Identification of C2CD4A and C2CD4B binding partners in MIN6 cells
Ontology highlight
ABSTRACT: Variants close to the VPS13C/C2CD4A/C2CD4B locus are associated with altered risk of type 2 diabetes in genome-wide association studies. Whilst previous functional work has suggested roles for VPS13C and C2CD4A in disease development, none has explored the role of C2CD4B. Here, we show that systemic inactivation of C2cd4b in mice leads to marked, but highly sexually dimorphic, changes in body weight and glucose homeostasis. Female C2cd4b mice display unchanged body weight but abnormal glucose tolerance and defective in vivo, but not in vitro, insulin secretion, associated with a marked decrease in follicle stimulating hormone levels. In sharp contrast, male C2cd4b null mice displayed normal glucose tolerance but an increase in body weight and fasting glycemia after maintenance on high fat diet. No metabolic disturbances were observed after global inactivation of C2cd4a in mice, or in pancreatic β cell function at larval stages in C2cd4ab null zebrafish. These studies suggest that C2cd4b may act centrally to influence sex-dependent circuits which control pancreatic β cell function and glucose tolerance in rodents. However, the absence of sexual dimorphism in the impact of diabetes risk variants argues for additional roles for C2CD4A or VPS13C in the control of glucose homeostasis in man.
Project description:In the setting of obesity and insulin resistance, glycemia is controlled in part by beta cell compensation and subsequent hyperinsulinemia. Weight loss improves glycemia and decreases hyperinsulinemia, whereas weight cycling worsens glycemic control. The mechanisms responsible for weight cycling-induced deterioration in glucose homeostasis are poorly understood. Thus, we aimed to pinpoint the main regulatory junctions at which weight cycling alters glucose homeostasis in mice. Using in vivo and ex vivo procedures we show that despite having worsened glucose tolerance, weight-cycled mice do not manifest impaired whole-body insulin action. Instead, weight cycling reduces insulin secretory capacity in vivo during clamped hyperglycemia and ex vivo in perifused islets. Islets from weight-cycled mice have reduced expression of drivers of b-cell identity (Mafa, Pdx1, Nkx6.1, Ucn3) and lower islet insulin content, compared to those from obese mice, suggesting inadequate transcriptional and posttranscriptional response to repeated nutrient overload. Collectively, these data support a model in which pancreatic plasticity is challenged in the face of large fluctuations in body weight resulting in a mismatch between glycemia and insulin secretion in mice.
Project description:Objective: Nuclear receptor action is mediated in part by the nuclear receptor corepressor 1 (NCOR1) and the silencing mediator of retinoic acid and thyroid hormone receptor (SMRT; also known as NCOR2). NCOR1 and SMRT regulate metabolic pathways that govern body mass, insulin sensitivity and energy expenditure and represent an understudied area in the realm of metabolic health and disease. Previously, we found that NCOR1 and SMRT are essential for maintaining metabolic homeostasis and their knockout (KO) leads to rapid weight loss and hypoglycemia, which is not survivable. Because of a potential defect in glucose absorption, we sought to determine the role of NCOR1 and SMRT specifically in intestinal epithelial cells (IECs). Methods: We used a post-natal strategy to disrupt NCOR1 and SMRT throughout IECs in adult mice. These mice were characterized metabolically by assessing body weight, glucose levels and subjecting the mice to metabolic phenotyping, body composition analysis and glucose tolerance testing. IECs were isolated from the jejunum of the small intestine and profiled by bulk RNA sequencing. Results: We found that the post-natal KO of NCOR1 and SMRT from IECs leads to rapid weight loss and hypoglycemia with a significant reduction in survival. This was accompanied by alterations in glucose metabolism and activation of fatty acid oxidation in IECs. Metabolic phenotyping confirmed a reduction in body mass driven by a loss of body fat without any difference in food intake. This appeared to be driven by a reduction of key intestinal carbohydrate transporters, including SGLT1, GLUT2 and GLUT5. Conclusions: Intestinal NCOR1 and SMRT act in tandem to regulate glucose levels and body weight. This in part may be mediated by regulation of intestinal carbohydrate transporters.
