and sources of CXCR4 positivity, and to investigate the clinical utility of chemokine receptor–directed imaging of atherosclerosis, are highly warranted.

¹⁸F-prostate-specific membrane antigen (PSMA)-1007 is excreted mainly through the liver. We benchmarked the performance of ¹⁸F-PSMA-1007 against 3 renally excreted PSMA tracers. Methods: Among 668 patients, we selected 27 in whom PET/CT results obtained with ⁶⁸Ga-PSMA-11, ¹⁸F-DCFPyL (2-(3-(1-carboxy-5-[(6-[¹⁸F]fluoro-pyridine-3-carbonyl)-amino]-pentyl)-ureido)-pentanedioic acid), or ¹⁸F-JK-PSMA-7 (JK, Juelich-Koeln) were interpreted as equivocal or negative or as oligometastatic disease (PET-1). Within 3 wk, a second PET scan with ¹⁸F-PSMA-1007 was performed (PET-2). The confidence in the interpretation of PSMA-positive locoregional findings was scored on a 5-point scale, first in routine diagnostics (reader 1) and then by an independent second evaluation (reader 2). Discordant PSMA-positive skeletal findings were examined by contrast-enhanced MRI. Results: For both readers, ¹⁸F-PSMA-1007 facilitated the interpretability of 27 locoregional lesions. In PET-2, the clinical readout led to a significantly lower number of equivocal locoregional lesions (P = 0.024), and reader 2 reported a significantly higher rate of suspected lesions that were falsely interpreted as probably benign in PET-1 (P = 0.023). Exclusively in PET-2, we observed a total of 15 PSMA-positive spots in the bone marrow of 6 patients (22%). None of the 15 discordant spots had a morphologic correlate on the corresponding CT scan or on the subsequent MRI scan. Thus, ¹⁸F-PSMA-1007 exhibits a significantly higher rate of unspecific medullary spots (P = 0.0006). Conclusion: ¹⁸F-PSMA-1007 may increase confidence in interpreting small locoregional lesions adjacent to the urinary tract but may decrease the interpretability of skeletal lesions.

¹⁸F-rhPSMA-7 (radiohybrid prostate-specific membrane antigen [PSMA]) is a novel ligand for PET imaging. Here, we present data from a retrospective analysis using PET/CT and PET/MRI examinations to investigate the efficacy of ¹⁸F-rhPSMA-7 PET for primary N-staging of patients with prostate cancer (PC) compared with morphologic imaging (CT or MRI) and validated by histopathology. Methods: Data from 58 patients with high-risk PC (according to the D’Amico criteria) who were staged with ¹⁸F-rhPSMA-7 PET/CT or PET/MRI at our institution between July 2017 and June 2018 were reviewed. The patients had a median prescan prostate-specific antigen value of 12.2 ng/mL (range, 1.2–81.6 ng/mL). The median injected activity of ¹⁸F-rhPSMA-7 was 327 MBq (range, 132–410 MBq), with a median uptake time of 79.5 min (range, 60–153 min). All patients underwent subsequent radical prostatectomy and extended pelvic lymph node dissection. The presence of lymph node metastases was determined by an experienced reader independently for both the PET and the morphologic datasets using a template-based analysis on a 5-point scale. Patient-level and template-based results were both compared with histopathologic findings. Results: Lymph node metastases were present in 18 patients (31.0%) and were located in 52 of 375 templates (13.9%). Receiver-operating-characteristic analyses showed ¹⁸F-rhPSMA-7 PET to perform significantly better than morphologic imaging on both patient-based and template-based analyses (areas under curve, 0.858 vs. 0.649 [P = 0.012] and 0.765 vs. 0.589 [P < 0.001], respectively). On patient-based analyses, the sensitivity, specificity, and accuracy of ¹⁸F-rhPSMA-7 PET were 72.2%, 92.5%, and 86.2%, respectively, and those of morphologic imaging were 50.0%, 72.5%, and 65.5%, respectively. On template-based analyses, the sensitivity, specificity, and accuracy of ¹⁸F-rhPSMA-7 PET were 53.8%, 96.9%, and 90.9%, respectively, and those of morphologic imaging were 9.6%, 95.0%, and 83.2%, respectively. Conclusion: ¹⁸F-rhPSMA-7 PET is superior to morphologic imaging for N-staging of high-risk primary PC. The efficacy of ¹⁸F-rhPSMA-7 is similar to published data for ⁶⁸Ga-PSMA-11.

