Angiotensin II signaling to phospholipase D in renal microvascular smooth muscle cells in SHR.
Angiotensin II (Ang II)-induced phospholipase D (PLD) activity is greater in aortic smooth muscle from spontaneously hypertensive rats (SHR) versus normotensive Wistar-Kyoto rats (WKY). Whether and how this signaling pathway is altered in preglomerular microvascular smooth muscle cells (PGSMCs), a cell type that may participate in genetic hypertension, is unknown. The goals of the present study were to determine in SHR and WKY PGSMCs the following: (1) whether Ang II induces PLD activity; (2) whether the effect of Ang II on PLD activity is greater in SHR; (3) which PLD isoform is stimulated by Ang II; (4) what signaling pathway mediates Ang II-induced PLD stimulation; and (5) whether the signaling pathways mediating Ang II-induced PLD activity are different in SHR and WKY. The EC(50) for Ang II-induced PLD stimulation in SHR was 10-fold lower than the EC(50) in WKY, and both were inhibited by L-158,805, an AT(1) antagonist. Inhibitors of phosphoinositol-3-kinase and protein kinase C did not block Ang II-induced PLD activity in SHR and WKY PGSMCs. Catalytically-inactive constructs of PLD2 and RhoA, but not PLD1, ADP ribosylation factor 1 (ARF1), ARF6, or ADP ribosylation factor nucleotide exchange factor (ARNO) blocked Ang II-induced PLD activity in SHR and WKY PGSMCs. Brefeldin A completely blocked Ang II-induced PLD activity in SHR but only slightly reduced Ang II-induced PLD activity in WKY PGSMCs. Therefore, we conclude that in PGSMCs, the effect of Ang II on PLD activity is (1) greater in SHR; (2) mediated by AT(1) receptors signaling to PLD2; (3) transduced primarily by Rho proteins; and (4) inhibited in SHR by brefeldin A.
Department of Pharmacology, University of Pittsburgh, Pittsburgh, PA, USA. btast6@pitt.edu
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Andresen
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Jackson
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Romero
D000803:Angiotensin I / Q000037:antagonists & inhibitors; D000804:Angiotensin II / Q000494:pharmacology*; D057911:Angiotensin Receptor Antagonists; D000818:Animals; D020126:Brefeldin A / Q000494:pharmacology; D002478:Cells, Cultured; D006973:Hypertension / Q000503:physiopathology; D008956:Models, Chemical; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000201:enzymology; D010739:Phospholipase D / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D012077:Renal Artery / Q000187:drug effects* / Q000201:enzymology; D015398:Signal Transduction
D057911:Angiotensin Receptor Antagonists; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D000804:Angiotensin II; D020126:Brefeldin A; D000803:Angiotensin I; D010739:Phospholipase D