Figure 5.
Spironolactone‐induced XPB degradation requires Cdk7 ATPase activity form CAK complex. (a) HCT116-Cdk7as/as cells, harboring homologous ATP analog-sensitive (as) Cdk7 gene, were pretreated with 10 µM 1-NMPP1 or mock-treated for 14 h. The cells were then further treated with 10 µM spironolactone for 2, 4 or 6 h or mock-treated. The XPB levels in cell lysates were detected by Western blotting. The β-Actin blots serves as loading control. (b) the Western blotting images from 3 independent experiments in Figure 5(a) were quantitatively examined by ImageJ. The relative amount of XPB was calculated in comparison to the control without 1-NMPP1 and spironolactone treatment. (c) HeLa cells were pretreated with UV radiation at 50 or 100 J/m2, and allowed to repair DNA photolesions for 1 h. The cells were further treated with spironolactone or mock-treated and harvested at indicated time points. The XPB, XPD and β-Actin levels were detected by Western blotting. (d) the Western blotting images from 4 independent experiments in Figure 5(c) were quantitatively examined by ImageJ. Asterisk symbols * and ** indicate p ≤ 0.05 and in p ≤ 0.01 paired student’s-t-tests, respectively