Modulation of muscle mass and myogenic stem cells with natural products

Muscle satellite cells are widely accepted as the resident stem cells of skeletal muscle, supplying myoblasts for growth, homeostasis and repair. Activation of these cells in response to muscle mechanical change or injury involves activation of the muscle-specific transcription networks. Previously we reported that brassinosteroids, a group of natural plant hormones that regulate growth and development, triggered an anabolic response when fed orally to rats. Here we show that this effect was associated with increased expression of the myogenic transcription factors and quiescent myogenic satellite cell Pax3/7 markers. In L6 rat myoblast lineage cells, brassinosteroid treatment accelerated differentiation, expression of structural proteins, and fusion into multinucleated myotubes. Collectively, these data indicate that activation, increased proliferation, and subsequent fusion of myogenic cells may be an important mechanism by which brassinosteroids enhance muscle hypertrophy. Thus, in appropriate doses, brassinosteroids may have therapeutic applications for the treatment of diseases associated with muscle loss.