Cell cycle regulation of poly(ADP-ribose) synthetase in FR3T3 cells.
The properties of poly(ADP-ribose) synthetase were studied throughout the cell cycle progression of non-synchronized rat FR3T3 fibroblasts using an immunological and biochemical approach. Cells in the various phases of the cell cycle were sorted from an asynchronously growing population by using flow cytofluorometry. G1, S and G2 + M fractions were used for enzymatic assays in the presence of saturating concentrations of DNAase I for the analysis of total poly(ADP-ribose) synthetase; maximal enzyme activity was found in the G2 + M phase. Purified IgG, specific for the FR3T3 poly(ADP-ribose) synthetase were used for the labelling of endogenous synthetase in order to quantify the enzyme immunologically. Localization of nuclear immunofluorescence was observed and analysis of poly(ADP-ribose) synthetase content throughout the cell cycle were carried out using double fluorescent staining and cytofluorometry. Poly(ADP-ribose) synthetase content as measured immunologically was found to increase from G1 to S and G2 + M phases. Quiescent cells showed a lower content as measured immunologically of poly(ADP-ribose) synthetase than cells in the G1 phase. In exponentially growing cells, the ratio between enzyme activity of poly(ADP-ribose) synthetase over the amount of enzyme measured immunologically was found to be higher in the G2 + M phase. These results show that a cell-cycle specific event activates poly(ADP-ribose) synthetase in the G2 + M phase.
D000818:Animals; D000918:Antibody Specificity; D002453:Cell Cycle; D002460:Cell Line; D005347:Fibroblasts; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D007118:Immunoassay; D007074:Immunoglobulin G / Q000276:immunology; D007399:Interphase; D008938:Mitosis; D011065:Poly(ADP-ribose) Polymerases / Q000276:immunology / Q000378:metabolism*; D051381:Rats
D007074:Immunoglobulin G; D011065:Poly(ADP-ribose) Polymerases