A novel mitogenic signaling pathway of bradykinin in the human colon carcinoma cell line SW-480 involves sequential activation of a Gq/11 protein, phosphatidylinositol 3-kinase beta, and protein kinase Cepsilon.
The signaling routes connecting G protein-coupled receptors to the mitogen-activated protein kinase (MAPK) pathway reveal a high degree of complexity and cell specificity. In the human colon carcinoma cell line SW-480, we detected a mitogenic effect of bradykinin (BK) that is mediated via a pertussis toxin-insensitive G protein of the Gq/11 family and that involves activation of MAPK. Both BK-induced stimulation of DNA synthesis and activation of MAPK in response to BK were abolished by two different inhibitors of phosphatidylinositol 3-kinase (PI3K), wortmannin and LY 294002, as well as by two different inhibitors of protein kinase C (PKC), bisindolylmaleimide and Ro 31-8220. Stimulation of SW-480 cells by BK led to increased formation of PI3K lipid products (phosphatidylinositol 3,4,5-trisphosphate and phosphatidylinositol 3, 4-bisphosphate) and to enhanced translocation of the PKCepsilon isoform from the cytosol to the membrane. Both effects of BK were inhibited by wortmannin, too. Using subtype-specific antibodies, only the PI3K subunits p110beta and p85, but not p110alpha and p110gamma, were detected in SW-480 cells. Finally, p110beta was found to be co-immunoprecipitated with PKCepsilon. Our data suggest that in SW-480 cells, (i) dimeric PI3Kbeta is activated via a Gq/11 protein; (ii) PKCepsilon is a downstream target of PI3Kbeta mediating the mitogenic signal to the MAPK pathway; and (iii) PKCepsilon associates with the p110 subunit of PI3Kbeta. Thus, these results add a novel possibility to the emerging picture of multiple pathways linking G protein-coupled receptors to MAPK.
Graness
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A
Institute of Biochemistry and Biophysics, Biological and Pharmaceutical Faculty, Friedrich Schiller University, Philosophenweg 12, D-07743 Jena, Germany.
Adomeit
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A
Heinze
R
R
Wetzker
R
R
Liebmann
C
C
D001920:Bradykinin / Q000494:pharmacology / Q000502:physiology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002867:Chromones / Q000494:pharmacology; D003110:Colonic Neoplasms; D004273:DNA, Neoplasm / Q000096:biosynthesis; D019281:Dimerization; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D007295:Inositol Phosphates / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism*; D007700:Kinetics; D046911:Macromolecular Substances; D008301:Maleimides / Q000494:pharmacology; D008954:Models, Biological; D009025:Morpholines / Q000494:pharmacology; D037342:Pertussis Toxin; D019869:Phosphatidylinositol 3-Kinases / Q000737:chemistry / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism*; D051744:Protein Kinase C-epsilon; D018002:Receptors, Bradykinin / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D014407:Tumor Cells, Cultured; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D002867:Chromones; D004273:DNA, Neoplasm; D004791:Enzyme Inhibitors; D007211:Indoles; D007295:Inositol Phosphates; D007527:Isoenzymes; D046911:Macromolecular Substances; D008301:Maleimides; D009025:Morpholines; D018002:Receptors, Bradykinin; D010566:Virulence Factors, Bordetella; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D037342:Pertussis Toxin; D019869:Phosphatidylinositol 3-Kinases; C497255:PRKCE protein, human; D011493:Protein Kinase C; D051744:Protein Kinase C-epsilon; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019204:GTP-Binding Proteins; C088060:bisindolylmaleimide; D001920:Bradykinin; C064758:Ro 31-8220