eLife Assessment
This valuable study provides solid support for the participation of the BMP-binding domain of MuSK, a tyrosine kinase mostly known for its role at the neuromuscular junction, in the maintenance and activation of muscle stem cells (SCs). These mononucleated cells, located between the muscle fiber basal lamina and its plasma membrane, are normally quiescent, but following muscle damage, become activated, proliferate, and mediate muscle regeneration. These cells are known to respond to a variety of signaling pathways, but this study makes the case for BMP acting via binding to MuSK in maintaining the quiescent state.