On the mechanism of action of free purine bases on DNA synthesis in serum-starved L-cells treated with platelet extract.
It has previously been found that there is a synergistic effect of free purine bases and low concentrations of dialyzed platelet extract on net synthesis of DNA in serum-starved fibroblast-like mouse L-cells. Experiments with a mutant line of L-cells that was deficient in hypoxanthine phosphoribosyl transferase (EC 2.4.2.8) indicated that purine bases had a stimulatory effect only if they were incorporated into cellular ribonucleotides. In the present paper it was shown that platelet extract induced the incorporation of hypoxanthine or adenine into both ATP and DNA. The induced net synthesis of DNA appears to take place in the nuclei and it requires that platelet extract is present in the medium only initially while free purine bases have to be present only later in the period of the experiment when DNA is being synthesized. The induction of both incorporation of free purine bases into DNA and ATP and of net DNA synthesis is dependent on heat-labile components in platelet extract. The extract cannot be substituted for by platelet derived growth factor.
D000225:Adenine / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001769:Blood; D001792:Blood Platelets / Q000032:analysis*; D002457:Cell Extracts / Q000494:pharmacology*; D002460:Cell Line; D003470:Culture Media; D004247:DNA / Q000378:metabolism; D004261:DNA Replication / Q000187:drug effects*; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism*; D005434:Flow Cytometry; D006358:Hot Temperature; D019271:Hypoxanthine; D007041:Hypoxanthine Phosphoribosyltransferase / Q000172:deficiency; D007042:Hypoxanthines / Q000378:metabolism; D051379:Mice; D011687:Purines / Q000494:pharmacology*; D014020:Tissue Extracts / Q000494:pharmacology*
D002457:Cell Extracts; D003470:Culture Media; D007042:Hypoxanthines; D011687:Purines; D014020:Tissue Extracts; D019271:Hypoxanthine; D000255:Adenosine Triphosphate; D004247:DNA; D007041:Hypoxanthine Phosphoribosyltransferase; D000225:Adenine