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Although macroautophagy/autophagy deficiency causes degenerative diseases, the deletion of essential autophagy genes in adipocytes paradoxically reduces body weight. Brown adipose tissue (BAT) plays an important role in body weight regulation and metabolic control. However, the key cellular mechanisms that maintain BAT function remain poorly understood. in this study, we showed that global or brown adipocyte-specific deletion of pink1, a Parkinson disease-related gene involved in selective mitochondrial autophagy (mitophagy), induced BAT dysfunction, and obesity-prone type in mice. Defective mitochondrial function is among the upstream signals that activate the NLRP3 inflammasome. NLRP3 was induced in brown adipocyte precursors (BAPs) from pink1 knockout (KO) mice. Unexpectedly, NLRP3 induction did not induce canonical inflammasome activity. Instead, NLRP3 induction led to the differentiation of pink1 KO BAPs into white-like adipocytes by increasing the expression of white adipocyte-specific genes and repressing the expression of brown adipocyte-specific genes. nlrp3 deletion in pink1 knockout mice reversed BAT dysfunction. Conversely, adipose tissue-specific atg7 KO mice showed significantly lower expression of Nlrp3 in their BAT. Overall, our data suggest that the role of mitophagy is different from general autophagy in regulating adipose tissue and whole-body energy metabolism. Our results uncovered a new mitochondria-NLRP3 pathway that induces BAT dysfunction. The ability of the nlrp3 knockouts to rescue BAT dysfunction suggests the transcriptional function of NLRP3 as an unexpected, but a quite specific therapeutic target for obesity-related metabolic diseases.Abbreviations: ACTB: actin, beta; BAPs: brown adipocyte precursors; BAT: brown adipose tissue; BMDMs: bone marrow-derived macrophages; CASP1: caspase 1; CEBPA: CCAAT/enhancer binding protein (C/EBP), alpha; ChIP: chromatin immunoprecipitation; EE: energy expenditure; HFD: high-fat diet; IL1B: interleukin 1 beta; ITT: insulin tolerance test; KO: knockout; LPS: lipopolysaccharide; NLRP3: NLR family, pyrin domain containing 3; PINK1: PTEN induced putative kinase 1; PRKN: parkin RBR E3 ubiquitin protein ligase; RD: regular diet; ROS: reactive oxygen species; RT: room temperature; UCP1: uncoupling protein 1 (mitochondrial, proton carrier); WT: wild-type.

Aim: To evaluate the long‐term safety and efficacy of enavogliflozin 0.3 mg/day added to metformin in patients with type 2 diabetes mellitus. Materials and Methods: After 24 weeks of a randomized, double‐blind treatment period with enavogliflozin 0.3 mg/day (n = 101) or dapagliflozin 10 mg/day (n = 99) added to metformin, all patients received enavogliflozin 0.3 mg/day plus metformin for an additional 28 weeks during the open‐label extension period. Results: Eighty‐two patients continued enavogliflozin (maintenance group), and 77 were switched from dapagliflozin to enavogliflozin (switch group). All adverse drug reactions (ADR) were mild in severity. In the maintenance group, ADRs (cystitis and vaginal infection) were reported in two patients (2.44%) during 52 weeks. In the switch group, ADR (hypoglycaemia) was reported in one patient (1.30%) during a 28‐week open‐label extension period. At week 52, glycated haemoglobin and fasting plasma glucose were significantly lower than at the baseline, by 0.85% and 29.08 mg/dl, respectively, in the maintenance group (p <.0001 for both), and by 0.81% and 32.77 mg/dl, respectively, in the switch group (p <.0001 for both). At week 52, 68.92% of patients from the maintenance group and 64.29% from the switch group achieved glycated haemoglobin <7%. A significant increase in the urine glucose‐creatinine ratio was observed at week 52, by 58.81 g/g and 63.77 g/g in the maintenance and switch groups, respectively (p <.0001). Conclusions: Enavogliflozin added to metformin was tolerated well for up to 52 weeks and provided continual glycaemic control in type 2 diabetes mellitus, along with a significant increase in the urine glucose‐creatinine ratio. [ABSTRACT FROM AUTHOR]

