Research Paper Volume 9, Issue 11 pp 2411—2435

TNFα-senescence initiates a STAT-dependent positive feedback loop, leading to a sustained interferon signature, DNA damage, and cytokine secretion

Figure 4. Prolonged activation of JAK/ STAT signaling in TNFα-induced senescence. (A) Immunoblot detection of p-Ser727-STAT1 and total STAT1 in cells exposed to TNFα 20ng/ml for the indicated times. (B) SA-β-gal activity in TNFα (20ng/ml)-treated or control cells for 3 or 6 days. (C) Immunoblot detection of p-Ser727-STAT1, total STAT1, p-Tyr705-STAT3, and total STAT3 in cells exposed to TNFα (5ng/ml) for the indicated intervals. (D) Immunoblot detection of pSTAT1, total STAT1, pSTAT3, and total STAT3 in cells stimulated with IL6 (10ng/ml) or IFNγ (1ng/ml) for the indicated intervals. (E) Secretion of IFNγ/IL6 quantified by ELISA in conditioned medium collected in the presence or absence of TNFα. (F) Immunoblot detection of p-Ser727-STAT1, p-Tyr705-STAT3, STAT1, and STAT3 in cells treated with conditioned medium (CM) (cell free-culture supernatants from control and cells stimulated with TNFα for 3 days transferred after 1:4 dilution with fresh culture medium) from TNFα-induced senescent cells or from non-senescent cells for the indicated times