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Adipose tissues accumulate excess energy as fat and heavily influence metabolic homeostasis. O-GlcNAc modification (O-GlcNAcylation), which involves the addition of N­acetylglucosamine to proteins by O-GlcNAc transferase (Ogt), modulates multiple cellular processes. However, little is known about the role of O-GlcNAcylation in adipose tissues during bodyweight gain due to overnutrition. Here, we report on O-GlcNAcylation in mice with high-fat diet (HFD)-induced obesity. Mice with knockout of Ogt in adipose tissue achieved using adiponectin promoter-driven Cre recombinase ( Ogt-FKO) gained less bodyweight than control mice under HFD. Surprisingly, Ogt-FKO mice exhibited glucose intolerance and insulin resistance, despite their reduced bodyweight gain, as well as decreased expression of de novo lipogenesis genes and increased expression of inflammatory genes, resulting in fibrosis at 24 weeks of age. Primary cultured adipocytes derived from Ogt-FKO mice showed decreased lipid accumulation. Both in primary cultured adipocytes and 3T3-L1 adipocytes treated with Ogt inhibitor showed increased secretion of free fatty acids. Medium derived from these adipocytes stimulated inflammatory genes in RAW 264.7 macrophages, suggesting that cell-to-cell communication via free fatty acids might be a cause of adipose inflammation in Ogt-FKO mice. In conclusion, O-GlcNAcylation is important for healthy adipose expansion in mice. Glucose flux into adipose tissues may be a signal to store excess energy as fat.

Introduction: This trial assessed safety and effectiveness of an advanced hybrid closed-loop (AHCL) system with automated basal (Auto Basal) and automated bolus correction (Auto Correction) in adol...

Recent research has shed light on the cellular and molecular functions of bioactive lipids that go far beyond what was known about their role as dietary lipids. Bioactive lipids regulate inflammation and its resolution as signaling molecules. Genetic studies have identified key factors that can increase the risk of cardiovascular diseases and metabolic syndrome through their effects on lipogenesis. Lipid scientists have explored how these signaling pathways affect lipid metabolism in the liver, adipose tissue, and macrophages by utilizing a variety of techniques in both humans and animal models, including novel lipidomics approaches and molecular dynamics models. Dissecting out these lipid pathways can help identify mechanisms that can be targeted to prevent or treat cardiometabolic conditions. Continued investigation of the multitude of functions mediated by bioactive lipids may reveal additional components of these pathways that can provide a greater understanding of metabolic homeostasis.

Highly variable insulin sensitivity, susceptibility to hypoglycemia and inability to effectively communicate hypoglycemic symptoms pose significant challenges for young children with type 1 diabetes (T1D). Herein, outcomes during clinical MiniMed™ 670G system use were evaluated in children aged 2-6 years with T1D.Participants (N = 46, aged 4.6 ± 1.4 years) at seven investigational centers used the MiniMed™ 670G system in Manual Mode during a two-week run-in period followed by Auto Mode during a three-month study phase. Safety events, mean A1C, sensor glucose (SG), and percentage of time spent in (TIR, 70-180 mg/dl), below (TBR,70 mg/dl) and above (TAR,180 mg/dl) range were assessed for the run-in and study phase and compared using a paired t-test or Wilcoxon signed-rank test.From run-in to end of study (median 87.1% time in auto mode), mean A1C and SG changed from 8.0 ± 0.9% to 7.5 ± 0.6% (p 0.001) and from 173 ± 24 to 161 ± 16 mg/dl (p 0.001), respectively. Overall TIR increased from 55.7 ± 13.4% to 63.8 ± 9.4% (p 0.001), while TBR and TAR decreased from 3.3 ± 2.5% to 3.2 ± 1.6% (p = 0.996) and 41.0 ± 14.7% to 33.0 ± 9.9% (p 0.001), respectively. Overnight TBR remained unchanged and TAR was further improved 12:00 am-6:00 am. Throughout the study phase, there were no episodes of severe hypoglycemia or diabetic ketoacidosis (DKA) and no serious adverse device-related events.At-home MiniMed™ 670G Auto Mode use by young children safely improved glycemic outcomes compared to two-week open-loop Manual Mode use. The improvements are similar to those observed in older children, adolescents and adults with T1D using the same system for the same duration of time.

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease, in which prognosis is determined by liver fibrosis. A common variant in hydroxysteroid 17-beta dehydrogenase 13 ( HSD17B13 , rs72613567-A) is associated with a reduced risk of fibrosis in NAFLD, but the underlying mechanism(s) remains unclear. We investigated the effects of this variant in the human liver and in Hsd17b13 knockdown in mice by using a state-of-the-art metabolomics approach. We demonstrate that protection against liver fibrosis conferred by the HSD17B13 rs72613567-A variant in humans and by the Hsd17b13 knockdown in mice is associated with decreased pyrimidine catabolism at the level of dihydropyrimidine dehydrogenase. Furthermore, we show that hepatic pyrimidines are depleted in two distinct mouse models of NAFLD and that inhibition of pyrimidine catabolism by gimeracil phenocopies the HSD17B13 -induced protection against liver fibrosis. Our data suggest pyrimidine catabolism as a therapeutic target against the development of liver fibrosis in NAFLD.

Thermogenesis in brown and beige adipose tissue has important roles in maintaining body temperature and countering the development of metabolic disorders such as obesity and type 2 diabetes1,2. Although much is known about commitment and activation of brown and beige adipose tissue, its multiple and abundant immunological factors have not been well characterized3–6. Here we define a critical role of IL-27–IL-27Rα signalling in improving thermogenesis, protecting against diet-induced obesity and ameliorating insulin resistance. Mechanistic studies demonstrate that IL-27 directly targets adipocytes, activating p38 MAPK–PGC-1α signalling and stimulating the production of UCP1. Notably, therapeutic administration of IL-27 ameliorated metabolic morbidities in well-established mouse models of obesity. Consistently, individuals with obesity show significantly decreased levels of serum IL-27, which can be restored after bariatric surgery. Collectively, these findings show that IL-27 has an important role in orchestrating metabolic programs, and is a highly promising target for anti-obesity immunotherapy. Therapeutic administration of IL-27—serum levels of which are decreased in individuals with obesity—improves thermogenesis, protects against diet-induced obesity and ameliorates insulin resistance in mouse models of obesity.

OBJECTIVE This study investigated whether variations in cell death-inducing DNA fragmentation factor alpha subunit-like effector A (CIDEA) mRNA expression and protein levels are modulated by the pattern of abdominal fat distribution in adolescent girls with obesity. METHODS This study recruited 35 adolescent girls with obesity and characterized their abdominal fat distribution by magnetic resonance imaging. Participants had only a periumbilical/abdominal (n = 14) or a paired abdominal and gluteal subcutaneous adipose tissue (SAT) biopsy (n = 21). CIDEA expression was determined by reverse transcription-polymerase chain reaction, CIDEA protein level by Western blot, and the turnover of adipose lipids and adipocytes by 2 H2 O labeling. In six girls, a second abdominal SAT biopsy was performed (after ~34.2 months) to explore the weight gain effect on CIDEA expression in abdominal SAT. RESULTS CIDEA expression decreased in abdominal SAT from participants with high visceral adipose tissue (VAT)/(VAT+SAT); CIDEA inversely correlated with number of small adipocytes, with the increase in preadipocyte proliferation, and with adipogenesis. A strong inverse correlation was found between CIDEA protein level with the newly synthetized glycerol (r = -0.839, p = 0.0047). Following weight gain, an increase in adipocytes' cell diameter with a decrease in CIDEA expression and RNA-sequencing transcriptomic profile typical of adipocyte dysfunction was observed. CONCLUSIONS Reduced expression of CIDEA in girls with high VAT/(VAT+SAT) is associated with adipocyte hypertrophy and insulin resistance.

