Targeted Screening and Identification of Chlorhexidine as a Pro-myogenic Circadian Clock Activator

Abstract

BackgroundCircadian clock is an evolutionarily-conserved mechanism that exerts pervasive temporal control in stem cell behavior. This time-keeping machinery is required for orchestrating myogenic progenitor properties in regenerative myogenesis that ameliorates muscular dystrophy. Here we report a screening platform to discover circadian clock modulators that promote myogenesis, with the identification of chlorhexidine (CHX) as a clock-activating molecule with pro-myogenic activities. MethodsA high-throughput molecular docking pipeline was applied to identify candidate compounds with a structural fit for a hydrophobic pocket within the key circadian transcription factor protein, Circadian Locomotor Output Cycles Kaput (CLOCK). Secondary biochemical screen for clock-modulatory activities of these molecules were preformed, together with functional validations of myogenic regulations to identify modulators with pro-myogenic properties. ResultsCHX was identified as a clock activator that promotes distinct aspects of myogenesis. CHX activated circadian clock that reduced cycling period length and augmented amplitude. This action was mediated by the targeted CLOCK structure via augmented interaction with heterodimer partner Bmal1, leading to enhanced CLOCK/Bmal1-controlled transcription with up-regulation of core clock genes. Consistent with its clock-activating function, CHX displayed robust effects on stimulating myogenic differentiation in a clock-dependent manner. In addition, CHX augmented the proliferative and migratory activities of myoblasts. ConclusionOur findings demonstrate the feasibility of a screening platform to discover clock modulators with myogenic regulatory activities. Discovery of CHX as a pro-myogenic molecule could be applicable to promote regenerative capacities in ameliorating dystrophic or degenerative muscle diseases.