Project description:Metabolic dysfunction of skeletal muscle is often prevalent at an early stage in the development of several non-communicable diseases. Here, we investigated the effect of a myokine, secreted protein acidic and rich in cysteine (SPARC), on glucose tolerance in human and mouse skeletal muscles. SPARC knockout mice showed marked decreases in parameters for whole-body glucose metabolism, along with reduced phosphorylation of AMPK and Akt in skeletal muscle tissues compared with wild-type mice. Furthermore, mice injected with SPARC showed improved glucose tolerance concomitant with AMPK activation. Exogenous SPARC treatment accelerated glucose uptake in muscle tissues isolated from wild-type mice but not from AMPKγ3 knockout mice. In muscle cells, SPARC increased glucose uptake concomitant with AMPK activation, mediated by a calcium-dependent signal. Chronic treatment of SPARC restored metabolic functions in diet-induced obese mice. These findings suggest that SPARC improves glucose metabolism via AMPK activation in skeletal muscle, providing mechanistic insights on exercise-induced metabolic benefits and physical inactivity-induced glucose intolerance.
Project description:Changes in the rate and fidelity of mitochondrial protein synthesis impact the metabolic and physiological roles of mitochondria. Here we explored how environmental stress in the form of a high fat diet modulates mitochondrial translation using mutant mice with error-prone (Mrps12ep/ep) or hyper-accurate (Mrps12ha/ha) mitochondrial ribosomes. We find that while, metabolically both mutations are beneficial in reducing body weight, decreasing circulating insulin and increasing glucose tolerance they cause tissue specific defects when placed on a high fat diet. In contrast to the effect of the mutations on a normal diet the Mrps12ha/ha mice show more pronounced phenotypic and molecular defects as a result of the slow, accurate nature of their protein synthesis. While the Mrps12ep/ep mice accumulate more fat, exhibit larger vacuoles in the liver and lose glucose tolerance, the Mrps12ha/ha mice develop severe hypertrophic cardiomyopathy and hypoxia due to the stress of the diet, showing that benefit or detriment of error-prone and hyper-accurate protein synthesis in mitochondria is dependent on tissue and environmental conditions.
Project description:The aim of this experiment was to use microarray analysis to examine the phenotype of dis-regulated insulin secretion and abnormal beta cell growth in HNF4 alpha null mice. These mice show impaired glucose tolerance and elevated fasting and fed plasma insulin levels. Rana Gupta from Klaus Kaestner's Lab extracted RNA from isolated islets. Three controls and five mutants were provided for the study.
Project description:The aim of this study was to identify anti-obesity peptide from Allomyrina dichotoma (A. dichotoma) and investigate the biochemical signaling pathway. For that, A. dichotoma larvae was hydrolyzed enzymatically, and further purified by using tangential flow filtration and consecutive chromatographic method. Finally, anti-obesity peptide was obtained, and their sequences identified as Gln-Ile-Ala-Gln-Asp-Phe-Lys-Thr-Asp-Leu (EIA10). EIA10 prevented adipocyte differentiation in vitro and was further investigated the mechanism underlying the effects in vivo. Our results indicated that EIA10 reduced body weight gain, organ weight and adipose tissue volume. Glucose tolerance and insulin resistance in high fat diet-fed obese mice significantly improved after EIA10 administration for four weeks. In addition, EIA10 significantly decreased TC and LDL, increased HDL, improved lipid metabolism, and downregulated mRNA and protein expression of transcription factors implicated in lipid adipogenesis. Taken together our results suggest that EIA10 from possessed potential for the treatment and prevention of obesity.
Project description:Six strain/genotype combinations (BKS wt, BKS db/+, ?) were fed control (5LOD) or high fat (54 % lard) chow from 5 to 36 weeks of age. Longitudinal changes in small and large nerve fiber function, glucose tolerance, fasting blood glucose, body weight etc. were assessed in all groups
Project description:People with obesity who do not have the metabolic syndrome or components of the metabolic syndrome have been characterized as having metabolically healthy obesity (MHO). However, the existence of MHO has been questioned because people with MHO are at greater risk of developing diabetes and fatal cardiovascular disease than people who are lean and healthy. A 25 year-old woman with rigorously defined MHO (based on normal oral glucose tolerance, insulin sensitivity (assessed by using the hyperinsulinemic-euglycemic clamp procedure), plasma triglyceride and HDL-cholesterol, intrahepatic triglyceride content and carotid intima-media thickness [CIMT]) was evaluated at baseline (BMI=37.7 kg/m2) and 5 years later, after gaining 30.8 kg (32%) in weight (BMI=49.6 kg/m2). The increase in weight was comprised of an 8.8 kg (20%) increase in FFM, 22.0 kg (42%) increase in total body fat, 8.1 kg (37%) increase in leg fat mass, 57% increase in subcutaneous abdominal fat and a 78% in intra-abdominal fat. Weight gain did not have adverse effects on fasting plasma glucose, oral glucose tolerance, beta-cell function, insulin sensitivity, plasma triglyceride, intrahepatic triglyceride content and CIMT. Adipose tissue expression of genes involved in extracellular matrix formation did not change. Adipose tissue expression of several inflammation-related genes increased by more than 30%, but was not associated with a corresponding increase in plasma cytokine concentrations, with the exception of an increase in plasma IL-6. The present case study demonstrates that some people with obesity are resistant to the adverse cardiometabolic effects of excess adiposity and marked weight gain.