Aims: The study aimed to evaluate and compare the efficacy and safety of enavogliflozin, a newly developed sodium‐glucose cotransporter 2 inhibitor, with placebo in Korean patients with type 2 diabetes mellitus. Materials and Methods: Patients with glycated haemoglobin (HbA1c) of 7.0‐10.0%, entered a 2‐week placebo run‐in period, and were randomized to receive once‐daily enavogliflozin (0.1, 0.3 or 0.5 mg) or placebo for 12 weeks. The primary efficacy endpoint was the change in HbA1c from baseline at week 12. Results: Overall, 194 patients were included in the full analysis set [placebo, n = 46; enavogliflozin (0.1 mg, n = 49; 0.3 mg, n = 50; 0.5 mg, n = 49)]. Patients receiving 0.1, 0.3 and 0.5 mg enavogliflozin showed significantly reduced HbA1c compared with those receiving placebo at week 12 (−0.79%, −0.89%, −0.92% and −0.08%, respectively; p <.001 vs. placebo). Mean changes in fasting plasma glucose from baseline at week 12 were −30.5, −31.1, −35.0 and 4.9 mg/dl in patients receiving enavogliflozin doses and placebo, respectively. The proportion of patients achieving HbA1c <7.0% at week 12 was significantly higher in the three enavogliflozin groups than in the placebo group (42.9%, 44.0%, 61.2% and 17.4%, respectively). A higher proportion of patients showed HbA1c reduction by >0.5% after receiving enavogliflozin doses than those receiving placebo (61.2%, 72.0%, 65.3% and 26.1%, respectively). There were no significant differences in incidences of adverse events of hypoglycaemia and genital infection between the groups. Conclusions: Once‐daily enavogliflozin monotherapy for 12 weeks is an effective, safe, and well‐tolerated treatment for Korean patients with type 2 diabetes mellitus. [ABSTRACT FROM AUTHOR]

Insulin resistance contributes to the pathophysiology of diabetes, obesity, and their cardiovascular complications. Mouse models of these human diseases are useful for gaining insight into pathophysiological mechanisms. The reference standard for measuring insulin sensitivity in both humans and animals is the euglycemic glucose clamp. Many studies have compared surrogate indexes of insulin sensitivity and resistance with glucose clamp estimates in humans. However, regulation of metabolic physiology in humans and rodents differs and comparisons between surrogate indexes and the glucose clamp have not been directly evaluated in rodents previously. Therefore, in the present study, we compared glucose clamp-derived measures of insulin sensitivity (GIR and S[I.sub.Clamp]) with surrogate indexes, including quantitative insulin-sensitivity check index (QUICKI), homeostasis model assessment (HOMA), 1/HOMA, log(HOMA), and 1/fasting insulin, using data from 87 mice with a wide range of insulin sensitivities. We evaluated simple linear correlations and performed calibration model analyses to evaluate the predictive accuracy of each surrogate. All surrogate indexes tested were modestly correlated with both GIR and S[I.sub.Clamp]. However, a stronger correlation between body weight per se and both GIR and S[I.sub.Clamp] was noted. Calibration analyses of surrogate indexes adjusted for body weight demonstrated improved predictive accuracy for GIR [e.g., R = 0.68, for QUICKI and log(HOMA)]. We conclude that linear correlations of surrogate indexes with clamp data and predictive accuracy of surrogate indexes in mice are not as substantial as in humans. This may reflect intrinsic differences between human and rodent physiology as well as increased technical difficulties in performing glucose clamps in mice. calibration model; quantitative insulin-sensitivity check index

