Ca2+ channels mediate protein tyrosine kinase activation by endothelin-1.
To investigate the novel interaction between endothelin-1 (ET-1) and cellular protein tyrosine kinases (PTK), we asked whether Ca2+ influx links ET-1 receptors to PTK activation. In glomerular mesangial cells, ET-1 stimulated a biphasic increase in PTK activity in anti-phosphotyrosine immunoprecipitates that temporally correlated with increased tyrosine phosphorylation of cellular proteins. ET-1 increased tyrosine phosphorylation of proteins in the cytosol and in a puncture distribution consistent with focal adhesions. Addition of ionomycin to increase Ca2+ influx stimulated PTK activity, and inhibition of extracellular Ca2+ influx blocked PTK activation by ET-1. ET-1 increased autophosphorylation of pp60c-src, which was mimicked by addition of ionomycin and inhibited by chelation of extracellular Ca2+. In addition, a selective PTK inhibitor blocked induction of c-fos mRNA by ionomycin, suggesting that Ca(2+)-stimulated PTKs contribute to a signaling pathway regulating immediate early gene expression. Taken together, these results demonstrate that ET-1 stimulates nonreceptor PTK activity, including pp60c-src, by activating Ca2+ channels and subsequent influx of extracellular Ca2+.
Simonson
M S
MS
Department of Medicine, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA. mss5@po.cwru.edu
Wang
Y
Y
Herman
W H
WH
D000818:Animals; D016227:Benzoquinones; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000502:physiology*; D019332:Endothelin-1 / Q000494:pharmacology*; D004789:Enzyme Activation; D015759:Ionomycin / Q000494:pharmacology; D047029:Lactams, Macrocyclic; D008297:Male; D010766:Phosphorylation / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics; D011809:Quinones / Q000494:pharmacology; D012333:RNA, Messenger / Q000037:antagonists & inhibitors; D051381:Rats; D017207:Rats, Sprague-Dawley; D017828:Rifabutin / Q000031:analogs & derivatives; D019061:src-Family Kinases / Q000378:metabolism
D016227:Benzoquinones; D015220:Calcium Channels; D019332:Endothelin-1; D047029:Lactams, Macrocyclic; D016760:Proto-Oncogene Proteins c-fos; D011809:Quinones; D012333:RNA, Messenger; D017828:Rifabutin; D015759:Ionomycin; C020754:herbimycin; D011505:Protein-Tyrosine Kinases; D019061:src-Family Kinases; D002118:Calcium