Post-Transcriptional Regulation of Keratinocyte Progenitor Cell Expansion, Differentiation, and Hair Follicle Regression by miR-22

In 2015, researchers studied the role of a microRNA, miR-22, in hair growth and found it to be a critical regulator of the hair cycle. Overexpression of miR-22 led to hair loss by promoting the transition from the growth phase to the regression phase of the hair follicle, while deletion of miR-22 delayed this transition and accelerated hair growth. The study also found that miR-22 overexpression reduced the number of proliferative cells in the hair follicle, inhibited keratinocyte differentiation, and induced apoptosis of hair follicle keratinocytes. Conversely, miR-22 knockout mice had longer hair follicles and delayed entry into the regression phase. The study identified several transcription factors as direct targets of miR-22, suggesting that miR-22 represses these factors to control keratin gene expression and keratinocyte differentiation. The findings suggest that miR-22 could potentially be a target for treating hair loss conditions.