Deconstructing nuclear speckles contribution to muscle stem cell activation across lifespan

About This Grant

Abstract Skeletal muscle contains a population of adult stem cells called satellite cells or muscle stem cells (MuSCs) that are responsible for regeneration after injury. MuSCs utilize gene expression programs to maintain quiescence and differentiate after injury and a key regulator of gene expression is splicing, which uniquely changes when transcripts interact with nuclear speckles. Nuclear speckles are membrane-less biomolecular condensates that phase separate proteins, RNAs and chromatin, but how these organelles regulate molecular processes in MuSCs remains unknown. Key experiments from our laboratory provide rigorous support for a role of nuclear speckles and splicing in MuSC function, which were attenuated in old age. The overarching objective of this program is to establish a systems-based approach to understand how nuclear speckles and alternative splicing contribute to MuSC programs of activation and regeneration across lifespan. In Aim 1, we will demonstrate that the loss of a nuclear speckle scaffolding protein, Srrm2, will reduce regenerative potential of muscle stem cells. In Aim 2, we will establish that increases in oxidative stress from old age attenuate nuclear speckles and RNA splicing that regulate muscle stem cell activation and repair of muscle injury. In both Aims, we will use novel transgenic animal models, sophisticated bioinformatics analysis and highly innovative molecular tools to build a comprehensive and new understanding of nuclear speckles influence on alternative splicing and stem cell activity. Successful completion of this program will advance our knowledge of fundamental cell biology for regenerative medicine, and provide a myriad set of insights across molecular, cellular and tissue scales.