Transcriptional profiles of skeletal muscle stem cells from mice of different ages, exercise status, and Ccnd1 genotypes

Voluntary exercise enhances old skeletal muscle stem cell (MuSC) function in vivo and ex vivo, dependent on upregulation of Ccnd1. To determine the transcriptional changes associated with these phenotypes, RNA-Seq was performed on MuSCs from young and old mice that had exercised or not exercised, and from young mice with MuSC-specific loss-of-function deletions in zero, one, or both alleles of Ccnd1. To study the effects of exercise on MuSCs, 3-month-old (Y) or 18-month-old (O) C57BL6 male mice were given access to a running wheel that was locked (-Ex) or free (+Ex) for three weeks, and hindlimb MuSCs were FACS-isolated as CD31-, CD45-, Sca1-, VCAM+, and viable (DAPI-) cells. To study the effects of Ccnd1 loss in MuSCs, 3-month-old or 18-month-old C57BL6 Pax7_CreERT2; R26R_YFP; Ccnd1_+/+ (WT), Ccnd1_+/flox (HET), or Ccnd1_flox/flox (KO) mice were injected with tamoxifen to induce recombination in MuSCs, which were FACS-isolated six weeks later as YFP+, viable (DAPI-) cells. PolyA-selected RNA libraries were constructed and sequenced on a HiSeq2000, generating paired-end 101-bp reads. Each replicate represents MuSCs from an individual mouse. Y(-Ex) = young, no exercise; O(-Ex) = old, no exercise; Y(+Ex) = young, exercise; O(+Ex) = old, exercise; Y(WT) = young, Pax7_CreERT2; R26R_YFP; Ccnd1_+/+; Y(HET) = young, Pax7_CreERT2; R26R_YFP; Ccnd1_+/flox; Y(KO) = young, Pax7_CreERT2; R26R_YFP; Ccnd1_flox/flox; O(WT) = old, Pax7_CreERT2; R26R_YFP; Ccnd1_+/+.