Single-nucleotide polymorphisms in the human juxtaposed with another zinc finger protein 1 ( JAZF1 ) gene have repeatedly been associated with both type 2 diabetes (T2D) and height in multiple genome-wide association studies (GWAS); however, the mechanism by which JAZF1 causes these traits is not yet known. To investigate the possible functional role of JAZF1 in growth and glucose metabolism in vivo, we generated Jazf1 knockout (KO) mice and examined body composition and insulin sensitivity both in young and adult mice by using 1 H-nuclear magnetic resonance and hyperinsulinemic-euglycemic clamp techniques. Plasma concentrations of insulin-like growth factor 1 (IGF-1) were reduced in both young and adult Jazf1 KO mice, and young Jazf1 KO mice were shorter in stature than age-matched wild-type mice. Young Jazf1 KO mice manifested reduced fat mass, whereas adult Jazf1 KO mice manifested increased fat mass and reductions in lean body mass associated with increased plasma growth hormone (GH) concentrations. Adult Jazf1 KO manifested muscle insulin resistance that was further exacerbated by high-fat diet feeding. Gene set enrichment analysis in Jazf1 KO liver identified the hepatocyte hepatic nuclear factor 4 alpha (HNF4α), which was decreased in Jazf1 KO liver and in JAZF1 knockdown cells. Moreover, GH-induced IGF-1 expression was inhibited by JAZF1 knockdown in human hepatocytes. Taken together these results demonstrate that reduction of JAZF1 leads to early growth retardation and late onset insulin resistance in vivo which may be mediated through alterations in the GH-IGF-1 axis and HNF4α.

Single-nucleotide polymorphisms in the human juxtaposed with another zinc finger protein 1 (

Problem Statement and Purpose. In Transnistria, the deposits of Sarmatian-age limestone are explored and exploited. These minerals are used as raw materials for cement production, as well as for the production of buta and rubble. The issues of genesis and facial transitions of these deposits remain under-studied. Data & Methods. The purpose of this work is to determine the genetic affiliation of the limestone deposits of the Gidirim and Severin deposits on the basis of facial and chemical analysis. The materials of the research are the limestones of two deposits of Transnistria. The object is the limestone of the Sarmatian age of the deposits of Transnistria. The subject of the study is the lithological and paleontological characteristic, the chemical composition of these limestones. Research methods: topical; biofacial, computer processing with GIS – programs; Laboratory quality diagnostics, chemical and physical-chemical methods of quantifying the main components of carbonate rocks. Results. The geological conditions of the Severin and Gidirim deposits were studied, and the place of productive layers of deposits in the stratigraphic scheme of Transnistria was determined on the basis of the lithological and paleontological characteristics of the rocks. Limestones mined at the Gidirim field belong to the May Day retinue, and the limestone of Severinovsky belongs to the Bessarabian reefs. Chemical analysis of limestone samples extracted from the deposits was carried out and differences in the chemical composition of the limestone of these deposits were determined. The limestone deposits in the content of calcium carbonate are clean. The concentration of silicon dioxide in the samples of the Severin field is higher than in the samples of the Giderim field, the content of one-and-a-half oxides, on the contrary, in Severinovka – 0.68%, in samples of the Giderim field – 1.04%. Analysis of the lithological composition and fauna of limestones has made it possible to distinguish within the Middle-Sarmatian basin of sedimentopulation: (a) accumulation of biogenic-chemogenic limestone of the near shelf, b) biogenic precipitation of the transition zone (reefs), c) silicate-terrigenous formations of the far shelf. The variety of phased conditions in the basin is associated with the position of the coastline and the inflection of the bottom on the boundary of the near and far shelf. The limestone of the studied deposits was formed in two different facial environments: the chemogenic-carbonate and the transient, which is associated with the formation of a strip of Bessarabian reefs. The study of paleontological residues, lithology and chemical composition of rhypogenic limestone showed the autonomy of this environment, as it has features of sedimentogenesis and near and far shelf.

Uncoupling protein-3 (UCP3) is a mitochondrial transmembrane protein highly expressed in the muscle that has been implicated in regulating the efficiency of mitochondrial oxidative phosphorylation. Increasing UCP3 expression in skeletal muscle enhances proton leak across the inner mitochondrial membrane and increases oxygen consumption in isolated mitochondria, but its precise function in vivo has yet to be fully elucidated. To examine whether muscle-specific overexpression of UCP3 modulates muscle mitochondrial oxidation in vivo, rates of ATP synthesis were assessed by

The cJun NH2-terminal kinase (JNK) signaling pathway is activated by metabolic stress and promotes the development of metabolic syndrome, including hyperglycemia, hyperlipidemia, and insulin resistance. This integrated physiological response involves cross-talk between different organs. Here we demonstrate that JNK signaling in adipocytes causes an increased circulating concentration of the hepatokine fibroblast growth factor 21 (FGF21) that regulates systemic metabolism. The mechanism of organ crosstalk is mediated by a feed-forward regulatory loop caused by JNK-regulated FGF21 autocrine signaling in adipocytes that promotes increased expression of the adipokine adiponectin and subsequent hepatic expression of the hormone FGF21. The mechanism of organ cross-talk places circulating adiponectin downstream of autocrine FGF21 expressed by adipocytes and upstream of endocrine FGF21 expressed by hepatocytes. This regulatory loop represents a novel signaling paradigm that connects autocrine and endocrine signaling modes of the same hormone in different tissues.

Significance As it is estimated that one in three Americans will suffer from type 2 diabetes by 2050, interventions to ameliorate insulin resistance are of great interest. Adiponectin has emerged as a promising insulin-sensitizing adipokine; however, the mechanisms by which adiponectin administration improves insulin sensitivity are unclear. Here, we show that globular adiponectin (gAcrp30) and full-length adiponectin (Acrp30) reverse insulin resistance in HFD-fed mice through reductions in ectopic lipid in liver and muscle likely by stimulation of LPL activity in eWAT and increased eNOS/AMPK activation and fat oxidation in muscle. These effects, in turn, lead to decreased plasma membrane diacylglycerol content, resulting in decreased PKCε activation in liver and decreased PKCε/PKCθ activity in muscle and improved insulin signaling in these tissues., Adiponectin has emerged as a potential therapy for type 2 diabetes mellitus, but the molecular mechanism by which adiponectin reverses insulin resistance remains unclear. Two weeks of globular adiponectin (gAcrp30) treatment reduced fasting plasma glucose, triglyceride (TAG), and insulin concentrations and reversed whole-body insulin resistance, which could be attributed to both improved insulin-mediated suppression of endogenous glucose production and increased insulin-stimulated glucose uptake in muscle and adipose tissues. These improvements in liver and muscle sensitivity were associated with ∼50% reductions in liver and muscle TAG and plasma membrane (PM)-associated diacylglycerol (DAG) content and occurred independent of reductions in total ceramide content. Reductions of PM DAG content in liver and skeletal muscle were associated with reduced PKCε translocation in liver and reduced PKCθ and PKCε translocation in skeletal muscle resulting in increased insulin-stimulated insulin receptor tyrosine1162 phosphorylation, IRS-1/IRS-2–associated PI3-kinase activity, and Akt-serine phosphorylation. Both gAcrp30 and full-length adiponectin (Acrp30) treatment increased eNOS/AMPK activation in muscle and muscle fatty acid oxidation. gAcrp30 and Acrp30 infusions also increased TAG uptake in epididymal white adipose tissue (eWAT), which could be attributed to increased lipoprotein lipase (LPL) activity. These data suggest that adiponectin and adiponectin-related molecules reverse lipid-induced liver and muscle insulin resistance by reducing ectopic lipid storage in these organs, resulting in decreased plasma membrane sn-1,2-DAG–induced nPKC activity and increased insulin signaling. Adiponectin mediates these effects by both promoting the storage of TAG in eWAT likely through stimulation of LPL as well as by stimulation of AMPK in muscle resulting in increased muscle fat oxidation.

In a healthy person, the kidney filters nearly 200 g of glucose per day, almost all of which is reabsorbed. The primary transporter responsible for renal glucose reabsorption is sodium-glucose cotransporter-2 (SGLT2). Based on the impact of SGLT2 to prevent renal glucose wasting, SGLT2 inhibitors have been developed to treat diabetes and are the newest class of glucose-lowering agents approved in the United States. By inhibiting glucose reabsorption in the proximal tubule, these agents promote glycosuria, thereby reducing blood glucose concentrations and often resulting in modest weight loss. Recent work in humans and rodents has demonstrated that the clinical utility of these agents may not be limited to diabetes management: SGLT2 inhibitors have also shown therapeutic promise in improving outcomes in heart failure, atrial fibrillation, and, in preclinical studies, certain cancers. Unfortunately, these benefits are not without risk: SGLT2 inhibitors predispose to euglycemic ketoacidosis in those with type 2 diabetes and, largely for this reason, are not approved to treat type 1 diabetes. The mechanism for each of the beneficial and harmful effects of SGLT2 inhibitors—with the exception of their effect to lower plasma glucose concentrations—is an area of active investigation. In this review, we discuss the mechanisms by which these drugs cause euglycemic ketoacidosis and hyperglucagonemia and stimulate hepatic gluconeogenesis as well as their beneficial effects in cardiovascular disease and cancer. In so doing, we aim to highlight the crucial role for selecting patients for SGLT2 inhibitor therapy and highlight several crucial questions that remain unanswered.

