Methionine, through S-adenosylmethionine, activates a multifaceted growth program in which ribosome biogenesis, carbon metabolism, and amino acid and nucleotide biosynthesis are induced. This growth program requires the activity of the Gcn4 transcription factor (called ATF4 in mammals), which facilitates the supply of metabolic precursors that are essential for anabolism. However, how Gcn4 itself is regulated in the presence of methionine is unknown. Here, we discover that Gcn4 protein levels are increased by methionine, despite conditions of high cell growth and translation (in which the roles of Gcn4 are not well-studied). We demonstrate that this mechanism of Gcn4 induction is independent of transcription, as well as the conventional Gcn2/eIF2α-mediated increased translation of Gcn4. Instead, when methionine is abundant, Gcn4 phosphorylation is decreased, which reduces its ubiquitination and therefore degradation. Gcn4 is dephosphorylated by the protein phosphatase 2A (PP2A); our data show that when methionine is abundant, the conserved methyltransferase Ppm1 methylates and alters the activity of the catalytic subunit of PP2A, shifting the balance of Gcn4 toward a dephosphorylated, stable state. The absence of Ppm1 or the loss of the PP2A methylation destabilizes Gcn4 even when methionine is abundant, leading to collapse of the Gcn4-dependent anabolic program. These findings reveal a novel, methionine-dependent signaling and regulatory axis. Here methionine directs the conserved methyltransferase Ppm1 via its target phosphatase PP2A to selectively stabilize Gcn4. Through this, cells conditionally modify a major phosphatase to stabilize a metabolic master regulator and drive anabolism.

Visual Abstract

The Wnt/β-catenin pathway is one of the major pathways that regulates embryonic development, adult homeostasis, and stem cell self-renewal. In this pathway, transcription factors T-cell factor and lymphoid enhancer factor (TCF/LEF) serve as a key switch to repress or activate Wnt target gene transcription by recruiting repressor molecules or interacting with the β-catenin effector, respectively. It has become evident that the protein stability of the TCF/LEF family members may play a critical role in controlling the activity of the Wnt/β-catenin signaling pathway. However, factors that regulate the stability of TCF/LEFs remain largely unknown. Here, we report that pVHL binding protein 1 (VBP1) regulates the Wnt/β-catenin signaling pathway by controlling the stability of TCF/LEFs. Surprisingly, we found that either overexpression or knockdown of VBP1 decreased Wnt/β-catenin signaling activity in both cultured cells and zebrafish embryos. Mechanistically, VBP1 directly binds to all four TCF/LEF family members and von Hippel-Lindau tumor-suppressor protein (pVHL). Either overexpression or knockdown of VBP1 increases the association between TCF/LEFs and pVHL and then decreases the protein levels of TCF/LEFs via proteasomal degradation. Together, our results provide mechanistic insights into the roles of VBP1 in controlling TCF/LEFs protein stability and regulating Wnt/β-catenin signaling pathway activity.

Genetic mutations related to ALS, a progressive neurological disease, have been discovered in the gene encoding σ-1 receptor (σ1R). We previously reported that σ1RE102Q elicits toxicity in cells. The σ1R forms oligomeric states that are regulated by ligands. Nevertheless, little is known about the effect of ALS-related mutations on oligomer formation. Here, we transfected NSC-34 cells, a motor neuronal cell line, and HEK293T cells with σ1R-mCherry (mCh), σ1RE102Q-mCh, or nontagged forms to investigate detergent solubility and subcellular distribution using immunocytochemistry and fluorescence recovery after photobleaching. The oligomeric state was determined using crosslinking procedure. σ1Rs were soluble to detergents, whereas the mutants accumulated in the insoluble fraction. Within the soluble fraction, peak distribution of mutants appeared in higher sucrose density fractions. Mutants formed intracellular aggregates that were co-stained with p62, ubiquitin, and phosphorylated pancreatic eukaryotic translation initiation factor-2-α kinase in NSC-34 cells but not in HEK293T cells. The aggregates had significantly lower recovery in fluorescence recovery after photobleaching. Acute treatment with σ1R agonist SA4503 failed to improve recovery, whereas prolonged treatment for 48 h significantly decreased σ1RE102Q-mCh insolubility and inhibited apoptosis. Whereas σ1R-mCh formed monomers and dimers, σ1RE102Q-mCh also formed trimers and tetramers. SA4503 reduced accumulation of the four types in the insoluble fraction and increased monomers in the soluble fraction. The σ1RE102Q insolubility was diminished by σ1R-mCh co-expression. These results suggest that the agonist and WT σ1R modify the detergent insolubility, toxicity, and oligomeric state of σ1RE102Q, which may lead to promising new treatments for σ1R-related ALS.