Although insulin resistance has been traditionally associated with type 2 diabetes, recent evidence in humans and animal models indicates that insulin resistance may also develop in type 1 diabetes. A point mutation of insulin 2 gene in [Ins2.sup.Akita] mice leads to pancreatic [beta]-cell apoptosis and hyperglycemia, and these mice are commonly used to investigate type 1 diabetes and complications. Since insulin resistance plays an important role in diabetic complications, we performed hyperinsulinemic-euglycemic clamps in awake Ins2Aldta and wild-type mice to measure insulin action and glucose metabolism in vivo. Nonobese [Ins2.sup.Akita] mice developed insulin resistance, as indicated by an ~80% reduction in glucose infusion rate during clamps. Insulin resistance was due to ~50% decreases in glucose uptake in skeletal muscle and brown adipose tissue as well as hepatic insulin action. Skeletal muscle insulin resistance was associated with a 40% reduction in total GLUT4 and a threefold increase in PKC[epsilon] levels in [Ins2.sup.Akita] mice. Chronic phloridzin treatment lowered systemic glucose levels and normalized muscle insulin action, GLUT4 and PKC[epsilon] levels in [Ins2.sup.Akita] mice, indicating that hyperglycemia plays a role in insulin resistance. Echocardiography showed significant cardiac remodeling with ventricular hypertrophy that was ameliorated following chronic phloridzin treatment in [Ins2.sup.Akita] mice. Overall, we report for the first time that nonobese, insulin-deficient [Ins2.sup.Akita] mice develop type 2 diabetes phenotypes including peripheral and hepatic insulin resistance and cardiac remodeling. Our findings provide important insights into the pathogenesis of metabolic abnormalities and complications affecting type 1 diabetes and lean type 2 diabetes subjects. type 1 diabetes; mouse model; hyperglycemia; ventricular hypertrophy

As a new mouse model of obesity-induced diabetes generated by combining quantitative trait loci from New Zealand Obese (NZO/H1Lt) and Nonobese Nondiabetic (NON/LtJ) mice, NONcNZO10/LtJ (RCS10) male mice developed type 2 diabetes characterized by maturity onset obesity, hyperglycemia, and insulin resistance. To metabolically profile the progression to diabetes in preobese and obese states, a 2-h hyperinsulinemic euglycemic clamp was performed and organ-specific changes in insulin action were assessed in awake RCS 10 and NON/Ld (control) males at 8 and 13 wk of age. Prior to development of obesity and attendant increases in hepatic lipid content, 8-wk-old RCS10 mice developed insulin resistance in liver and skeletal muscle due to significant decreases in insulin-stimulated glucose uptake and GLUT4 expression in muscle. Transition to an obese and hyperglycemic state by 13 wk of age exacerbated insulin resistance in skeletal muscle, liver, and heart associated with organ-specific increases in lipid content. Thus, this polygenic mouse model of type 2 diabetes, wherein plasma insulin is only modestly elevated and obesity develops with maturity yet insulin action and glucose metabolism in skeletal muscle and liver are reduced at an early prediabetic age, should provide new insights into the etiology of type 2 diabetes. glucose metabolism; skeletal muscle; liver; lipid; transgenic mouse doi:10.1152/ajpendo.00376.2006

Mice with liver-specific overexpression of dominant negative phosphorylation-defective S503A-CEACAM1 mutant (L-SACC1) developed chronic hyperinsulinemia resulting from blunted hepatic clearance of insulin, visceral obesity, and glucose intolerance. To determine the underlying mechanism of altered glucose homeostasis, a 2-h hyperinsulinemic euglycemic clamp was performed, and tissue-specific glucose and lipid metabolism was assessed in awake L-SACC1 and wild-type mice. Inactivation of carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) caused insulin resistance in liver that was mostly due to increased expression of fatty acid synthase and lipid metabolism, resulting in elevated intrahepatic levels of triglyceride and long-chain acyl-CoAs. Whole body insulin resistance in the L-SACC1 mice was further attributed to defects in insulin-stimulated glucose uptake in skeletal muscle and adipose tissue. Insulin resistance in peripheral tissues was associated with significantly elevated intramuscular fat contents that may be secondary to increased whole body adiposity (assessed by [sup.1]H-MRS) in the L-SACC1 mice. Overall, these results demonstrate that L-SACC1 is a mouse model in which chronic hyperinsulinemia acts as a cause, and not a consequence, of insulin resistance. Our findings further indicate the important role of CEACAM1 and hepatic insulin clearance in the pathogenesis of obesity and insulin resistance. insulin clearance; insulin resistance; skeletal muscle; liver; lipid metabolism doi: 10.1152/ajpendo.00077.2006

