The long-long objectives of our research project are to understand the molecular basis for heterogeneity in K channel function in normal heart, and the mechanisms for alterations in K channel function in diseased heart. In normal heart, the pattern of K channel heterogeneity helps maintain the cardiac electrical stability. Perturbations of such normal heterogeneity will likely predispose the heart to arrhythmias. Such situation occurs in hypertrophied/failing hearts where alterations in K channel function contribute to a dispersion of repolarization, setting the stage for reentrant arrhythmias. To design effective therapies for these pathological conditions, it is important to know, at the molecular level, what causes such a normal pattern of K channel distribution and how it is perturbed in diseased heart. The focus of this proposal is the transient outward (Ito), slow delayed rectifier (IKs) and rapid delayed rectifier (IKr) currents, the three major repolarizing K currents in cardiac myocytes. We will use dog as our animal model, and compare K channel function in normal hearts and in hearts with chronic myocardial infarction where various remodeling processes have occurred. We will apply the techniques of electrophysiology, molecular biology, immunoblotting and immunocytochemistry to examine channel function and subunit expression. The strategy is to use an iterative process between experiments on native channels in cardiac myocytes and experiments on channel clones expressed in in vitro systems to establish a correlation between subunit composition and channel function.
Four Specific Aims are proposed. Under the first 3 Aims, we will study why the current density and gating kinetics of Ito, IKs and IKr, respectively, are heterogeneous in normal heart. The information, as well as the tools (K channel subunit cDNAs and antibodies) we develop during these Aims, will be applied under Aim 4 to examine the molecular basis for K channel remodeling in postinfarction heart. Results from these experiments will provide new insights into molecular physiology and pathology of cardiac K channels, which will aid the design of therapeutic interventions for arrhythmias in postinfarction remodeled hearts.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
1R01HL067840-01
Application #
6361367
Study Section
Cardiovascular and Pulmonary Research A Study Section (CVA)
Program Officer
Spooner, Peter
Project Start
2001-09-01
Project End
2005-08-31
Budget Start
2001-09-01
Budget End
2002-08-31
Support Year
1
Fiscal Year
2001
Total Cost
$326,250
Indirect Cost
Name
Virginia Commonwealth University
Department
Physiology
Type
Schools of Medicine
DUNS #
City
Richmond
State
VA
Country
United States
Zip Code
23298
Wang, Yuhong; Zhang, Mei; Xu, Yu et al. (2012) Probing the structural basis for differential KCNQ1 modulation by KCNE1 and KCNE2. J Gen Physiol 140:653-69
Zhang, Mei; Wang, Yuhong; Jiang, Min et al. (2012) KCNE2 protein is more abundant in ventricles than in atria and can accelerate hERG protein degradation in a phosphorylation-dependent manner. Am J Physiol Heart Circ Physiol 302:H910-22
Wang, Yu Hong; Jiang, Min; Xu, Xu Lin et al. (2011) Gating-related molecular motions in the extracellular domain of the IKs channel: implications for IKs channelopathy. J Membr Biol 239:137-56
Lundby, Alicia; Tseng, Gea-Ny; Schmitt, Nicole (2010) Structural basis for K(V)7.1-KCNE(x) interactions in the I(Ks) channel complex. Heart Rhythm 7:708-13
Xu, Xulin; Jiang, Min; Wang, Yuhong et al. (2010) Long-term fish oil supplementation induces cardiac electrical remodeling by changing channel protein expression in the rabbit model. PLoS One 5:e10140
Tseng, Gea-Ny (2010) Can biologic pacemakers respond to physiologic emotional arousal? Heart Rhythm 7:1841-2
Xu, Xulin; Jiang, Min; Hsu, Kai-Ling et al. (2008) KCNQ1 and KCNE1 in the IKs channel complex make state-dependent contacts in their extracellular domains. J Gen Physiol 131:589-603
Xu, Xulin; Recanatini, Maurizio; Roberti, Marinella et al. (2008) Probing the binding sites and mechanisms of action of two human ether-a-go-go-related gene channel activators, 1,3-bis-(2-hydroxy-5-trifluoromethyl-phenyl)-urea (NS1643) and 2-[2-(3,4-dichloro-phenyl)-2,3-dihydro-1H-isoindol-5-ylamino]-nicotinic acid (PD3 Mol Pharmacol 73:1709-21
Tseng, Gea-Ny; Sonawane, Kailas D; Korolkova, Yuliya V et al. (2007) Probing the outer mouth structure of the HERG channel with peptide toxin footprinting and molecular modeling. Biophys J 92:3524-40
Liu, Xian-Sheng; Zhang, Mei; Jiang, Min et al. (2007) Probing the interaction between KCNE2 and KCNQ1 in their transmembrane regions. J Membr Biol 216:117-27

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