Stephanie E. Hood
Dec 1, 2020; 61:1720-1732
Research Articles

Elisa Vidal
Dec 1, 2020; 61:1733-1746
Research Articles

Ying Zou
Dec 1, 2020; 61:1589-1604
Research Articles

Oktawia Nilsson
Nov 17, 2020; 0:jlr.RA120000920v1-jlr.RA120000920
Research Articles

Apolipoprotein A-I (ApoA-I) of high-density lipoprotein (HDL) is essential for the transportation of cholesterol between peripheral tissues and the liver. However, specific mutations in Apolipoprotein A-I (ApoA-I) of high-density lipoprotein (HDL) are responsible for a late-onset systemic amyloidosis, the pathological accumulation of protein fibrils in tissues and organs. Carriers of these mutations do not exhibit increased cardiovascular disease risk despite displaying reduced levels of ApoA-I/ HDL-cholesterol. To explain this paradox, we show that the HDL particle profile of patients carrying either L75P or L174S ApoA-I amyloidogenic variants a higher relative abundance of the 8.4 nm vs 9.6 nm particles, and that serum from patients, as well as reconstituted 8.4 and 9.6 nm HDL particles (rHDL), possess increased capacity to catalyze cholesterol efflux from macrophages. Synchrotron radiation circular dichroism and hydrogen-deuterium exchange revealed that the variants in 8.4 nm rHDL have altered secondary structure composition and display a more flexible binding to lipids compared to their native counterpart. The reduced HDL-cholesterol levels of patients carrying ApoA-I amyloidogenic variants are thus balanced by higher proportion of small, dense HDL particles and better cholesterol efflux due to altered, region-specific protein structure dynamics.

Bile acids (BAs) have been established as ubiquitous regulatory molecules implicated in a large variety of healthy and pathological processes. However, the scope of BA heterogeneity is often underrepresented in current literature. This is due in part to inadequate detection methods, which fail to distinguish the individual constituents of the BA pool. Thus, the primary aim of this study was to develop a method that would allow the simultaneous analysis of specific C24 BA species, and to apply that method to biological systems of interest. Herein, we describe the generation and validation of an LC-MS/MS assay for quantification of numerous BAs in a variety of cell systems and relevant biofluids and tissue. These studies included the first baseline level assessment for planar BAs, including allocholic acid, in cell lines, biofluids, and tissue in a nonhuman primate (NHP) laboratory animal, Macaca mulatta, in healthy conditions. These results indicate that immortalized cell lines make poor models for the study of BA synthesis and metabolism, whereas human primary hepatocytes represent a promising alternative model system. We also characterized the BA pool of M. mulatta in detail. Our results support the use of NHP models for the study of BA metabolism and pathology in lieu of murine models. Moreover, the method developed here can be applied to the study of common and planar C24 BA species in other systems.