Microsomal triglyceride transfer protein (MTTP) deficiency results in a syndrome of hypolipidemia and accelerated NAFLD. Animal models of decreased hepatic MTTP activity have revealed an unexplained dissociation between hepatic steatosis and hepatic insulin resistance. Here, we performed comprehensive metabolic phenotyping of liver-specific MTTP knockout (L-Mttp(-/-)) mice and age-weight matched wild-type control mice. Young (10-12-week-old) L-Mttp(-/-) mice exhibited hepatic steatosis and increased DAG content; however, the increase in hepatic DAG content was partitioned to the lipid droplet and was not increased in the plasma membrane. Young L-Mttp(-/-) mice also manifested normal hepatic insulin sensitivity, as assessed by hyperinsulinemic-euglycemic clamps, no PKC epsilon activation, and normal hepatic insulin signaling from the insulin receptor through AKT Ser/Thr kinase. In contrast, aged (10-month-old) L-Mttp(-/-) mice exhibited glucose intolerance and hepatic insulin resistance along with an increase in hepatic plasma membrane sn-1,2-DAG content and PKC epsilon activation. Treatment with a functionally liver-targeted mitochondrial uncoupler protected the aged L-Mttp(-/-) mice against the development of hepatic steatosis, increased plasma membrane sn-1,2-DAG content, PKC epsilon activation, and hepatic insulin resistance. Furthermore, increased hepatic insulin sensitivity in the aged controlled-release mitochondrial protonophore-treated L-Mttp(-/-) mice was not associated with any reductions in hepatic ceramide content. Taken together, these data demonstrate that differences in the intracellular compartmentation of sn-1,2-DAGs in the lipid droplet versus plasma membrane explains the dissociation of NAFLD/lipid-induced hepatic insulin resistance in young L-Mttp(-/-) mice as well as the development of lipid-induced hepatic insulin resistance in aged L-Mttp(-/-) mice This work was supported by National Institutes of Health Grants R01 DK116774, R01 DK119968, R01 DK114793, R01 DK113984, K23 DK10287, P30 DK045735, DK121490, and HL137202 and the Veterans Health Administration Merit Review Awards I01 BX000901 and BX004113. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health or the U.S. Department of Veterans Affairs

Metformin is a first-line therapy for the treatment of type 2 diabetes, due to its robust glucose-lowering effects, well-established safety profile, and relatively low cost. While metformin has been shown to have pleotropic effects on glucose metabolism, there is a general consensus that the major glucose-lowering effect in patients with type 2 diabetes is mostly mediated through inhibition of hepatic gluconeogenesis. However, despite decades of research, the mechanism by which metformin inhibits this process is still highly debated. A key reason for these discrepant effects is likely due to the inconsistency in dosage of metformin across studies. Widely studied mechanisms of action, such as complex I inhibition leading to AMPK activation, have only been observed in the context of supra-pharmacological (>1 mM) metformin concentrations, which do not occur in the clinical setting. Thus, these mechanisms have been challenged in recent years and new mechanisms have been proposed. Based on the observation that metformin alters cellular redox balance, a redox-dependent mechanism of action has been described by several groups. Recent studies have shown that clinically relevant (50-100 μM) concentrations of metformin inhibit hepatic gluconeogenesis in a substrate-selective manner both in vitro and in vivo, supporting a redox-dependent mechanism of metformin action. Here, we review the current literature regarding metformin’s cellular and molecular mechanisms of action., Graphical Abstract Graphical Abstract

Objectives: Physicians and other mental health experts are increasingly called on to assist the courts with the determination of testamentary capacity. We aim to improve the understanding of the retrospective assessment of testamentary capacity for medical experts in order to provide more useful reports for the court’s determinations and to provide a methodology for the retrospective assessment of testamentary capacity. Method: Medical experts with experience in the retrospective assessment of testamentary capacity collaborated with lawyers who practice estate litigation. The medical literature on the assessment of testamentary capacity was reviewed and integrated. The medical experts provided a clinical perspective, while the lawyers ensured that the case law and legal perspective were integrated into this review. Results: The focus and limitations of the medical expert are outlined including the need to be objective, nonpartisan, and fair. For the benefit of the court, the medical expert should describe the nature and severity of relevant medical, psychiatric, and cognitive disorders, and how they may impact on the specific criteria for testamentary capacity as defined by the leading case of Banks v Goodfellow. Medical experts should opine only on the issue of vulnerability to influence and defer to the court to determine the facts of the case regarding any influence that may have been exerted. Conclusions: Although the ultimate determination of testamentary capacity is a legal one, medical experts can help the court achieve the most informed legal decision by providing relevant information on clinical issues that may impact the criteria for testamentary capacity.

Objective: A CGM sensor that is disposable and requires no calibration may make glucose management easier for people living with diabetes. The present study reports on the interim analysis of a new disposable zero-calibration sensor in adults and youth with type 1 (T1D) or type 2 diabetes (T2D) . Methods: A prospective study enrolled individuals (N=123 adults, aged 18-80 years and N=120 youth, aged 2-17 years) with diabetes at 13 sites in the United States. Raw sensor data were compared with a YSI (Yellow Springs Instruments) or blood glucose (BG) reference and involved N=15388 paired points (pps) from the arm of adults, and N=8627pps from the arm and 7781pps from the buttock of youth. Data were processed using a new zero-calibration algorithm. The primary endpoint was agreement within 20%/20mg/dL (sensor glucose [SG] ≥80mg/dL/ Results: The overall 20%/20mg/dL agreement rate was 90.6% for adults, and 87.8% and 88.5% for youth arm and buttock, respectively. For adults, the 15%/15mg/dL agreement rates were 90.1% and 87.6% (SG 180 mg/dL, respectively) . For youth, the 15%/15mg/dL rates were 93.2% and 86.5% for the arm (SG 180 mg/dL, respectively) and 90.3% and 89.5% for the buttock (SG 180 mg/dL, respectively) . The MARDs were 10.2% for adults, and 10.7% and 10.1% for youth arm and buttock, respectively. Conclusion: These interim findings on the clinical performance of the new disposable and calibration-free sensor are good and may support non-adjunctive insulin dosing in standalone CGM and automated insulin delivery systems. Disclosure B.W.Bode: Advisory Panel; CeQur SA, MannKind Corporation, Medtronic, Novo Nordisk, Zealand Pharma A/S, Consultant; Bigfoot Biomedical, Inc., Research Support; Abbott, Beta Bionics, Inc., Dexcom, Inc., Diasome, Dompé, Eli Lilly and Company, Insulet Corporation, IQVIA Inc., Jaeb Center for Health Research, Medtronic, Novo Nordisk, Provention Bio, Inc., REMD Biotherapeutics, Sanvita Medical, Senseonics, ViaCyte, Inc., Speaker’s Bureau; Abbott, Boehringer Ingelheim International GmbH, Eli Lilly and Company, Insulet Corporation, MannKind Corporation, Novo Nordisk, Sanofi, Xeris Pharmaceuticals, Inc., Stock/Shareholder; AgaMatrix, Glytec, LLC. J.Shin: Employee; Medtronic. F.Peng: None. S.Huang: n/a. A.S.Rhinehart: Employee; Medtronic, Stock/Shareholder; Medtronic. R.A.Vigersky: Employee; Medtronic. T.S.Bailey: Advisory Panel; Abbott Diabetes, CeQur SA, MannKind Corporation, Medtronic, Novo Nordisk, Consultant; LifeScan, Sanofi, Research Support; Abbott Diabetes, Abbott Diagnostics, Biolinq, Capillary Biomedical, Inc., Dexcom, Inc., Eli Lilly and Company, Kowa Research Institute, Inc., Livongo, MannKind Corporation, Medtronic, Novo Nordisk, REMD Biotherapeutics, Sanofi, Sanvita Medical, Senseonics, ViaCyte, Inc., vTv Therapeutics, Zealand Pharma A/S, Speaker’s Bureau; Becton, Dickinson and Company, Medtronic, Sanofi. K.N.Castorino: Consultant; Lilly Diabetes, Research Support; Abbott Diabetes, Dexcom, Inc., Drawbridge Health, Inc., Eyenuk, Inc., Laxmi Therapeutic Devices, Medtronic, National Institute of Diabetes and Digestive and Kidney Diseases, Novo Nordisk, Speaker’s Bureau; Dexcom, Inc. M.P.Christiansen: Research Support; Abbott Diabetes, Ascensia Diabetes Care, AstraZeneca, Biolinq, Dexcom, Inc., Eli Lilly and Company, Helixmith, MannKind Corporation, Medtronic, Merck Sharp & Dohme Corp. S.K.Garg: Advisory Panel; Bayer AG, Medtronic, Zealand Pharma A/S, Consultant; Novo Nordisk, Research Support; Dexcom, Inc., Medtronic. K.B.Kaiserman: Advisory Panel; Medtronic, Consultant; Medtronic, Employee; MannKind Corporation, Research Support; Medtronic, Speaker’s Bureau; Medtronic, Stock/Shareholder; MannKind Corporation. D.R.Liljenquist: None. D.I.Shulman: Advisory Panel; Medtronic. R.H.Slover: None.