Radiohybrid PSMA (rhPSMA) ligands, a new class of theranostic prostate-specific membrane antigen (PSMA)–targeting agents, feature fast ¹⁸F synthesis and utility for labeling with radiometals. Here, we assessed the biodistribution and image quality of ¹⁸F-rhPSMA-7 to determine the best imaging time point for patients with prostate cancer. Methods: In total, 202 prostate cancer patients who underwent a clinically indicated ¹⁸F-rhPSMA-7 PET/CT were retrospectively analyzed, and 12 groups based on the administered activity and uptake time of PET scanning were created: 3 administered activities (low, 222–296 MBq; moderate, 297–370 MBq; and high, 371–444 MBq) and 4 uptake time points (short, 50–70 min; intermediate, 71–90 min; long, 91–110 min; and extra long, ≥111 min). For quantitative analyses, SUV_mean and organ- or tumor-to-background ratio were determined for background, healthy organs, and 3 representative tumor lesions. Qualitative analyses assessed overall image quality, nonspecific blood-pool activity, and background uptake in bone or marrow using 3- or 4-point scales. Results: In quantitative analyses, SUV_mean showed a significant decrease in the blood pool and lungs and an increase in the kidneys, bladder, and bones as the uptake time increased. SUV_mean showed a trend to increase in the blood pool and bones as the administered activity increased. However, no significant differences were found in 377 tumor lesions with respect to the administered activity or uptake time. In qualitative analyses, the overall image quality was stable along with the uptake time, but the proportion rated to have good image quality decreased as the administered activity increased. All other qualitative image parameters showed no significant differences for the administered activities, but they showed significant trends with increasing uptake time: less nonspecific blood activity, more frequent background uptake in the bone marrow, and increased negative impact on clinical decision making. Conclusion: The biodistribution of ¹⁸F-rhPSMA-7 was similar to that of established PSMA ligands, and tumor uptake of ¹⁸F-rhPSMA-7 was stable across the administered activities and uptake times. An early imaging time point (50–70 min) is recommended for ¹⁸F-rhPSMA-7 PET/CT to achieve the highest overall image quality.

¹⁸F-labeled prostate-specific membrane antigen (PSMA) PET tracers are increasingly used in preference to ⁶⁸Ga-PSMA-11 for restaging biochemical recurrence (BCR) of prostate cancer. They are associated with longer half-lives, larger-scale production, and lower positron range than their ⁶⁸Ga-labeled counterparts. Here, we describe the efficacy of an ¹⁸F-labeled radiohybrid PSMA, rhPSMA-7, a novel theranostic PSMA-targeting agent for imaging BCR of prostate cancer. Methods: Datasets from 261 consecutive patients with noncastrate BCR after radical prostatectomy who underwent ¹⁸F-rhPSMA-7 PET/CT at our institution between June 2017 and March 2018 were reviewed retrospectively. All lesions suspected of being recurrent prostate cancer were recorded. The detection rate for sites of presumed recurrence was correlated with patients’ prostate-specific antigen (PSA) level, primary Gleason score, and prior therapy (androgen deprivation therapy and external-beam radiation therapy). Results: The 261 patients had a median PSA level of 0.96 ng/mL (range, 0.01–400 ng/mL). The median injected activity of ¹⁸F-rhPSMA-7 was 336 MBq, with a median uptake time of 76 min. In total, 211 patients (81%) showed pathologic findings on ¹⁸F-rhPSMA-7 PET/CT. The detection rates were 71% (42/59), 86% (44/51), 86% (42/49), and 95% (76/80) at PSA levels of 0.2 to <0.5 ng/mL, 0.5 to <1 ng/mL, 1 to <2 ng/mL, and ≥2 ng/mL, respectively. In 32% patients (7/22) with a PSA of less than 0.2 ng/mL, suggestive lesions were present. ¹⁸F-rhPSMA-7 PET/CT revealed local recurrence in 43% of patients (113). Lymph node metastases were present in the pelvis in 42% of patients (110), in the retroperitoneum in 17% (45), and in a supradiaphragmatic location in 8.0% (21). Bone and visceral metastases were detected in 21% (54) and 3.8% (10), respectively. Detection efficacy was not influenced by prior external-beam radiation therapy (79.1% vs. 82.1%, P = 0.55), androgen deprivation therapy within the 6 mo preceding imaging (80.6% vs. 80.9%, P = 0.54), or primary Gleason score (77.9% for ≤7 vs. 82.6% for ≥8, P = 0.38). Conclusion: ¹⁸F-rhPSMA-7 PET/CT offers high detection rates in early BCR after radical prostatectomy, especially among patients with low PSA values.

