application) The Ang II type 2 (AT2) receptor is expressed in the rat embryonic blood vessel at late gestation (embryonic days 16-21) and in the early neonatal period, but declines to very low levels in the adult. Cell culture studies and in vivo gene transfer experiments suggest that this receptor can inhibit DNA synthesis and induce apoptosis. Pharmacological blockade of the AT2 receptor using the specific antagonist PD123319 during embryonic days 16-21 results in decreased aortic DNA synthesis and subsequently in increased systemic blood pressure when measured at 3-5 weeks of age. Recently, the applicant's group and Inagami's group have obtained, using homologous recombination, AT2 receptor knockout mouse strains which exhibit enhanced pressor response to acute angiotensin infusion as compared to the wild type strain. In preliminary experiments, the applicant has observed that the knockout mouse has higher systemic vascular resistance, especially in response to Ang II infusion, and increased vascular thickening, especially of the small mesenteric arteries. These data have led the applicant to hypothesize that this receptor plays an important role in vascular development in late gestation. This proposal will employ homologous recombination and gene exchange technology to define further the role of the AT2 receptor in vascular remodeling in mouse development. 1) The applicant will characterize the relationship of receptor expression to vascular smooth muscle cell DNA synthesis, vascular smooth muscle cell differentiation and/or apoptosis. The structural influence of AT2 receptor expression will be studied by a systemic analysis of histology and morphometry of the blood vessels in knockout and wild type animals. The physiological consequence will be defined by in vivo hemodynamic and in vitro vascular contractility experiments. To amplify the phenotype, the applicant proposes to examine the effects of in utero Ang II infusion on vascular remodeling and development. 2) The investigators will perform AT1 vs AT2 gene exchange studies by generating recombinant animals using gene replacement technology. Thus, the coding region for the AT2 receptor gene will be replaced by that of the AT1a receptor, with the 5' and 3' flanking regions of the AT2 receptor gene remaining intact. This will enhance AT1 receptor expression at the time when the AT2 receptor would be expressed, and will amplify the AT1 receptor expression without AT2 receptor effect. Conversely, the reverse exchange of AT1 for AT2 will generate animals with """"""""unopposed"""""""" vascular AT2 receptor expression. Further modifications will involve the generation of mutations within the AT1a or AT2 receptors to obtain constitutively active receptors that are signaling in an angiotensin independent manner. Analysis of the effects of the gene exchanges on vascular remodeling and functional (phenotypic) consequences will be performed. Taken together, the above studies should define the role of the AT2 receptor in vascular development.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
1R01HL058516-01
Application #
2372942
Study Section
Experimental Cardiovascular Sciences Study Section (ECS)
Project Start
1997-09-01
Project End
2002-08-31
Budget Start
1997-09-01
Budget End
1998-08-31
Support Year
1
Fiscal Year
1997
Total Cost
Indirect Cost
Name
Brigham and Women's Hospital
Department
Type
DUNS #
071723621
City
Boston
State
MA
Country
United States
Zip Code
02115
Matsushita, Kenichi; Wu, Yaojiong; Pratt, Richard E et al. (2016) Deletion of angiotensin II type 2 receptor accelerates adipogenesis in murine mesenchymal stem cells via Wnt10b/beta-catenin signaling. Lab Invest 96:909-17
Matsushita, Kenichi; Morello, Fulvio; Zhang, Zhiping et al. (2016) Nuclear hormone receptor LXR? inhibits adipocyte differentiation of mesenchymal stem cells with Wnt/beta-catenin signaling. Lab Invest 96:230-8
Matsushita, Kenichi; Morello, Fulvio; Wu, Yaojiong et al. (2010) Mesenchymal stem cells differentiate into renin-producing juxtaglomerular (JG)-like cells under the control of liver X receptor-alpha. J Biol Chem 285:11974-82
Zhang, Zhiping; Dzau, Victor J (2010) Angiotensin II type 1 receptor-associated protein is an endogenous inhibitor of angiotensin II type 1 receptor action in cardiac hypertrophy: role in check and balance. Hypertension 55:1086-7
He, Wei; Zhang, Lunan; Ni, Aiguo et al. (2010) Exogenously administered secreted frizzled related protein 2 (Sfrp2) reduces fibrosis and improves cardiac function in a rat model of myocardial infarction. Proc Natl Acad Sci U S A 107:21110-5
Gnecchi, Massimiliano; He, Huamei; Melo, Luis G et al. (2009) Early beneficial effects of bone marrow-derived mesenchymal stem cells overexpressing Akt on cardiac metabolism after myocardial infarction. Stem Cells 27:971-9
Zhang, Zhongyan; Deb, Arjun; Zhang, Zhiping et al. (2009) Secreted frizzled related protein 2 protects cells from apoptosis by blocking the effect of canonical Wnt3a. J Mol Cell Cardiol 46:370-7
Hirsch, Jan; Hansen, Kirk C; Sapru, Anil et al. (2007) Impact of low and high tidal volumes on the rat alveolar epithelial type II cell proteome. Am J Respir Crit Care Med 175:1006-13
Ip, James E; Wu, Yaojiong; Huang, Jing et al. (2007) Mesenchymal stem cells use integrin beta1 not CXC chemokine receptor 4 for myocardial migration and engraftment. Mol Biol Cell 18:2873-82
Noiseux, Nicolas; Gnecchi, Massimiliano; Lopez-Ilasaca, Marco et al. (2006) Mesenchymal stem cells overexpressing Akt dramatically repair infarcted myocardium and improve cardiac function despite infrequent cellular fusion or differentiation. Mol Ther 14:840-50

Showing the most recent 10 out of 49 publications