title: Caveolin-3 regulates protein kinase A modulation of the Ca(V)3.2 (alpha1H) T-type Ca2+ channels.
abstract: Voltage-gated T-type Ca(2+) channel Ca(v)3.2 (α(1H)) subunit, responsible for T-type Ca(2+) current, is expressed in different tissues and participates in Ca(2+) entry, hormonal secretion, pacemaker activity, and arrhythmia. The precise subcellular localization and regulation of Ca(v)3.2 channels in native cells is unknown. Caveolae containing scaffolding protein caveolin-3 (Cav-3) localize many ion channels, signaling proteins and provide temporal and spatial regulation of intracellular Ca(2+) in different cells. We examined the localization and regulation of the Ca(v)3.2 channels in cardiomyocytes. Immunogold labeling and electron microscopy analysis demonstrated co-localization of the Ca(v)3.2 channel and Cav-3 relative to caveolae in ventricular myocytes. Co-immunoprecipitation from neonatal ventricular myocytes or transiently transfected HEK293 cells demonstrated that Ca(v)3.1 and Ca(v)3.2 channels co-immunoprecipitate with Cav-3. GST pulldown analysis confirmed that the N terminus region of Cav-3 closely interacts with Ca(v)3.2 channels. Whole cell patch clamp analysis demonstrated that co-expression of Cav-3 significantly decreased the peak Ca(v)3.2 current density in HEK293 cells, whereas co-expression of Cav-3 did not alter peak Ca(v)3.1 current density. In neonatal mouse ventricular myocytes, overexpression of Cav-3 inhibited the peak T-type calcium current (I(Ca,T)) and adenovirus (AdCa(v)3.2)-mediated increase in peak Ca(v)3.2 current, but did not affect the L-type current. The protein kinase A-dependent stimulation of I(Ca,T) by 8-Br-cAMP (membrane permeable cAMP analog) was abolished by siRNA directed against Cav-3. Our findings on functional modulation of the Ca(v)3.2 channels by Cav-3 is important for understanding the compartmentalized regulation of Ca(2+) signaling during normal and pathological processes.
authors.affiliation: Department of Medicine, Cellular and Molecular Arrhythmia Research Program, University of Wisconsin, Madison, Wisconsin 53706, USA.
authors.forename: Yogananda S
authors.initials: YS
authors.lastname: Markandeya
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Fahey
authors.forename: Florentina
authors.initials: F
authors.lastname: Pluteanu
authors.forename: Leanne L
authors.initials: LL
authors.lastname: Cribbs
authors.forename: Ravi C
authors.initials: RC
authors.lastname: Balijepalli
mesh_terms: D000256:Adenoviridae; D000818:Animals; D002118:Calcium / Q000378:metabolism; D020747:Calcium Channels, T-Type / Q000235:genetics / Q000378:metabolism*; D051244:Caveolin 3 / Q000235:genetics / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006352:Heart Ventricles / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D051379:Mice; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism*; D014161:Transduction, Genetic
chemical_list: C479952:CACNA1H protein, human; C417736:CAV3 protein, human; C504883:Cacna1h protein, mouse; D020747:Calcium Channels, T-Type; C495548:Cav3 protein, mouse; D051244:Caveolin 3; D017868:Cyclic AMP-Dependent Protein Kinases; D002118:Calcium