Milk production may involve a transient development of insulin resistance in non-mammary tissues to support redistribution of maternal macronutrients to match the requirements of the lactating mammary gland. In the present study, adipose and liver metabolic responses were measured in the fasting state and during a 2-step (10 and 20 mU/m²/min) hyperinsulinemic-euglycemic clamp with stable isotopes, in 6-week postpartum women who were lactating (n=12) or formula-feeding (n=6) their infants and who were closely matched for baseline characteristics (e.g., parity, body composition, intrahepatic lipid). When controlling for the low insulin concentrations of both groups, the lactating women exhibited a fasting rate of endogenous glucose production (EGP) that was 2.6-fold greater, and a lipolysis rate that was 2.3-fold greater than the formula-feeding group. During the clamp, the groups exhibited similar suppression rates of EGP and lipolysis. In the lactating women only, higher prolactin concentrations were associated with greater suppression rates of lipolysis, lower intrahepatic lipid and plasma triacylglycerol concentrations. These data suggest that whole-body alterations in glucose transport may be organ specific and facilitate nutrient partitioning during lactation. Recapitulating a shift toward noninsulin-mediated glucose uptake could be an early postpartum strategy to enhance lactation success in women at risk for delayed onset of milk production.

Paraphrasing the Swiss physician and father of toxicology Paracelsus (1493–1541) on chemical agents used as therapeutics, "the dose makes the poison," it is now realized that this aptly applies to the calorigenic nutrients. The case here is the pancreatic islet β-cell presented with excessive levels of nutrients such as glucose, lipids, and amino acids. The short-term effects these nutrients exert on the β-cell are enhanced insulin biosynthesis and secretion and changes in glucose sensitivity. However, chronic fuel surfeit triggers additional compensatory and adaptive mechanisms by β-cells to cope with the increased insulin demand or to protect itself. When these mechanisms fail, toxicity due to the nutrient surplus ensues, leading to β-cell dysfunction, dedifferentiation, and apoptosis. The terms glucotoxicity, lipotoxicity, and glucolipotoxicity have been widely used, but there is some confusion as to what they mean precisely and which is most appropriate for a given situation. Here we address the gluco-, lipo-, and glucolipo-toxicities in β-cells by assessing the evidence both for and against each of them. We also discuss potential mechanisms and defend the view that many of the identified "toxic" effects of nutrient excess, which may also include amino acids, are in fact beneficial adaptive processes. In addition, candidate fuel-excess detoxification pathways are evaluated. Finally, we propose that a more general term should be used for the in vivo situation of overweight-associated type 2 diabetes reflecting both the adaptive and toxic processes to mixed calorigenic nutrients excess: "nutrient-induced metabolic stress" or, in brief, "nutri-stress."

Accumulating evidence suggests that brown adipose tissue (BAT) is a potential therapeutic target for managing obesity and related diseases. PGAM family member 5, mitochondrial serine/threonine protein phosphatase (PGAM5), is a protein phosphatase that resides in the mitochondria and regulates many biological processes, including cell death, mitophagy, and immune responses. Because BAT is a mitochondria-rich tissue, we have hypothesized that PGAM5 has a physiological function in BAT. We previously reported that PGAM5-knockout (KO) mice are resistant to severe metabolic stress. Importantly, lipid accumulation is suppressed in PGAM5-KO BAT, even under unstressed conditions, raising the possibility that PGAM5 deficiency stimulates lipid consumption. However, the mechanism underlying this observation is undetermined. Here, using an array of biochemical approaches, including quantitative RT-PCR, immunoblotting, and oxygen consumption assays, we show that PGAM5 negatively regulates energy expenditure in brown adipocytes. We found that PGAM5-KO brown adipocytes have an enhanced oxygen consumption rate and increased expression of uncoupling protein 1 (UCP1), a protein that increases energy consumption in the mitochondria. Mechanistically, we found that PGAM5 phosphatase activity and intramembrane cleavage are required for suppression of UCP1 activity. Furthermore, utilizing a genome-wide siRNA screen in HeLa cells to search for regulators of PGAM5 cleavage, we identified a set of candidate genes, including phosphatidylserine decarboxylase (PISD), which catalyzes the formation of phosphatidylethanolamine at the mitochondrial membrane. Taken together, these results indicate that PGAM5 suppresses mitochondrial energy expenditure by down-regulating UCP1 expression in brown adipocytes and that its phosphatase activity and intramembrane cleavage are required for UCP1 suppression.

