ABSTRACT: Near-whole-genome transcriptome analysis of gene expression in human skeletal muscle tissue at baseline in obese individuals with Type 2 Diabetes
Project description:Analysis of gene expression associated with exercise response. The hypothesis tested was that individuals with Type 2 Diabetes that failed to demonstrate exercise-induced metabolic improvements would also reflect this lack of response in their skeletal muscle transcriptional profile at baseline. Of 186 genes identified by microarray analysis, 70% were upregulated in Responders and downregulated in Non-responders. Several genes involved in substrate metabolism and mitochondrial biogenesis differed significantly between the groups at baseline. This differential baseline gene expression indicated that Non-responders had blunted oxidative capacity. Total RNA extracted from baseline samples of skeletal muscle of obese individuals with Type 2 Diabetes who were characterized as either Responders or Non-responders was examined for differential expression of exercise response-assocated genes.
Project description:miRNA profiles were investigated in skeletal muscle in severely obese individuals with or without diabetes before and after Roux-en-Y gastric bypass surgery.
Project description:Obesity is a strong risk factor for the development of type 2 diabetes. We have previously reported that in adipose tissue of obese (ob/ob) mice, the expression of adipogenic genes is decreased. When made genetically obese, the BTBR mouse strain is diabetes susceptible and the C57BL/6J (B6) strain is diabetes resistant. We used DNA microarrays and RT-PCR to compare the gene expression in BTBR-ob/ob versus B6-ob/ob mice in adipose tissue, liver, skeletal muscle, and pancreatic islets. Our results show: 1) there is an increased expression of genes involved in inflammation in adipose tissue of diabetic mice; 2) lipogenic gene expression was lower in adipose tissue of diabetes-susceptible mice, and it continued to decrease with the development of diabetes, compared with diabetes-resistant obese mice; 3) hepatic expression of lipogenic enzymes was increased and the hepatic triglyceride content was greatly elevated in diabetes-resistant obese mice; 4) hepatic expression of gluconeogenic genes was suppressed at the prediabetic stage but not at the onset of diabetes; and 5) genes normally not expressed in skeletal muscle and pancreatic islets were expressed in these tissues in the diabetic mice. We propose that increased hepatic lipogenic capacity protects the B6-ob/ob mice from the development of type 2 diabetes. Diabetes 52:688â700, 2003 Experiment Overall Design: Four B6-ob/ob and four BTBR-ob/ob male mice at 14 weeks of age were used in the microarray study. RNA samples from two individuals were pooled for each tissue, and each pooled RNA sample was applied to an Affymetrix MGU74AV2 array. Because of the scarcity of islets in the BTBR-ob/ob mice, 4 additional mice were pooled to obtain islet RNA from these animals. Sixteen MGU74Av2 arrays (2 strains X 4 tissues X 2 replicates = 16 arrays) were used to monitor the expression level of â12,000 genes or ESTs.
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:Skeletal muscle insulin resistance, an early metabolic defect in the pathogenesis of type 2 diabetes, may be a cause or consequence of altered protein expressions profiles. Proteomics technology offers enormous promise to investigate molecular mechanisms underlying pathologies, however, the analysis of skeletal muscle is challenging. Using a state-of-the-art mass spectrometry (MS) based workflow, we performed a global proteomics analysis of skeletal muscle from leptin-deficient, obese, type 2 diabetic (ob/ob) and lean mice, identifying more than 6,000 proteins with 118 proteins differentially regulated in obesity. This included protein kinases, phosphatases, and secreted and fiber type associated proteins. Enzymes involved in lipid metabolism in skeletal muscle from ob/ob mice were increased, providing evidence against reduced fatty acid oxidation in lipid-induced insulin resistance. Mitochondrial and peroxisomal proteins, as well as components of pyruvate and lactate metabolism were likewise increased. Finally, the skeletal muscle proteome from ob/ob mice displayed a shift towards the ‘slow fiber type’. This detailed characterization of obese rodent models of type 2 diabetes demonstrates an efficient workflow for skeletal muscle proteomics, which may easily be adapted to other complex tissues.