Background: Safety and effectiveness outcomes of individuals using the MiniMed™ 780G system with the no-calibration Guardian™ 4 sensor during the first three months of use were analyzed. Methods: Participants (N=176, aged 7-75 years) with T1D used the Conformitè Europëenne-marked MiniMed™ 780G system. Safety and effectiveness endpoints (mean A1C, sensor glucose [SG], percentage of time spent at SG ranges and glucose variability) were collected over three months and summarized. Endpoints were also assessed when recommended settings (target of 100mg/dL and active insulin time of 2-3 hours) were used. Results: There was no DKA or severe hypoglycemia. At 3 months, A1C was 7.1% (N=164) , 7.2% (N=101) and 6.8% (N=63) for overall, pediatric and adult participants, respectively. Additional glycemic metrics are shown (Table) . With recommended settings, time spent in target range (TIR, 70-180 mg/dL) was 74.7% (N=119) , 72.7% (N=65) and 77.0% (N=54) , respectively, and time spent below range (TBR Conclusion: This analysis demonstrates that individuals safely exceeded international consensus-recommended TIR and TBR goals when using the MiniMed™ 780G system with the Guardian™ 4 sensor. These results mirror those of the pivotal trial during use of the calibration-requiring Guardian™ sensor 3. Disclosure R. A. Vigersky: Employee; Medtronic. C. Pihoker: None. R. Pop-busui: Advisory Panel; Averitas Pharma, Inc., Boehringer Ingelheim International GmbH, Nevro Corp., Novo Nordisk, Reata Pharmaceuticals, Inc., Regenacy Pharmaceuticals, Inc. J. Reed: None. J. Sherr: Advisory Panel; Bigfoot Biomedical, Inc., Cecelia Health, Insulet Corporation, Medtronic, Vertex Pharmaceuticals Incorporated, Consultant; Insulet Corporation, Lexicon Pharmaceuticals, Inc., Research Support; Dexcom, Inc., Insulet Corporation, Jaeb Center for Health Research, JDRF, Medtronic, National Institute of Diabetes and Digestive and Kidney Diseases, Speaker’s Bureau; Lilly Diabetes. D. I. Shulman: Advisory Panel; Medtronic. R. H. Slover: None. J. Thrasher: Advisory Panel; Eli Lilly and Company, Medtronic, Board Member; Medtronic, Consultant; Eli Lilly and Company, Medtronic, Research Support; Eli Lilly and Company, Medtronic, Novo Nordisk, Speaker’s Bureau; Bayer AG, Eli Lilly and Company, Medtronic, Sanofi. X. Chen: Employee; Medtronic, Medtronic. M. Liu: None. T. L. Cordero: Employee; Medtronic, Medtronic. B. W. Bode: Advisory Panel; CeQur SA, MannKind Corporation, Medtronic, Novo Nordisk, Zealand Pharma A/S, Consultant; Bigfoot Biomedical, Inc., Research Support; Abbott, Beta Bionics, Inc., Dexcom, Inc., Diasome, Dompé, Eli Lilly and Company, Insulet Corporation, IQVIA Inc., Jaeb Center for Health Research, Medtronic, Novo Nordisk, Provention Bio, Inc., REMD Biotherapeutics, Sanvita Medical, Senseonics, ViaCyte, Inc., Speaker’s Bureau; Abbott, Boehringer Ingelheim International GmbH, Eli Lilly and Company, Insulet Corporation, MannKind Corporation, Novo Nordisk, Sanofi, Xeris Pharmaceuticals, Inc., Stock/Shareholder; AgaMatrix, Glytec, LLC. M. Vella: Employee; Medtronic. A. S. Rhinehart: Employee; Medtronic, Stock/Shareholder; Medtronic. J. Shin: Employee; Medtronic. R. L. Brazg: Research Support; Abbott Diabetes, Lilly Diabetes, Medtronic, Novo Nordisk, Roche Diagnostics, Senseonics. B. A. Buckingham: Advisory Panel; Arecor, Lilly Diabetes, Medtronic, Other Relationship; Insulet Corporation, Research Support; Insulet Corporation, Lilly Diabetes, Medtronic. A. L. Carlson: Advisory Panel; MannKind Corporation, Employee; Bright Health Group, Other Relationship; Medtronic, Research Support; Abbott Diabetes, Dexcom, Inc., Eli Lilly and Company, Insulet Corporation, Novo Nordisk, Sanofi, UnitedHealth Group. K. B. Kaiserman: Advisory Panel; Medtronic, Consultant; Medtronic, Employee; MannKind Corporation, Research Support; Medtronic, Speaker’s Bureau; Medtronic, Stock/Shareholder; MannKind Corporation. M. Kipnes: None. D. R. Liljenquist: None. A. Philis-tsimikas: Advisory Panel; Bayer AG, Novo Nordisk, Research Support; Lilly Diabetes, National Institute of Diabetes and Digestive and Kidney Diseases, Novo Nordisk, Viking Therapeutics.

FoxO1 is a major target of insulin action and regulates expression of ATGL and its inhibitor, G0S2, in the liver (Cell Rep 15:349, 2016) . Here, we asked whether ATGL mediates effects of FoxO1 in liver-specific insulin receptor knockout (LIRKO) mice. Studies in LIRKO and IR/FoxO1 double knockout (LIRFKO) mice show ATGL expression is increased and G0S2 is suppressed in a FoxO1-dependent fashion when insulin signaling is disrupted in the liver. ATGL knockdown (KD) reduces high plasma glucose and insulin concentrations, HOMA-IR and fatty acid oxidation, and improves glucose tolerance in LIRKO mice. Hyperinsulinemic-euglycemic clamp studies show ATGL KD improves insulin sensitivity due to effects on both HGP and glucose utilization, reflecting changes in WAT lipolysis, BAT metabolism and hepatic gene expression. The expression of FoxO1-regulated gluconeogenic genes (PEPCK, G6Pase, PCO, PGC-1α) , hepatokines (e.g., follistatin) and IGFBP-1 is increased in LIRKO mice and reduced by ATGL KD, reflecting changes in acetylation of FoxO1 and its co-activator, PGC-1α (decreased in LIRKO, increased by ATGL KD) . Rictor acetylation, which promotes activation of Akt and phosphorylation of FoxO1, also is increased by ATGL KD in LIRKO mice and isolated hepatocytes. Since ATGL promotes activation of Sirt1 (Mol Cell 77:810, 2020) and Sirt1 deacetylates FoxO1, PGC-1α and rictor, these studies suggest FoxO1 promotes increased ATGL and Sirt1 activity, and that Sirt1 activation enhances the effects of FoxO1 on gene expression and glucose homeostasis in a feed forward fashion (FoxO1 -> ATGL -> Sirt1 -> FoxO1) . Targeting the FoxO1/ATGL/Sirt1 pathway may provide a useful strategy for improving glucose homeostasis when insulin signaling is impaired in the liver. Disclosure I.O-sullivan: None. S.Bhattacharyya: None. C.Liew: None. S.M.Lee: None. J.Cordoba-chacon: None. R.J.Perry: None. G.I.Shulman: Advisory Panel; 89bio, Inc., AstraZeneca, Equator Therapeutics, Inc., Janssen Research & Development, LLC, Merck & Co., Inc., Consultant; DiCerna Pharmaceuticals, Inc., Novo Nordisk, Other Relationship; Generian Pharmaceuticals, iMetabolic Biopharma Corporation, Maze Therapeutics, The Liver Company, Stock/Shareholder; Levels Health, Inc. . T.Unterman: None. Funding Department of Veterans Affairs (5I01BX001968)