S-Palmitoylation is a reversible post-translational lipid modification that dynamically regulates protein functions. Voltage-gated sodium channels are subjected to S-palmitoylation and exhibit altered functions in different S-palmitoylation states. Our aim was to investigate whether and how S-palmitoylation regulates Nav1.6 channel function and to identify S-palmitoylation sites that can potentially be pharmacologically targeted. Acyl-biotin exchange assay showed that Nav1.6 is modified by S-palmitoylation in the mouse brain and in a Nav1.6 stable HEK 293 cell line. Using whole-cell voltage clamp, we discovered that enhancing S-palmitoylation with palmitic acid increases Nav1.6 current, whereas blocking S-palmitoylation with 2-bromopalmitate reduces Nav1.6 current and shifts the steady-state inactivation in the hyperpolarizing direction. Three S-palmitoylation sites (Cys1169, Cys1170, and Cys1978) were identified. These sites differentially modulate distinct Nav1.6 properties. Interestingly, Cys1978 is exclusive to Nav1.6 among all Nav isoforms and is evolutionally conserved in Nav1.6 among most species. Cys1978 S-palmitoylation regulates current amplitude uniquely in Nav1.6. Furthermore, we showed that eliminating S-palmitoylation at specific sites alters Nav1.6-mediated excitability in dorsal root ganglion neurons. Therefore, our study reveals S-palmitoylation as a potential isoform-specific mechanism to modulate Nav activity and neuronal excitability in physiological and diseased conditions.

Extracellular matrix-evoked angiostasis and autophagy within the tumor microenvironment represent two critical, but unconnected, functions of the small leucine-rich proteoglycan, decorin. Acting as a partial agonist of vascular endothelial growth factor 2 (VEGFR2), soluble decorin signals via the energy sensing protein, AMP-activated protein kinase (AMPK), in the autophagic degradation of intracellular vascular endothelial growth factor A (VEGFA). Here, we discovered that soluble decorin evokes intracellular catabolism of endothelial VEGFA that is mechanistically independent of mTOR, but requires an autophagic regulator, paternally expressed gene 3 (PEG3). We found that administration of autophagic inhibitors such as chloroquine or bafilomycin A1, or depletion of autophagy-related 5 (ATG5), results in accumulation of intracellular VEGFA, indicating that VEGFA is a basal autophagic substrate. Mechanistically, decorin increased the VEGFA clearance rate by augmenting autophagic flux, a process that required RAB24 member RAS oncogene family (RAB24), a small GTPase that facilitates the disposal of autophagic compartments. We validated these findings by demonstrating the physiological relevance of this process in vivo. Mice starved for 48 h exhibited a sharp decrease in overall cardiac and aortic VEGFA that could be blocked by systemic chloroquine treatment. Thus, our findings reveal a unified mechanism for the metabolic control of endothelial VEGFA for autophagic clearance in response to decorin and canonical pro-autophagic stimuli. We posit that the VEGFR2/AMPK/PEG3 axis integrates the anti-angiogenic and pro-autophagic bioactivities of decorin as the molecular basis for tumorigenic suppression. These results support future therapeutic use of decorin as a next-generation protein therapy to combat cancer.

