title: Endothelin downregulates SERCA2 gene and protein expression in adult rat ventricular myocytes: regulation by pertussis toxin-sensitive Gi protein and cAMP.
abstract: Downregulation of the sarcoplasmic reticulum calcium ATPase (SERCA2) is associated with diastolic dysfunction in the failing heart. Elevated plasma endothelin-1 (ET) levels are correlated with congestive heart failure suggesting that ET may play a pathophysiological role. We have investigated the ability of ET to regulate SERCA2 gene expression in isolated adult rat ventricular myocytes. We find that ET enhances net protein synthesis by approximately 40% but significantly downregulates SERCA2 mRNA expression, time dependently, by approximately 30-50%, and the expression of SERCA2 protein by approximately 50%. In myoyctes, ET binds to ET(A) receptor that couples to G(q) and G(i) proteins. Inhibition of G(q)-PLC-induced phosphoinositide (PI) hydrolysis with U73122 (1 muM) or inhibition of G(i) protein with pertussis toxin (PTX) abolishes the ability of ET to downregulate SERCA2 mRNA gene expression. Further investigation suggests that ET coupling to PTX-sensitive G(i) with consequent lowering of cAMP is required for downregulation of SERCA2 mRNA levels. Increasing intracellular cAMP quantity using cAMP-specific PDE inhibitor Ro20-1724 or cAMP analog dibutyryl-cAMP reverses ET-induced downregulation of SERCA2 mRNA levels. The data indicate that, in adult myocytes, ET downregulates SERCA2 mRNA and protein levels, and the effect requires cross-talk between G(q) and PTX-sensitive G(i) pathways.
authors.affiliation: Univ. of California, San Diego, Dept. of Pharmacology, 9500 Gilman Dr., La Jolla, CA 92093-0636, USA. rdandan@ucsd.edu
authors.forename: Randa
authors.initials: R
authors.lastname: Hilal-Dandan
authors.forename: Huaping
authors.initials: H
authors.lastname: He
authors.forename: Jody L
authors.initials: JL
authors.lastname: Martin
authors.forename: Laurence L
authors.initials: LL
authors.lastname: Brunton
authors.forename: Wolfgang H
authors.initials: WH
authors.lastname: Dillmann
mesh_terms: D012368:4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism*; D003563:Cyclic CMP / Q000031:analogs & derivatives / Q000494:pharmacology; D015536:Down-Regulation; D019332:Endothelin-1 / Q000378:metabolism*; D004963:Estrenes / Q000494:pharmacology; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000378:metabolism; D006352:Heart Ventricles / Q000201:enzymology; D008297:Male; D009154:Mutation; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000201:enzymology*; D037342:Pertussis Toxin / Q000494:pharmacology; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D044022:Receptor, Endothelin A / Q000378:metabolism; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D014162:Transfection; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: C506948:Atp2a2 protein, rat; D019332:Endothelin-1; D004963:Estrenes; C522851:Gnai1 protein, rat; D010726:Phosphodiesterase Inhibitors; D011760:Pyrrolidinones; D012333:RNA, Messenger; D044022:Receptor, Endothelin A; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D012368:4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone; D003563:Cyclic CMP; C053441:dibutyryl cyclic-3',5'-cytidine monophosphate; D000242:Cyclic AMP; D037342:Pertussis Toxin; D010738:Type C Phospholipases; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D043802:GTP-Binding Protein alpha Subunits, Gq-G11