Asymmetric Distribution of Primary Cilia Allocates Satellite Cells for Self-Renewal

Abstract

Summary: Regeneration of vertebrate skeletal muscles requires satellite cells, a population of stem cells that are quiescent in normal conditions and divide, differentiate, and self-renew upon activation triggered by exercise, injury, and degenerative diseases. Satellite cell self-renewal is essential for long-term tissue homeostasis, and previous work has identified a number of external cues that control this process. However, little is known of the possible intrinsic control mechanisms of satellite cell self-renewal. Here, we show that quiescent satellite cells harbor a primary cilium, which is rapidly disassembled upon entry into the cell cycle. Contrasting with a commonly accepted belief, cilia reassembly does not occur uniformly in cells exiting the cell cycle. We found that primary cilia reassemble preferentially in cells committed to self-renew, and disruption of cilia reassembly causes a specific deficit in self-renewing satellite cells. These observations indicate that primary cilia provide an intrinsic cue essential for satellite cell self-renewal. : In this article, Borycki and colleagues investigate the role of primary cilia in skeletal muscle satellite stem cells. They report on the specific association of primary cilia with quiescent and self-renewing satellite cells during adult myogenesis. Blocking cilia reassembly following cell division impairs satellite cell self-renewal, demonstrating that primary cilia are intrinsic cues required for stem cell self-renewal.