Hairless Up-Regulates Tgf-β2 Expression via Down-Regulation of miR-31 in the Skin of 'Hairpoor' ( Hr Hp) Mice.

Hairless (HR) has been shown to regulate hair follicle (HF) morphogenesis and hair cycling. The Hr mutant hair loss mouse referred to as 'hairpoor' ( Hr Hp) displays overexpression of the HR protein through translational derepression. In this study, we found that 64 miRNAs were differentially expressed between the skin of Hr Hp/ Hr Hp and wild type mice at P7 using miRNA-microarray analysis and miR-31 displayed the most reduced expression in Hr Hp/ Hr Hp skin. In vivo observation and investigation using an in vitro reporter expression system revealed that miR-31 and pri-miR-31 were consistently down-regulated in the HR over-expressed condition. In addition, we found that the transforming growth factor β 2 ( Tgf-β2), a known catagen inducer, is the putative target of miR-31. Furthermore, Tgf-β2 level was also increased in HR over-expressed keratinocyte and Hr Hp/ Hr Hp mice. These study results suggest that HR controls Tgf-β2 expression via regulation of miR-31, thus causing abnormal hair cycle in Hr Hp/ Hr Hp mice. J. Cell. Physiol. 230: 2075-2085, 2015. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]