Abstract
To study the mechanism of gene expression during cell proliferation, the effect of insulin as a growth factor on purine metabolism was studied in primary cultued rat hepatocytes. Hepatocytes were prepared by the collagenase perfusion methods of Berry and Friend from seven-week-old male Wistar rats. After the first plating culture for 4 hours, hepatocytes were cultured in Williams E medium without fetal calf serum or insulin for 20 hours. Then insulin was administered. Both the rates of DNA and de nove purine synthesis, assayed respectively by [3H] thymidine and [14C]formate incorporation, increased dose- and time-dependently to the maximum of 260 and 250%, respectively, with the same range of insulin concentrations between 10−7 and 10−5 M at 24 and 8 hours. Insulin at 10−7 M at 8 hours increased the specific activities of amidophosphoribosyltransferase, hypoxanthine guanine phosphoribosyltransferase and adenine phosphoribosyltransferase, respectively, to 180, 130 and 200%, whereas that of xanthine oxydase remained unchanged at 80%. The selective increases in the specific activities of anabolic enzymes of purine metabolic pathway were due to the induction of enzyme proteins shown by increased Vmax and unchanged Km and by the dissappearance of the increases by Actinomycin D or cycloheximide. It is concluded that the proliferative effect of insulin,, associated with the increased rate of purine synthesis, is a result of selective gene expression of anabolic enzymes.
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Yoshikawa, H., Sato, M., Yamaoka, T. et al. 184 PROLIFERATIVE EFFECT OF INSULIN BY SELECTIVE GENE EXPRESSION IN PURINE METABOLISM IN RAT HEPATOCYTES. Pediatr Res 24, 141 (1988). https://doi.org/10.1203/00006450-198807000-00208
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DOI: https://doi.org/10.1203/00006450-198807000-00208