Acute activation of the serine-threonine kinase Akt is cardioprotective and increases glucose uptake, at least in part, through enhanced expression of GLUT4 on the sarcolemma. The effects of chronic Akt activation on glucose uptake in the heart remain unclear. To address this issue, we examined the effects of chronic Akt activation on glucose uptake, glycogen storage, and relevant glucose transporters in the hearts of transgenic mice. We found that chronic cardiac activation of Akt led to a substantial increase in the rate of basal glucose uptake (P < 0.05) but blunted the response to insulin (1.9 vs. 18.1-fold increase compared with baseline) using NMR in ex vivo perfused heart. Basal glucose uptake was also increased in Akt transgenic mice in vivo (P < 0.005). These changes were associated with an increase on glycogen deposition, examined with histochemical staining, biochemical (>6-fold, P < 0.001) and in vivo radioactive (5-fold, P < 0.01) assays. Studies in chimeric hearts of female X-linked transgenic Akt mice suggested that increased glycogen deposition occurred as a cell autonomous effect of transgene expression. Interestingly, although sarcolemmal GLUT1 was not significantly altered, chronic Akt activation actually decreased plasma membrane GLUT4. Moreover, intracellular pools of GLUT1 were modestly reduced, whereas intracellular GLUT4 was substantially reduced. It seems likely that neither GLUT1 nor GLUT4 explains the increase in basal glucose uptake but that these reductions contribute to the loss of insulin responsiveness that we observed. These data demonstrate that chronic Akt activation increases basal glucose uptake and glycogen deposition while inhibiting the response to insulin. glucose transporters; transgenic mice; heart

Aim: To evaluate the efficacy and safety of a fixed‐dose combination (FDC) of gemigliptin and rosuvastatin in patients with type 2 diabetes and dyslipidaemia. Research Design and Methods: A total of 33 hospitals in Korea participated in this randomized, double‐blind trial of diabetic patients with dyslipidaemia. A total of 290 participants were randomly assigned at a 1:1:1 ratio to receive an FDC of gemigliptin (50 mg) and rosuvastatin (20 mg) (GEMI/ROSU FDC group), gemigliptin (50 mg) (GEMI group) or rosuvastatin (20 mg) (ROSU group). Rosuvastatin was up‐titrated from 5 to 20 mg/d throughout the study period. Primary efficacy measures were changes in HbA1c and LDL‐C from baseline to Week 24 between the GEMI/ROSU FDC and ROSU groups and between the GEMI/ROSU FDC and GEMI groups, respectively. Secondary efficacy measures were changes in HbA1c and LDL‐C between the GEMI/ROSU FDC and GEMI groups and between the GEMI/ROSU FDC and ROSU groups, respectively. Results: After 24 weeks of treatment, a significant reduction in HbA1c from baseline was noted in the GEMI/ROSU FDC group (−0.81% of LS mean; P < 0.0001 vs ROSU group), in addition to a significant reduction in LDL‐C concentration (−51.9% of LS mean percentage changes, P < 0.0001 vs GEMI group). HbA1c was significantly reduced from baseline in both the GEMI/ROSU FDC and GEMI groups, but the reduction in HbA1c was significantly greater in the GEMI group than in the GEMI/ROSU FDC group, despite receiving the same dose of gemigliptin. The decrease in LDL‐C over time was similar between the GEMI/ROSU FDC and ROSU groups. There were no significant differences in adverse events among the groups. Conclusion: The FDC of gemigliptin and rosuvastatin is safe and is effective in reducing both blood glucose and LDL‐C levels; thus, it could be a good therapeutic choice for type 2 diabetic patients with dyslipidaemia. [ABSTRACT FROM AUTHOR]