Our recent work demonstrates that several vascular smooth muscle (VSM) integrins are capable of acutely regulating the tone of resistance blood vessels. The activation of two VSM integrins, alpha v beta 3 and alpha 5 beta 1,produces transient constriction, followed by sustained dilation, of arterioles. Patch clamp methods show that L-type Ca 2+ current in arteriolar myocytes is regulated by both integrins. The signaling pathway through alpha 5 beta 1 integrin involves phosphorylation of the pore-forming alpha channel subunit by pp60c-Src. Potentiation of Ca 2+ current is consistent with alpha 5 beta 1-mediated vasoconstriction but does not explain the sustained vasodilation. However, the vasodilation is blocked by IC channel antagonists, and large-conductance, Ca+ - activated K+ (BK) current in arteriolar myocytes is potentiated by alpha 5 beta 1 ligands, suggesting a specific role for the BK channel. We also find that cloned BK channels expressed in HEK cells are potentiated by integrin activation in the absence of intracellular Ca 2+ changes. The central hypothesis of this proposal is that BK current in arteriolar myocytes is potentiated by alpha 5 beta 1 integrin ligands through a signaling pathway that involves phosphorylation of the channel alpha subunit by an integrin-linked tyrosine kinase. To test this hypothesis, we propose three aims, utilizing a combination of methods involving isolated arterioles, electrophysiology and molecular biology: A) to determine how arteriolar diameter and native arteriolar smooth muscle BK channels are acutely regulated by alpha 5 beta 1 integrin; B) to define the mechanism by which VSM BK current is potentiated by alpha 5 beta 1 integrin; C) to elucidate the tyrosine kinase(s) involved in potentiation of BK current by alpha 5 beta 1 integrin. The results will provide a more complete picture of a previously unappreciated signaling mechanism whereby the extracellular matrix (ECM) can regulate microvascular tone and organ blood flow. These studies will have wide-ranging implications for vascular ion channel regulation in both normal and disease states. For example, it is known that vascular function is compromised subsequent to changes in ECM composition and integrin expression in pathological conditions where vascular remodeling occurs, such as hypertension, atherosclerosis and restenosis. In addition, our results will establish a paradigm for understanding how other ion channels in other tissues may be regulated by integrins.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL071796-04
Application #
7120559
Study Section
Cardiovascular and Renal Study Section (CVB)
Program Officer
Goldman, Stephen
Project Start
2003-08-01
Project End
2008-06-30
Budget Start
2006-07-01
Budget End
2008-06-30
Support Year
4
Fiscal Year
2006
Total Cost
$317,011
Indirect Cost
Name
University of Missouri-Columbia
Department
Pharmacology
Type
Schools of Medicine
DUNS #
153890272
City
Columbia
State
MO
Country
United States
Zip Code
65211
Chao, Jun-Tzu; Gui, Peichun; Zamponi, Gerald W et al. (2011) Spatial association of the Cav1.2 calcium channel with ýý5ýý1-integrin. Am J Physiol Cell Physiol 300:C477-89
Yang, Yan; Wu, Xin; Gui, Peichun et al. (2010) Alpha5beta1 integrin engagement increases large conductance, Ca2+-activated K+ channel current and Ca2+ sensitivity through c-src-mediated channel phosphorylation. J Biol Chem 285:131-41
Zuidema, Mozow Y; Yang, Yan; Wang, Meifang et al. (2010) Antecedent hydrogen sulfide elicits an anti-inflammatory phenotype in postischemic murine small intestine: role of BK channels. Am J Physiol Heart Circ Physiol 299:H1554-67
Davis, Michael J; Lane, Megan M; Scallan, Joshua P et al. (2007) An automated method to control preload by compensation for stress relaxation in spontaneously contracting, isometric rat mesenteric lymphatics. Microcirculation 14:603-12
Guo, Hong; Humphrey, Jay D; Davis, Michael J (2007) Effects of biaxial stretch on arteriolar function in vitro. Am J Physiol Heart Circ Physiol 292:H2378-86
Davis, Michael J; Zawieja, David C; Gashev, Anatoliy A (2006) Automated measurement of diameter and contraction waves of cannulated lymphatic microvessels. Lymphat Res Biol 4:3-10
Qamirani, Erion; Razavi, Habib M; Wu, Xin et al. (2006) Sodium azide dilates coronary arterioles via activation of inward rectifier K+ channels and Na+-K+-ATPase. Am J Physiol Heart Circ Physiol 290:H1617-23
Davis, Michael J (2005) An improved, computer-based method to automatically track internal and external diameter of isolated microvessels. Microcirculation 12:361-72