title: Role of prolylcarboxypeptidase in angiotensin II type 2 receptor-mediated bradykinin release in mouse coronary artery endothelial cells.
abstract: Activation of angiotensin II type 2 receptors (AT(2)R) causes the release of kinins, which have beneficial effects on the cardiovascular system. However, it is not clear how AT(2)R interact with the kallikrein-kinin system to generate kinins. Prolylcarboxypeptidase is an endothelial membrane-bound plasma prekallikrein activator that converts plasma prekallikrein to kallikrein, leading to generation of bradykinin from high-molecular-weight kininogen. We hypothesized that AT(2)R-induced bradykinin release is at least in part mediated by activation of prolylcarboxypeptidase. Cultures of mouse coronary artery endothelial cells were transfected with an adenoviral vector containing the AT(2)R gene (Ad-AT(2)R) or green fluorescent protein only (Ad-GFP) as control. We found that overexpression of AT(2)R increased prolylcarboxypeptidase mRNA by 1.7-fold and protein 2.5-fold compared with Ad-GFP controls. AT(2)R overexpression had no effect on angiotensin II type 1 receptor mRNA. Bradykinin release was increased 2.2-fold in AT(2)R-transfected cells. Activation of AT(2)R by CGP42112A, a specific AT(2)R agonist, increased bradykinin further in AT(2)R-transfected cells. These effects were diminished or abolished by AT(2)R blockade or a plasma kallikrein inhibitor. Furthermore, blocking prolylcarboxypeptidase with a small interfering RNA partially but significantly reduced bradykinin release by transfected AT(2)R cells either at the basal condition or when stimulated by the AT(2)R agonist CGP42112A. These findings suggest that overexpression of AT(2)R in mouse coronary artery endothelial cells increases expression of prolylcarboxypeptidase, which may contribute to kinin release.
authors.affiliation: Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, 2799 West Grand Blvd, Detroit, MI 48202-2689, USA.
authors.forename: Liping
authors.initials: L
authors.lastname: Zhu
authors.forename: Oscar A
authors.initials: OA
authors.lastname: Carretero
authors.forename: Tang-Dong
authors.initials: TD
authors.lastname: Liao
authors.forename: Pamela
authors.initials: P
authors.lastname: Harding
authors.forename: Hongwei
authors.initials: H
authors.lastname: Li
authors.forename: Colin
authors.initials: C
authors.lastname: Sumners
authors.forename: Xiao-Ping
authors.initials: XP
authors.lastname: Yang
mesh_terms: D000818:Animals; D015153:Blotting, Western; D001920:Bradykinin / Q000378:metabolism*; D002268:Carboxypeptidases / Q000378:metabolism*; D002478:Cells, Cultured; D003331:Coronary Vessels / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D018014:Gene Transfer Techniques; D007124:Immunoenzyme Techniques; D016234:Kallikrein-Kinin System / Q000502:physiology; D007610:Kallikreins / Q000378:metabolism; D008297:Male; D051379:Mice; D034741:RNA, Small Interfering; D044139:Receptor, Angiotensin, Type 2 / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D034741:RNA, Small Interfering; D044139:Receptor, Angiotensin, Type 2; D002268:Carboxypeptidases; C022448:lysosomal Pro-X carboxypeptidase; D007610:Kallikreins; D001920:Bradykinin