SUMOylation is a posttranslational modification (PTM) at a lysine residue and is crucial for the proper functions of many proteins, particularly of transcription factors, in various biological processes. Zinc finger homeobox 3 (ZFHX3), also known as AT motif-binding factor 1 (ATBF1), is a large transcription factor that is active in multiple pathological processes, including atrial fibrillation and carcinogenesis, and in circadian regulation and development. We have previously demonstrated that ZFHX3 is SUMOylated at three or more lysine residues. Here, we investigated which enzymes regulate ZFHX3 SUMOylation and whether SUMOylation modulates ZFHX3 stability and function. We found that SUMO1, SUMO2, and SUMO3 each are conjugated to ZFHX3. Multiple lysine residues in ZFHX3 were SUMOylated, but Lys-2806 was the major SUMOylation site, and we also found that it is highly conserved among ZFHX3 orthologs from different animal species. Using molecular analyses, we identified the enzymes that mediate ZFHX3 SUMOylation; these included SUMO1-activating enzyme subunit 1 (SAE1), an E1-activating enzyme; SUMO-conjugating enzyme UBC9 (UBC9), an E2-conjugating enzyme; and protein inhibitor of activated STAT2 (PIAS2), an E3 ligase. Multiple analyses established that both SUMO-specific peptidase 1 (SENP1) and SENP2 deSUMOylate ZFHX3. SUMOylation at Lys-2806 enhanced ZFHX3 stability by interfering with its ubiquitination and proteasomal degradation. Functionally, Lys-2806 SUMOylation enabled ZFHX3-mediated cell proliferation and xenograft tumor growth of the MDA-MB-231 breast cancer cell line. These findings reveal the enzymes involved in, and the functional consequences of, ZFHX3 SUMOylation, insights that may help shed light on ZFHX3's roles in various cellular and pathophysiological processes.

Mammalian cytochrome P450 enzymes often metabolize many pharmaceuticals and other xenobiotics, a feature that is valuable in a biotechnology setting. However, extant P450 enzymes are typically relatively unstable, with T50 values of ∼30–40 °C. Reconstructed ancestral cytochrome P450 enzymes tend to have variable substrate selectivity compared with related extant forms, but they also have higher thermostability and therefore may be excellent tools for commercial biosynthesis of important intermediates, final drug molecules, or drug metabolites. The mammalian ancestor of the cytochrome P450 1B subfamily was herein characterized structurally and functionally, revealing differences from the extant human CYP1B1 in ligand binding, metabolism, and potential molecular contributors to its thermostability. Whereas extant human CYP1B1 has one molecule of α-naphthoflavone in a closed active site, we observed that subtle amino acid substitutions outside the active site in the ancestor CYP1B enzyme yielded an open active site with four ligand copies. A structure of the ancestor with 17β-estradiol revealed only one molecule in the active site, which still had the same open conformation. Detailed comparisons between the extant and ancestor forms revealed increases in electrostatic and aromatic interactions between distinct secondary structure elements in the ancestral forms that may contribute to their thermostability. To the best of our knowledge, this represents the first structural evaluation of a reconstructed ancestral cytochrome P450, revealing key features that appear to contribute to its thermostability.

Philip Newsholme
Dec 1, 2006; 55:S39-S47
Section II: The Muscle and Liver Connections

Oct 1, 1992; 41:1368-1369
System[egrave] International (SI) Units Table

Patrice D. Cani
Jun 1, 2008; 57:1470-1481
Metabolism

Juli Bai
Jun 1, 2019; 68:1099-1108
Perspectives in Diabetes

Aldi T. Kraja
Apr 1, 2011; 60:1329-1339
Genetics

Patrice D. Cani
Jul 1, 2007; 56:1761-1772
Obesity Studies

VOLUME 294 (2019) PAGES 2555–2568Due to publisher error, “150 l/mm” was changed to “150 liters/mm” in the second paragraph of the “Vibrational spectroscopy of samples” section under “Experimental Procedures.” The correct phrase should be “150 l/mm.”