Neuroendocrinelike transdifferentiation of prostate cancer adenocarcinomas correlates with serum levels of chromogranin A (CgA) and drives treatment resistance. The aim of this work was to evaluate whether CgA can serve as a response predictor for ¹⁷⁷Lu-prostate-specific membrane antigen 617 (PSMA) radioligand therapy (RLT) in comparison with the established tumor markers. Methods: One hundred consecutive patients with metastasized castration-resistant prostate cancer scheduled for PSMA RLT were evaluated for prostate-specific antigen (PSA), lactate dehydrogenase (LDH), and CgA at baseline and in follow-up of PSMA RLT. Tumor uptake of PSMA ligand, a known predictive marker for response, was assessed as a control variable. Results: From the 100 evaluated patients, 35 had partial remission, 16 stable disease, 15 mixed response, and 36 progression of disease. Tumor uptake above salivary gland uptake translated into partial remission, with an odds ratio (OR) of 60.265 (95% confidence interval [CI], 5.038–720.922). Elevated LDH implied a reduced chance for partial remission, with an OR of 0.094 (95% CI, 0.017–0.518), but increased the frequency of progressive disease (OR, 2.717; 95% CI, 1.391–5.304). All patients who achieved partial remission had a normal baseline LDH. Factor-2 elevation of CgA increased the risk for progression, with an OR of 3.089 (95% CI, 1.302–7.332). Baseline PSA had no prognostic value for response prediction. Conclusion: In our cohort, baseline PSA had no prognostic value for response prediction. LDH was the marker with the strongest prognostic value, and elevated LDH increased the risk for progression of disease under PSMA RLT. Elevated CgA demonstrated a moderate impact as a negative prognostic marker in general but was explicitly related to the presence of liver metastases. Well in line with the literature, sufficient tumor uptake is a prerequisite to achieve tumor response.

In around 20% of men with prostate cancer, metastasis develops during the course of their disease. Accordingly, discovering and developing new potent treatment strategies for patients with metastatic prostate cancer has been a major research focus during the last few decades. Identifying disease progression, especially within clinical trials, is essential in determining drug effectiveness. One major remaining question is how best to define disease progression. The criteria of the Prostate Cancer Clinical Trials Working Group (PCWG2) include clinical and laboratory parameters, as well as conventional imaging modalities such as MRI, CT, and bone scan findings, but advanced molecular imaging techniques, especially prostate-specific membrane antigen (PSMA) PET findings, are not considered. This is a problem because PSMA PET is used not only for detecting biochemical recurrence but also for restaging and as an intermediate-endpoint biomarker in ongoing clinical trials. Therefore, response criteria and PSMA PET progression (PPP) criteria need to be established with some urgency. The intent of this article is therefore to define prostate cancer progression by PSMA PET criteria. Our PPP proposal is based on the same principles as were applied for the PCGW2 criteria but adds value by including PSMA PET criteria. PPP defines PSMA treatment response using 3 different criteria. The first is the appearance of 2 or more new PSMA-positive distant lesions. The second is the appearance of 1 new PSMA-positive lesion plus consistent clinical or laboratory data and recommended confirmation by biopsy or correlative imaging within 3 mo of PSMA PET. The third is an increase in size or PSMA uptake of 1 or more existing lesions by at least 30%, plus consistent clinical or laboratory data or confirmation by biopsy or correlative imaging within 3 mo of PSMA PET.

