Activation of protein kinase C by phorbol esters induces DNA synthesis and protein phosphorylations in glomerular mesangial cells

FEBS Letters

Darbon, Jean-Marie¹  Issandou, Marc¹ 

[1] INSERM U133, Facultè de Médecine, 133 route de Narbonne, 31062 Toulouse, France

关键词: Phorbol ester;    DNA synthesis;    Protein kinase C;    Protein phosphorylation;    Mesangial cell;    TPA;    12-o-tetradecanoylphorbol 13-acetate;    PDBu;    phorbol 12;    13-dibutyrate;    PKC;    protein kinase C;    SDS-PAGE;    sodium dodecyl sulfate-polyacrylamide gel electrophoresis;    EGF;    epidermal growth factor;    PBS;    phosphate-buffered saline;   

DOI  :  10.1016/0014-5793(91)80392-G

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The tumor-promoting phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA) is shown to be mitogenic for quiescent glomerular mesangial cells cultured in serum-free conditions. TPA induces DNA synthesis measured by PH thymidine incorporation in a dose-dependent manner with an ED₁₀ of 7 ng/ml and an optimal response for 50 ng/ml. The phorbol ester action is potentiated by insulin with an increase of the maximal effect from 232 ± 15% of TPA alone to 393 ± 96% for TPA plus insulin. Down-regulation of protein kinase C by prolonged exposure to TPA completely abolishes the mitogenic effect of the phorbol ester. Using a highly resolutive 2D electrophoresis, we have shown that TPA is able to stimulate the phosphorylation of 2 major proteins of M ₁ 80000, pI 4.5 (termed 80K) and M ₁ 28000, pI 5.7–5.9 (termed 28K). The 80K protein phosphorylation is time- and dose-dependent with an ED₁₀ of 8 ng/ml TPA. Exposure or mesangial cells to heat-shock induces synthesis of a 28K protein among a set of other proteins suggesting that the 28K protein kinase C substrate belongs to the family of low molecular mass stress proteins. Mitogenic concentrations of TPA and phorbol 12,13-dibutyrate inhibit [¹²⁵I]epidermal growth factor binding and stimulate the 80K protein phosphorylation with the same order of potency. The inactive tumor-promoter 4x-phorbol was found to be ineffective both on these 2 parameters and on DNA synthesis. These results suggest a positive role of protein kinase C on mesangial cell proliferation and indicate the existence in this cell line of 2 major protein kinase C substrates.

【 授权许可】

Unknown