Sympathetic stimulation of adult cardiomyocytes requires association of AKAP5 with a subpopulation of L-Type calcium channels

C. Blake Nichols, Charles F. Rossow, Manuel F Navedo, Ruth E. Westenbroek, William A. Catterall, Luis Fernando Santana, G. Stanley McKnight

Research output: Contribution to journalArticle

109 Scopus citations

Abstract

Rationale: Sympathetic stimulation of the heart increases the force of contraction and rate of ventricular relaxation by triggering protein kinase (PK)A-dependent phosphorylation of proteins that regulate intracellular calcium. We hypothesized that scaffolding of cAMP signaling complexes by AKAP5 is required for efficient sympathetic stimulation of calcium transients. Objective: We examined the function of AKAP5 in the β-adrenergic signaling cascade. Methods and results: We used calcium imaging and electrophysiology to examine the sympathetic response of cardiomyocytes isolated from wild type and AKAP5 mutant animals. The β-adrenergic regulation of calcium transients and the phosphorylation of substrates involved in calcium handling were disrupted in AKAP5 knockout cardiomyocytes. The scaffolding protein, AKAP5 (also called AKAP150/79), targets adenylyl cyclase, PKA, and calcineurin to a caveolin 3-associated complex in ventricular myocytes that also binds a unique subpopulation of Cav1.2 L-type calcium channels. Only the caveolin 3-associated Cav1.2 channels are phosphorylated by PKA in response to sympathetic stimulation in wild-type heart. However, in the AKAP5 knockout heart, the organization of this signaling complex is disrupted, adenylyl cyclase 5/6 no longer associates with caveolin 3 in the T-tubules, and noncaveolin 3-associated calcium channels become phosphorylated after β-adrenergic stimulation, although this does not lead to an enhanced calcium transient. The signaling domain created by AKAP5 is also essential for the PKA-dependent phosphorylation of ryanodine receptors and phospholamban. Conclusions: These findings identify an AKAP5-organized signaling module that is associated with caveolin 3 and is essential for sympathetic stimulation of the calcium transient in adult heart cells.

Original languageEnglish (US)
Pages (from-to)747-756
Number of pages10
JournalCirculation Research
Volume107
Issue number6
DOIs
StatePublished - Sep 17 2010
Externally publishedYes

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Keywords

  • adenylyl cyclase
  • AKAP
  • Ca
  • cAMP
  • channels
  • PKA

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Medicine(all)

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