Project description:We address the function of HDAC3 in skeletal muscle metabolism We performed HDAC3 ChIP-seq, RNA-seq, and GRO-seq in mouse muscles at different times of the day and compared between WT and HDAC3-depleted muscles.
Project description:We address whether the functions of HDAC3 in skeletal muscle require its enzyme activity. By mutating the NCoR/SMRT corepressors in a knock-in mouse model named NS-DADm, we ablated the enzymatic activity of HDAC3 without affecting its protein levels. Compared to the control mice, skeletal muscles from NS-DADm mice showed lower force generation, enhanced fatigue resistance, enhanced fatty acid oxidation, reduced glucose uptake during exercise, upregulated expression of metabolic genes involved in branched-chain amino acids (BCAAs) catabolism, and aging-associated reduction in muscle mass, without changes in the muscle fiber type composition or mitochondrial protein content. These findings demonstrate that the metabolic function of HDAC3 in skeletal muscles requires its enzymatic activity.
Project description:Histone deacetylase 3 (HDAC3) is a major HDAC, whose enzymatic activity is targeted by small molecule inhibitors for treating a variety of conditions. However, its enzymatic activity is largely dispensable for its function in embryonic development and hepatic lipid metabolism. HDAC3 plays a pivotal role in regulating muscle fuel metabolism and contractile function. Here, we address whether these muscular functions of HDAC3 require its enzymatic activity. By mutating the NCoR/SMRT corepressors in a knock-in mouse model named NS-DADm, we ablated the enzymatic activity of HDAC3 without affecting its protein levels. Compared to the control mice, skeletal muscles from NS-DADm mice showed lower force generation, enhanced fatigue resistance, enhanced fatty acid oxidation, reduced glucose uptake during exercise, upregulated expression of metabolic genes involved in branched-chain amino acids catabolism, and reduced muscle mass during aging, without changes in the muscle fiber-type composition or mitochondrial protein content. These muscular phenotypes are similar to those observed in the HDAC3-depleted skeletal muscles, which demonstrates that, unlike that in the liver or embryonic development, the metabolic function of HDAC3 in skeletal muscles requires its enzymatic activity. These results suggest that drugs specifically targeting HDAC3 enzyme activity could be developed and tested to modulate muscle energy metabolism and exercise performance.
Project description:Krill oil is a dietary supplement derived from Antarctic krill; a small crustacean found in the ocean. Krill oil is a rich source of omega-3 fatty acids, specifically eicosapentaenoic acid and docosahexaenoic acid, as well as the antioxidant astaxanthin. The aim of this study was to investigate the effects of krill oil supplementation, compared to placebo oil (high oleic sunflower oil added astaxanthin), in vivo on energy metabolism and substrate turnover in skeletal muscle cells. Skeletal muscle cells (myotubes) were obtained before and after a 7-week krill oil or placebo oil intervention, and glucose and oleic acid metabolism and leucine accumulation, as well as effects of different stimuli in vitro, were studied in the myotubes. In addition, myotubes were also exposed to krill oil in vitro. The in vitro study revealed that 24 h of krill oil treatment increased both glucose and oleic acid metabolism, enhancing energy substrate utilization. In vivo intervention with krill oil increased oleic acid oxidation and leucine accumulation in skeletal muscle cells, however no effects were observed on glucose metabolism. The krill oil-intervention-induced increase in oleic acid oxidation correlated negatively with changes in serum low-density lipoprotein (LDL) concentration. Transcriptomic analysis comparing myotubes obtained before and after krill oil-supplementation identified differentially expressed genes associated with e.g. glycolysis/gluconeogenesis, metabolic pathways and calcium signaling pathway, while proteomic analysis demonstrated upregulation of e.g. LDL-receptor. These findings suggest that krill oil intervention promotes increased fuel metabolism and protein synthesis in human skeletal muscle cells, with potential implications for metabolic health.