Hyperglucagonemia is a hallmark of type 2 diabetes mellitus (T2DM) and contributes to increased rates of endogenous glucose production (EGP) , mostly through increased rates of hepatic gluconeogenesis (GNG) , but the anaplerotic pathways and respective substrates that support this process are unclear. To address this question, we developed a novel and extensively validated 13C5 glutamine-based in vivo metabolic flux analysis method (Q Flux) , which allows for quantitation of both the relative and absolute rates of hepatic gluconeogenesis from pyruvate (via pyruvate carboxylase [PC]) , succinyl CoA (via methylmalonyl CoA mutase [MUT]) , glutamine (via glutaminase [GLS2]) , and glycerol. Male Sprague-Dawley rats (∼300 g) were infused for 90 minutes with either low-dose (LD) glucagon (1.25 ng/[kg-min]) or high-dose (HD) glucagon (ng/[kg-min]) , plus insulin (0.5 mU/[kg-min]) , somatostatin (4 μg/[kg-min]) , and 13C5 glutamine (3 μmol/[kg-min]) after a 16-hour fast to deplete hepatic glycogen. HD animals displayed significantly increased plasma glucose concentrations and EGP relative to LD controls. Analyses of liver tissues collected at sacrifice revealed that in LD animals, 70% of mitochondrial GNG was from pyruvate, 15% from succinyl CoA, and 15% from glutamine. In HD animals, 59% of mitochondrial GNG was derived from pyruvate (p=0.vs. LD) , 26% from succinyl CoA (p=0.0vs. LD) , and 15% from glutamine (p=0.99 vs. LD) . Conclusion: We find an unexpected role for succinyl CoA anaplerosis and methylmalonyl CoA mutase flux in supporting increased rates of mitochondrial GNG during hyperglucagonemia. Furthermore, relative contributions of glutamine to hepatic gluconeogenesis were unchanged, contrary to previous reports. Taken together, these results identify novel targets to reduce hyperglucagonemia-induced increases in rates of gluconeogenesis and hyperglycemia in T2DM. Disclosure B.T.Hubbard: None. G.I.Shulman: Advisory Panel; 89bio, Inc., AstraZeneca, Equator Therapeutics, Inc., Janssen Research & Development, LLC, Merck & Co., Inc., Consultant; DiCerna Pharmaceuticals, Inc. , Novo Nordisk, Other Relationship; Generian Pharmaceuticals, iMetabolic Biopharma Corporation, Maze Therapeutics, The Liver Company, Stock/Shareholder; Levels Health, Inc. .

Several studies highlight the potential for SGLT2 inhibitors (i) to exert their cardioprotective effects by shifting myocardial fuel utilization towards ketone oxidation. However, direct in vivo measurements of cardiac mitochondrial substrate oxidation in awake rodents during heart failure are lacking, and whether SGLT2i-mediated increases in ketone availability and oxidation are able to improve cardiac efficiency remains unclear. Here, we examined the effect of acute SGLT2 inhibition with dapagliflozin (dapa) on cardiac function and mitochondrial metabolism in awake male Sprague Dawley rats 2 weeks after induction of heart failure by permanent ligation of the left anterior descending coronary artery. Echocardiography and in vivo metabolic flux studies were performed 4-6 h after oral dapa (1.5 mg/kg) or vehicle treatment in sham-surgerized rats and rats with myocardial infarction (MI) . Acute dapa treatment caused a 15% decrease in fasting plasma glucose concentrations and 50% increase in fasting plasma NEFAs, whole-body βOHB turnover and plasma βOHB levels in sham and MI rats (all P Conclusion: Taken together, these results demonstrate that single-dose dapa treatment, which acutely decreased LV myocardial pyruvate oxidation and increased LV ketone oxidation, was not sufficient to alter cardiac output or LV ejection fraction. Disclosure L. Goedeke: Other Relationship; The Liver Company, Inc. . G. I. Shulman: Advisory Panel; 89bio, Inc., AstraZeneca, Equator Therapeutics, Inc., Janssen Research & Development, LLC, Merck & Co., Inc., Consultant; DiCerna Pharmaceuticals, Inc., Novo Nordisk, Other Relationship; Generian Pharmaceuticals, iMetabolic Biopharma Corporation, Maze Therapeutics, The Liver Company, Stock/Shareholder; Levels Health, Inc. . Y. Ma: None. J. Zhang: n/a. N. Guerrera: None. X. Wu: None. D. Zhang: None. M. Kahn: None. X. Zhang: None. L. H. Young: None. Funding NIH (P30 DK045735 and K99 HL150234) , AstraZeneca (NCR-19-20028)

The mitochondrial calcium uniporter (MCU) facilitates mitochondrial calcium influx, and several enzymes that catalyze key steps of the tricarboxylic acid (TCA) cycle require calcium for their activation. As such, it is generally accepted that rates of mitochondrial oxidation correlate with mitochondrial calcium activity. Decreased rates of hepatic mitochondrial oxidation are associated with metabolic dysfunction and ectopic lipid accumulation as seen with type 2 diabetes and nonalcoholic fatty liver disease. Despite this, a role for MCU and mitochondrial calcium in regulating hepatic mitochondrial oxidation is still unclear. To address this question, we generated a liver-specific MCU knockout (MCU KO) mouse model which displayed significantly reduced mitochondrial calcium ([Ca2+]mt, p Disclosure T. E. Lamoia: n/a. B. T. Hubbard: None. M. Guerra: None. R. Goodman: None. M. H. Nathanson: None. V. Mootha: Advisory Panel; 5AM Ventures, LLC, Janssen Research & Development, LLC. G. I. Shulman: Advisory Panel; 89bio, Inc., AstraZeneca, Equator Therapeutics, Inc., Janssen Research & Development, LLC, Merck & Co., Inc., Consultant; DiCerna Pharmaceuticals, Inc. , Novo Nordisk, Other Relationship; Generian Pharmaceuticals, iMetabolic Biopharma Corporation, Maze Therapeutics, The Liver Company, Stock/Shareholder; Levels Health, Inc. . Funding F31 DK126362/DK/NIDDK NIH HHST32 GM007324/GM/NIGMS NIH HHS

Brown adipose tissue (BAT), a crucial heat-generating organ, regulates whole-body energy metabolism by mediating thermogenesis. BAT inflammation is implicated in the pathogenesis of mitochondrial dysfunction and impaired thermogenesis. However, the link between BAT inflammation and systematic metabolism remains unclear. Herein, we use mice with BAT deficiency of thioredoxin-2 (TRX2), a protein that scavenges mitochondrial reactive oxygen species (ROS), to evaluate the impact of BAT inflammation on metabolism and thermogenesis and its underlying mechanism. Our results show that BAT-specific TRX2 ablation improves systematic metabolic performance via enhancing lipid uptake, which protects mice from diet-induced obesity, hypertriglyceridemia, and insulin resistance. TRX2 deficiency impairs adaptive thermogenesis by suppressing fatty acid oxidation. Mechanistically, loss of TRX2 induces excessive mitochondrial ROS, mitochondrial integrity disruption, and cytosolic release of mitochondrial DNA, which in turn activate aberrant innate immune responses in BAT, including the cGAS/STING and the NLRP3 inflammasome pathways. We identify NLRP3 as a key converging point, as its inhibition reverses both the thermogenesis defect and the metabolic benefits seen under nutrient overload in BAT-specific Trx2-deficient mice. In conclusion, we identify TRX2 as a critical hub integrating oxidative stress, inflammation, and lipid metabolism in BAT, uncovering an adaptive mechanism underlying the link between BAT inflammation and systematic metabolism.

