Inducible Deletion of Epidermal Dicer and Drosha Reveals Multiple Functions for miRNAs in Postnatal Skin

The study investigated the roles of miRNAs in postnatal skin by deleting the miRNA biogenesis enzymes Drosha and Dicer in mouse skin epithelial cells. Deletion during the growth phase (anagen) led to failure in transitioning to the regression phase (catagen), resulting in hair follicle degradation and stem cell loss, while deletion during the resting phase did not affect follicular structure or stem cell maintenance. The study concluded that Drosha and Dicer are crucial for suppressing DNA damage in proliferating follicular matrix cells, facilitating catagen, and maintaining follicular structures and stem cells. Additionally, Dicer deletion led to the upregulation of targets of the miRNA miR-205, indicating their role in preventing matrix cell apoptosis and interfollicular epidermal hyperproliferation.