Progranulin regulates zebrafish muscle growth and regeneration through maintaining the pool of myogenic progenitor cells.

Myogenic progenitor cell (MPC) is responsible for postembryonic muscle growth and regeneration. Progranulin (PGRN) is a pluripotent growth factor that is correlated with neuromuscular disease, which is characterised by denervation, leading to muscle atrophy with an abnormal quantity and functional ability of MPC. However, the role of PGRN in MPC biology has yet to be elucidated. Here, we show that knockdown of zebrafish progranulin A (GrnA) resulted in a reduced number of MPC and impaired muscle growth. The decreased number of Pax7-positive MPCs could be restored by the ectopic expression of GrnA or MET. We further confirmed the requirement of GrnA in MPC activation during muscle regeneration by knockdown and transgenic line with muscle-specific overexpression of GrnA. In conclusion, we demonstrate a critical role for PGRN in the maintenance of MPC and suggest that muscle atrophy under PGRN loss may begin with MPC during postembryonic myogenesis.