7 May 2020 , Volume 96, Number 3

Invitation Only Research Event

Event participants

John Zogby, Founder and Senior Partner, John Zogby Strategies
Chair: Dr Lindsay Newman, Senior Research Fellow, US and Americas Programme, Chatham House

Invitation Only Research Event

Event participants

Anne Applebaum, Staff Writer, The Atlantic; Pulitzer-Prize Winning Historian
Amy Pope, Partner, Schillings; Deputy Homeland Security Advisor, US National Security Council, 2015 - 17
Chair: Dr Leslie Vinjamuri, Director, US and the Americas Programme, Chatham House

Invitation Only Research Event

Event participants

Megan Greene, Dame DeAnne Senior Academy Fellow in International Relations, Chatham House; Senior Fellow, Harvard Kennedy School
Lord Jim O'Neill, Chairman, Chatham House
Chair: Creon Butler, Director, Global Economy and Finance, Chatham House

Invitation Only Research Event

Event participants

Invitation Only Research Event

Event participants

Dr Kurt Campbell, Chairman, CEO and Co-Founder, The Asia Group; Assistant Secretary of State for East Asian and Pacific Affairs, 2009-13
Chair: Dr Leslie Vinjamuri, Director, US and the Americas Programme, Chatham House

Research Event

Event participants

Penny Abeywardena, Commissioner, International Affairs, City of New York
Ambassador Nina Hachigian, Deputy Mayor for International Affairs, City of Los Angeles; US Ambassador to the Association of Southeast Asian Nations (2014-17)
Steven Erlanger, Chief Diplomatic Correspondent, Europe, The New York Times  
Chair: Dr Leslie Vinjamuri, Director, US and the Americas Programme, Chatham House

Research Event

Event participants

Michèle Flournoy, Co-Founder and Managing Partner, Westexec Advisors; US Under Secretary of Defense for Policy, 2009 - 12
Chair: Dr Leslie Vinjamuri, Director, US and the Americas Programme; Dean, Queen Elizabeth II Academy for Leadership in International Affairs, Chatham House

Research Event

Event participants

Research Event

Event participants

Research Event

Research Event

Lord Mark Malloch-Brown, Chairman, SGO; Former Deputy Secretary-General and Chief of Staff, United Nations
Dr Elizabeth Cousens, President and CEO, United Nations Foundation
Ambassador Nicholas Burns, Roy and Barbara Goodman Family Professor of the Practice of Diplomacy and International Relations at the Harvard Kennedy School; US Under Secretary of State for Political Affairs, 2005 – 2008
Chair: Dr Leslie Vinjamuri, Director, US and the Americas Programme, Chatham House

17 December 2019

How is it possible for the directors of the Russian economy to pursue an orthodox stabilization policy with a great measure of success and yet to have achieved so little to stem the growth slowdown? This paper examines the reasons for the divergence in economic management.

Invitation Only Research Event

Event participants

Mathieu Boulegue, Research Fellow, Russia and Eurasia Programme, Chatham House
Nikolai Petrov, Senior Research Fellow, Russia and Eurasia Programme, Chatham House
Ekaterina Schulmann, Associate Fellow, Russia and Eurasia Programme, Chatham House
Chair: James Nixey, Programme Director, Russia and Eurasia, Chatham House

Invitation Only Research Event

Event participants

Christopher Davis, Professorial Fellow, Institute of Population Ageing, University of Oxford
Nino Evgenidze, Executive Director, EPRC
Katya Gorchinskaya, Journalist, former CEO of Hromadske.ua
Konstantin Sokulskiy, Head of Governance, UNDP, Kazakhstan
Chair: James Nixey, Programme Director, Russia and Eurasia, Chatham House

Invitation Only Research Event

Event participants

Paul D’anieri, Professor of Public Policy and Political Science, University of California, Riverside
Vlad Mykhnenko, Associate Professor of Sustainable Urban Development, St Peter’s College, University of Oxford
Chair: Orysia Lutsevych, Research Fellow and Manager, Ukraine Forum, Chatham House

Invitation Only Research Event

Customer Database Management Software, Customer Management Software, Customer Database Software in Mumbai, Customer Database Management Software in Pune, Customer Database Management Software in Ahmedabad, India.

