Regulation of Regeneration in Mouse Ear Hair Follicles

The hair follicle is a dynamic mini-organ that regenerates cyclically. The hair cycle consists of growth (anagen), regression (catagen), and rest (telogen). In mice, telogen consists of two sub-phases: competent telogen,in which the regenerative response is induced, and refractory telogen, in which the regenerative response is inhibited. In humans, scalp hair follicles affected by androgenetic alopecia enter an extended phase of telogen and become arrested in a refractory-like state. Currently, no mouse models for androgenetic alopecia exist. Dorsal skin hair follicle that are commonly studied in mice to not experience arrest in refractory telogen and continue to cycle multiple times over the course of animal life span. The objective of this study is to characterize hair cycle regulation in anatomical location on the mouse, other than dorsal skin, and to determine if mouse hair follicles in some locations can serve as a potential model for studying the mechanism of extended androgenetic alopecia-like telogen. Previously, plucking was determined as an efficient method in inducing hair follicle regeneration. Therefore, in this study, we plucked hairs in distinct anatomical locations to establish the presence of regional specificity.  EdU, a (5-ethynyl-2'-deoxyuridine) nucleotide analog that marks actively proliferating cells, was administered to mice before ear collection. EdU staining was used to identify actively regenerating hair follicles. Heat maps of hair follicle growth enabled standardized comparison between experimental groups. Non-stimulated, spontaneous hair follicle regeneration was characterized similarly. In my work I will discuss the result of these comparative hair plucking studies. My future research will aim to determine the signaling basis of regional differences in hair regeneration. Supported by NSF-URM Grant DBI-0731655