ABSTRACT: Transcription profiling of human skeletal muscle from obese vs.normal individuals to identify the mRNA of proteins involved in fat oxidation that may be reduced in obese and morbidly obese individuals
Project description:It has been found that fat oxidation is reduced in the skeletal muscle of obese humans. This study aims to identify the mRNA of proteins involved in fat oxidation that may be reduced in obese and morbidly obese individuals. Information gathered will help in understanding how obesity contributes to cardiovascular disease via insulin resistance. Samples were obtained from patients undergoing elective abdominal surgery.
Project description:It has been found that fat oxidation is reduced in the skeletal muscle of obese humans. This study aims to identify the mRNA of proteins involved in fat oxidation that may be reduced in obese and morbidly obese individuals. Information gathered will help in understanding how obesity contributes to cardiovascular disease via insulin resistance. Keywords: other
Project description:The health benefits of physical activity are well documented, but several exercise response parameters are attenuated in obese individuals. The goal of this study was to identify molecular mechanisms that may influence exercise response in skeletal muscle of obese individuals. We performed comparison of the transcriptome in muscle from lean and obese individuals before and after an acute exercise bout.
Project description:Alternative mRNA splicing provides transcript diversity and has been proposed to contribute to several human diseases. Here, we demonstrate that expression of genes regulating RNA processing is decreased in both liver and skeletal muscle of obese humans. To determine the metabolic impact of reduced splicing factor expression, we further evaluated the splicing factor, SFRS10, identified as down-regulated in obese human liver and skeletal muscle and in high fat fed rodents. siRNA-mediated reductions in SFRS10 expression induced lipogenesis and lipid accumulation in cultured hepatocytes. Moreover, SFRS10 heterozygous mice have both increased hepatic lipogenic gene expression and hypertriglyceridemia. We also demonstrate that LPIN1, a key regulator of lipid metabolism, is a splicing target of SFRS10, with reduced SFRS10 levels favoring the lipogenic β isoform of LPIN1. Importantly, LPIN1β-specific siRNA abolished the lipogenic effects of decreased SFRS10 expression. Together, our results indicate reduced expression of SFRS10 alters LPIN1 splicing and induces lipogenesis, demonstrating that reduced splicing factor expression observed in human tissues may contribute to metabolic phenotypes associated with human obesity. Skeletal muscle samples were obtained from 10 lean control subjects and 7 obese subjects with either IGT or DM2 undergoing elective cholecystectomy. Data for liver samples presented in the same manuscript are available at GEO GSE15653. In this analysis RNA was isolated for cRNA preparation and hybridized to Affymetrix Human Genome U133 Plus 2.0 microarrays.
Project description:We investigated the effect of weight loss maintenance (WLM) and weight regain on skeletal muscle in rodents. In skeletal muscle of obesity prone rats, WLM reduced fat oxidative capacity and down-regulated genes involved in fat metabolism. After weight was regained in rats, the genes involved in fat metabolism were still reduced. Mice with skeletal muscle lipoprotein lipase overexpression (mCK-hLPL), which augments fat metabolism, were subjected to our WLM and weight regain paradigm. We found that mCK-hLPL attenuated weight regain by potentiating energy expenditure.Irrespective of genotype, weight regain suppressed dietary fat oxidation and down-regulated genes involved in fat metabolism in skeletal muscle. However, mCK-hLPL mice oxidized more fat throughout weight regain and had greater expression of genes involved in fat metabolism and lower expression of genes involved in carbohydrate metabolism during WLM and regain.
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: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:The Hippo signalling pathway effector Yap positively regulates adult skeletal muscle mass. However, the biological processes that are modulated by Yap in skeletal muscle remain elusive. Using an integrated transcriptomics and proteomics approach, we define the transcriptional programme regulated by Yap in adult skeletal muscle and demonstrate that Yap is a regulator of metabolic substrate utilisation. Inhibition of Yap in mammalian skeletal muscle results in increased, but incomplete, oxidation of fatty acids and features of lipotoxicity. In line with these findings, we demonstrate that Yap abundance is reduced in the skeletal musculature of obese db/db mice, and in muscle biopsies from obese, insulin-resistant humans where YAP levels positively correlate with whole-body metabolic flexibility. Increasing Yap abundance in the striated muscle of db/db mice attenuated the accumulation of fat mass and development of hepatic steatosis. Our findings demonstrate a vital role for Yap in skeletal muscle as a mediator of metabolic substrate utilisation. Modulating Yap activity in skeletal muscle warrants consideration as part of comprehensive approaches to treat metabolic disease.
Project description:The Hippo signalling pathway effector Yap positively regulates adult skeletal muscle mass. However, the biological processes that are modulated by Yap in skeletal muscle remain elusive. Using an integrated transcriptomics and proteomics approach, we define the transcriptional programme regulated by Yap in adult skeletal muscle and demonstrate that Yap is a regulator of metabolic substrate utilisation. Inhibition of Yap in mammalian skeletal muscle results in increased, but incomplete, oxidation of fatty acids and features of lipotoxicity. In line with these findings, we demonstrate that Yap abundance is reduced in the skeletal musculature of obese db/db mice, and in muscle biopsies from obese, insulin-resistant humans where YAP levels positively correlate with whole-body metabolic flexibility. Increasing Yap abundance in the striated muscle of db/db mice attenuated the accumulation of fat mass and development of hepatic steatosis. Our findings demonstrate a vital role for Yap in skeletal muscle as a mediator of metabolic substrate utilisation. Modulating Yap activity in skeletal muscle warrants consideration as part of comprehensive approaches to treat metabolic disease.
Project description:Obese and lean-type pig breeds show obvious differences in adipose deposition and muscle growth; however, the molecular mechanisms underlying this phenotypic variation remains unclear. Landrace (a leaner, Western breed), Rongchang (a fatty, Chinese breed) and Tibetan (a feral, indigenous Chinese breed that has not undergone artificial selection) pig breeds were used in this study. We collected eight diverse adipose tissues and two phenotypically distinct skeletal muscle tissues from three well-defined pig models with distinct fat rates, and studied mRNA expression differences among breeds, males and females, and tissues. These results highlight some possible candidate genes for porcine adipose deposition and muscle growth and provide some data on which to base further studies of the molecular basis of energy metabolism. The mRNA expression differences of eight diverse adipose tissues and two phenotypically distinct skeletal muscle tissues from three well-defined pig models with distinct fat rates are measured.