Localization of cardiac L-type Ca 2+ channels to a caveolar macromolecular signaling complex is required for β 2 -adrenergic regulation
| Autor: | Jason D. Foell, Johannes W. Hell, Timothy J. Kamp, Ravi C. Balijepalli, Duane D. Hall |
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| Rok vydání: | 2006 |
| Předmět: |
Caveolar macromolecular signaling complex
Cell signaling Patch-Clamp Techniques Calcium Channels L-Type Caveolin 3 Biology Caveolae Adenylyl cyclase Mice chemistry.chemical_compound Dogs Microscopy Electron Transmission Receptors Adrenergic beta Animals Humans RNA Small Interfering Microscopy Immunoelectron Protein kinase A Multidisciplinary Voltage-dependent calcium channel Myocardium beta-Cyclodextrins Heart Intracellular Membranes Biological Sciences Coronary Vessels Cyclic AMP-Dependent Protein Kinases Cell biology Electrophysiology chemistry Commentary Calcium Receptors Adrenergic beta-2 Signal transduction Adenylyl Cyclases Protein Binding Signal Transduction |
| Zdroj: | Proceedings of the National Academy of Sciences. 103:7500-7505 |
| ISSN: | 1091-6490 0027-8424 |
| Popis: | L-type Ca 2+ channels play a critical role in regulating Ca 2+ -dependent signaling in cardiac myocytes, including excitation-contraction coupling; however, the subcellular localization of cardiac L-type Ca 2+ 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 Ca 2+ channels is localized to caveolae in ventricular myocytes as part of a macromolecular signaling complex necessary for β 2 -adrenergic receptor (AR) regulation of I Ca,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 (Ca v 1.2). Immunogold electron microscopy revealed that these proteins colocalize in caveolae. Immunoprecipitation from ventricular myocytes using anti-Ca v 1.2 or anti-caveolin-3 followed by Western blot analysis showed that caveolin-3, Ca v 1.2, β 2 -AR (not β 1 -AR), G protein α s , adenylyl cyclase, protein kinase A, and protein phosphatase 2a are closely associated. To determine the functional impact of the caveolar-localized β 2 -AR/Ca v 1.2 signaling complex, β 2 -AR stimulation (salbutamol plus atenolol) of I Ca,L was examined in pertussis toxin-treated neonatal mouse ventricular myocytes. The stimulation of I Ca,L in response to β 2 -AR activation was eliminated by disruption of caveolae with 10 mM methyl β-cyclodextrin or by small interfering RNA directed against caveolin-3, whereas β 1 -AR stimulation (norepinephrine plus prazosin) of I Ca,L was not altered. These findings demonstrate that subcellular localization of L-type Ca 2+ channels to caveolar macromolecular signaling complexes is essential for regulation of the channels by specific signaling pathways. |
| Databáze: | OpenAIRE |
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