Atypical Protein Kinase C Isoform, aPKCλ, Is Essential for Maintaining Hair Follicle Stem Cell Quiescence

June 2015 in “ Journal of Investigative Dermatology ”

Shin‐Ichi Osada, Naoko Minematsu, Fumino Oda, Kazunori Akimoto, Seiji Kawana, Shigeo Ohno

atypical protein kinase C lambda aPKCλ hair follicle stem cell HFSC hair cycling quiescence-inducing factors Fgf18 Bmp6 Lrig1 hyperplasia anagen phase bulge stem cells

Studysummary This study observed that epidermal-specific deletion of aPKCλ in mice disrupts hair follicle stem cell quiescence, leading to altered hair follicle cycling and skin anomalies. Our plain-language summary of this paper — not a Tressless recommendation.

The study demonstrated that the atypical protein kinase C isoform, aPKCλ, was essential for maintaining hair follicle stem cell (HFSC) quiescence and proper hair cycling. In mice with epidermal-specific deletion of aPKCλ, there was abnormal hair follicle cycling, progressive hair loss, and altered epidermal differentiation. This was due to decreased expression of quiescence-inducing factors Fgf18 and Bmp6, leading to dysregulated HFSC marker expression and increased Lrig1-positive cells, causing hyperplasia and prolonged anagen-like phases. The persistent activation of bulge stem cells gradually depleted HFSC reservoirs, highlighting the critical role of aPKCλ in regulating signaling pathways for HFSC quiescence.

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