The circadian clock is a target in muscle stem cells to promote regenerative repair and sarcolemma stability

Background: The circadian clock, driven by a transcriptional-translation negative feedback loop, exerts critical oscillatory control of key biological processes to maintain tissue homeostasis. In skeletal muscle, circadian clock plays a key role in orchestrating muscle stem cell behavior in regenerative myogenesis. However, whether clock function could be targeted to promote regenerative repair for disease applications remains unexplored. The current study employed genetic and pharmacological clock-enhancing approaches to interrogate clock-controlled mechanisms in promoting regenerative repair, with discovery of the pro-myogenic efficacy of clock-activating molecules in a preclinical mdx model of dystrophic disease and primary myoblasts derived from Duchenne Muscular Dystrophy (DMD) patients. Hypothesis: Genetic and pharmacological activation of clock-controlled pro-myogenic mechanisms may promote regenerative capacity to mitigate dystrophic disease. Methods: We generated a novel mouse model with Bmal1-mediated clock gain-of-function to dissect its modulation of muscle stem cell properties involved in regeneration and restoring regenerative capacity in muscular dystrophy. In addition, the pro-myogenic properties of clock-activating small molecules, Chlorhexidine and CM002, were determined in normal and dystrophic primary myoblasts, with determination of their in vivo efficacy on promoting regenerative myogenesis in cardiotoxin-induced injury and within the chronic dystrophic milieu. Results: Clock gain-of-function in satellite cells promoted their proliferative and myogenic properties upon acute muscle injury, leading to a prolonged regenerative phase. Mechanistically, enhanced Notch activation with Wnt signaling stimulation underlies clock effect on promoting muscle regeneration. In line with these findings, pharmacological activation of clock promoted the proliferation and myogenic differentiation of normal or dystrophic murine primary myoblasts, with induction of myogenic response in human DMD myoblasts. Upon acute muscle injury, clock activators were able to promote nascent myofiber formation and regenerative repair. In mdx mice, intramuscular deliveries of these molecules activated clock regulation with augmented regenerative myogenesis, suggesting their utility in restoring regenerative capacity in dystrophic muscle. Conclusions: Collectively, our findings revealed the actions of clock in prolonging myogenic precursor proliferative expansion while maintaining their myogenic potential, thereby establishing the mechanistic basis for targeting clock to promote regenerative capacity. More importantly, this study uncovered novel clock-activating molecules with in vivo pro-myogenic efficacy toward drug development for dystrophic disease therapy. Funding sources: R01DK137515, R56AG080294, Arthur Riggs Diabetes and Metabolism Research Institute Innovative Award, CIRM Pre-Doctoral Training Grant This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.