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.

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