Accompanied with nutrition transition, non-HDL-C levels of individuals in Asian countries has increased rapidly, which has caused the global epicenter of nonoptimal cholesterol to shift from Western countries to Asian countries. Thus, it is critical to underline major genetic and dietary determinants. In the current study of 2,330 Chinese individuals, genetic risk scores (GRSs) were calculated for total cholesterol (TC; GRS_TC, 57 SNPs), LDL-C (GRS_LDL-C, 45 SNPs), and HDL-C (GRS_HDL-C, 65 SNPs) based on SNPs from the Global Lipid Genetics Consortium study. Cholesterol intake was estimated by a 74-item food-frequency questionnaire. Associations of dietary cholesterol intake with plasma TC and LDL-C strengthened across quartiles of the GRS_TC (effect sizes: –0.29, 0.34, 2.45, and 6.47; P_interaction = 0.002) and GRS_LDL-C (effect sizes: –1.35, 0.17, 5.45, and 6.07; P_interaction = 0.001), respectively. Similar interactions with non-HDL-C were observed between dietary cholesterol and GRS_TC (P_interaction = 0.001) and GRS_LDL-C (P_interaction = 0.004). The adverse effects of GRS_TC on TC (effect sizes across dietary cholesterol quartiles: 0.51, 0.82, 1.21, and 1.31; P_interaction = 0.023) and GRS_LDL-C on LDL-C (effect sizes across dietary cholesterol quartiles: 0.66, 0.52, 1.12, and 1.56; P_interaction = 0.020) were more profound in those having higher cholesterol intake compared with those with lower intake. Our findings suggest significant interactions between genetic susceptibility and dietary cholesterol intake on plasma cholesterol profiles in a Chinese population.

Bile acids, which are synthesized from cholesterol by the liver, are chemically transformed along the intestinal tract by the gut microbiota, and the products of these transformations signal through host receptors, affecting overall host health. These transformations include bile acid deconjugation, oxidation, and 7α-dehydroxylation. An understanding of the biogeography of bile acid transformations in the gut is critical because deconjugation is a prerequisite for 7α-dehydroxylation and because most gut microorganisms harbor bile acid transformation capacity. Here, we used a coupled metabolomic and metaproteomic approach to probe in vivo activity of the gut microbial community in a gnotobiotic mouse model. Results revealed the involvement of Clostridium scindens in 7α-dehydroxylation, of the genera Muribaculum and Bacteroides in deconjugation, and of six additional organisms in oxidation (the genera Clostridium, Muribaculum, Bacteroides, Bifidobacterium, Acutalibacter, and Akkermansia). Furthermore, the bile acid profile in mice with a more complex microbiota, a dysbiosed microbiota, or no microbiota was considered. For instance, conventional mice harbor a large diversity of bile acids, but treatment with an antibiotic such as clindamycin results in the complete inhibition of 7α-dehydroxylation, underscoring the strong inhibition of organisms that are capable of carrying out this process by this compound. Finally, a comparison of the hepatic bile acid pool size as a function of microbiota revealed that a reduced microbiota affects host signaling but not necessarily bile acid synthesis. In this study, bile acid transformations were mapped to the associated active microorganisms, offering a systematic characterization of the relationship between microbiota and bile acid composition.

Spatial changes of FAs in the retina in response to different dietary n-3 formulations have never been explored, although a diet rich in EPA and DHA is recommended to protect the retina against the effects of aging. In this study, Wistar rats were fed for 8 weeks with balanced diet including either EPA-containing phospholipids (PLs), EPA-containing TGs, DHA-containing PLs, or DHA-containing TGs. Qualitative changes in FA composition of plasma, erythrocytes, and retina were evaluated by gas chromatography-flame ionization detector. Following the different dietary intakes, changes to the quantity and spatial organization of PC and PE species in retina were determined by LC coupled to MS/MS and MALDI coupled to MS imaging. The omega-3 content in the lipids of plasma and erythrocytes suggests that PLs as well as TGs are good omega-3 carriers for retina. However, a significant increase in DHA content in retina was observed, especially molecular species as di-DHA-containing PC and PE, as well as an increase in very long chain PUFAs (more than 28 carbons) following PL-EPA and TG-DHA diets only. All supplemented diets triggered spatial organization changes of DHA in the photoreceptor layer around the optic nerve. Taken together, these findings suggest that dietary omega-3 supplementation can modify the content of FAs in the rat retina.

