Isolation and Characterization of a Novel Hair Follicle-Specific Gene, Hacl-1

In 1994, researchers discovered a new gene, hacl-1, which is specifically expressed in the hair follicles of ICR mice. This gene is unique to the skin and its expression is linked to the active growth phases of hair follicles. The hacl-1 gene is composed of a single exon and encodes a protein with a distinctive structure, featuring six repeats of a decapeptide. It is particularly expressed in the keratogenous zone of the hair shaft's cortical cells, and not in other parts of the hair follicle or the epidermis. The gene's expression pattern suggests it may belong to the intermediate-filaments-associated proteins (IFAP) keratin family, although its amino acid composition was not typical for this family. The specific expression of hacl-1 in hair follicles, especially during periods of active hair growth, indicates its potential importance in hair biology and its possible applications in medical and cosmetic fields for hair growth and regeneration.