The incidence of abnormal cerebrospinal fluid (CSF) flow dynamics in children with central nervous system (CNS) tumors before intraventricular therapy has not been described. Methods: We performed a single-institution, retrospective review of patients with primary or metastatic CNS tumors treated between 2003 and 2018 (15 y). Patients underwent ¹¹¹In-diethylenetriaminepentaacetic acid injection into the CSF intraventricular space followed by nuclear medicine imaging at 90 min, 4 h, 24 h, and 48 h (if required). CSF flow was classified as normal, delayed, asymmetric, or obstructed. Results: In total, 278 CSF flow studies were performed on 224 patients, 202 of whom (90%) were less than 18 y old. Of these, 116 patients (52%) had metastatic CNS neuroblastoma, 57 (25%) had medulloblastoma, and 51 (23%) had other histologic types of CNS tumors. Of the 278 studies, 237 (85%) were normal, 9 (3%) required neurosurgical intervention, 25 (9%) were delayed, and 7 (3%) were asymmetric. Conclusion: Abnormal CSF flow and the necessity for neurosurgical intervention must be considered when attempting to ensure appropriate intraventricular therapy in the pediatric population.

Monoclonal antibodies (mAbs) against programmed cell death 1 (PD-1), such as nivolumab and pembrolizumab, are associated with high response rates in patients with relapsed or refractory classic Hodgkin lymphoma (HL). To date, no prognostic factor for overall survival (OS) has been established with these agents in HL. We examined whether the first early response assessment evaluated using ¹⁸F-FDG PET/CT may be associated with OS in this setting. Methods: This retrospective study included 45 patients from 34 institutions. In a masked, centralized review, 3 independent radiologists classified PET/CT scans obtained at a median of 2.0 mo (interquartile range, 1.7–3.7 mo) after nivolumab initiation using existing criteria (i.e., 2014 Lugano classification and 2016 LYRIC). Patients were classified according to 4 possible response categories: complete metabolic response (CMR), partial metabolic response (PMR), no metabolic response (NMR), or progressive metabolic disease (PMD). Because the OS of patients with NMR and PMR was similar, they were grouped together. OS was estimated using the Kaplan–Meier method and compared between groups using log-rank testing. Results: Eleven patients (24%) died after a median follow-up of 21.2 mo. The classification was identical between Lugano and LYRIC because all 16 progression events classified as indeterminate response per LYRIC were confirmed on subsequent evaluations. Both Lugano and LYRIC classified patients as CMR in 13 cases (29%), PMD in 16 (36%), NMR in 4 (9%), and PMR in 12 (27%). The 2-y OS probability was significantly different in patients with PMD (0.53; 95% confidence interval [95%CI], 0.32–0.87), NMR or PMR (0.80; 95%CI, 0.63–1.00), and CMR (1.00; 95%CI, 1.00–1.00) in the overall population (P = 0.02, 45 patients), as well as according to a landmark analysis at 3 mo (P = 0.05, 32 patients). Conclusion: In relapsed or refractory HL patients treated with anti-PD-1 mAbs, the first early PET/CT assessment using either Lugano or LYRIC predicted OS and allowed early risk stratification, suggesting that PET/CT might be used to develop risk-adapted strategies.

Parallel to the application of new PET radiopharmaceuticals for pheochromocytoma and paraganglioma (collectively named PPGLs) imaging, several studies have increased our understanding on their biology, genetics, metabolomics, and embryologic origin. In this review, we highlight the current relationship between genotypes and molecular imaging phenotypes. Additionally, we summarize the referral guidelines for imaging of PPGL patients with or without knowledge of their genetic background.

Covalent chemical modifications of cellular RNAs directly impact all biological processes. However, our mechanistic understanding of the enzymes catalyzing these modifications, their substrates and biological functions, remains vague. Amongst RNA modifications N⁶-methyladenosine (m⁶A) is widespread and found in messenger (mRNA), ribosomal (rRNA), and noncoding RNAs. Here, we undertook a systematic screen to uncover new RNA methyltransferases. We demonstrate that the methyltransferase-like 5 (METTL5) protein catalyzes m⁶A in 18S rRNA at position A₁₈₃₂. We report that absence of Mettl5 in mouse embryonic stem cells (mESCs) results in a decrease in global translation rate, spontaneous loss of pluripotency, and compromised differentiation potential. METTL5-deficient mice are born at non-Mendelian rates and develop morphological and behavioral abnormalities. Importantly, mice lacking METTL5 recapitulate symptoms of patients with DNA variants in METTL5, thereby providing a new mouse disease model. Overall, our biochemical, molecular, and in vivo characterization highlights the importance of m⁶A in rRNA in stemness, differentiation, development, and diseases.