Lipins are eukaryotic proteins with functions in lipid synthesis and the homeostatic control of energy balance. They execute these functions by acting as phosphatidate phosphatase enzymes in the cytoplasm and by changing gene expression after translocation into the cell nucleus, in particular under fasting conditions. Here, we asked whether nuclear translocation and the enzymatic activity of Drosophila Lipin serve essential functions and how gene expression changes, under both fed and fasting conditions, when nuclear translocation is impaired. To address these questions, we created a Lipin null mutant, a mutant expressing Lipin lacking a nuclear localization signal (Lipin^NLS), and a mutant expressing enzymatically dead Lipin. Our data support the conclusion that the enzymatic but not nuclear gene regulatory activity of Lipin is essential for survival. Notably, adult Lipin^NLS flies were not only viable but also exhibited improved life expectancy. In contrast, they were highly susceptible to starvation. Both the improved life expectancy in the fed state and the decreased survival in the fasting state correlated with changes in metabolic gene expression. Moreover, increased life expectancy of fed flies was associated with a decreased metabolic rate. Interestingly, in addition to metabolic genes, genes involved in feeding behavior and the immune response were misregulated in Lipin^NLS flies. Altogether, our data suggest that the nuclear activity of Lipin influences the genomic response to nutrient availability with effects on life expectancy and starvation resistance. Thus, nutritional or therapeutic approaches that aim at lowering nuclear translocation of lipins in humans may be worth exploring.

Beiging of white adipose tissue (WAT) has beneficial effects on metabolism. Although it is known that beige adipocytes are active in lipid catabolism and thermogenesis, how they are regulated deserves more explorations. In this study, we demonstrate that stearoyl-CoA desaturase 1 (SCD1) in subcutaneous WAT (scWAT) responded to cold stimulation and was able to promote mobilization of triacylglycerol [TAG (triglyceride)]. In vitro studies showed that SCD1 promoted lipolysis in C3H10T1/2 white adipocytes. The lipolytic effect was contributed by one of SCD1’s products, oleic acid (OA). OA upregulated adipose TAG lipase and hormone-sensitive lipase expression. When SCD1 was overexpressed in the scWAT of mice, lipolysis was enhanced, and oxygen consumption and heat generation were increased. These effects were also demonstrated by the SCD1 knockdown experiments in mice. In conclusion, our study suggests that SCD1, known as an enzyme for lipid synthesis, plays a role in upregulating lipid mobilization through its desaturation product, OA.

The divalent anion sodium symporter (DASS) family (SLC13) plays critical roles in metabolic homeostasis, influencing many processes, including fatty acid synthesis, insulin resistance, and adiposity. DASS transporters catalyze the Na+-driven concentrative uptake of Krebs cycle intermediates and sulfate into cells; disrupting their function can protect against age-related metabolic diseases and can extend lifespan. An inward-facing crystal structure and an outward-facing model of a bacterial DASS family member, VcINDY from Vibrio cholerae, predict an elevator-like transport mechanism involving a large rigid body movement of the substrate-binding site. How substrate binding influences the conformational state of VcINDY is currently unknown. Here, we probe the interaction between substrate binding and protein conformation by monitoring substrate-induced solvent accessibility changes of broadly distributed positions in VcINDY using a site-specific alkylation strategy. Our findings reveal that accessibility to all positions tested is modulated by the presence of substrates, with the majority becoming less accessible in the presence of saturating concentrations of both Na+ and succinate. We also observe separable effects of Na+ and succinate binding at several positions suggesting distinct effects of the two substrates. Furthermore, accessibility changes to a solely succinate-sensitive position suggests that substrate binding is a low-affinity, ordered process. Mapping these accessibility changes onto the structures of VcINDY suggests that Na+ binding drives the transporter into an as-yet-unidentified conformational state, involving rearrangement of the substrate-binding site–associated re-entrant hairpin loops. These findings provide insight into the mechanism of VcINDY, which is currently the only structurally characterized representative of the entire DASS family.

Secrets and Spies: UK Intelligence Accountability After Iraq and Snowden Book sysadmin 15 January 2020

How can democratic governments hold intelligence and security agencies to account when what they do is largely secret? Jamie Gaskarth explores how intelligence professionals view accountability in the context of 21st century politics.

Using the UK as a case study, this book provides the first systematic exploration of how accountability is understood inside the secret world. It is based on new interviews with current and former UK intelligence practitioners, as well as extensive research into the performance and scrutiny of the UK intelligence machinery.

The result is the first detailed analysis of how intelligence professionals view their role, what they feel keeps them honest, and how far external overseers impact on their work.

