Involvement of epithelial Wntless in the regulation of postnatal hair follicle morphogenesis.

The roles of the Wnt cargo receptor Wntless (Wls) during hair follicle (HF) induction and postnatal HF cycling in skin have been elucidated. However, whether Wls regulates postnatal HF morphogenesis remains unclear. In this study, we found that Wls is expressed in developing HF during the morphogenesis stage after birth. By knocking out Wls in mouse skin epithelia with hypomorphic K14-cre, we found that Wls is required for normal HF morphogenesis. Wls-deficient HFs prematurely regressed, which was possibly caused by abnormally activated TGF-β/JNK pathway. Although Wls was reported to be a direct target of the Wnt/β-catenin pathway, we found that epithelial β-catenin was not necessary to maintain Wls expression. Therefore, other signals are involved in regulating Wls transcription in mouse skin.