Sestrins regulate muscle stem cell metabolic homeostasis

Abstract The health and homeostasis of skeletal muscle is preserved by a population of tissue resident stem cells called satellite cells. Young healthy satellite cells maintain a state of quiescence, but aging or metabolic insults results in reduced capacity to prevent premature activation and stem cell exhaustion. As such, understanding genes and pathways that protect satellite cell maintenance of quiescence are needed. Sestrins are a class of stress-inducible proteins that act as antioxidants and inhibit the activation of the mammalian target of mTOR(definition)-inhibiting drug studied for extending healthspan and lifespan." style="text-decoration:underline dotted; text-underline-offset:2px; cursor:help;">rapamycin(definition) complex 1 (mTORC1) signaling complex. Despite these pivotal roles, the role of Sestrins has not been explored in adult stem cells. Herein, we show that Sestrin1,2 loss results in hyperactivation of the mTORC1 complex, increased propensity to enter the cell cycle and shifts in metabolic flux. Aging of Sestrin1,2 knockout mice demonstrated a loss of MuSCs and reduced ability to regenerate. These findings demonstrate Sestrins function to help maintain MuSC metabolism that supports quiescence and against aging. Highlights Sestrin deficiency alters mTORC1 signaling in muscle stem cells (MuSCs). In young mice, Sestrins are dispensable for regenerative responses of MuSCs. Sestrin deficiency accelerates age-dependent loss and dysfunction of MuSCs.