Athletes exhibit increased muscle insulin sensitivity, despite increased intramuscular triacylglycerol content. This phenomenon has been coined the 'athlete's paradox' and is poorly understood. Recent findings suggest that the subcellular distribution of sn-1,2-diacylglycerols (DAGs) in the plasma membrane leading to activation of novel protein kinase Cs (PKCs) is a crucial pathway to inducing insulin resistance. Here, we hypothesised that regular aerobic exercise would preserve muscle insulin sensitivity by preventing increases in plasma membrane sn-1,2-DAGs and activation of PKCε and PKCθ despite promoting increases in muscle triacylglycerol content.C57BL/6J mice were allocated to three groups (regular chow feeding [RC]; high-fat diet feeding [HFD]; RC feeding and running wheel exercise [RC-EXE]). We used a novel LC-MS/MS/cellular fractionation method to assess DAG stereoisomers in five subcellular compartments (plasma membrane [PM], endoplasmic reticulum, mitochondria, lipid droplets and cytosol) in the skeletal muscle.We found that the HFD group had a greater content of sn-DAGs and ceramides in multiple subcellular compartments compared with the RC mice, which was associated with an increase in PKCε and PKCθ translocation. However, the RC-EXE mice showed, of particular note, a reduction in PM sn-1,2-DAG and ceramide content when compared with HFD mice. Consistent with the PM sn-1,2-DAG-novel PKC hypothesis, we observed an increase in phosphorylation of threonineThese results demonstrate that lower PKCθ/PKCε activity and sn-1,2-DAG content, especially in the PM compartment, can explain the preserved muscle insulin sensitivity in RC-EXE mice.

Significance Metformin is the most commonly prescribed drug for the treatment of type 2 diabetes mellitus, yet the mechanism by which it lowers plasma glucose concentrations has remained elusive. Most studies to date have attributed metformin’s glucose-lowering effects to inhibition of complex I activity. Contrary to this hypothesis, we show that inhibition of complex I activity in vitro and in vivo does not reduce plasma glucose concentrations or inhibit hepatic gluconeogenesis. We go on to show that metformin, and the related guanides/biguanides, phenformin and galegine, inhibit complex IV activity at clinically relevant concentrations, which, in turn, results in inhibition of glycerol-3-phosphate dehydrogenase activity, increased cytosolic redox, and selective inhibition of glycerol-derived hepatic gluconeogenesis both in vitro and in vivo.

BackgroundNonalcoholic fatty liver affects 25% to 30% of the US and European populations; is associated with insulin resistance (IR), type 2 diabetes, and increased cardiovascular risk; and is defined by hepatic triglyceride (HTG) content greater than 5.56%. However, it is unknown whether HTG content less than 5.56% is associated with cardiometabolic risk factors and whether there are ethnic (Asian Indian, AI, versus non-AI) and/or sex differences in these parameters in lean individuals.MethodsWe prospectively recruited 2331 individuals and measured HTG, using 1H magnetic resonance spectroscopy, and plasma concentrations of triglycerides, total cholesterol, LDL-cholesterol, HDL-cholesterol, and uric acid. Insulin sensitivity was assessed using Homeostatic Model Assessment of Insulin Resistance and the Matsuda Insulin Sensitivity Index.ResultsThe 95th percentile for HTG in lean non-AI individuals was 1.85%. Plasma insulin, triglycerides, total cholesterol, LDL-cholesterol, and uric acid concentrations were increased and HDL-cholesterol was decreased in individuals with HTG content1.85% and ≤ 5.56% compared with those individuals with HTG content ≤ 1.85%, and these altered parameters were associated with increased IR. Mean HTG was lower in lean non-AI women compared with lean non-AI men, whereas lean AI men and women had a 40% to 100% increase in HTG when compared with non-AI men and women, which was associated with increased cardiometabolic risk factors.ConclusionWe found that the 95th percentile of HTG in lean non-AI individuals was 1.85% and that HTG concentrations above this threshold were associated with IR and cardiovascular risk factors. Premenopausal women were protected from these changes whereas young, lean AI men and women manifested increased HTG content and associated cardiometabolic risk factors.FundingGrants from the United States Department of Health and Human Resources (NIH/National Institute of Diabetes and Digestive and Kidney Diseases): R01 DK113984, P30 DK45735, U24 DK59635, and UL1 RR024139; and the Novo Nordisk Foundation (NNF18CC0034900).

The mammalian succinate dehydrogenase (SDH) complex has recently been shown as capable of operating bidirectionally. Here, we develop a method (Q-Flux) capable of measuring absolute rates of both forward (V

Mild uncoupling of oxidative phosphorylation is an intrinsic property of all mitochondria and may have evolved to protect cells against the production of damaging reactive oxygen species. Therefore, compounds that enhance mitochondrial uncoupling are potentially attractive anti-aging therapies; however, chronic ingestion is associated with a number of unwanted side effects. We have previously developed a controlled-release mitochondrial protonophore (CRMP) that is functionally liver-directed and promotes oxidation of hepatic triglycerides by causing a subtle sustained increase in hepatic mitochondrial inefficiency. Here, we sought to leverage the higher therapeutic index of CRMP to test whether mild mitochondrial uncoupling in a liver-directed fashion could reduce oxidative damage and improve age-related metabolic disease and lifespan in diet-induced obese mice. Oral administration of CRMP (20 mg/[kg-day] × 4 weeks) reduced hepatic lipid content, protein kinase C epsilon activation, and hepatic insulin resistance in aged (74-week-old) high-fat diet (HFD)-fed C57BL/6J male mice, independently of changes in body weight, whole-body energy expenditure, food intake, or markers of hepatic mitochondrial biogenesis. CRMP treatment was also associated with a significant reduction in hepatic lipid peroxidation, protein carbonylation, and inflammation. Importantly, long-term (49 weeks) hepatic mitochondrial uncoupling initiated late in life (94-104 weeks), in conjugation with HFD feeding, protected mice against neoplastic disorders, including hepatocellular carcinoma (HCC), in a strain and sex-specific manner. Taken together, these studies illustrate the complex variation of aging and provide important proof-of-concept data to support further studies investigating the use of liver-directed mitochondrial uncouplers to promote healthy aging in humans.

Intricate regulatory networks govern the net balance of cholesterol biosynthesis, uptake and efflux; however, the mechanisms surrounding cholesterol homeostasis remain incompletely understood. Here, we develop an integrative genomic strategy to detect regulators of LDLR activity and identify 250 genes whose knockdown affects LDL-cholesterol uptake and whose expression is modulated by intracellular cholesterol levels in human hepatic cells. From these hits, we focus on MMAB, an enzyme which catalyzes the conversion of vitamin B12 to adenosylcobalamin, and whose expression has previously been linked with altered levels of circulating cholesterol in humans. We demonstrate that hepatic levels of MMAB are modulated by dietary and cellular cholesterol levels through SREBP2, the master transcriptional regulator of cholesterol homeostasis. Knockdown of MMAB decreases intracellular cholesterol levels and augments SREBP2-mediated gene expression and LDL-cholesterol uptake in human and mouse hepatic cell lines. Reductions in total sterol content were attributed to increased intracellular levels of propionic and methylmalonic acid and subsequent inhibition of HMGCR activity and cholesterol biosynthesis. Moreover, mice treated with antisense inhibitors of MMAB display a significant reduction in hepatic HMGCR activity, hepatic sterol content and increased expression of SREBP2-mediated genes. Collectively, these findings reveal an unexpected role for the adenosylcobalamin pathway in regulating LDLR expression and identify MMAB as an additional control point by which cholesterol biosynthesis is regulated by its end product., The mechanisms governing cholesterol homeostasis remain incompletely understood. Here, the authors develop an integrative genomic strategy to identify MMAB, and enzyme in the adenosylcobalamin pathway, as a regulator of hepatic LDLR activity and cholesterol biosynthesis.