The UK gathers material that helps inform global decisions on such issues as nuclear proliferation, terrorism, transnational crime, and breaches of international humanitarian law. On the flip side, the UK was a major contributor to the intelligence failures leading to the Iraq war in 2003, and its agencies were complicit in the widely discredited U.S. practices of torture and ‘rendition’ of terrorism suspects. UK agencies have come under greater scrutiny since those actions, but it is clear that problems remain.

Secrets and Spies is the result of a British Academy funded project (SG151249) on intelligence accountability. The book is published as part of the Insights series.

Praise for Secrets and Spies

About the author

Jamie Gaskarth is Professor of Foreign Policy and International Relations at The Open University. He was previously senior lecturer at the University of Birmingham where he taught strategy and decision-making. His research focused on the ethical dilemmas of leadership and accountability in intelligence, foreign policy, and defence. He is author/editor or co-editor of six books and served on the Academic Advisory panel for the 2015 UK National Security Strategy and Strategic Defence and Security Review.

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• UK (via Amazon)
• Rest of world (via Brookings Institution Press)
• Students (via Browns Books)

Public Service, Accountability and Delivery in Malawi 17 October 2018 — 12:00PM TO 1:00PM Anonymous (not verified) 11 October 2018 Chatham House, London

I’m often asked if I miss working in the House of Commons. Of course I do; it’s one of the most amazing places in the world and remains the cockpit of our nation.There are obviously days I miss it more than others, usually around the big national moments. Whatever your view of Kim Leadbeater’s private member’s bill—the Terminally Ill Adults (End of Life) Bill—its second reading this month will be one of those big moments.Kim is a friend of mine, and we spoke before she decided to put her bill forward after it topped the private members’ ballot at the start of the new parliament. My advice was to proceed with great care, to remember that this will take over your career in many ways, and to read the report produced earlier this year by the Health and Social Care Committee, which I chaired, on the subject of assisted dying/assisted...

Tumor hypoxia, an integral biomarker to guide radiotherapy, can be imaged with ¹⁸F-fluoromisonidazole (¹⁸F-FMISO) hypoxia PET. One major obstacle to its broader application is the lack of standardized interpretation criteria. We sought to develop and validate practical interpretation criteria and a dedicated training protocol for nuclear medicine physicians to interpret ¹⁸F-FMISO hypoxia PET. Methods: We randomly selected 123 patients with human papillomavirus–positive oropharyngeal cancer enrolled in a phase II trial who underwent 123 ¹⁸F-FDG PET/CT and 134 ¹⁸F-FMISO PET/CT scans. Four independent nuclear medicine physicians with no ¹⁸F-FMISO experience read the scans. Interpretation by a fifth nuclear medicine physician with over 2 decades of ¹⁸F-FMISO experience was the reference standard. Performance was evaluated after initial instruction and subsequent dedicated training. Scans were considered positive for hypoxia by visual assessment if ¹⁸F-FMISO uptake was greater than floor-of-mouth uptake. Additionally, SUV_max was determined to evaluate whether quantitative assessment using tumor-to-background ratios could be helpful to define hypoxia positivity. Results: Visual assessment produced a mean sensitivity and specificity of 77.3% and 80.9%, with fair interreader agreement ( = 0.34), after initial instruction. After dedicated training, mean sensitivity and specificity improved to 97.6% and 86.9%, with almost perfect agreement ( = 0.86). Quantitative assessment with an estimated best SUV_max ratio threshold of more than 1.2 to define hypoxia positivity produced a mean sensitivity and specificity of 56.8% and 95.9%, respectively, with substantial interreader agreement ( = 0.66), after initial instruction. After dedicated training, mean sensitivity improved to 89.6% whereas mean specificity remained high at 95.3%, with near-perfect interreader agreement ( = 0.86). Conclusion: Nuclear medicine physicians without ¹⁸F-FMISO hypoxia PET reading experience demonstrate much improved interreader agreement with dedicated training using specific interpretation criteria.

The British parliament published an assisted-dying draft bill Tuesday that would give terminally ill adults with less than six months to live the legal right to end their lives with the help of medical professionals.

Billy Napier will remain in place as head football coach at Florida, despite the Gators producing another lackluster campaign during his third season, athletic director Scott Stricklin announced Thursday.

