Mechanical Tension Mobilizes Lgr6+ Epidermal Stem Cells to Drive Skin Growth (I)

Uniquely among mammalian organs, skin is capable of dramatic size change in adults, yet the mechanisms underlying this striking capacity are unclear. Here, we utilize a system of controlled tissue expansion in mice to uncover cellular and molecular determinants of skin growth. Through machine learning-guided three-dimensional tissue reconstruction, we capture morphometric changes in growing skin. We find that most growth is driven by the proliferation of the epidermis in response to mechanical tension, with more limited changes in dermal and subdermal compartments. Epidermal growth is achieved through preferential activation and differentiation of not Lgr5+, but instead Lgr6+ stem cells of the interfollicular epidermis, driven in part by the Hippo pathway. By single-cell RNA sequencing, we uncover further changes in mechanosensitive and metabolic pathways underlying growth control in the skin. These studies point to therapeutic strategies to enhance skin growth and establish a platform for understanding organ size dynamics in adult mammals. scRNA profiles of 8- week-old expander-implanted male mice. The ones with expansion induced as E, and the ones are not induced as NE(ctrl).