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:Obesity is a major risk factor underlying the development of metabolic disease and a growing public health concern globally. Strategies to promote skeletal muscle metabolism can be effective to limit the progression of metabolic disease. Here, we demonstrate that the levels of the Hippo pathway transcriptional co-activator YAP are decreased in muscle biopsies from obese, insulin-resistant humans and mice. Targeted disruption of Yap in adult skeletal muscle resulted in incomplete oxidation of fatty acids and lipotoxicity. Integrated ‘omics analysis including proteomics from isolated adult muscle nuclei revealed that Yap regulates a transcriptional profile associated with metabolic substrate utilisation. In line with these findings, increasing Yap abundance in the striated muscle of obese (db/db) mice enhanced energy expenditure and attenuated adiposity. Our results demonstrate a vital role for Yap as a mediator of skeletal muscle metabolism. Strategies to enhance Yap activity in skeletal muscle warrant consideration as part of comprehensive approaches to treat metabolic disease.
Project description:Obesity is a major risk factor underlying the development of metabolic disease and a growing public health concern globally. Strategies to promote skeletal muscle metabolism can be effective to limit the progression of metabolic disease. Here, we demonstrate that the levels of the Hippo pathway transcriptional co-activator YAP are decreased in muscle biopsies from obese, insulin-resistant humans and mice. Targeted disruption of Yap in adult skeletal muscle resulted in incomplete oxidation of fatty acids and lipotoxicity. Integrated 'omics analysis from isolated adult muscle nuclei revealed that Yap regulates a transcriptional profile associated with metabolic substrate utilisation. In line with these findings, increasing Yap abundance in the striated muscle of obese (db/db) mice enhanced energy expenditure and attenuated adiposity. Our results demonstrate a vital role for Yap as a mediator of skeletal muscle metabolism. Strategies to enhance Yap activity in skeletal muscle warrant consideration as part of comprehensive approaches to treat metabolic disease.
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:Existing controversy regarding the importance of AMP-activated protein kinase (AMPK) in fatty acid (FA) oxidation in skeletal muscle with contraction/exercise may to some extent pertain to redundant AMPKα1 signaling. Using a mouse model lacking both AMPKα1 and -α2 in skeletal muscle specifically (mdKO) we hypothesized that FA utilization would be impaired in skeletal muscle. Calorimetric analysis showed a similar respiratory exchange ratio (RER) of AMPKα WT and mdKO mice when fed normal chow, a high fat diet or with prolonged fasting. Though, in vivo treadmill exercise at the same relative intensity induced a higher RER in mdKO mice compared to WT (WT=0.81; mdKO=0.87; p<0.01) indicating a decreased utilization of FA. Ex vivo incubation of soleus muscle revealed that basal and contraction-induced FA oxidation was impaired in mdKO mice, suggesting that the increased RER during in vivo running exercise originated from decreased skeletal muscle FA oxidation. A decreased muscle protein expression of CD36 and FABPpm (by 17-40%) together with abolishment of TBC1D1 Ser237 phosphorylation in mdKO mice, may result in lower FA transport capacity and FA transport protein translocation to sarcolemma, respectively. In summary this study shows that the catalytically active AMPKα subunits are required for normal stimulation of FA utilization during exercise and contractions.
Project description:The Hippo signalling pathway effector protein Yap positively regulates adult skeletal muscle mass and limits muscle atrophy in settings of neuromuscular perturbation. However, the mechanisms that lead to changes in muscle mass following alterations in Yap activity remain unclear. Here, we show in the limb musculature of adult mice, that Yap inhibition alters the expression of genes associated with metabolic capacity, with sustained inhibition of Yap resulting in incomplete metabolism of fatty acids. In the context of metabolic disease, we demonstrate that Yap levels are lower in both the glycolytic skeletal musculature of Lepr db/db mice and in the muscles of insulin-resistant humans. Restoring Yap levels in the striated muscles of Lepr db/db mice was associated with an increase in skeletal muscle oxidative potential and resulted in a reduction in adiposity and hepatic steatosis. Our findings provide the first evidence of a metabolic role for the Hippo pathway effector Yap in post-mitotic skeletal muscle cells and suggest that modulating Yap activity may be an approach to promote skeletal muscle lipid metabolism.