Early events in thymocyte activation. II. Changes in nonhistone chromatin proteins induced by a thymus-dependent human serum factor.
Previously, it has been shown that a human thymus-dependent serum factor (SF), isolated from peripheral blood and acting on precursors of mature T lymphocytes, induces an increase in the synthesis of cyclic AMP and proteins in thymocytes. We have now investigated the action of SF on the incorporation of 3H-leucine and 32P-orthophosphate into nuclear proteins of thymocytes after 15 to 240 min of culture. SF induced a rapid increase in the synthesis and phosphorylation of nuclear proteins, especially in the phosphorylated nonhistone chromatin proteins (P-NHCP). Electrophoretic patterns in polyacrylamide gels of the P-NHCP fractions, extracted from the chromatin of the stimulated cells, showed that proteins with m.w. higher than 50 x 10(3) were synthesized to a larger extent as compared with unstimulated cells. These data suggest that SF acts specifically on the synthesis of P-NHCP and may in this way control DNA-template activity.
D002868:Chromosomal Proteins, Non-Histone; D000242:Cyclic AMP / Q000096:biosynthesis; D006801:Humans; D007930:Leucine / Q000378:metabolism; D008213:Lymphocyte Activation; D010761:Phosphorus Radioisotopes; D011506:Proteins / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D013935:Thymic Factor, Circulating / Q000494:pharmacology*; D013951:Thymus Hormones / Q000494:pharmacology*; D013997:Time Factors
D002868:Chromosomal Proteins, Non-Histone; D010761:Phosphorus Radioisotopes; D011506:Proteins; D013951:Thymus Hormones; D013935:Thymic Factor, Circulating; D000242:Cyclic AMP; D007930:Leucine