Paxbp1 is indispensable for cell cycle re-entry of adult muscle stem cells

Adult muscle stem cells (MuSCs) transit from a quiescent state to a highly proliferative state to support muscle repair. Paxbp1 deletion in MuSCs blocked their cell cycle re-entry and caused subsequent muscle regeneration failures. To understand the underlying molecular mechanisms, we compared the transcriptomes of control and Paxbp1 mutant MuSCs by RNA-seq. Our data confirmed a marked repression of cell cycle machineries in Paxbp1 mutant MuSCs. We also uncovered down-regulation of mutliple metabolic pathways in mutant MuSCs. In summary, our study highlights an essential role of Paxbp1 in MuSCs growth and cell cycle re-entry. 3 pairs of control (Pax7creER:Paxbp1flox/+:R26R-YFP) and Paxbp1-iKO (Pax7creER:Paxbp1flox/flox:R26R-YFP) mice were subjected to lower hindlimb muscle injury by cardiotoxin (CTX). 24 hours post injury, satellite cells were sorted using FACS based on their YFP fluorescence. Total RNAs were then extracted and used for RNA-seq experiments.