mTORC1 regulates the proliferation of SOX9+ porcine skin-derived stem cells (pSDSCs) by promoting S6K phosphorylation.

Skin-derived stem cells (SDSCs) are a subtype of adult stem cells (ASCs) that are widely harvested and exempt from ethical restrictions in clinical applications. These cells possess capabilities for self-renewal, proliferation, and multi-lineage differentiation. Compared to model animals like rats and mice, pigs exhibit greater physiological similarity to humans. Porcine skin has very similar histological and physiological characteristics to human skin. Therefore, porcine skin is becoming increasingly significant as an in vitro model for research. In this study, porcine skin-derived stem cells (pSDSCs) were isolated and cultured in vitro for experiments. The expression of stemness-related gene SOX9 was detected. RNA sequencing (RNA-seq) results found that the mammalian target of rapamycin (mTOR) signaling pathway was significantly enriched in SOX9⁺ pSDSCs. To investigate the role of the mTOR signaling pathway, we added rapamycin (RAPA), an inhibitor of the mTOR complex 1 (mTORC1), and found that the proliferation rate of SOX9⁺ pSDSCs decreased significantly during culture. In addition, western blotting (WB) results demonstrated that mTORC1 promoted proliferation by phosphorylating S6 kinase (S6K) and then activating cyclin D1(CCND1) in SOX9⁺ pSDSCs. These findings provide insights into the mechanisms of adult stem cell proliferation.