Basonuclin as a Cell Marker in the Formation and Cycling of the Murine Hair Follicle

Basonuclin, a zinc-finger protein, was identified as a key marker in the formation and cycling of murine hair follicles. It was primarily located in the cytoplasm of basal keratinocytes in mouse epidermis but concentrated in the nuclei of basal cells during hair follicle development. As hair follicles matured, nuclear basonuclin was found in the basal layers of the outer root sheath and bulbar matrix, areas associated with cell proliferation. During the hair cycle, the presence of nuclear basonuclin varied, regressing during catagen and remaining in small numbers during telogen to form the secondary hair germ. In the subsequent anagen phase, these cells expanded to regenerate the hair-producing portion of the follicle, indicating that the transient segment of the follicle originated from germinative cells with nuclear basonuclin.