Cellular Regulation of ADP-Ribosylation of Proteins. 3. Selective Augmentation of In vitro ADP-Ribosylation of Histone H3 in Murine Thymic Cells after In vivo Emetine Treatment.

摘要

Thymic cells were isolated at intervals of between 0 and 144 h from mice that received one intraperitoneal injection of emetine (33 mg/kg), and thymus weight, incorporation of Cleucine into proteins and Hthymidine into DNA in intact thymic cells, as well as initial rates of protein ADP-ribosylation in permeabilized cells were simultaneously monitored. The effect of emetine as an inhibitor of protein synthesis corresponds to the induction of sequential cellular events, such as cell exit and remigration, by other antimitotic agents and produces an activation of proliferation of cells reentering into this organ. Proliferation, as demonstrated by a large increase in DNA synthesis and entrance into S phase, was kinetically related to an apparent increase in poly(ADP-ribose) polymerase activity in thymic cells and a highly significant in vitro ADP-ribosylation of histone H3. Since no DNA fragmentation occurred in thymic cells, as tested by a fluorometric technique it is probable that a selective activation of poly(ADP-ribose) polymerase may have been induced in cells that undergo differentiation and proliferation while repopulating the thymus. Reprints. (sdw)