Characterization of Hair Follicles in Hirosaki Hairless Rats with Deletion of Basic Hair Keratin Genes. Enlarged Medulla, Loss of Cuticle and Long Catagen

概要

論文の詳細を見る
The Hirosaki hairless rat （HHR） is a mutant strain spontaneously derived from the Sprague-Dawley rat（SDR） and its inheritance is autosomal recessive. Our recent study has revealed that an 80-kb genomic DNA on 7q36containing basic hair keratin genes, Kb21, Kb23, Kb26 and Krt2-25, is deleted in HHR. To characterize hair follicles inHHR, progression of hair cycle and expression profi les of basic hair keratins were immunohistochemically studied andcompared with those of SDR. The HHR exhibited sparse hairs and their twisted hairs were shorter than SDR hairs.HHR hair follicles entered the catagen phase earlier than SDR and massive destruction of HHR hair follicles andinfi ltration of infl ammatory cells occurred in the catagen phase. In HHR the hair medulla was enlarged and the innerroot sheath was thinned while the hair cortex was formed where Kb25 was expressed. In SDR Kb25 was expressedin the hair matrix and medulla. Electron microscopy indicated loss of the cuticle in HHR. These results suggest thathypotrichosis of HHR is due to the deletion of hair keratin genes and expression of a keratin fusion gene. Thus, HHRseems to be a useful model to examine the role of hair keratins in the hair follicle formation.