Significance Hepatic glycogen synthesis plays a critical role in maintaining normal glucose homeostasis; however, the rate-controlling step regulating this process is unknown. Applying metabolic control analysis in vivo, we show that the regulation of insulin-stimulated hepatic glycogen synthesis under both normal and pathophysiological conditions of fatty liver-associated hepatic insulin resistance is controlled at the glucokinase (GCK) step through GCK translocation., Multiple insulin-regulated enzymes participate in hepatic glycogen synthesis, and the rate-controlling step responsible for insulin stimulation of glycogen synthesis is unknown. We demonstrate that glucokinase (GCK)-mediated glucose phosphorylation is the rate-controlling step in insulin-stimulated hepatic glycogen synthesis in vivo, by use of the somatostatin pancreatic clamp technique using [13C6]glucose with metabolic control analysis (MCA) in three rat models: 1) regular chow (RC)-fed male rats (control), 2) high fat diet (HFD)-fed rats, and 3) RC-fed rats with portal vein glucose delivery at a glucose infusion rate matched to the control. During hyperinsulinemia, hyperglycemia dose-dependently increased hepatic glycogen synthesis. At similar levels of hyperinsulinemia and hyperglycemia, HFD-fed rats exhibited a decrease and portal delivery rats exhibited an increase in hepatic glycogen synthesis via the direct pathway compared with controls. However, the strong correlation between liver glucose-6-phosphate concentration and net hepatic glycogen synthetic rate was nearly identical in these three groups, suggesting that the main difference between models is the activation of GCK. MCA yielded a high control coefficient for GCK in all three groups. We confirmed these findings in studies of hepatic GCK knockdown using an antisense oligonucleotide. Reduced liver glycogen synthesis in lipid-induced hepatic insulin resistance and increased glycogen synthesis during portal glucose infusion were explained by concordant changes in translocation of GCK. Taken together, these data indicate that the rate of insulin-stimulated hepatic glycogen synthesis is controlled chiefly through GCK translocation.

Aims/hypothesis Physical inactivity, low mitochondrial function, increased intramyocellular lipid (IMCL) deposition and reduced insulin sensitivity are common denominators of chronic metabolic disorders, like obesity and type 2 diabetes. Yet, whether low mitochondrial function predisposes to insulin resistance in humans is still unknown. Methods Here we investigated, in an intervention study, whether muscle with low mitochondrial oxidative capacity, induced by one-legged physical inactivity, would feature stronger signs of lipid-induced insulin resistance. To this end, ten male participants (age 22.4 ± 4.2 years, BMI 21.3 ± 2.0 kg/m2) underwent a 12 day unilateral lower-limb suspension with the contralateral leg serving as an active internal control. Results In vivo, mitochondrial oxidative capacity, assessed by phosphocreatine (PCr)-recovery half-time, was lower in the inactive vs active leg. Ex vivo, palmitate oxidation to 14CO2 was lower in the suspended leg vs the active leg; however, this did not result in significantly higher [14C]palmitate incorporation into triacylglycerol. The reduced mitochondrial function in the suspended leg was, however, paralleled by augmented IMCL content in both musculus tibialis anterior and musculus vastus lateralis, and by increased membrane bound protein kinase C (PKC) θ. Finally, upon lipid infusion, insulin signalling was lower in the suspended vs active leg. Conclusions/interpretation Together, these results demonstrate, in a unique human in vivo model, that a low mitochondrial oxidative capacity due to physical inactivity directly impacts IMCL accumulation and PKCθ translocation, resulting in impaired insulin signalling upon lipid infusion. This demonstrates the importance of mitochondrial oxidative capacity and muscle fat accumulation in the development of insulin resistance in humans. Trial registration ClinicalTrial.gov NCT01576250. Funding PS was supported by a ‘VICI’ Research Grant for innovative research from the Netherlands Organization for Scientific Research (Grant 918.96.618).

Significance Ketogenic diet is an effective treatment for nonalcoholic fatty liver disease (NAFLD). Here, we present evidence that hepatic mitochondrial fluxes and redox state are markedly altered during ketogenic diet-induced reversal of NAFLD in humans. Ketogenic diet for 6 d markedly decreased liver fat content and hepatic insulin resistance. These changes were associated with increased net hydrolysis of liver triglycerides and decreased endogenous glucose production and serum insulin concentrations. Partitioning of fatty acids toward ketogenesis increased, which was associated with increased hepatic mitochondrial redox state and decreased hepatic citrate synthase flux. These data demonstrate heretofore undescribed adaptations underlying the reversal of NAFLD by ketogenic diet and highlight hepatic mitochondrial fluxes and redox state as potential treatment targets in NAFLD., Weight loss by ketogenic diet (KD) has gained popularity in management of nonalcoholic fatty liver disease (NAFLD). KD rapidly reverses NAFLD and insulin resistance despite increasing circulating nonesterified fatty acids (NEFA), the main substrate for synthesis of intrahepatic triglycerides (IHTG). To explore the underlying mechanism, we quantified hepatic mitochondrial fluxes and their regulators in humans by using positional isotopomer NMR tracer analysis. Ten overweight/obese subjects received stable isotope infusions of: [D7]glucose, [13C4]β-hydroxybutyrate and [3-13C]lactate before and after a 6-d KD. IHTG was determined by proton magnetic resonance spectroscopy (1H-MRS). The KD diet decreased IHTG by 31% in the face of a 3% decrease in body weight and decreased hepatic insulin resistance (−58%) despite an increase in NEFA concentrations (+35%). These changes were attributed to increased net hydrolysis of IHTG and partitioning of the resulting fatty acids toward ketogenesis (+232%) due to reductions in serum insulin concentrations (−53%) and hepatic citrate synthase flux (−38%), respectively. The former was attributed to decreased hepatic insulin resistance and the latter to increased hepatic mitochondrial redox state (+167%) and decreased plasma leptin (−45%) and triiodothyronine (−21%) concentrations. These data demonstrate heretofore undescribed adaptations underlying the reversal of NAFLD by KD: That is, markedly altered hepatic mitochondrial fluxes and redox state to promote ketogenesis rather than synthesis of IHTG.

Meal ingestion increases body temperature in multiple species, an effect that is blunted by obesity. However, the mechanisms responsible for these phenomena remain incompletely understood. Here we show that refeeding increases plasma leptin concentrations approximately 8-fold in 48-hour-fasted lean rats, and this normalization of plasma leptin concentrations stimulates adrenomedullary catecholamine secretion. Increased adrenal medulla–derived plasma catecholamines were necessary and sufficient to increase body temperature postprandially, a process that required both fatty acids generated from adipose tissue lipolysis and β-adrenergic activation of brown adipose tissue (BAT). Diet-induced obese rats, which remained relatively hyperleptinemic while fasting, did not exhibit fasting-induced reductions in temperature. To examine the impact of feeding-induced increases in body temperature on energy balance, we compared rats fed chronically by either 2 carbohydrate-rich boluses daily or a continuous isocaloric intragastric infusion. Bolus feeding increased body temperature and reduced weight gain compared with continuous feeding, an effect abrogated by treatment with atenolol. In summary, these data demonstrate that leptin stimulates a hypothalamus–adrenal medulla–BAT axis, which is necessary and sufficient to induce lipolysis and, as a result, increase body temperature after refeeding.

Although it is well-established that reductions in the ratio of insulin to glucagon in the portal vein have a major role in the dysregulation of hepatic glucose metabolism in type-2 diabetes1–3, the mechanisms by which glucagon affects hepatic glucose production and mitochondrial oxidation are poorly understood. Here we show that glucagon stimulates hepatic gluconeogenesis by increasing the activity of hepatic adipose triglyceride lipase, intrahepatic lipolysis, hepatic acetyl-CoA content and pyruvate carboxylase flux, while also increasing mitochondrial fat oxidation—all of which are mediated by stimulation of the inositol triphosphate receptor 1 (INSP3R1). In rats and mice, chronic physiological increases in plasma glucagon concentrations increased mitochondrial oxidation of fat in the liver and reversed diet-induced hepatic steatosis and insulin resistance. However, these effects of chronic glucagon treatment—reversing hepatic steatosis and glucose intolerance—were abrogated in Insp3r1 (also known as Itpr1)-knockout mice. These results provide insights into glucagon biology and suggest that INSP3R1 may represent a target for therapies that aim to reverse nonalcoholic fatty liver disease and type-2 diabetes. A role and mechanism of action are identified for INSP3R1 in the stimulation of hepatic gluconeogenesis and mitochondrial oxidation by glucagon, suggesting that INSP3R1 may be a target for ameliorating dysregulation of hepatic glucose metabolism.

Obesity and type 2 diabetes (T2D) increase the prevalence and worsen the prognosis of more than a dozen tumor types; however, the mechanism for this association remains hotly debated. Here we discuss a potential role for insulin as the key hormonal mediator of tumor metabolism and growth in obesity-associated insulin resistance.

Mediators of Insulin Resistance Insulin resistance is a precursor to and accelerant of coexisting conditions such as type 2 diabetes, atherosclerosis, and nonalcoholic liver disease. A recent study...

