Regulation of ion channel function plays a pivotal role in controlling heart rate and contractility via changes in cardiac myocyte excitability. Humoral mediators and receptors are involved in determining channel responses to changing cardiovascular demands. The dynamic beat-to-beat regulation of ion channels is precisely controlled by autonomic stimulation through complex interplay of second messengers, kinases, G-proteins, and protein-protein interactions. The rapidly activating delayed rectifier current (IKr) produced by the HERG gene is uniquely qualified for an integrative transduction of cellular/hormonal signals due to its unusual biophysical properties and the growing number of second-messenger and protein interactions ascribed to the channel. We have begun mapping alpha- and beta-adrenergic signaling pathways to modulation of HERG/IKr. Beta-adrenergic stimulation leads to a complex series of events that includes; direct binding of cAMP to HERG, interactions with AKAPs, PKA-mediated phosphorylation of the channel, and binding of 14-3-3 to HERG. Thus, an evolving picture of adrenergic regulation of HERG is emerging. It will be essential to understand the mechanisms by which acute and chronic stress adaptation leads to arrhythmia and sudden death in both acquired and hereditary cardiac disease. Accordingly, we propose to explore the effects and mechanisms of each of these interactions in a multidisciplinary approach combining protein biochemistry, immunochemistry, and patch clamp electrophysiology on heterologously expressed proteins and endogenous cardiac tissue. Specifically, we aim to: 1. Determine the significance of 14-3-3e and PKA regulation of HERG 2. Examine PKA targeting to HERG channels by AKAPs. 3. Examine PKA-mediated control of trafficking of HERG protein.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL077326-02
Application #
6917859
Study Section
Electrical Signaling, Ion Transport, and Arrhythmias Study Section (ESTA)
Program Officer
Lathrop, David A
Project Start
2004-07-01
Project End
2008-06-30
Budget Start
2005-07-01
Budget End
2006-06-30
Support Year
2
Fiscal Year
2005
Total Cost
$417,500
Indirect Cost
Name
Albert Einstein College of Medicine
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
110521739
City
Bronx
State
NY
Country
United States
Zip Code
10461
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Krishnan, Yamini; Li, Yan; Zheng, Renjian et al. (2012) Mechanisms underlying the protein-kinase mediated regulation of the HERG potassium channel synthesis. Biochim Biophys Acta 1823:1273-84
Krishnan, Yamini; Zheng, Renjian; Walsh, Christine et al. (2012) Partially dominant mutant channel defect corresponding with intermediate LQT2 phenotype. Pacing Clin Electrophysiol 35:3-16
Sroubek, Jakub; McDonald, Thomas V (2011) Protein kinase A activity at the endoplasmic reticulum surface is responsible for augmentation of human ether-a-go-go-related gene product (HERG). J Biol Chem 286:21927-36
Chen, Jian; Chen, Kun; Sroubek, Jakub et al. (2010) Post-transcriptional control of human ether-a-go-go-related gene potassium channel protein by alpha-adrenergic receptor stimulation. Mol Pharmacol 78:186-97
Chen, Jian; Sroubek, Jakub; Krishnan, Yamini et al. (2009) PKA phosphorylation of HERG protein regulates the rate of channel synthesis. Am J Physiol Heart Circ Physiol 296:H1244-54
Li, Yan; Sroubek, Jakub; Krishnan, Yamini et al. (2008) A-kinase anchoring protein targeting of protein kinase A and regulation of HERG channels. J Membr Biol 223:107-16
Li, Yan; Um, Sung Yon; McDonald, Thomas V (2006) Voltage-gated potassium channels: regulation by accessory subunits. Neuroscientist 12:199-210