PMID: 7526918Jul 1, 1994Paper

Growth factor-regulated phosphatidylinositol-3-kinase in astrocytes. Involvement of pp60c-src

Cellular and Molecular Biology
M PomeranceM Pierre

Abstract

Growth factors differently regulate astroglial cell differentiation and proliferation. In an effort to understand the early intracellular events promoted by growth factors in astroglial cells, we have determined the effects of IGF1, insulin, PDGF, EGF and FGFs on phosphatidylinositol-3 kinase. IGF1, PDGF and EGF which stimulate cell proliferation of astroglial cells, increased phosphatidylinositol-3 kinase activity immunoprecipitated with anti-phosphotyrosine antibodies as shown by thin layer chromatography and high performance liquid chromatography. FGFa and FGFb, which strongly stimulate proliferation of astroglial cells, have no effect on phosphatidylinositol-3 kinase activity. Addition of 1 nM PDGF, 10 nM IGF1 or 100 nM EGF to the culture medium rapidly stimulated phosphatidylinositol-3 kinase activity which declined slowly after 2 min. The stimulation of phosphatidylinositol-3 kinase increased with growth factor concentration. The maximum increase in phosphatidylinositol-3 kinase activity occurred with 50 nM IGF1, 1 nM PDGF or 100 nM EGF. Since insulin was active only at high concentration (1 microM), its effect was probably mediated through IGF1 receptors and not through insulin receptors. Treatment with IGF1-plus-EGF, ha...Continue Reading

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