Calcium-dependent inactivation (CDI) of voltage-gated L-type Ca2+ channels is of fundamental importance in cardiac physiology. It is a major determinant of the action potential duration and thus an essential regulator of excitation-contraction coupling. Disturbed in heart failure, abnormal CDI may be a trigger for arrhythmogenesis. CDI is also a pre-eminent example of feedback inhibition, in which the very Ca2+ that permeates the channel triggers accelerated channel inactivation. This proposal aims to identify the molecular mechanisms underlying CDI by focusing on the molecular components that have recently been identified: 1) the Ca2-sensor is calmodulin (CaM), constitutively bound to the channel's pore-forming subunit alpha 1c; 2) the CDI effector in alpha 1c is the """"""""IQ motif', a CaM binding site in the alpha 1c C-terminal tail; and 3) an EF-hand motif in the C-terminal tail serves an essential structural role.This proposal contains three specific aims:
Aim 1) Determine the structural role of CaM in the regulation of inactivation Aim 2) Determine the structural role of the IQ motif in the regulation of inactivation and Aim 3) Define the role of the EF-hand(s) in CDI. The first two Aims will identify the molecular roles of CaM and the IQ motif, essential in both Ca2+-dependent and Ca2+-independent inactivation.
The third Aim proposes novel hypotheses regarding the role of the controversial EF-hand motif within alpha 1c. We have identified a second EF-hand, and show preliminary results indicating that the two EF-hands form a structural pair, similar to a single lobe of CaM. Our preliminary data allow us to propose a model that incorporates how CaM, the IQ motif, and the EF-hand pair function in regulating inactivation. These novel hypotheses promise to significantly alter the current model of CDI and also provide a template for the understanding of voltage-gated channel inactivation. This work will augment our understanding of normal cardiac function and how these processes are perturbed under pathophysiological states, such as heart failure and arrhythmogenesis.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL071165-05
Application #
7095988
Study Section
Cardiovascular and Renal Study Section (CVB)
Program Officer
Wang, Lan-Hsiang
Project Start
2002-08-20
Project End
2008-03-14
Budget Start
2006-08-01
Budget End
2008-03-14
Support Year
5
Fiscal Year
2006
Total Cost
$319,316
Indirect Cost
Name
Columbia University (N.Y.)
Department
Pharmacology
Type
Schools of Medicine
DUNS #
621889815
City
New York
State
NY
Country
United States
Zip Code
10032
Wei, Eric Q; Sinden, Daniel S; Mao, Lan et al. (2017) Inducible Fgf13 ablation enhances caveolae-mediated cardioprotection during cardiac pressure overload. Proc Natl Acad Sci U S A 114:E4010-E4019
Wang, Xiangchong; Tang, He; Wei, Eric Q et al. (2017) Conditional knockout of Fgf13 in murine hearts increases arrhythmia susceptibility and reveals novel ion channel modulatory roles. J Mol Cell Cardiol 104:63-74
Cao, Chike; Ren, Yinshi; Barnett, Adam S et al. (2017) Increased Ca2+ signaling through CaV1.2 promotes bone formation and prevents estrogen deficiency-induced bone loss. JCI Insight 2:
Wang, Hong-Gang; Zhu, Wandi; Kanter, Ronald J et al. (2016) A novel NaV1.5 voltage sensor mutation associated with severe atrial and ventricular arrhythmias. J Mol Cell Cardiol 92:52-62
Pablo, Juan L; Pitt, Geoffrey S (2016) Fibroblast Growth Factor Homologous Factors: New Roles in Neuronal Health and Disease. Neuroscientist 22:19-25
Yang, Jing; Wang, Zhihua; Sinden, Daniel S et al. (2016) FGF13 modulates the gating properties of the cardiac sodium channel Nav1.5 in an isoform-specific manner. Channels (Austin) 10:410-420
Matsui, Maiko; Pitt, Geoffrey S (2016) Genetic variants and disease: correlate or cause? Eur Heart J 37:1476-8
Zhang, Hengtao; Sun, Albert Y; Kim, Jong J et al. (2015) STIM1-Ca2+ signaling modulates automaticity of the mouse sinoatrial node. Proc Natl Acad Sci U S A 112:E5618-27
Betzenhauser, Matthew J; Pitt, Geoffrey S; Antzelevitch, Charles (2015) Calcium Channel Mutations in Cardiac Arrhythmia Syndromes. Curr Mol Pharmacol 8:133-42
Andersen, Nicholas D; Ramachandran, Kapil V; Bao, Michelle M et al. (2015) Calcium signaling regulates ventricular hypertrophy during development independent of contraction or blood flow. J Mol Cell Cardiol 80:1-9

Showing the most recent 10 out of 53 publications