Project description:Endurance exercise training has been shown to decrease whole-body and skeletal muscle insulin resistance and increase glucose tolerance in conditions of both pre-diabetes and overt type 2 diabetes. However, the adaptive responses in skeletal muscle at the molecular and genetic level for these beneficial effects of exercise training have not been clearly established in an animal model of pre-diabetes. The present study identifies alterations in skeletal muscle gene expression that occur with exercise training in pre-diabetic, insulin-resistant obese Zucker (fa/fa) rats and insulin-sensitive lean Zucker (Fa/-) rats. Treadmill running for up to 4 weeks caused significant enhancements of glucose tolerance as assessed by the integrated area under the curve for glucose (AUCg) during an oral glucose tolerance test in both lean and obese animals. Using microarray analysis, a set of only 12 genes was identified as both significantly altered (>1.5-fold change relative to sedentary controls; p<0.05) and significantly correlated (p<0.05) with the AUCg. Two of these genes, peroxisome proliferator-activated receptor-g coactivator 1a (PGC-1a) and the z-isoform of protein kinase C (PKC-z), have known involvement in the regulation of skeletal muscle glucose transport. We confirmed that protein expression levels of PGC-1a and PKC-z were positively correlated with the mRNA expression levels for these two genes. Overall, this study has identified a limited number of genes in soleus muscle of lean and obese Zucker rats that are associated with decreased insulin resistance and increase glucose tolerance following endurance exercise training. These findings could guide the development of pharmaceutical M-^Sexercise mimeticsM-^T in the treatment of insulin-resistant, pre-diabetic or overtly type 2 diabetic individuals.
Project description:The global prevalence of obesity is increasing across age and gender. The rising burden of obesity in young people contributes to the early emergence of type 2 diabetes. Having one parent obese is an independent risk factor for childhood obesity. While the detrimental impact of diet-induced maternal obesity on offspring is well established, the extent of the contribution of obese fathers is unclear, as is the role of non-genetic factors in the casual pathway. Here we show that paternal high fat diet exposure programmed β-cell âdysfunctionâ in their F1 female offspring. Chronic high fat diet consumption in Sprague Dawley fathers led to increased body weight, adiposity, impaired glucose tolerance and insulin sensitivity. Relative to controls, their female offspring had lower body weight at day-1, increased pubertal growth rate, impaired insulin secretion and glucose tolerance, in the absence of obesity or increased adiposity. Paternal high fat diet was observed to alter gene expression of pancreatic islet genes in adult female offspring (P < 0.001); affected functional clusters includes calcium ion binding, insulin, apoptosis, Wnt and cell cycle organ/system development. This is the first reported study in mammals describing non-genetic, intergenerational transmission of metabolic sequelae of high fat diet from father to offspring. These findings support a role of fathers in metabolic programming of offspring and form a framework for further studies. F0 founders were male Sprague Dawley rats, divided into two groups, high fat (HF) and control. The HF fathers were given commercially prepared high-fat pellets (43% as fat); while the controls ate standard laboratory chow (9% as fat). The two groups of fathers had distinct phenotype; the HF fathers were significantly heavier with increased adiposity, they were also glucose intolerant and insulin resistant. At 15 weeks of age, fathers were mated with normal females consuming chow, to generate the F1 offspring. Only female offspring were studied. Female offspring were weaned unto standard laboratory chow at 3 weeks. At 6 and 12 weeks, intraperitoneal glucose tolerance test (IpGTT) was performed to measure blood glucose and insulin profile; at 11 weeks, intraperitoneal insulin tolerance test was done. The body weight and adiposity of these offspring were not different between the two groups. The HF offspring had glucose intolerance and impaired glucose-induced insulin response, mainly at the acute phase, observed since 6 weeks. The IpITT was not different between groups. At 13 weeks, islets were harvested from the two groups of offspring.