Molecular mechanisms for activation of voltage-independent Ca2+ channels by endothelin-1/endothelin-A receptors.
Endothelin-1 (ET-1) activates two types of Ca2+- permeable non-selective cation channels (designated NSCC-1 and NSCC-2) and a store-operated Ca2+ channel (SOCC) in Chinese hamster ovary cells expressing endothelin-A receptors (CHOETAR), which couple with Gq, Gs and G12. The purpose of this study was to identify the G proteins involved in the activation of these Ca channels, using mutated ETARs with coupling to either Gq or Gs/G12 (designated ETAR(Delta)385 and SerETAR, respectively) and a dominant negative mutant of G12 (G12G228A). ETAR(Delta)385 is truncated downstream of Cys385 in the C-terminal as palmitoylation sites, whereas SerET(A)R is unpalmitoylated because of substitution of all the cysteine residues to serine (CysCys --> SerSer). ET-1 activated SOCC in CHO-ET(A)R(Delta)385. In CHO-SerET(A)R or CHO-ET(A)R pretreated with U73122, an inhibitor of phospholipase C, ET-1 activated NSCC-1. ET-1 activated SOCC in CHO-ETAR microinjected with G12G228A. Moreover, ET-1 activated NSCC-1 in CHO-ETAR treated with LY 294002, the phosphoinositide 3-kinase inhibitor. These results indicate that NSCC-1 is activated via a G12-dependent pathway, NSCC-2 via Gq/phospholipase C-dependent and G12-dependent pathways, and SOCC via a Gq-phospholipase C-dependent pathway. In addition, NSCC-2 and SOCC are stimulated by ET-1 via a phosphoinositide 3-kinase-dependent cascade, whereas NSCC-1 is stimulated via a phosphoinositide 3-kinase-independent cascade.
Kawanabe
Yoshifumi
Y
Department of Neurosurgery and Pharmacology, Kyoto University Graduate School of Medicine, Kyoto, Japan. kawanabe@takatsuki.jrc.or.jp
Okamoto
Yasuo
Y
Hashimoto
Nobuo
N
Masaki
Tomoh
T
D000818:Animals; D016466:CHO Cells; D015220:Calcium Channels / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D002867:Chromones / Q000494:pharmacology; D006224:Cricetinae; D003412:Cricetulus; D019332:Endothelin-1 / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004963:Estrenes / Q000494:pharmacology; D044365:GTP-Binding Protein alpha Subunits, G12-G13 / Q000235:genetics / Q000378:metabolism*; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000235:genetics / Q000378:metabolism*; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000235:genetics / Q000378:metabolism*; D009025:Morpholines / Q000494:pharmacology; D009154:Mutation; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011760:Pyrrolidinones / Q000494:pharmacology; D044022:Receptor, Endothelin A / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism
D015220:Calcium Channels; D002867:Chromones; D019332:Endothelin-1; D004791:Enzyme Inhibitors; D004963:Estrenes; D044365:GTP-Binding Protein alpha Subunits, G12-G13; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D019205:GTP-Binding Protein alpha Subunits, Gs; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011760:Pyrrolidinones; D044022:Receptor, Endothelin A; D010738:Type C Phospholipases; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one