Multiomics profiling of young and old quiescent skeletal muscle stem cells [aging WGBS]

To uncover new pathways that are important for skeletal muscle stem cell aging, we performed multiomics profiling, including transcriptomics, DNA methylomics, proteomics, and metabolomics on quiescent muscle stem cells from young and old mice. Our goals were to discover pathways that have been overlooked by isolated profiling approaches and to gain insight into which changes are causal, compensatory, correlational, and consequential. In our work, we found that glutathione metabolism is a key pathway of muscle stem cell aging that involves a compensatory feedback loop. Follow-up experiments showed that old muscle stem cells actually form a dichotomy between glutathione-high muscle stem cells and glutathione-low muscle stem cells. RNA-Seq showed that glutathione-high old muscle stem cells are able to synthesize adequate glutathione and thus compensate adequately for oxidative stress with increased glutathione turnover, while glutathione-low old muscle stem cells have failed to compensate for oxidative stress metabolically and instead show increased inflammatory signaling. C57BL/6 male mice were used at two ages: young (4 months) and old (22 months). Quiescent muscle stem cells were isolated from limb muscles by FACS (CD45- CD31- Sca1- VCAM+) and immediately used for analysis. Each replicate represents the muscle stem cells from a single animal. There are 4 replicates in each group.