Brief Report: Requirement of TACE/ADAM17 for Hair Follicle Bulge Niche Establishment

The study investigated the role of TACE/ADAM17 in hair follicle (HF) stem cell niche establishment using a mouse model with conditional depletion of TACE in SOX9-expressing cells. Mice lacking TACE (Tace/Sox9) exhibited brittle hair, prolonged anagen phase, and progressive hair loss, culminating in complete hair loss by 20 weeks. These mice showed a lack of CD34(+) bulge cells, downregulation of key transcription factors (Sox9, Lhx2, Gata3), and upregulation of Lef1, indicating a failure to establish the bulge niche and maintain HF stem cell "stemness." Additionally, impaired EGFR signaling in Tace/Sox9 keratinocytes suggested that EGFR is a downstream pathway of TACE in HF homeostasis. The findings provided insights into the mechanistic implications of TACE deficiency and hair abnormalities associated with EGFR inhibitors.