Fig. 5. The GATA4 pathway functions independently of the p53 and p16 pathways and is regulated by the DDR kinases ATM and ATR.

(A) BJ cells expressing either control or p53 shRNAs were treated with Dox for 4 days to induce GATA4 driven by the TRE promoter. Immunoblotting analysis (left) and SA-β-Gal staining (right) were performed. Data are mean ± SEM; cont refers to the control shRNA targeting firefly luciferase. (B) BJ cells expressing either HPV E6 or E6 and E7 were treated with Dox for 3.5 days to induce GATA4 driven by the Tet promoter, and SA-β-Gal staining was performed. Data are mean ± SEM. (C) Abundance of the GATA4 protein was examined in control (−IR) or IR-treated [+IR, 7 days after exposure to IR (12 Gy)] cells expressing either HPV E6 or E6 and E7. (D) Top: BJ and IMR90 cells were treated with 10 mM nutlin-3 for 7 days. Media were refreshed every 2 days. Bottom: p16 driven by the TRE promoter was induced for either 4 or 7 days. Media were refreshed every 2 days. Abundance of the indicated proteins was analyzed by Western blotting. (E) IMR90 cells were pretreated with 10 mM nutlin-3 for 7 days and nutlin-3 was washed out before exposure to IR (12 Gy). Abundance of the indicated protein was analyzed by Western blotting 7 days after IR. (F) IMR90 cells were pretreated with caffeine (ATM and ATR inhibitor, 1 mM) (left) or ATM inhibitor (ku55933, 10 mM), ATR inhibitor (VE-821, 10 mM), or both (right) for 1 hour before exposure to IR (12 Gy). Media were refreshed every 2 days for 7 days, and abundance of the indicated proteins was analyzed by Western blotting. Data are representative of three [(A), (E), (F)] or two [(B), (C), (D)] independent experiments. (G) Model of how GATA4 links autophagy and the DDR to SASP and cellular senescence. See text for details.