Customer Database Management Software

Invitation Only Research Event

Event participants

Christophe McGlade, Research Associate, UCL Institute for Sustainable Resources
Chair: Shane Tomlinson, Senior Research Fellow, Energy, Environment and Resources, Chatham House

Active maintenance of β-cell identity through fine-tuned regulation of key transcription factors ensures β-cell function. Tacrolimus, a widely used immunosuppressant, accelerates onset of diabetes after organ transplantation, but underlying molecular mechanisms are unclear. Here we show that tacrolimus induces loss of human β-cell maturity and β-cell failure through activation of the BMP/SMAD signaling pathway when administered under mild metabolic stress conditions. Tacrolimus-induced phosphorylated SMAD1/5 acts in synergy with metabolic stress–activated FOXO1 through formation of a complex. This interaction is associated with reduced expression of the key β-cell transcription factor MAFA and abolished insulin secretion, both in vitro in primary human islets and in vivo in human islets transplanted into high-fat diet–fed mice. Pharmacological inhibition of BMP signaling protects human β-cells from tacrolimus-induced β-cell dysfunction in vitro. Furthermore, we confirm that BMP/SMAD signaling is activated in protocol pancreas allograft biopsies from recipients on tacrolimus. To conclude, we propose a novel mechanism underlying the diabetogenicity of tacrolimus in primary human β-cells. This insight could lead to new treatment strategies for new-onset diabetes and may have implications for other forms of diabetes.

The ability to switch fuels for oxidation in response to changes in macronutrient composition of diet (metabolic flexibility) may be informative of individuals’ susceptibility to weight gain. Seventy-nine healthy, weight-stable participants underwent 24-h assessments of energy expenditure and respiratory quotient (RQ) in a whole-room calorimeter during energy balance (EBL) (50% carbohydrate, 30% fat) and then during 24-h fasting and three 200% overfeeding diets in a crossover design. Metabolic flexibility was defined as the change in 24-h RQ from EBL during fasting and standard overfeeding (STOF) (50% carbohydrate, 30% fat), high-fat overfeeding (HFOF) (60% fat, 20% carbohydrate), and high-carbohydrate overfeeding (HCOF) (75% carbohydrate, 5% fat) diets. Free-living weight change was assessed after 6 and 12 months. Compared with EBL, RQ decreased on average by 9% during fasting and by 4% during HFOF but increased by 4% during STOF and by 8% during HCOF. A smaller decrease in RQ, reflecting a smaller increase in lipid oxidation rate, during HFOF but not during the other diets predicted greater weight gain at both 6 and 12 months. An impaired metabolic flexibility to acute HFOF can identify individuals prone to weight gain, indicating that an individual’s capacity to oxidize dietary fat is a metabolic determinant of weight change.

Iqbal Malik, consultant cardiologist at Imperial College Healthcare NHS Trust in London, joins Mabel Chew to discuss the role of angioplasty and stenting in patients with stable angina. Read the full article online: http://www.bmj.com/content/352/bmj.i205

The BMJ recently held a discussion between experts in the fields of general practice, emergency medicine, and paediatrics about the state of out of hours care in the UK, and crucially offered their vision for a better service. Are children a special case, can urgent care ‘hubs’ be a silver bullet, is NHS 111 up to the job of triaging patients,...

You’ll have read in a clinical trial “Most patients had an acceptable adverse-event profile.” Or that a drug “has a manageable and mostly reversible safety profile.” And that “the tolerability was good overall.” In this podcast, Bishal Gyawali (@oncology_bg) joins us to describe what events those terms were actually describing in cancer drug...

