Fig. 5.
Expression of E6 inhibits phosphorylation of ATM and ATR. a Representative immunoblots (n = 3) showing that HPV5 and HPV8 E6 inhibit ATR as well as Chk1 phosphorylation measured 24 h following UVB irradiation or 4 h of camptothecin treatment. Normal phosphorylation patterns are restored through mutation of HPV5-E6 at K138. Total levels of ATR and Chk1 were unaffected by E6 expression. b Expression of HPV8-E6 in organotypic cultures delays DNA repair and DNA damage sensing. Cultures expressing HPV8-E6 or pLXSN empty vector grown in parallel were irradiated with 20 mJ/cm2 UVB 24 hours prior to fixation. Representative immunohistochemical staining (n = 3) experiments showing phosphorylation of ATM and ATR in control cells and lack of phosphorylation in HPV8-E6 expressing cells, which correlates with the presence of un-repaired T∧T