Expression of E6 and E7 Papillomavirus Oncogenes in the Outer Root Sheath of Hair Follicles Extends the Growth Phase and Bypasses Resting at Telogen

The study investigated the effects of expressing human papillomavirus type 16 E6/E7 oncogenes in the outer root sheath of hair follicles in transgenic mice. These mice exhibited a fur phenotype with lower hair density but faster hair regeneration compared to wild-type mice. The expression of these oncogenes extended the growth phase (anagen) of hair follicles and bypassed the resting phase (telogen), leading to continuous hair follicle cycling. Although the first hair growth cycle appeared normal, the second cycle showed delayed initiation of catagen and insensitivity to telogen resting signals, even with estradiol present. This indicated that E6/E7 expression in the ORS delayed catagen entry and prevented telogen rest, resulting in ongoing hair follicle cycling.