Morphogenesis- and Hair Cycle-dependent Expression of Trichohyalin, Peptidylarginine Deiminase Type III and Deiminated Trichohyalin in Rat Dorsal Skin Hair Follicles

The study investigated the expression of trichohyalin (THH), peptidylarginine deiminase type III (PAD type III), and deiminated THH in rat dorsal skin hair follicles during the first and second hair cycles. It was found that THH and PAD type III appeared together in the inner root sheath during the early anagen phase, while deiminated THH appeared later. In the second hair cycle, the hair follicles developed larger, with a thicker cortex and longer follicles compared to the first cycle. THH was present in the inner root sheath and medulla, while deiminated THH was more intensely detected in the inner root sheath and medulla from the middle follicle region to the hair shaft. PAD type III was found in the inner root sheath and medulla cells but not in the outer root sheath. These findings suggested that while THH and PAD type III are initially expressed together, the deimination of THH occurs later, indicating the involvement of an additional factor in this process.