Figure 1
From: ΔNp63 transcriptionally regulates ATM to control p53 Serine-15 phosphorylation
The ATM pathway is active in HaCaT cells. (A) Damage-induced p53 Serine-15 is mediated by ATM. HaCat cells were treated with DMSO carrier, 10 μM KU-55933 (ATM inhibitor) or 1 μM NU7441 (DNA-PK inhibitor) for 2 hours, then with 0.5 μM doxorubicin, and cells were harvested after 2hrs, or cells were treated with 20Jm2 UV radiation and harvested after 6hrs. Lysates were blotted for phosphoSerine-15 p53, phosphoSerine-392 p53, total p53 protein and p63, as indicated. (B) ATM inhibition blocks constitutive p53 Serine-15 phosphorylation. Cells were treated with DMSO carrier, 10 μM KU-55933 (ATM inhibitor) or 1 μM NU7441 (DNA-PK inhibitor) for 24 hrs, and lysates were immunoblotted for phosphoSerine-15 p53 and total p53 protein. (C) ATM inhibition blocks constitutive ATM-dependent phosphorylation. Cells were treated with DMSO carrier or 10 μM KU-55933 for 24 hrs, and lysates were immunoblotted for: phosphoSerine-15 p53, phosphoSerine-392 p53, total p53 protein, phosphoThreonine-68 Chk2, total Chk2 protein, phosphoSerine-1891 ATM, and total ATM protein. (D) siRNA-mediated ATM depletion blocks p53 Serine-15 phosphorylation. HaCat cells were treated with control siRNA or siRNA to ATM for 24, 48 or 96hrs, and cell lysates were blotted for ATM, phosphoSerine-15 p53, and total p53 protein.