Role of lysine acetylation in skeletal muscle contractile function - PROJECT SUMMARY Skeletal muscle contractile function (i.e. its ability to generate force) underlies functional independence and is an important determinant of morbidity and mortality risk. In order to develop strategies to optimize muscle function and quality of life, it is necessary to fully understand how skeletal muscle contractile function is regulated. Our understanding of the role of post-translational modifications of contractile proteins in skeletal muscle force generating capacity lags behind other striated muscle (cardiac), where identification of phosphorylation-based modifications has led to development of new therapies to treat heart failure. Here, we propose that the post- translational modification lysine acetylation, rather than phosphorylation, is fundamental to skeletal muscle contractile function. Based on our preliminary data that muscle contractile force and cytoplasmic calcium release are dramatically impaired with loss of the acetyltransferases, p300 (E1A binding protein p300) and CBP (CREB binding protein), we hypothesize that lysine acetylation of excitation contraction (EC)-coupling proteins by p300/CBP is required for cytoplasmic calcium flux and skeletal muscle force generation. To address our hypothesis, we will measure skeletal muscle contractile function and calcium dynamics in mature mouse skeletal muscle (both whole muscle and single fibers) in which p300 and CBP acetyltransferase activity is modulated, as well as primary human muscle cells and 3D-microtissues. Aim #1 will elucidate the importance of cytosolic versus nuclear p300/CBP and gene transcription to skeletal muscle contractile function, Aim #2 will determine the step(s) of EC-coupling that are regulated by p300/CBP and, Aim #3 will determine the off-target effects of clinically-pursued p300/CBP inhibitors on contractile function in mice and engineered 3D human muscle microtissues. By broadening our understanding of the contribution of acetylation to skeletal muscle contractile function, these studies will address an important gap in knowledge related to the post-translational regulation of skeletal muscle contractile function. Ultimately, we expect this knowledge to provide a new framework for therapeutic approaches aimed at modulating skeletal muscle contractile function, as well as guidance for the use of p300/CBP inhibitors in the pre-clinical pipeline, with the ultimate goal being the promotion of functional independence, quality of life and human health.
