Journal article
Localization of cardiac L-type Ca2+ channels to a caveolar macromolecular signaling complex is required for β2-adrenergic regulation
Proceedings of the National Academy of Sciences - PNAS, Vol.103(19), pp.7500-7505
From the Cover
05/09/2006
DOI: 10.1073/pnas.0503465103
PMCID: PMC1564282
PMID: 16648270
Abstract
L-type Ca2+ channels play a critical role in regulating Ca2+-dependent signaling in cardiac myocytes, including excitation-contraction coupling; however, the subcellular localization of cardiac L-type Ca2+ channels and their regulation are incompletely understood. Caveolae are specialized microdomains of the plasmalemma rich in signaling molecules and supported by the structural protein caveolin-3 in muscle. Here we demonstrate that a subpopulation of L-type Ca2+ channels is localized to caveolae in ventricular myocytes as part of a macromolecular signaling complex necessary for β2-adrenergic receptor (AR) regulation of ICa,L. Immunofluorescence studies of isolated ventricular myocytes using confocal microscopy detected extensive colocalization of caveolin-3 and the major pore-forming subunit of the L-type Ca channel (Cav1.2). Immunogold electron microscopy revealed that these proteins colocalize in caveolae. Immunoprecipitation from ventricular myocytes using anti-Cav1.2 or anti-caveolin-3 followed by Western blot analysis showed that caveolin-3, Cav1.2, β2-AR (not β1-AR), G protein αs, adenylyl cyclase, protein kinase A, and protein phosphatase 2a are closely associated. To determine the functional impact of the caveolar-localized β2-AR/Cav1.2 signaling complex, β2-AR stimulation (salbutamol plus atenolol) of ICa,L was examined in pertussis toxin-treated neonatal mouse ventricular myocytes. The stimulation of ICa,L in response to β2-AR activation was eliminated by disruption of caveolae with 10 mM methyl β-cyclodextrin or by small interfering RNA directed against caveolin-3, whereas β1-AR stimulation (norepinephrine plus prazosin) of ICa,L was not altered. These findings demonstrate that subcellular localization of L-type Ca2+ channels to caveolar macromolecular signaling complexes is essential for regulation of the channels by specific signaling pathways.
Details
- Title: Subtitle
- Localization of cardiac L-type Ca2+ channels to a caveolar macromolecular signaling complex is required for β2-adrenergic regulation
- Creators
- Ravi C Balijepalli - Department of Medicine, University of Wisconsin, Madison, WI 53706 andJason D Foell - Department of Medicine, University of Wisconsin, Madison, WI 53706 andDuane D Hall - Department of Pharmacology, University of Iowa, Iowa City, IA 52242Johannes W Hell - Department of Pharmacology, University of Iowa, Iowa City, IA 52242Timothy J Kamp - Department of Medicine, University of Wisconsin, Madison, WI 53706 and
- Resource Type
- Journal article
- Publication Details
- Proceedings of the National Academy of Sciences - PNAS, Vol.103(19), pp.7500-7505
- Series
- From the Cover
- DOI
- 10.1073/pnas.0503465103
- PMID
- 16648270
- PMCID
- PMC1564282
- NLM abbreviation
- Proc Natl Acad Sci U S A
- ISSN
- 0027-8424
- eISSN
- 1091-6490
- Publisher
- National Academy of Sciences
- Language
- English
- Date published
- 05/09/2006
- Academic Unit
- Cardiovascular Medicine; Internal Medicine
- Record Identifier
- 9984094762202771
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