Differential Distribution of the Epigenetic Marker 5-hydroxymethylcytosine Occurs in Hair Follicle Stem Cells during Bulge Activation.

BACKGROUND: Hair follicle cycling is dependent upon activation and differentiation of an epithelial subpopulation of cells with stem-like characteristics. These cells express cytokeratin 15 (CK15) and are sequestered within a specialized niche termed the follicular bulge. The pathways that mediate bulge activation are poorly understood, although growing evidence suggests a role for epigenetic events.

METHODS: Here we investigated murine and human hair follicles to determine whether a recently described epigenetic hydroxymethylation marker, 5-hmC, known to mediate cell growth and differentiation, may play a role in bulge activation.

RESULTS: We found the bulge region of murine hair follicles to demonstrate variable 5-hmC distribution within the nuclei of CK15-positive stem cells during early anagen, a pattern that was not associated with resting stem cells of telogen follicles which did not express 5-hmC. Moreover, during phases of early anagen that were induced in an organ culture model, spatial alterations in bulge stem cell 5-hmC reactivity, as assessed by dual labeling, were noted.

CONCLUSIONS: These preliminary findings suggest that 5-hmC may play a dynamic role in bulge activation during anagen growth, and provide a foundation for further experimental inquiry into epigenomic regulation of hair follicle stem cells. This article is protected by copyright. All rights reserved.