Nuclear polyadenosine diphosphoribosylation during restricted macromolecular synthesis of HeLa cells

Abstract

The relationships of macromolecular synthesis of intact HeLa cells has been correlated with the ability of nuclei to carry out the ADP ribosylation of nuclear proteins. 1. 1. Selective restriction of DNA replication by hydroxyurea and cytosine arabinoside caused an increase in the rate of enzyme activity similar to that observed when DNA synthesis ceased during the asynchronous growth cycle of the cells. 2. 2. Restriction of cellular protein synthesis, by either amino acid deprivation or cycloheximide inhibition did not affect the specific activity of poly(ADP-ribose) polymerase. 3. 3. A significant inhibition of both the rate of poly(ADP-ribose) polymerase and ADP-ribose acceptor activity of nuclei and chromatin was noted when RNA synthesis was inhibited by actinomycin D only in vivo and not in vitro. Response was dose dependent, with a minimum of 1 μg/ml required for inhibition. Inhibition occurred within 30 min indicating the possibility of a labile species of RNA being involved. 4. 4. Inhibition of cellular RNA by cordycepin (3′-deoxyadenosine) also caused inhibition of poly(ADP-ribose) polymerase in purified nuclei. The data further characterize the structural nucleic acid components of chromatin necessary for ADP ribosylation of nuclear proteins.