title: Angiotensin type 1 receptor is linked to inhibition of nitric oxide production in pulmonary endothelial cells.
abstract: We previously demonstrated that angiotensin II (Ang II) stimulates an increase in nitric oxide synthase (NOS) mRNA levels, eNOS protein expression and NO production via the type 2 (AT2) receptor, whereas signaling via the type 1 (AT1) receptor negatively regulates NO production in bovine pulmonary artery endothelial cells (BPAECs). In the present study, we investigated the components of the AT1 receptor-linked signaling pathway(s) that are involved in the downregulation of eNOS protein expression in BPAECs. Treatment of BPAECs with either AT1 receptor antagonists or an anti-AT1 receptor antibody induced eNOS protein expression. Furthermore, intracellular delivery of GP-Antagonist-2A, an inhibitor of Galphaq proteins, and treatment of BPAECs with U73122, a phosphatidylinositol-phospholipase C (PLC)-specific inhibitor, enhanced eNOS protein expression. Treatment of BPAECs with the cell-permeable calcium chelator, BAPTA/AM, increased eNOS protein expression at 8 h, while increasing intracellular calcium with either thapsigargin or A23187 prevented Ang II-induced eNOS protein expression. Phorbol myristate acetate (PMA), a protein kinase C (PKC) activator, completely prevented Ang II-stimulated eNOS protein expression at 8 h, whereas depletion of PKC by long-term treatment with PMA, induced eNOS protein expression. Treatment of BPAECs with a PKCalpha-specific inhibitor or transfection of BPAECs with an anti-PKCalpha neutralizing antibody stimulated eNOS protein expression. Conversely, rottlerin, a PKCdelta specific isoform inhibitor had no effect on basal or Ang II-stimulated eNOS protein expression. Moreover, treatment of BPAECs with U73122, BAPTA/AM and PKCalpha-specific inhibitors increased NO production at 8 h. In conclusion, Ang II downregulates eNOS protein expression via an AT1 receptor-linked pathway involving Galphaq/PLC/calcium/PKCalpha signaling pathway in BPAECs.
authors.affiliation: Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, NY 10595, USA.
authors.forename: Xiangmin
authors.initials: X
authors.lastname: Zhao
authors.forename: Xinmei
authors.initials: X
authors.lastname: Li
authors.forename: Sandra
authors.initials: S
authors.lastname: Trusa
authors.forename: Susan C
authors.initials: SC
authors.lastname: Olson
mesh_terms: D000804:Angiotensin II; D047228:Angiotensin II Type 1 Receptor Blockers / Q000494:pharmacology*; D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005786:Gene Expression Regulation; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000096:biosynthesis / Q000235:genetics; D052250:Nitric Oxide Synthase Type III / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011651:Pulmonary Artery / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D044140:Receptor, Angiotensin, Type 1 / Q000187:drug effects* / Q000378:metabolism
chemical_list: D047228:Angiotensin II Type 1 Receptor Blockers; D012333:RNA, Messenger; D044140:Receptor, Angiotensin, Type 1; D000804:Angiotensin II; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III