The Mouse Keratin 6 Isoforms Are Differentially Expressed in the Hair Follicle, Footpad, Tongue, and Activated Epidermis

The study characterized two isoforms of mouse keratin 6 (K6), encoded by separate genes K6a and K6b, which were differentially expressed in various tissues such as the hair follicle, footpad, tongue, and activated epidermis. Both genes were actively transcribed and had distinct regulatory regions, leading to different expression patterns. Transgenic mice were used to analyze these patterns, revealing that K6a was constitutively expressed in all K6-expressing tissues except the tongue, while K6b was expressed only in suprabasal cells. Upon induction with phorbol esters, K6a was expressed in all layers of the treated epidermis, whereas K6b remained restricted to suprabasal cells. This suggested that K6 isoforms had overlapping yet distinct expression profiles.