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Stimulation of ICa by basal PKA activity is facilitated by caveolin-3 in cardiac ventricular myocytes
- Source :
- Journal of Molecular and Cellular Cardiology
- Publication Year :
- 2014
- Publisher :
- Elsevier BV, 2014.
-
Abstract
- L-type Ca channels (LTCC), which play a key role in cardiac excitation–contraction coupling, are located predominantly at the transverse (t-) tubules in ventricular myocytes. Caveolae and the protein caveolin-3 (Cav-3) are also present at the t-tubules and have been implicated in localizing a number of signaling molecules, including protein kinase A (PKA) and β2-adrenoceptors. The present study investigated whether disruption of Cav-3 binding to its endogenous binding partners influenced LTCC activity. Ventricular myocytes were isolated from male Wistar rats and LTCC current (ICa) recorded using the whole-cell patch-clamp technique. Incubation of myocytes with a membrane-permeable peptide representing the scaffolding domain of Cav-3 (C3SD) reduced basal ICa amplitude in intact, but not detubulated, myocytes, and attenuated the stimulatory effects of the β2-adrenergic agonist zinterol on ICa. The PKA inhibitor H-89 also reduced basal ICa; however, the inhibitory effects of C3SD and H-89 on basal ICa amplitude were not summative. Under control conditions, myocytes stained with antibody against phosphorylated LTCC (pLTCC) displayed a striated pattern, presumably reflecting localization at the t-tubules. Both C3SD and H-89 reduced pLTCC staining at the z-lines but did not affect staining of total LTCC or Cav-3. These data are consistent with the idea that the effects of C3SD and H-89 share a common pathway, which involves PKA and is maximally inhibited by H-89, and suggest that Cav-3 plays an important role in mediating stimulation of ICa at the t-tubules via PKA-induced phosphorylation under basal conditions, and in response to β2-adrenoceptor stimulation.<br />Graphical abstract<br />Highlights • Basal L type calcium current was reduced by interfering with caveolin-3 binding. • L type calcium current is tonically regulated by PKA phosphorylation. • Interfering with caveolin-3 binding reduced beta2 adrenergic stimulation of ICa.
- Subjects :
- Male
medicine.medical_specialty
Patch-Clamp Techniques
Ca
Calcium Channels, L-Type
Caveolin 3
Heart Ventricles
Stimulation
Biology
chemistry.chemical_compound
Sarcolemma
β2-Adrenoceptors
Internal medicine
medicine
Animals
Myocyte
Myocytes, Cardiac
Calcium Signaling
Patch clamp
Phosphorylation
Rats, Wistar
Zinterol
Protein kinase A
Adrenergic beta-2 Receptor Agonists
Protein Kinase Inhibitors
Molecular Biology
Sulfonamides
Voltage-dependent calcium channel
t-tubules
3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester
Isoquinolines
Cyclic AMP-Dependent Protein Kinases
Rats
Cell biology
Endocrinology
chemistry
Ethanolamines
cardiovascular system
Original Article
Cardiology and Cardiovascular Medicine
Protein Processing, Post-Translational
Protein Binding
Subjects
Details
- ISSN :
- 00222828
- Volume :
- 68
- Database :
- OpenAIRE
- Journal :
- Journal of Molecular and Cellular Cardiology
- Accession number :
- edsair.doi.dedup.....51f0c6b757899c0588e73019abace654