Mcad-mediated intercellular interactions activate satellite cell division

The adult stem cells of the muscle and their committed myogenic precursors, commonly referred to as the satellite cell population, are involved in both muscle growth after birth and regeneration after damage. It has been previously proposed that, under these circumstances, satellite cells first become activated, divide and differentiate, and only later fuse to the existing myofiber through M-cadherin-mediated intercellular interactions. Our data shows that satellite cells fuse with the myofiber concomitantly to cell division, and only when the daughter cells' nuclei are inside the myofiber, do they complete the process of differentiation. In here we demonstrate that M-cadherin plays an important role in cell-to-cell recognition and fusion, and that is critical for cell division activation. Treatment of satellite cells with M-cadherin in vitro stimulates cell division while addition of anti M-cadherin antibodies reduces the cell division rate. Our results suggest an alternative model for the contribution of satellite cells to muscle development, which might be useful to understand muscle regeneration, as well as muscle-related dystrophies.