Project description:Context: Although androgen treatment increases muscle mass in HIV-infected men, the underlying mechanisms are poorly understood. Analysis of genome-wide microarray data obtained from skeletal muscle biopsies can be used to profile androgen-regulated pathways. Objective: To identify genes and pathways associated with testosterone treatment and myogenesis in the context of HIV-infected men using genome-wide microarray analysis of skeletal muscle biopsies. Results: A significant weight gain was observed in subjects treated with testosterone compared to placebo (+2.05 kgs and â??1.07 kgs, respectively; P = 0.003) as well as gains in DEXA lean; mass (2.93 kgs vs. 0.35 kgs, respectively; P = 0.003). Microarray expression profiles and RTPCR validation of RNA after 14 days of treatment indicated that several gene sets including; transcriptional control, myogenesis, adipogenesis, insulin signaling, apoptosis, cell cycle, chromatin remodeling, and stress response genes were differentially expressed with testosterone treatment. Protein expression analysis of myogenic differentiation and protein synthesis markers (MyoD, Myogenin, phosphorylated p38 MAPK and phosphorylated AKT) in muscle biopsies and skeletal muscle cells treated with DHT confirmed that testosterone engages; a network of pro-myogenic genes. Conclusions: Testosterone-associated gain in muscle mass in HIV-infected men engaged a network of regulatory pathways involved in broad transcriptional control, myogenesis, insulin signaling, chromatin remodeling, and stress response. Further evaluation of precise signaling intermediates within androgen regulated pathways may help to better define improvements in muscle mass, both in healthy and HIV infected patients. Experiment Overall Design: Design, Setting, and Participants: 44 HIV+ men with weight loss were randomized to receive either 300mg testosterone enanthate or placebo injections IM weekly for 16 weeks. Muscle Experiment Overall Design: biopsies were obtained at baseline and on treatment day 14. A random subset of specimens was chosen for microarray analysis; changes in selected genes were confirmed by reverse transcriptase - polymerase chain reaction (RT-PCR), and western blot analysis. Human skeletal Experiment Overall Design: myogenic precursor cells (SkMCs) were cultured in vitro in the presence of dihydrotestosterone (DHT) to evaluate activation of myogenic protein expression. Experiment Overall Design: Main outcome measures: Relative RNA levels in skeletal muscle biopsies were measured by expression profiling with microarrays and expression levels were validated in samples using quantitative RT-PCR. Further confirmation of changes in key myogenic biomarkers was obtained in DHT treated SkMCs.
Project description:Context: Although androgen treatment increases muscle mass in HIV-infected men, the underlying mechanisms are poorly understood. Analysis of genome-wide microarray data obtained from skeletal muscle biopsies can be used to profile androgen-regulated pathways. Objective: To identify genes and pathways associated with testosterone treatment and myogenesis in the context of HIV-infected men using genome-wide microarray analysis of skeletal muscle biopsies. Results: A significant weight gain was observed in subjects treated with testosterone compared to placebo (+2.05 kgs and –1.07 kgs, respectively; P = 0.003) as well as gains in DEXA lean mass (2.93 kgs vs. 0.35 kgs, respectively; P = 0.003). Microarray expression profiles and RTPCR validation of RNA after 14 days of treatment indicated that several gene sets including transcriptional control, myogenesis, adipogenesis, insulin signaling, apoptosis, cell cycle, chromatin remodeling, and stress response genes were differentially expressed with testosterone treatment. Protein expression analysis of myogenic differentiation and protein synthesis markers (MyoD, Myogenin, phosphorylated p38 MAPK and phosphorylated AKT) in muscle biopsies and skeletal muscle cells treated with DHT confirmed that testosterone engages a network of pro-myogenic genes. Conclusions: Testosterone-associated gain in muscle mass in HIV-infected men engaged a network of regulatory pathways involved in broad transcriptional control, myogenesis, insulin signaling, chromatin remodeling, and stress response. Further evaluation of precise signaling intermediates within androgen regulated pathways may help to better define improvements in muscle mass, both in healthy and HIV infected patients. Keywords: Dose Response, Myogenesis
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:Exercise is a behavior modification indispensable for long-term weight loss. Exercise activates the Creb-Regulated Transcriptional Coactivator (Crtc) family of transcriptional coregulators to drive Creb1-mediated anabolic transcriptional programs in skeletal muscle. Here, we show that induced overexpression of a skeletal muscle specific Crtc2 transgene in aged mice leads to greater weight loss during alternate day fasting, and selective loss of fat rather than lean mass. Transcriptional profiling revealed that fasting and weight loss downregulated most of the mitochondrial electron transport genes and other regulators of mitochondrial function that were substantially reversed in the Crtc2 mice, which maintained higher energy expenditure during fasting. The Crtc2 mice displayed greater mitochondrial activity, metabolic flux capacity for both carbohydrates and fats, improved glucose tolerance and insulin sensitivity, and increased oxidative capacity before the fast, suggesting muscle-intrinsic mechanisms in support of improved weight loss. This work reveals that Crtc2/Creb1-mediated signaling coordinates metabolic adaptations in skeletal muscle that explain how Crtc2/Creb contribute to the effects of exercise on metabolism and weight loss.