Project description:Habitual exercise modulates the composition of the intestinal microbiota. We examined whether transplanting fecal microbiota from trained mice improved skeletal muscle metabolism in high-fat diet-fed mice. The recipient mice that received fecal samples from trained donor mice for 1 week showed elevated levels of metabolic signalings in skeletal muscle. Glucose tolerance was improved by fecal microbiota transplantation after 8 weeks of HFD administration. Intestinal microbiota may mediate exercise-induced metabolic improvement in mice. We performed a microarray analysis to compare the metabolic gene expression profiles in the skeletal muscle from each mouse.
Project description:Circadian misalignment, such as in shift work, has been associated with obesity and type 2 diabetes, however, direct effects of circadian misalignment on skeletal muscle insulin sensitivity and muscle molecular circadian clock have never been investigated in humans. Here we investigated insulin sensitivity and muscle metabolism in fourteen healthy young lean men (age 22.4 ± 2.8 years; BMI 22.3 ± 2.1 kg/m2 [mean ± SD]) after a 3-day control protocol and a 3.5-day misalignment protocol induced by a 12-h rapid shift of the behavioral cycle. We show that circadian misalignment results in a significant decrease in peripheral insulin sensitivity due to a reduced skeletal muscle non-oxidative glucose disposal (Rate of disappearance: 23.7 ± 2.4 vs. 18.4 ± 1.4 mg/kg/min; control vs. misalignment; p=0.024). Fasting glucose and FFA levels as well as sleeping metabolic rate were higher during circadian misalignment. Molecular analysis of skeletal muscle biopsies revealed that the molecular circadian clock was not aligned to the new behavourial rhythm, and microarray analysis revealed the human PPAR pathway as a key player in the disturbed energy metabolism upon circadian misallignement. Our findings may provide a mechanism underlying the increased risk of type 2 diabetes among shift workers.
Project description:Aims: Skeletal muscle (SkM) abnormalities may impact exercise capacity in patients with Heart Failure with Preserved Ejection Fraction (HFpEF). We sought to quantify differences in SkM oxidative phosphorylation capacity (OxPhos), fiber composition, and the SkM proteome between HFpEF, hypertensive (HTN), and Healthy participants. Methods: 59 subjects (20 Healthy, 19 HTN, 20 HFpEF) performed a maximal-effort cardiopulmonary exercise test to define peak oxygen consumption (VO2, peak), ventilatory threshold (VT), and VO2 efficiency (ratio of total work performed to O2 consumed). SkM OxPhos was assessed using Creatine Chemical-Exchange Saturation Transfer (CrCEST, n=51), which quantifies unphosphorylated Cr, before and after plantar flexion exercise. The half-time of Cr recovery (t1/2, Cr) was taken as a metric of in vivo SkM OxPhos. In a subset of subjects (Healthy=13, HTN=9, HFpEF=12), percutaneous biopsy of the vastus lateralis was performed for myofiber typing, mitochondrial morphology, and proteomic and phosphoproteomic analysis. Results: HFpEF subjects demonstrated lower VO2,peak, VT, and VO2 efficiency than either control group (all p<0.05). The t1/2, Cr was significantly longer in HFpEF (p=0.005), indicative of impaired SkM OxPhos, and correlated with cycle ergometry exercise parameters. HFpEF SkM contained fewer Type-I myofibers (p=0.003). Proteomic analyses demonstrated (a) reduced levels of proteins related to OxPhos that correlated with exercise capacity and (b) reduced ERK signaling in HFpEF. Conclusions: HFpEF patients demonstrate impaired functional capacity and SkM OxPhos. Reductions in the proportions of type 1 myofibers, proteins required for OxPhos, and altered phosphorylation signaling in the SkM may contribute to exercise intolerance in HFpEF.
Project description:In intact animals, time of drug administration may be an important factor influencing drug response. Our general goal seeks to incorporate circadian time into the study of corticosteroid regulated gene expression. This study is designed to examine fluctuations in gene expression in skeletal muscle within the 24 hour circadian cycle in normal animals. Circadian time is relevant to designing optimal corticosteroid dosing regimens. Since levels of endogenous steroid exhibit circadian fluctuations, it is our hypothesis that the expression of genes controlled by corticosteroids either directly or indirectly will also exhibit a circadian pattern in normal animals. Keywords: time series design