GLI3 regulates muscle stem cell entry into G<sub>Alert</sub> and self-renewal.

Brun, Caroline E; Sincennes, Marie-Claude; Lin, Alexander Y T; Hall, Derek; Jarassier, William; Feige, Peter; Le Grand, Fabien; Rudnicki, Michael A · Nat Commun · 2022

basic_science · Level V

Where this comes from

Abstract

Satellite cells are required for the growth, maintenance, and regeneration of skeletal muscle. Quiescent satellite cells possess a primary cilium, a structure that regulates the processing of the GLI family of transcription factors. Here we find that GLI3 processing by the primary cilium plays a critical role for satellite cell function. GLI3 is required to maintain satellite cells in a G<sub>0</sub> dormant state. Strikingly, satellite cells lacking GLI3 enter the G<sub>Alert</sub> state in the absence of injury. Furthermore, GLI3 depletion stimulates expansion of the stem cell pool. As a result, satellite cells lacking GLI3 display rapid cell-cycle entry, increased proliferation and augmented self-renewal, and markedly enhanced regenerative capacity. At the molecular level, we establish that the loss of GLI3 induces mTORC1 signaling activation. Therefore, our results provide a mechanism by which GLI3 controls mTORC1 signaling, consequently regulating muscle stem cell activation and fate.

Medical subject headings