715 Hunting the hair cycle clock (HCC): Evidence that mitochondrially localized MPZL3 is a key HCC element in murine and human hair follicles

Abstract

Hair follicles (HFs) undergo cycles of growth (anagen), regression (catagen) and relative quiescence (telogen), whose timing and velocity are controlled by the “hair cycle clock (HCC)”, an intrinsic and autonomous oscillator system whose molecular nature remains to be elucidated. In this study, we have further explored the hypothesis that Myelin Protein Zero-like 3 (MPZL3), a nuclear-encoded protein localized to the mitochondria, is a key element of the HCC. We have previously shown that a) MPZL3 is expressed in the secondary hair germ, a known epicenter of murine hair cycle regulation, and b) Mpzl3 global knockout mice display strikingly accelerated HF cycling, i.e., a precocious telogen-anagen transition during the second hair cycle, suggesting that MPZL3 functions as a molecular brake on anagen entry.