Metabolism and development must be closely coupled to meet the changing physiological needs of each stage in the life cycle. The molecular mechanisms that link these pathways, however, remain poorly understood. Here we show that the Drosophila estrogen-related receptor (dERR) directs a transcriptional switch in mid-pupae that promotes glucose oxidation and lipogenesis in young adults. dERR mutant adults are viable but display reduced locomotor activity, susceptibility to starvation, elevated glucose, and an almost complete lack of stored triglycerides. Molecular profiling by RNA-seq, ChIP-seq, and metabolomics revealed that glycolytic and pentose phosphate pathway genes are induced by dERR, and their reduced expression in mutants is accompanied by elevated glycolytic intermediates, reduced TCA cycle intermediates, and reduced levels of long chain fatty acids. Unexpectedly, we found that the central pathways of energy metabolism, including glycolysis, the tricarboxylic acid cycle, and electron transport chain, are coordinately induced at the transcriptional level in mid-pupae and maintained into adulthood, and this response is partially dependent on dERR, leading to the metabolic defects observed in mutants. Our data support the model that dERR contributes to a transcriptional switch during pupal development that establishes the metabolic state of the adult fly.

Autophagy captures intracellular components and delivers them to lysosomes for degradation and recycling. Conditional autophagy deficiency in adult mice causes liver damage, shortens life span to 3 mo due to neurodegeneration, and is lethal upon fasting. As autophagy deficiency causes p53 induction and cell death in neurons, we sought to test whether p53 mediates the lethal consequences of autophagy deficiency. Here, we conditionally deleted Trp53 (p53 hereafter) and/or the essential autophagy gene Atg7 throughout adult mice. Compared with Atg7^/ mice, the life span of Atg7^/p53^/ mice was extended due to delayed neurodegeneration and resistance to death upon fasting. Atg7 also suppressed apoptosis induced by p53 activator Nutlin-3, suggesting that autophagy inhibited p53 activation. To test whether increased oxidative stress in Atg7^/ mice was responsible for p53 activation, Atg7 was deleted in the presence or absence of the master regulator of antioxidant defense nuclear factor erythroid 2-related factor 2 (Nrf2). Nrf2^–/–Atg7^/ mice died rapidly due to small intestine damage, which was not rescued by p53 codeletion. Thus, Atg7 limits p53 activation and p53-mediated neurodegeneration. In turn, NRF2 mitigates lethal intestine degeneration upon autophagy loss. These findings illustrate the tissue-specific roles for autophagy and functional dependencies on the p53 and NRF2 stress response mechanisms.

The proteostasis network is regulated by transcellular communication to promote health and fitness in metazoans. In Caenorhabditis elegans, signals from the germline initiate the decline of proteostasis and repression of cell stress responses at reproductive maturity, indicating that commitment to reproduction is detrimental to somatic health. Here we show that proteostasis and stress resilience are also regulated by embryo-to-mother communication in reproductive adults. To identify genes that act directly in the reproductive system to regulate somatic proteostasis, we performed a tissue targeted genetic screen for germline modifiers of polyglutamine aggregation in muscle cells. We found that inhibiting the formation of the extracellular vitelline layer of the fertilized embryo inside the uterus suppresses aggregation, improves stress resilience in an HSF-1-dependent manner, and restores the heat-shock response in the somatic tissues of the parent. This pathway relies on DAF-16/FOXO activation in vulval tissues to maintain stress resilience in the mother, suggesting that the integrity of the embryo is monitored by the vulva to detect damage and initiate an organismal protective response. Our findings reveal a previously undescribed transcellular pathway that links the integrity of the developing progeny to proteostasis regulation in the parent.

Cell type-specific transcriptional programs that drive differentiation of specialized cell types are key players in development and tissue regeneration. One of the most dramatic changes in the transcription program in Drosophila occurs with the transition from proliferating spermatogonia to differentiating spermatocytes, with >3000 genes either newly expressed or expressed from new alternative promoters in spermatocytes. Here we show that opening of these promoters from their closed state in precursor cells requires function of the spermatocyte-specific tMAC complex, localized at the promoters. The spermatocyte-specific promoters lack the previously identified canonical core promoter elements except for the Inr. Instead, these promoters are enriched for the binding site for the TALE-class homeodomain transcription factors Achi/Vis and for a motif originally identified under tMAC ChIP-seq peaks. The tMAC motif resembles part of the previously identified 14-bp β2UE1 element critical for spermatocyte-specific expression. Analysis of downstream sequences relative to transcription start site usage suggested that ACA and CNAAATT motifs at specific positions can help promote efficient transcription initiation. Our results reveal how promoter-proximal sequence elements that recruit and are acted upon by cell type-specific chromatin binding complexes help establish a robust, cell type-specific transcription program for terminal differentiation.

