PROJECT SUMMARY Our proposal exemplifies the NIH vision that the multidisciplinary approach to clinical care and research is the most fruitful paradigm for the development of significant advancements within a specific field. While it is unfortunate that the heavy focus of skeletal muscle research on the appendicular muscles in male animal models led to scarcity of preclinical investigations in the area of female pelvic skeletal muscles and provided little progress toward preventative or therapeutic approaches that target female-specific conditions, such as pelvic floor disorders; the current project builds on the discoveries of the landmark studies conducted in the limb muscles. Here, we focus on building the foundational knowledge pertaining to female pelvic floor muscle -specific muscle stem cells and the impact of such critical time-periods as pregnancy and childbirth on these cells. The above is necessary for future development of pragmatic preventative approaches to reduce the impact of morbid pelvic floor disorders on public health. This project represents a novel approach focused on elucidating the role of muscle stem cells in pregnancy-induced antepartum adaptations of the pelvic floor muscles as well as muscle regenerative potential following vaginal delivery. To achieve this objective, we will use our validated experimental model to examine the phenotypic, functional, transcriptional, and epigenomic signatures of pelvic muscle stem cells at multiple time points across gestation, parturition, and postpartum period to identify candidate signaling pathways regulating their functional state. We will then test whether exposure to different aspects of the ante- and peripartum environment modulates the regenerative potential of pelvic muscle stem cells and impacts muscle recovery following injury. Overall, this innovative study will provide fundamental insights into the biological processes involved in the regulation of female pelvic muscle satellite cells and factors that impact their regenerative capacity following mechanical injury. The resulting knowledge will enable the development of novel strategies to prevent or treat female pelvic muscle dysfunction.