Pancreatic islet beta-cells and insulin-producing RINm5F cells were electroporated in the presence of the c-Ha-ras oncogene, to assess the possible involvement of the encoded product in coupling extracellular receptors to phospholipase C. After two days the c-Ha-ras-transfected cells increased their expression of c-Ha-ras mRNA. These cells were also found to contain more [3H]InsP3, suggesting an increased basal (non-ligand-activated) phospholipase C activity. In addition, the transfected cells were unable to respond to ligand (bombesin) activation of phospholipase C. The ras-transfected insulin-producing cells showed enhanced phosphorylation of a 200 kDa substrate crossreacting with an antibody to an 80 kDa protein kinase C substrate. The phorbol ester 12-O-tetradecanoyl 13-acetate and bombesin also induced phosphorylation of the 200 kDa substrate. All of these changes occurred without changes in the rates of [3H]thymidine incorporation. The results suggest that the mutated c-Ha-ras oncogene directly or indirectly stimulates the basal phospholipase C activity of these cells.
Transfection of insulin-producing cells with a transforming c-Ha-ras oncogene stimulates phospholipase C activity
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P O Berggren, A Hallberg, N Welsh, P Arkahammar, T Nilsson, M Welsh; Transfection of insulin-producing cells with a transforming c-Ha-ras oncogene stimulates phospholipase C activity. Biochem J 1 May 1989; 259 (3): 701–707. doi: https://doi.org/10.1042/bj2590701
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