POLY-ADP-RIBOSYLATION OF HISTONE PROTEINS OF HUMAN KIDNEY T1-CELLS IN-VITRO FOLLOWING GAMMA-IRRADIATION

Poly-ADP-ribosylation of cellular proteins is involved with radiation induced damage and its repair. It has been observed that suspension of human kidney T1-cells in vitro attained elevated levels of poly-ADP-r ibosylation due to experimental manipulations necessary for preparatio n of single cell suspension from monolayer cell cultures. These cells in suspension were exposed to various doses of gamma-rays with or with out subsequent repair incubation. The PADPR of histones H3, H1 and H2B increased with increasing dose of radiation and decreased after 90 mi n of repair incubation. Concomitant with these changes, the affinity o f histones to DNA in chromatin reduced immediately after irradiation N ormal affinity was reestablished after post-irradiation repair incubat ion. The results indicate that induction of poly-ADP-ribosylation of h istone proteins by radiation and by manipulations to prepare single ce ll suspension involved different cellular components.