Aug. 19, 2024 — SURF’s innovation department recently collaborated with Cornelis Networks to advance networking capabilities for high-performance computing (HPC) clusters. The collaboration marks a new step forward for SURF […]

The post Cornelis Networks Partners with SURF to Enhance HPC Cluster Networking Capabilities appeared first on HPCwire.

The demand for high-performance computing (HPC) and artificial intelligence (AI) is rising dramatically as organizations rush to put their data to work. Several industries see a significant increase in HPC […]

The post Harness Insights with Cutting-edge AI Capabilities from HPE appeared first on HPCwire.

The Rapid Trident 21 exercise to enhance interoperability between Ukraine, U.S. and NATO partners started Monday, with an opening ceremony, and will run through Oct. 1.

The USNS Choctaw County has arrived in Beirut, Lebanon, to participate in a first-of-its-kind mission intended to strengthen military ties between the countries, the U.S. Navy said Tuesday.

In this era, expansion in digital infrastructure capacity is inevitable. Parallel to this, climate change consciousness is also rising, making sustainability a mandatory part of the organization’s functioning. As computing […]

The post Why IT Must Have an Influential Role in Strategic Decisions About Sustainability appeared first on HPCwire.

ATLANTA, Nov. 7, 2024 — As the high-performance computing (HPC) community gathers in Atlanta for SC24, the world’s largest HPC conference, the event will feature presentations from thought leaders and […]

The post SC24 Invited Talks to Spotlight HPC’s Role in AI, Quantum Computing, and Sustainability appeared first on HPCwire.

Around this same time last year, I expounded on what the “Future of AI” may entail. A lot has happened in the 12 months since then, including new approaches, new […]

The post Bill Gropp on ‘Different Approaches to AI’ appeared first on HPCwire.

Nov. 8, 2024 — Barcelona Supercomputing Center‘s Innostroke project aims to transform the prevention and monitoring of stroke, one of the leading causes of death and disability worldwide, through artificial […]

The post BSC Develops AI Model to Predict Stroke Risk Using Mobile Devices appeared first on HPCwire.

Congress is voting on a bill Tuesday that will empower the executive branch to remove the tax-exempt status from any nonprofit it deems to be supporting terrorists.

The Taurid meteor will make its annual appearance in the midnight sky starting Tuesday through Nov. 12, with the "shooting star" appearing best after in the early morning hours.

AI is shaping every aspect of our lives — but only a handful of tech giants have a say in what this technology can do. So what's going on with world governments? Bilawal Sidhu, host of "The TED AI Show," sits down with geopolitical expert Ian Bremmer to unpack the UN's just-released plan for "Governing AI for Humanity," a report that focuses on the urgent need to guide AI towards helping everyone thrive, rather than just the powerful few. Together, they explore the complexities of AI's rapid growth on a worldwide scale and take a clear-eyed look at the pivotal decisions facing us in the very near future.

Try these 5 quick tips when you’re feeling grumpy and irritable. 1. Do some kind of mindfulness practice. Try this or any of these. Learn enough about the philosophy of mindfulness meditation that you know what you’re doing. Since most people won’t want to do formal practice everyday on a permanent basis, do it everyday […]

The post 5 Tips for Irritability appeared first on Dr Alice Boyes.

North Dakota lawmakers fended off an effort to ensure that the state's new standards, and any tests that might be used with them, won't mirror the common core.

Academic achievement at Ohio schools eligible for School Improvement Grants during the Obama administration increased for a few years, a new study says, but SIG's legacy remains complicated.

A bill shielding what is now Ohio's largest online school and its sponsor from the negative consequences of accepting thousands of former Electronic Classroom of Tomorrow students is headed to Gov. John Kasich for his signature.

The U.S. Department of Education's office for civil rights said that some students were placed in self-contained special education settings without an individualized justification for doing so.

The state will be required to test all students using grade level tests, except for those with significant cognitive disabilities.

The money, which will be allocated over three years, is expected to make major and minor improvements to schools throughout the city.

A bill in Nebraska would require high school students to take a civics examination before graduating.

A Nebraska senator introduced a bill that would give teachers legal cover to physically restraint disruptive students, prompting a strong positive response from members of the state teachers' union.

The ability to discern fact from fiction and to recognize reliable news is fundamental, writes News Literacy Project’s Charles Salter.