Fig. 1

Linker histone H1.2 attenuates the ATM-dependent DNA damage response. a Immunoblots for H1.2, H1.3 and H1.4 protein levels in wild-type, H1.2, H1.3 or H1.4 KO HeLa cells. 1# and 2# indicate two clones which were generated using different sgRNAs. b Wild-type, H1.2, H1.3 or H1.4 KO (1#) HeLa cells were treated with 40 μM etoposide for 0, 30 and 60 min and analyzed by immunoblotting. c Wild-type and H1.2 KO (1#) HeLa cells were transfected with the indicated plasmids with or without exposure to 10 Gy IR and analyzed by immunoblotting 1 h post IR. d HeLa cells were transfected with GFP-H1.2 and exposed to 10 Gy irradiation (IR) with or without 2 h prior exposure to 2 μM Ku57788. Cells were collected 1 h post IR and subjected to immunofluorescent assay. Cells with >5 γ-H2AX foci were counted. The data represent the mean ± SD. Scale bars, 10 μm. e HeLa cells were transfected with the indicated siRNAs and treated with 40 μM etoposide for 2 h and analyzed by immunoblotting. f A-T cells were transfected with the indicated siRNAs and treated with 40 μM etoposide for 1 h and analyzed by immunoblotting. g, h Wild type and H1.2 KO (1#) HeLa cells were mixed and then treated with 40 μM etoposide for 2 h or left untreated (Ctr) and analyzed by immunofluorescence. The intensity of ATM or phospho-ATM S1981 in the etoposide-treated wild-type cells was normalized to 1. The arrows indicate representative cells. All data represent the mean ± SD. Scale bars, 10 μm