Coordinated Inhibition of SOX9 and Cell Cycle Progression by MicroRNA-200 Restricts Sebaceous Gland Fate Specification

The study investigates the role of the microRNA-200 family (miR-200s) in normal epithelial development, particularly in hair follicles. It finds that miR-200s are abundant in hair matrix progenitors but absent in the upper hair follicle, where sebaceous gland (SG) and hair follicle stem cells are specified. Elevated miR-200 expression in this region prevents SG fate specification while allowing hair morphogenesis. The study reveals that miR-200s regulate negative regulators of WNT signaling and cell cycle regulators, disrupting the expression patterns of WNT activity and SOX9, which is crucial for SG development. The research highlights miR-200's role in inhibiting SOX9-dependent lipid metabolism and cell cycle progression, blocking SG specification and revealing a SOX9 regulatory network essential for SG development.