Inducible deletion of Dicer or Drosha reveals multiple functions for miRNAs in postnatal epidermis and hair follicles

The study investigated the role of miRNAs in adult skin by inducing the deletion of Dicer and Drosha, key enzymes in miRNA biogenesis, in mice. The deletion resulted in shared phenotypes, indicating their primary function was miRNA-related. While neither enzyme was necessary for maintaining resting hair follicles, both were crucial during specific phases of hair follicle growth, including the viability of the transient amplifying population, normal hair shaft formation, and initiation of hair follicle regression. Prolonged loss led to follicular degradation, epidermal thickening, and dermal inflammation, suggesting miRNAs also played roles in hair follicle maintenance and epidermal homeostasis. The study highlighted the importance of miRNAs in hair follicle growth and regeneration, with miR-205 deregulation potentially contributing to observed phenotypes.