20-HETE activates the Raf/MEK/ERK pathway in renal epithelial cells through an EGFR- and c-Src-dependent mechanism.
20-Hydroxyeicosatetraenoic acid (20-HETE) has been reported to promote mitogenicity in a variety of cell types, including renal epithelial cells. However, the signal transduction pathways activated by 20-HETE have not been fully defined. The present study evaluated the effects of 20-HETE and its more stable agonist analogs 20-hydroxyeicosa-5(Z),14(Z)-dienoic acid (5,14-20-HEDE) and N-[20-hydroxyeicosa-5(Z),14(Z)-dienoyl]glycine (5,14-20-HEDGE) on the Raf/MEK/ERK and phosphatidylinositol 3-kinase (PI3K)-Akt pathway in LLC-PK(1) renal epithelial cells. 20-HETE (20 microM) increased phosphorylation of Raf-1 (2.5 +/- 0.2-fold), MEK1/2 (6.3 +/- 1.6-fold), and ERK1/2 (5.8 +/- 0.3-fold) compared with vehicle-treated cells. Similarly, the 20-HETE analogs also strongly activated ERK1/2 in a Raf-1- and MEK1/2-dependent manner. Moreover, 5,14-20-HEDE increased Akt phosphorylation by 2.2 +/- 0.3-fold. 20-HETE and 5,14-20-HEDE also promoted activation (Y1086) of epidermal growth factor receptor (EGFR; Y1086) by 1.9 +/- 0.2- and 2.5 +/- 0.2-fold, respectively. These effects were completely blocked by the EGFR inhibitor EKB-569 (0.1 microM). Moreover, EKB-569 (0.1 microM), as well as a c-Src inhibitor, SKI-606 (0.05 microM), completely abolished the 20-HETE-mediated activation of the Raf/MEK/ERK and PI3K-Akt pathways. Blockade of PKC with bisindolylmaleimide I had no effect on 20-HETE-induced ERK1/2 activation. This study demonstrated that 20-HETE activated the Raf/MEK/ERK and Akt pathways in renal epithelial cells secondary to the activation of c-Src and EGFR.
Akbulut
Talha
T
Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
Regner
Kevin R
KR
Roman
Richard J
RJ
Avner
Ellis D
ED
Falck
John R
JR
Park
Frank
F
D000818:Animals; D004847:Epithelial Cells / Q000187:drug effects / Q000201:enzymology*; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D006893:Hydroxyeicosatetraenoic Acids / Q000378:metabolism*; D007668:Kidney / Q000187:drug effects / Q000201:enzymology*; D018374:LLC-PK1 Cells; D055666:Lipopeptides / Q000378:metabolism; D048369:MAP Kinase Kinase 1 / Q000378:metabolism; D048370:MAP Kinase Kinase 2 / Q000378:metabolism; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism*; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism*; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects; D013552:Swine; D013997:Time Factors
C494665:20-hydroxyeicosa-5(Z),14(Z)-dienoic acid; D006893:Hydroxyeicosatetraenoic Acids; D055666:Lipopeptides; C533498:N-(20-hydroxyeicosa-5,14-dienoyl)glycine; D047428:Protein Kinase Inhibitors; C055987:20-hydroxy-5,8,11,14-eicosatetraenoic acid; D066246:ErbB Receptors; D016392:Proto-Oncogene Proteins pp60(c-src); D051057:Proto-Oncogene Proteins c-akt; D019908:Proto-Oncogene Proteins c-raf; D048049:Extracellular Signal-Regulated MAP Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; D020929:Mitogen-Activated Protein Kinase Kinases