Masayuki Saito
Jul 1, 2009; 58:1526-1531
Metabolism

Franz M Matschinsky
Feb 1, 1996; 45:223-241
Banting Lecture 1995

Charles M. Alexander
May 1, 2003; 52:1210-1214
Complications

Giulio Marchesini
Aug 1, 2001; 50:1844-1850
Pathophysiology

J. Denis McGarry
Jan 1, 2002; 51:7-18
Banting Lecture 2001

Patrice D. Cani
Jun 1, 2008; 57:1470-1481
Metabolism

Patrice D. Cani
Jul 1, 2007; 56:1761-1772
Obesity Studies

Children at increased genetic risk for type 1 diabetes (T1D) after environmental exposures may develop pancreatic islet autoantibodies (IA) at a very young age. Metabolic profile changes over time may imply responses to exposures and signal development of the first IA. Our present research in The Environmental Determinants of Diabetes in the Young (TEDDY) study aimed to identify metabolome-wide signals preceding the first IA against GAD (GADA-first) or against insulin (IAA-first). We profiled metabolomes by mass spectrometry from children’s plasma at 3-month intervals after birth until appearance of the first IA. A trajectory analysis discovered each first IA preceded by reduced amino acid proline and branched-chain amino acids (BCAAs), respectively. With independent time point analysis following birth, we discovered dehydroascorbic acid (DHAA) contributing to the risk of each first IA, and -aminobutyric acid (GABAs) associated with the first autoantibody against insulin (IAA-first). Methionine and alanine, compounds produced in BCAA metabolism and fatty acids, also preceded IA at different time points. Unsaturated triglycerides and phosphatidylethanolamines decreased in abundance before appearance of either autoantibody. Our findings suggest that IAA-first and GADA-first are heralded by different patterns of DHAA, GABA, multiple amino acids, and fatty acids, which may be important to primary prevention of T1D.

When the Reds overhauled their rotation with three offseason trades, the first deal brought right-hander Tanner Roark from the Nationals for reliever Tanner Rainey. Observers saw Roark as a solid middle-of-the rotation hurler who is steady and dependable while able to rack up innings.

Diabetic retinopathy (DR) is a widespread vision-threatening disease, and neuroretinal abnormality should be considered as an important problem. Brain-derived neurotrophic factor (BDNF) has recently been considered as a possible treatment to prevent DR-induced neuroretinal damage, but how BDNF is upregulated in DR remains unclear. We found an increase in hydrogen peroxide (H₂O₂) in the vitreous of patients with DR. We confirmed that human retinal endothelial cells secreted H₂O₂ by high glucose, and H₂O₂ reduced cell viability of MIO-M1, Müller glia cell line, PC12D, and the neuronal cell line and lowered BDNF expression in MIO-M1, whereas BDNF administration recovered PC12D cell viability. Streptozocin-induced diabetic rats showed reduced BDNF, which is mainly expressed in the Müller glia cell. Oral intake of eicosapentaenoic acid ethyl ester (EPA-E) ameliorated BDNF reduction and oscillatory potentials (OPs) in electroretinography (ERG) in DR. Mass spectrometry revealed an increase in several EPA metabolites in the eyes of EPA-E–fed rats. In particular, an EPA metabolite, 18-hydroxyeicosapentaenoic acid (18-HEPE), induced BDNF upregulation in Müller glia cells and recovery of OPs in ERG. Our results indicated diabetes-induced oxidative stress attenuates neuroretinal function, but oral EPA-E intake prevents retinal neurodegeneration via BDNF in Müller glia cells by increasing 18-HEPE in the early stages of DR.

Invitation Only Research Event

Event participants

Paula Hodges QC, Partner; Head, Global Arbitration Practice, Herbert Smith Freehills
Stéphane Brabant, Partner; Chairman, Africa Practice Group, Herbert Smith Freehills