Project description:Background: Diet induced weight reduction promotes a decrease in resting energy expenditure that could partly explain the difficulty to maintain reduced body mass. Whether this reduction remains after stabilized weight loss is still controversial. The molecular mechanisms are unknown. Objective: To investigate the effect of a stabilized 10%-weight loss on resting metabolic rate, body composition and skeletal muscle gene expression profile in obese women. Design: Obese women were successively submitted to a 4-w very low-calorie diet, a 3-6-wk low-calorie diet, and a 4-wk weight maintenance program to achieve a 10% weight loss. Resting energy expenditure, body composition, plasma parameters and skeletal muscle transcriptome were compared before weight loss and during stabilized weight reduction. Results: Energy restriction caused an 11% weight loss. Stabilization to the new weight was accompanied by an 11% decrease of the resting metabolic rate normalized to the body cellular mass which was below that of lean subjects. The range of the changes in the skeletal muscle transcriptome was modest. The main regulated genes were that of slow/oxidative fiber markers which were overexpressed and the gene encoding the glucose metabolism inhibitor PDK4 which was down-regulated. The knowledge based approach, gene set enrichment analysis, identified pathways related to insulin and interleukin 6 and long term calorie restriction adaptations during weight loss. Set of arrays that are part of repeated experiments Keywords: Biological Replicate
Project description:The mechanisms of weight loss and metabolic improvements following bariatric surgery in skeletal muscle are not well known, however epigenetic modifications are likely to contribute. The aim of our study was to investigate skeletal muscle DNA methylation after weight loss induced by Roux-en-Y gastric bypass (RYGB) surgery.
Project description:Genome-wide DNA methylation profiling of young men born with low birth weight following a control and high-fat overfeeding diet using Illumina's Infinium 27k Human DNA methylation Beadchip v. 1.2. DNA methylation profiles were obtained for 27,578 CpG sites in human skeletal muscle.
Project description:Skeletal muscle (rectus femoris) gene expression was analyzed from diet-resistant and diet-sensitive obese women undergoing clinically supervised weight-loss at a weight management clinic The goal of the study was to characterize global gene expression profiles in skeletal muscle from obese women, prior to their participation in a clinically supervised, low-calorie diet, weight management program. Following entry into the weight-loss program, subjects can be categorized as being 'diet-sensitive' or 'diet-resistant' depending on the rates of weight loss achieved. In the current study, we selected an equal number of diet-sensitive and diet-resistant subjects for comparative expression profiling
Project description:Cancer cachexia, highly prevalent in lung cancer, is a debilitating syndrome characterized by involuntary loss of skeletal muscle mass, and is associated with poor clinical outcome, decreased survival and negative impact on on tumor therapy. Here we sought to identify the muscle gene profile and pathways regulated in cachexia. Vastus lateralis muscle was obtained of newly diagnosed treatment-naïve NSCLC patients with cachexia (n = 8) and matched healthy controls (n = 8). Self-reported weight loss and body composition measurements defined cachexia status. RNA sequencing was performed on the Illumina NovasSeq 6000.