Determining decision-making capacity is part of everyday business for health care professionals working with older adults. We used a modified Delphi approach to develop an inclusive curriculum for a capacity education e-tool with global application and clinical relevance to a range of disciplines. The tool comprised: (i) 25 questions forming a “pre-test” for the adaptive and personalized e-Learning platform; (ii) a learning module based on the participant’s response to the “pre-test”; (iii) a “post-test” (the same baseline 25 questions) to test knowledge translation. The tool was tested on 31 health care professionals across Israel (8), Canada (15), and Australia (8) from the following disciplines: General Practitioners (GP) (19), Internal Medicine (1), Palliative Care GP (2); Palliative Care Physician (2), Geriatrician (2); and one of each: Psychologist, Occupational Therapist, Psychiatrist, Aged Care Researcher, and Aged Care Pharmacist. The mean baseline pre-test score was 19.1/25 (S.D. =1.61; range 15–22) and post-test score 21.7/25 (S.D.= 1.42; range 18–24); with a highly significant improvement in test scores (paired t-test P < 0.0001; t=10.81 on 30 df). This is the first such pilot study to demonstrate that generic capacity principles can be taught to health care professionals from different disciplines regardless of jurisdiction.

Significance Low levels of leptin, a hormone secreted by adipocytes that signals the body as to the availability of fuel stores, are known to increase food intake. Here, we demonstrate a mechanism by which low leptin stimulates food intake in rodents: Under conditions of hypoleptinemia, stress hormone (glucocorticoid) production is increased, and in turn stimulates AgRP neurons to promote appetite., Leptin informs the brain about sufficiency of fuel stores. When insufficient, leptin levels fall, triggering compensatory increases in appetite. Falling leptin is first sensed by hypothalamic neurons, which then initiate adaptive responses. With regard to hunger, it is thought that leptin-sensing neurons work entirely via circuits within the central nervous system (CNS). Very unexpectedly, however, we now show this is not the case. Instead, stimulation of hunger requires an intervening endocrine step, namely activation of the hypothalamic–pituitary–adrenocortical (HPA) axis. Increased corticosterone then activates AgRP neurons to fully increase hunger. Importantly, this is true for 2 forms of low leptin-induced hunger, fasting and poorly controlled type 1 diabetes. Hypoglycemia, which also stimulates hunger by activating CNS neurons, albeit independently of leptin, similarly recruits and requires this pathway by which HPA axis activity stimulates AgRP neurons. Thus, HPA axis regulation of AgRP neurons is a previously underappreciated step in homeostatic regulation of hunger.

The connection between adipose glucocorticoid action and whole-body metabolism is incompletely understood. Thus, we generated adipose tissue–specific glucocorticoid receptor–knockout (Ad-GcR(−/−)) mice to explore potential mechanisms. Ad-GcR(−/−) mice had a lower concentration of fasting plasma nonesterified fatty acids and less hepatic steatosis. This was associated with increased protein kinase B phosphorylation and increased hepatic glycogen synthesis after an oral glucose challenge. High-fat diet (HFD)–fed Ad-GcR(−/−) mice were protected against the development of hepatic steatosis and diacylglycerol-PKCε–induced impairments in hepatic insulin signaling. Under hyperinsulinemic-euglycemic conditions, hepatic insulin response was ∼10-fold higher in HFD-fed Ad-GcR(−/−) mice. Insulin-mediated suppression of adipose lipolysis was improved by 40% in Ad-GcR(−/−) mice. Adipose triglyceride lipase expression was decreased and insulin-mediated perilipin dephosphorylation was increased in Ad-GcR(−/−) mice. In metabolic cages, food intake decreased by 3 kcal/kg per hour in Ad-GcR(−/−) mice. Therefore, physiologic adipose glucocorticoid action appears to drive hepatic lipid accumulation during stressors such as fasting. The resultant hepatic insulin resistance prevents hepatic glycogen synthesis, preserving glucose for glucose-dependent organs. Absence of adipose glucocorticoid action attenuates HFD-induced hepatic insulin resistance; potential explanations for reduction in hepatic steatosis include reductions in adipose lipolysis and food intake.—Abulizi, A., Camporez, J.-P., Jurczak, M. J., Høyer, K. F., Zhang, D., Cline, G. W., Samuel, V. T., Shulman, G. I., Vatner, D. F. Adipose glucocorticoid action influences whole-body metabolism via modulation of hepatic insulin action.

CONTEXT: Excessive adipose glucocorticoid action is associated with insulin resistance, but the mechanisms linking adipose glucocorticoid action to insulin resistance are still debated. We hypothesized that insulin resistance from excess glucocorticoid action may be attributed in part to increased ectopic lipid deposition in liver. METHODS: We tested this hypothesis in the adipose specific 11β-Hydroxysteroid dehydrogenase-1 (HSD11B1) transgenic mouse, an established model of adipose glucocorticoid excess. Tissue specific insulin action was assessed by hyperinsulinemic-euglycemic clamps, hepatic lipid content was measured, hepatic insulin signaling was assessed by immunoblotting. The role of hepatic lipid content was further probed by administration of the functionally liver-targeted mitochondrial uncoupler, Controlled Release Mitochondrial Protonophore (CRMP). FINDINGS: High fat diet fed HSD11B1 transgenic mice developed more severe hepatic insulin resistance than littermate controls (endogenous suppression of hepatic glucose production was reduced by 3.8-fold, P < 0.05); this was reflected by decreased insulin-stimulated hepatic insulin receptor kinase tyrosine phosphorylation and AKT serine phosphorylation. Hepatic insulin resistance was associated with a 53% increase (P < 0.05) in hepatic triglyceride content, a 73% increase in diacylglycerol content (P < 0.01), and a 66% increase in PKCε translocation (P < 0.05). Hepatic insulin resistance was prevented with administration of CRMP by reversal of hepatic steatosis and prevention of hepatic diacylglycerol accumulation and PKCε activation. CONCLUSIONS: These findings are consistent with excess adipose glucocorticoid activity being a predisposing factor for the development of lipid (diacylglycerol-PKCε)-induced hepatic insulin resistance.

With the increasing prevalence of type 2 diabetes and fatty liver disease, there is still an unmet need to better treat hyperglycemia and hyperlipidemia. Here, we identify isthmin-1 (Ism1) as an adipokine and one that has a dual role in increasing adipose glucose uptake while suppressing hepatic lipid synthesis. Ism1 ablation results in impaired glucose tolerance, reduced adipose glucose uptake, and reduced insulin sensitivity, demonstrating an endogenous function for Ism1 in glucose regulation. Mechanistically, Ism1 activates a PI3K-AKT signaling pathway independently of the insulin and insulin-like growth factor receptors. Notably, while the glucoregulatory function is shared with insulin, Ism1 counteracts lipid accumulation in the liver by switching hepatocytes from a lipogenic to a protein synthesis state. Furthermore, therapeutic dosing of recombinant Ism1 improves diabetes in diet-induced obese mice and ameliorates hepatic steatosis in a diet-induced fatty liver mouse model. These findings uncover an unexpected, bioactive protein hormone that might have simultaneous therapeutic potential for diabetes and fatty liver disease.

Mutations in Dyrk1b are associated with metabolic syndrome and nonalcoholic fatty liver disease in humans. Our investigations showed that DYRK1B levels are increased in the liver of patients with nonalcoholic steatohepatitis (NASH) and in mice fed with a high-fat, high-sucrose diet. Increasing Dyrk1b levels in the mouse liver enhanced de novo lipogenesis (DNL), fatty acid uptake, and triacylglycerol secretion and caused NASH and hyperlipidemia. Conversely, knockdown of Dyrk1b was protective against high-calorie-induced hepatic steatosis and fibrosis and hyperlipidemia. Mechanistically, Dyrk1b increased DNL by activating mTORC2 in a kinase-independent fashion. Accordingly, the Dyrk1b-induced NASH was fully rescued when mTORC2 was genetically disrupted. The elevated DNL was associated with increased plasma membrane sn-1,2-diacylglyerol levels and increased PKCε-mediated IRKT1150 phosphorylation, which resulted in impaired activation of hepatic insulin signaling and reduced hepatic glycogen storage. These findings provide insights into the mechanisms that underlie Dyrk1b-induced hepatic lipogenesis and hepatic insulin resistance and identify Dyrk1b as a therapeutic target for NASH and insulin resistance in the liver.