The channels that comprise gap junctions, provide a conduit for diffusion of small molecules between neighboring cells. Two hemichannels, or connexons, comprise each gap junction channel; each connexon is composed of six subunits called connexins (Cx). The mammalian genome contains at least fifteen different Connexins, four of which are expressed in the cardiovascular system (Cxs 43, 40, 45 and 37). Gap junctions make coordinated contractile activity of the heart and blood vessels possible by providing a pathway for electrical communication. They also play important roles in growth and development. Cxs 40 and 43 form homomeric/homotypic channels (all connexins in the channel are identical) with very different functional properties. However, Cxs 40 and 43 are rarely expressed in isolation. They are co- expressed at ratios that vary as a function of development (and aging), injury, and disease in ventricular and atrial tissue as well as in vascular endothelium and smooth muscle. Cxs 40 and 43 form functional """"""""mixed"""""""" channels (heteromeric/heterotypic) with unknown properties. The long-term goal of the proposed studies is to determine how Cx40-43 comprised junctions contribute to cardiovascular development, injury and disease.
Our specific aims i nclude the following goals. 1) Determine whether long-term changes in Cx40: Cx43 expression ratio cause predictable changes in junctional permeability and cellular growth properties. 2) Assess whether the magnitude of the acute decrease in junctional conductance induced by PDGF depends on the Cx40: Cx43 ratio and whether junctional permeability decreases concomitantly. 3) Examine the role of Cx43 phosphorylation in these acute effects of PDGF. And 4) determine the time course and underlying mechanisms for recovery from the acute effects of PDGF. Smooth muscle cells induced to express varied Cx40: Cx43 ratios naturally and through genetic manipulation and Rin cells transfected with these genes will serve as model systems for these studies. Gap junction permeability and channel function will be assessed using dual whole cell and perforated patch voltage clamp techniques. Cell proliferation is evaluated using flow cytometry to assess cell cycle behavior of the cells. Connexin expression and distribution are evaluated using 3-D imaging of immumo-stained cells and quantitative Westerns. This powerful combination of approaches offers a unique opportunity to discover how gap junctions contribute to development, injury and disease in the heart and vasculature.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL058732-06
Application #
6537333
Study Section
Special Emphasis Panel (ZRG1-CDF-4 (01))
Program Officer
Rabadan-Diehl, Cristina
Project Start
1997-07-15
Project End
2004-06-30
Budget Start
2002-07-01
Budget End
2003-06-30
Support Year
6
Fiscal Year
2002
Total Cost
$265,125
Indirect Cost
Name
University of Arizona
Department
Physiology
Type
Schools of Medicine
DUNS #
City
Tucson
State
AZ
Country
United States
Zip Code
85721
Ek Vitorín, José F; Pontifex, Tasha K; Burt, Janis M (2016) Determinants of Cx43 Channel Gating and Permeation: The Amino Terminus. Biophys J 110:127-40
Dominguez Rieg, J A; Burt, J M; Ruth, P et al. (2015) P2Y? receptor activation decreases blood pressure via intermediate conductance potassium channels and connexin 37. Acta Physiol (Oxf) 213:628-41
Koval, Michael; Molina, Samuel A; Burt, Janis M (2014) Mix and match: investigating heteromeric and heterotypic gap junction channels in model systems and native tissues. FEBS Lett 588:1193-204
Good, Miranda E; Ek-Vitorín, José F; Burt, Janis M (2014) Structural determinants and proliferative consequences of connexin 37 hemichannel function in insulinoma cells. J Biol Chem 289:30379-86
Lancaster, Jordan J; Juneman, Elizabeth; Arnce, Sarah A et al. (2014) An electrically coupled tissue-engineered cardiomyocyte scaffold improves cardiac function in rats with chronic heart failure. J Heart Lung Transplant 33:438-45
Nelson, Tasha K; Sorgen, Paul L; Burt, Janis M (2013) Carboxy terminus and pore-forming domain properties specific to Cx37 are necessary for Cx37-mediated suppression of insulinoma cell proliferation. Am J Physiol Cell Physiol 305:C1246-56
Fang, Jennifer S; Angelov, Stoyan N; Simon, Alexander M et al. (2013) Compromised regulation of tissue perfusion and arteriogenesis limit, in an AT1R-independent fashion, recovery of ischemic tissue in Cx40(-/-) mice. Am J Physiol Heart Circ Physiol 304:H816-27
Fang, Jennifer S; Dai, Cuiping; Kurjiaka, David T et al. (2013) Connexin45 regulates endothelial-induced mesenchymal cell differentiation toward a mural cell phenotype. Arterioscler Thromb Vasc Biol 33:362-8
Furuta, Glenn T; Kagalwalla, Amir F; Lee, James J et al. (2013) The oesophageal string test: a novel, minimally invasive method measures mucosal inflammation in eosinophilic oesophagitis. Gut 62:1395-405
Ek-Vitorin, Jose F; Burt, Janis M (2013) Structural basis for the selective permeability of channels made of communicating junction proteins. Biochim Biophys Acta 1828:51-68

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