Kollu, SwapnaAbou-Khalil, RanaShen, CarlBrack, Andrew S.2015-07-132015Kollu, Swapna, Rana Abou-Khalil, Carl Shen, and Andrew S. Brack. 2015. “The Spindle Assembly Checkpoint Safeguards Genomic Integrity of Skeletal Muscle Satellite Cells.” Stem Cell Reports 4 (6): 1061-1074. doi:10.1016/j.stemcr.2015.04.006. http://dx.doi.org/10.1016/j.stemcr.2015.04.006.2213-6711http://nrs.harvard.edu/urn-3:HUL.InstRepos:17295625Summary To ensure accurate genomic segregation, cells evolved the spindle assembly checkpoint (SAC), whose role in adult stem cells remains unknown. Inducible perturbation of a SAC kinase, Mps1, and its downstream effector, Mad2, in skeletal muscle stem cells shows the SAC to be critical for normal muscle growth, repair, and self-renewal of the stem cell pool. SAC-deficient muscle stem cells arrest in G1 phase of the cell cycle with elevated aneuploidy, resisting differentiation even under inductive conditions. p21CIP1 is responsible for these SAC-deficient phenotypes. Despite aneuploidy’s correlation with aging, we find that aged proliferating muscle stem cells display robust SAC activity without elevated aneuploidy. Thus, muscle stem cells have a two-step mechanism to safeguard their genomic integrity. The SAC prevents chromosome missegregation and, if it fails, p21CIP1-dependent G1 arrest limits cellular propagation and tissue integration. These mechanisms ensure that muscle stem cells with compromised genomes do not contribute to tissue homeostasis.en-USJournal Article2015-07-1310.1016/j.stemcr.2015.04.006