PolyADP-ribosylation of histone H1 during apoptosis induced by DNA damaging agents in HL 60 cells

Abstract

The biochemical role of polyADP-ribosylation on the internucleosomal DNA fragmentation associated with apoptosis was investigated in HL 60 human premyelocytic leukemia cells. An increase in the activity of poly(ADP-ribose)polymerase preceded DNA fragmentation during the UV-induced apoptotic process. The DNA fragmentation was prevented by inhibitors of poly(ADP-ribose)polymerase, suggesting a requirement of polyADP-ribosylation for DNA fragmentation. There was no significant increase of intracellular $Ca^{2+}$ level and $Ca^{2+}/Mg^{2+}$-dependent nuclease activity during UV-induced apoptosis. Intracellular level of $NAD^+$ did not changed significantly. It was found that UV light and chemotherapeutic drugs including adriamycin, mitomycin C and cisplatin increased polyADP-ribosylation of nuclear proteins, particularly histone H1. A poly(ADP-ribose)polymerase inhibitor, 3-aminobenzamide, prevented both internucleosomal DNA fragmentation and histone H1 polyADP-ribosylation in cells treated with these apoptosis inducers. These results suggest a correlation between the polyADP-ribosylation of histone H1 and internucleosomal DNA fragmentation in the apoptotic processes induced by DNA damaging agents. Our suggestion is further supported by the finding that a xeroderma pigmentosum cell line, GM04312B, which is defective in introducing nicks at the site of DNA damage, failed to induce DNA fragmentation as well as histone H1 polyADP-ribosylation after UV irradiation. To investigate the possible role of histone H1 polyADP-ribosylation, the micrococcal nuclease-susceptibility of chromatin was measured. Nuclease-susceptibility of chromatin was increased during UV-induced apoptosis, and the cotreatment of 3-aminobenzamide reduced both polyADP-ribosylation of histone H1 and nuclease-susceptibility of chromatin. A23187, colchicine and cycloheximide which do not induce DNA damage and PARP activation also provoked apoptosis in HL 60 cells. Apoptotic processes induced by these ag...