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 (ORS) of hair follicles in transgenic mice. It was found that these oncogenes extended the growth phase (anagen) of hair follicles and bypassed the resting phase (telogen), leading to continuous hair follicle cycling. Although the initial hair growth cycle appeared normal, subsequent cycles showed delayed initiation of the regression phase (catagen) and an absence of the resting phase, even when exposed to estradiol, a known telogen signal. This resulted in a fur phenotype with lower hair density but faster hair regeneration compared to wild-type mice.