Telomeres consist of TTAGGG repeats bound by protein complexes that serve to protect the natural end of linear chromosomes. Most cells maintain telomere repeat lengths by using the enzyme telomerase, although there are some cancer cells that use a telomerase-independent mechanism of telomere extension, termed alternative lengthening of telomeres (ALT). Cells that use ALT are characterized, in part, by the presence of specialized PML nuclear bodies called ALT-associated PML bodies (APBs). APBs localize to and cluster telomeric ends together with telomeric and DNA damage factors, which led to the proposal that these bodies act as a platform on which ALT can occur. However, the necessity of APBs and their function in the ALT pathway has remained unclear. Here, we used CRISPR/Cas9 to delete PML and APB components from ALT-positive cells to cleanly define the function of APBs in ALT. We found that PML is required for the ALT mechanism, and that this necessity stems from APBs’ role in localizing the BLM–TOP3A–RMI (BTR) complex to ALT telomere ends. Strikingly, recruitment of the BTR complex to telomeres in a PML-independent manner bypasses the need for PML in the ALT pathway, suggesting that BTR localization to telomeres is sufficient to sustain ALT activity.

The emergence of drug resistance is a major obstacle for the success of targeted therapy in melanoma. Additionally, conventional chemotherapy has not been effective as drug-resistant cells escape lethal DNA damage effects by inducing growth arrest commonly referred to as cellular dormancy. We present a therapeutic strategy termed "targeted chemotherapy" by depleting protein phosphatase 2A (PP2A) or its inhibition using a small molecule inhibitor (1,10-phenanthroline-5,6-dione [phendione]) in drug-resistant melanoma. Targeted chemotherapy induces the DNA damage response without causing DNA breaks or allowing cellular dormancy. Phendione treatment reduces tumor growth of BRAF^V600E-driven melanoma patient-derived xenografts (PDX) and diminishes growth of NRAS^Q61R-driven melanoma, a cancer with no effective therapy. Remarkably, phendione treatment inhibits the acquisition of resistance to BRAF inhibition in BRAF^V600E PDX highlighting its effectiveness in combating the advent of drug resistance.

Peripheral somatosensory input is modulated in the dorsal spinal cord by a network of excitatory and inhibitory interneurons. PTF1A is a transcription factor essential in dorsal neural tube progenitors for specification of these inhibitory neurons. Thus, mechanisms regulating Ptf1a expression are key for generating neuronal circuits underlying somatosensory behaviors. Mutations targeted to distinct cis-regulatory elements for Ptf1a in mice, tested the in vivo contribution of each element individually and in combination. Mutations in an autoregulatory enhancer resulted in reduced levels of PTF1A, and reduced numbers of specific dorsal spinal cord inhibitory neurons, particularly those expressing Pdyn and Gal. Although these mutants survive postnatally, at ~3–5 wk they elicit a severe scratching phenotype. Behaviorally, the mutants have increased sensitivity to itch, but acute sensitivity to other sensory stimuli such as mechanical or thermal pain is unaffected. We demonstrate a requirement for positive transcriptional autoregulatory feedback to attain the level of the neuronal specification factor PTF1A necessary for generating correctly balanced neuronal circuits.

In this issue of Genes & Development, Lu and colleagues (pp. 663–677) have discovered a key new mechanism of alternative promoter choice that is involved in differentiation of spermatocytes. Promoter choice has strong potential as mechanism for differentiation of many different cell types.

Background and objective

Exercise is a cornerstone of management for type 2 diabetes; however, little is known about the cardiovascular (CV) response to submaximal functional exercise in people with type 2 diabetes. The aim of this study was to compare performance and CV response during a 6-minute walk test (6MWT) between people with type 2 diabetes and matched control subjects.