Single-cell RNA sequencing unveils the activation of EGR1-ATF3 signaling in EGR1 + muscle stem cells during human paravertebral muscle degeneration

Background: Paravertebral muscles (PVM) degeneration (PMD) is closely associated with low back pain. Muscle stem cells (MuSCs) can promote muscle regeneration and repair. However, our understanding of the cellular composition of PVM and the key genes-mediated MuSCs functions is limited. Methods: We analyzed cells heterogeneity and identified key genes using scRNA-seq. To validate the presence of EGR1 + MuSCs, we performed Flow cytometry assays. We utilized pseudo-time, CytoTRACE, and RNA velocity to reconstruct cells differentiation trajectory. CellPhoneDB was used to identify the interactions between MuSCs and other cells. Results: We identified 22 cell clusters and 10 cell types, including MuSCs. We found EGR1 + MuSCs representing the activated subset. We observed the overall number of MuSCs decreased, while the proportion of EGR1 + MuSCs gradually increased during PMD. We demonstrated the target ATF3 of EGR1 and EGR1 were significantly upregulated in PMD, suggesting EGR1-ATF3 signaling may regulate MuSCs functions. Cell differentiation trajectory indicated EGR1 + MuSCs exhibited higher stemness. We discovered immune cells, fibroblasts, and endothelial cells may collaborate with MuSCs through specific ligand-receptor pairs to regulate MuSCs functions. Conclusion: These findings unveils the activation of EGR1-ATF3 signaling in EGR1 + MuSCs, providing new insights into the cellular and molecular mechanisms underlying PMD.