A role for protein kinase C-epsilon in angiotensin II stimulation of phospholipase D in rat renal mesangial cells.
The role of Ca2+ and protein kinase C (PKC) in the regulation of phosphatidylcholine-hydrolyzing phospholipase D (PLD) was investigated in angiotensin II-stimulated mesangial cells. Elevation of cytosolic free Ca2+ by the calcium ionophore, A23187, or the Ca(2+)-ATPase inhibitor, thapsigargin, slightly increased PLD-stimulated phosphatidylethanol formation. However, chelation of cytosolic Ca2+ with high concentrations of quin 2 did not attenuate angiotensin II-induced phosphatidylethanol production, thus suggesting that Ca2+ is not crucially involved in agonist-stimulated PLD activation. Stimulation of PKC by phorbol esters increased PLD activity in mesangial cells. Down-regulation of PKC-alpha and -delta isoenzymes by 8 h phorbol ester treatment still resulted in full PLD activation. In contrast, a 24 h treatment of mesangial cells with phorbol ester, a regimen that also causes depletion of PKC-epsilon, abolished angiotensin II-evoked phosphatidylethanol formation. In addition, the selective PKC inhibitor, calphostin C, attenuated hormone-induced PLD activity. In summary, these data suggest that angiotensin II stimulation of phospholipase D appears to involve the PKC-epsilon isoenzyme, activated by DAG derived from phosphoinositide hydrolysis.
Department of Pharmacology, University of Basel, Switzerland.
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Huwiler
D000804:Angiotensin II / Q000502:physiology*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004789:Enzyme Activation; D005920:Glomerular Mesangium / Q000201:enzymology*; D020404:Glycerophospholipids; D066298:In Vitro Techniques; D010712:Phosphatidic Acids / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism; D010739:Phospholipase D / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D051381:Rats
D020404:Glycerophospholipids; D010712:Phosphatidic Acids; D010716:Phosphatidylinositols; C051521:phosphatidylethanol; D000804:Angiotensin II; D011493:Protein Kinase C; D010739:Phospholipase D; D002118:Calcium