The influx of Ca through L-type Ca channels in surface membrane of cardiomyocytes regulates a variety of cellular processes including contraction, secretion, cell signaling, and gene expression. The long-term goals of this research are 1) to discriminate between distinct populations of L-type Ca channels in cardiomyocytes based on the unique macromolecular complex of associated proteins;2) to determine how these different populations of channels specifically contribute to various Ca-regulated cellular processes;and 3) to understand how alterations in the different populations of Ca channels contribute to cardiovascular disease. These goals will be approached initially focusing on Cav1.2 L-type Ca channels localized to the specialized membrane microdomains known as caveolae which are defined by the signature protein caveolin-3 (Cav-3). The contribution of Cav1.2 channels to the genesis of the long QT syndrome associated with recently identified mutations in Cav-3 will be defined. Using immunoprecipitation techniques, GST-Cav-3 pull-down, immunoconfocal microscopy, immunogold electron microscopy, siRNA knockdown of targeted proteins, heterologous expression of Cav1.2 channels and key associate proteins, and conditional knockout of Cav-3 in mice, we will address three specific aims: 1) Define the relative abundance and composition of the Cav1.2 channels localized to caveolae in ventricular myocytes;2) Determine if Cav-3 and associated core scaffolding proteins are essential for normal basal L-type Ca current and its (?-AR regulation in ventricular myocytes;3) Determine the impact of long QT-related Cav-3 genetic mutations on Cav1.2 L- type Ca channels. Relevance: These studies will provide molecular definition of the subpopulation of Ca channel proteins localized to caveolae and thus offer mechanistic insights into the genesis of the long QT syndrome and life-threatening arrhythmias associated with mutations in the signature protein of caveolae in the heart, caveolin-3. Furthermore, this research will impact our understanding of heart failure and atrial fibrillation given that alterations in caveolae and Ca channels have been detected in these diseases. Ultimately, a molecular understanding of caveolae and L-type Ca2+ channels has the potential to inspire new therapies for these prevalent cardiovascular diseases.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL078878-04
Application #
7822940
Study Section
Electrical Signaling, Ion Transport, and Arrhythmias Study Section (ESTA)
Program Officer
Przywara, Dennis
Project Start
2007-06-01
Project End
2012-05-31
Budget Start
2010-06-01
Budget End
2012-05-31
Support Year
4
Fiscal Year
2010
Total Cost
$363,740
Indirect Cost
Name
University of Wisconsin Madison
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
161202122
City
Madison
State
WI
Country
United States
Zip Code
53715
Cadet, Jean Scotty; Kamp, Timothy J (2017) A Recipe for T-Tubules in Human iPS Cell-Derived Cardiomyocytes. Circ Res 121:1294-1295
Vaidyanathan, Ravi; Markandeya, Yogananda S; Kamp, Timothy J et al. (2016) IK1-enhanced human-induced pluripotent stem cell-derived cardiomyocytes: an improved cardiomyocyte model to investigate inherited arrhythmia syndromes. Am J Physiol Heart Circ Physiol 310:H1611-21
Schilling, Jan M; Horikawa, Yousuke T; Zemljic-Harpf, Alice E et al. (2016) Electrophysiology and metabolism of caveolin-3-overexpressing mice. Basic Res Cardiol 111:28
Kamp, Timothy J; January, Craig T (2015) Harry A. Fozzard, MD: 1931–2014. Circ Res 116:552-3
Markandeya, Yogananda S; Kamp, Timothy J (2015) Rational strategy to stop arrhythmias: Early afterdepolarizations and L-type Ca2+ current. J Gen Physiol 145:475-9
Bhattacharya, Dipankar; Mehle, Andrew; Kamp, Timothy J et al. (2015) Intramolecular ex vivo Fluorescence Resonance Energy Transfer (FRET) of Dihydropyridine Receptor (DHPR) ?1a Subunit Reveals Conformational Change Induced by RYR1 in Mouse Skeletal Myotubes. PLoS One 10:e0131399
Gao, Ge; Xie, An; Zhang, Jianhua et al. (2013) Unfolded protein response regulates cardiac sodium current in systolic human heart failure. Circ Arrhythm Electrophysiol 6:1018-24
Cheng, Jianding; Valdivia, Carmen R; Vaidyanathan, Ravi et al. (2013) Caveolin-3 suppresses late sodium current by inhibiting nNOS-dependent S-nitrosylation of SCN5A. J Mol Cell Cardiol 61:102-10
Boczek, Nicole J; Best, Jabe M; Tester, David J et al. (2013) Exome sequencing and systems biology converge to identify novel mutations in the L-type calcium channel, CACNA1C, linked to autosomal dominant long QT syndrome. Circ Cardiovasc Genet 6:279-89
Best, Jabe M; Kamp, Timothy J (2012) Different subcellular populations of L-type Ca2+ channels exhibit unique regulation and functional roles in cardiomyocytes. J Mol Cell Cardiol 52:376-87

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