title: Bradykinin-induced p42/p44 MAPK phosphorylation and cell proliferation via Src, EGF receptors, and PI3-K/Akt in vascular smooth muscle cells.
abstract: In our previous study, bradykinin (BK) exerts its mitogenic effect through Ras/Raf/MEK/MAPK pathway in vascular smooth muscle cells (VSMCs). In addition to this pathway, the non-receptor tyrosine kinases (Src), EGF receptor (EGFR), and phosphatidylinositol 3-kinase (PI3-K) have been implicated in linking a variety of G-protein coupled receptors to MAPK cascades. Here, we investigated whether these different mechanisms participating in BK-induced activation of p42/p44 MAPK and cell proliferation in VSMCs. We initially observed that BK- and EGF-dependent activation of Src, EGFR, Akt, and p42/p44 MAPK and [3H]thymidine incorporation were mediated by Src and EGFR, because the Src inhibitor PP1 and EGFR kinase inhibitor AG1478 abrogated BK- and EGF-dependent effects. Inhibition of PI3-K by LY294002 attenuated BK-induced Akt and p42/p44 MAPK phosphorylation and [3H]thymidine incorporation, but had no effect on EGFR phosphorylation, suggesting that EGFR may be an upstream component of PI3-K/Akt and MAPK in these responses. This hypothesis was supported by the tranfection with dominant negative plasmids of p85 and Akt which significantly attenuated BK-induced Akt and p42/p44 MAPK phosphorylation. Pretreatment with U0126 (a MEK1/2 inhibitor) attenuated the p42/p44 MAPK phosphorylation and [3H]thymidine incorporation stimulated by BK, but had no effect on Akt activation. Moreover, BK-induced transactivation of EGFR and cell proliferation was blocked by matrix metalloproteinase inhibitor GM6001. These results suggest that, in VSMCs, the mechanism of BK-stimulated activation of p42/p44 MAPK and cell proliferation was mediated, at least in part, through activation of Src family kinases, EGFR transactivation, and PI3-K/Akt.
authors.affiliation: Department of Physiology and Pharmacology, Chang Gung University, Kwei-San, Tao-Yuan, Taiwan. chuenmao@mail.cgu.edu.tw
authors.forename: Chuen-Mao
authors.initials: CM
authors.lastname: Yang
authors.forename: Meng-I
authors.initials: MI
authors.lastname: Lin
authors.forename: Hsi-Lung
authors.initials: HL
authors.lastname: Hsieh
authors.forename: Chi-Chin
authors.initials: CC
authors.lastname: Sun
authors.forename: Yunn-Hwa
authors.initials: YH
authors.lastname: Ma
authors.forename: Li-Der
authors.initials: LD
authors.lastname: Hsiao
mesh_terms: D000818:Animals; D001920:Bradykinin / Q000494:pharmacology*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066246:ErbB Receptors / Q000187:drug effects / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000187:drug effects / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000187:drug effects / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D009154:Mutation / Q000502:physiology; D019869:Phosphatidylinositol 3-Kinases / Q000187:drug effects / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D019061:src-Family Kinases / Q000187:drug effects / Q000378:metabolism*
chemical_list: D001920:Bradykinin; D004791:Enzyme Inhibitors; D066246:ErbB Receptors; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D019061:src-Family Kinases; C494920:Akt1 protein, rat