Calcium-regulated protein tyrosine phosphorylation is required for endothelin-1 to induce prostaglandin endoperoxide synthase-2 mRNA expression and protein synthesis in mesangial cells.
The role of endothelin (ET)-1-mediated cytosolic calcium ([Ca2+]i) elevation in regulating ET-1-induced prostaglandin endoperoxide synthase, prostaglandin G/H synthase (PGHS)-2 mRNA expression and protein synthesis was investigated in mesangial cells (MC). Ionomycin, a calcium ionophore, and thapsigargin, an inhibitor of calcium ATPase, mimicked the ET-1-stimulated PGHS-2 mRNA and protein induction. Inhibition of [Ca2+]i increases with (2-¿C2-bis-(carboxymethyl)-amino-5 methylphenoxy]methyl¿-6-methoxy-8-bis-(carboxymethyl)-aminoquinoline tetra-(acetoxymethyl)ester (Quin/AM), a calcium chelator, or with the combined presence of [8-(diethylamino)-octyl-3,4,5-trimethoxybenzoate, HCl] (TMB), an inhibitor of intracellular calcium stores release, and ethyleneglycol-bis-(beta-aminoethyl)- N,N,N',N'-tetra-acetic acid (EGTA) suppressed ET-1, as well as ionomycin and thapsigargin-mediated PGHS-2 mRNA and protein formation. Also, the ET-1-, ionomycin-, and thapsigargin-induced PGHS-2 mRNA expression and protein formation was inhibited in MC pretreated with inhibitors of calcium calmodulin kinase. In contrast, these conditions did not inhibit interleukin (IL)-1-induced PGHS-2 mRNA expression and protein synthesis. Pretreatment with tyrosine kinase inhibitors abolished the ET-1-, ionomycin-, thapsigargin-, and IL-1-mediated PGHS-2 mRNA and protein induction. ET-1-, ionomycin-, and thapsigargin- induced protein tyrosine phosphorylation, but not IL-1-induced protein tyrosine phosphorylation, was suppressed by inhibiting either [Ca2+]i elevation or calcium calmodulin kinase activation. It was concluded that elevation of [Ca2+]i and activation of calcium calmodulin kinases are upstream mediators of ET-1-induced PGHS-2 gene expression through activation of non-receptor-linked protein tyrosine kinase in MC.
Coroneos
E J
EJ
Department of Medicine, Houston Veterans Affairs Medical Center, Baylor College of Medicine, USA.
Kester
M
M
Maclouf
J
J
Thomas
P
P
Dunn
M J
MJ
D000634:Aminoquinolines / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism; D019332:Endothelin-1 / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005707:Gallic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D005920:Glomerular Mesangium / Q000187:drug effects / Q000378:metabolism; D015759:Ionomycin / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D010766:Phosphorylation; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis* / Q000235:genetics*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction; D019284:Thapsigargin / Q000494:pharmacology; D014443:Tyrosine / Q000378:metabolism
D000634:Aminoquinolines; D002121:Calcium Channel Blockers; D002614:Chelating Agents; D019332:Endothelin-1; D004791:Enzyme Inhibitors; D007476:Ionophores; D011506:Proteins; D012333:RNA, Messenger; D014443:Tyrosine; D015759:Ionomycin; C006014:8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate; D005707:Gallic Acid; D019284:Thapsigargin; C035738:Quin2-acetoxymethyl ester; D011451:Prostaglandin-Endoperoxide Synthases; D011505:Protein-Tyrosine Kinases; D000252:Calcium-Transporting ATPases; D002118:Calcium