Project description:Obesity is a strong risk factor for the development of type 2 diabetes. We have previously reported that in adipose tissue of obese (ob/ob) mice, the expression of adipogenic genes is decreased. When made genetically obese, the BTBR mouse strain is diabetes susceptible and the C57BL/6J (B6) strain is diabetes resistant. We used DNA microarrays and RT-PCR to compare the gene expression in BTBR-ob/ob versus B6-ob/ob mice in adipose tissue, liver, skeletal muscle, and pancreatic islets. Our results show: 1) there is an increased expression of genes involved in inflammation in adipose tissue of diabetic mice; 2) lipogenic gene expression was lower in adipose tissue of diabetes-susceptible mice, and it continued to decrease with the development of diabetes, compared with diabetes-resistant obese mice; 3) hepatic expression of lipogenic enzymes was increased and the hepatic triglyceride content was greatly elevated in diabetes-resistant obese mice; 4) hepatic expression of gluconeogenic genes was suppressed at the prediabetic stage but not at the onset of diabetes; and 5) genes normally not expressed in skeletal muscle and pancreatic islets were expressed in these tissues in the diabetic mice. We propose that increased hepatic lipogenic capacity protects the B6-ob/ob mice from the development of type 2 diabetes. Diabetes 52:688–700, 2003 Keywords: Genetic modifications
Project description:Insulin-stimulated muscle glucose uptake is a key process to alleviate hyperglycemia. This process depends on the redistribution of glucose transporters to the muscle surface membrane following phosphorylation of TBC1D1 and TBC1D4. Genetic evidence from a TBC1D4 loss-of-function mutation in human skeletal muscle is associated with an increased risk of type 2 diabetes (T2D). However, little is known about the potential regulating interactors of TBC1D4 in skeletal muscle. Here, we sought to identify interactors of TBC1D4 in human skeletal muscle by an unbiased proteomics approach. We detected 76 proteins as candidate TBC1D4 interactors, whereof 12 were regulated by insulin stimulation including known proteins involved in glucose metabolism (e.g. 14-3-3 proteins and ACTN4). TBC1D1 also co-precipitated with TBC1D4 and vice versa in both human and mouse skeletal muscle. This interaction was not regulated by insulin or exercise in young healthy lean individuals. In contrast, we observed an altered interaction as well as compromised insulin-stimulated phospho-regulation of the TBC1D1-TBC1D4 complex in muscle of obese individuals with T2D. In conclusion, we provide a list of TBC1D4 interactors in human and mouse skeletal muscle. These protein interactors serve as potential regulators of TBC1D4 function and thus insulin-stimulated glucose uptake in skeletal muscle.
Project description:Analysis of gene expression associated with exercise response. The hypothesis tested was that individuals with Type 2 Diabetes that failed to demonstrate exercise-induced metabolic improvements would also reflect this lack of response in their skeletal muscle transcriptional profile at baseline. Of 186 genes identified by microarray analysis, 70% were upregulated in Responders and downregulated in Non-responders. Several genes involved in substrate metabolism and mitochondrial biogenesis differed significantly between the groups at baseline. This differential baseline gene expression indicated that Non-responders had blunted oxidative capacity.
Project description:Global transcript profiling to identify differentially expressed skeletal muscle genes in insulin resistance, a major risk factor for Type II (non-insulin-dependent) diabetes mellitus. Compared gene expression profiles of skeletal muscle tissues from 18 insulin-sensitive versus 17 insulin-resistant equally obese, non-diabetic Pima Indians. Keywords: other
Project description:Adipose tissues play an important role in the pathophysiology of obesity-related disease including type 2 diabetes. To describe gene expression patterns and functional pathways in obesity-related type 2 diabetes, we performed global transcript profiling of omental adipose tissue in morbidly obese individuals with or without diabetes. Fourteen (14) morbidly obese diabetics (cases) and 6 morbidly obese non-diabetics (reference) were included in this study.