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J Mol Cell Cardiol. 2015 Aug;85:282-91. doi: 10.1016/j.yjmcc.2015.06.007. Epub 2015 Jun 14.

CaMKIIδ mediates β-adrenergic effects on RyR2 phosphorylation and SR Ca(2+) leak and the pathophysiological response to chronic β-adrenergic stimulation.

Author information

1
Department of Pharmacology, University of California, San Diego, CA, USA.
2
Department of Pharmacology, University of California, Davis, CA, USA.
3
Department of Molecular Physiology & Biophysics, Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA.
4
Department of Pharmacology, University of California, San Diego, CA, USA. Electronic address: jhbrown@ucsd.edu.

Abstract

Chronic activation of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) has been implicated in the deleterious effects of β-adrenergic receptor (β-AR) signaling on the heart, in part, by enhancing RyR2-mediated sarcoplasmic reticulum (SR) Ca(2+) leak. We used CaMKIIδ knockout (CaMKIIδ-KO) mice and knock-in mice with an inactivated CaMKII site S2814 on the ryanodine receptor type 2 (S2814A) to investigate the involvement of these processes in β-AR signaling and cardiac remodeling. Langendorff-perfused hearts from CaMKIIδ-KO mice showed inotropic and chronotropic responses to isoproterenol (ISO) that were similar to those of wild type (WT) mice; however, in CaMKIIδ-KO mice, CaMKII phosphorylation of phospholamban and RyR2 was decreased and isolated myocytes from CaMKIIδ-KO mice had reduced SR Ca(2+) leak in response to isoproterenol (ISO). Chronic catecholamine stress with ISO induced comparable increases in relative heart weight and other measures of hypertrophy from day 9 through week 4 in WT and CaMKIIδ-KO mice, but the development of cardiac fibrosis was prevented in CaMKIIδ-KO animals. A 4-week challenge with ISO resulted in reduced cardiac function and pulmonary congestion in WT, but not in CaMKIIδ-KO or S2814A mice, implicating CaMKIIδ-dependent phosphorylation of RyR2-S2814 in the cardiomyopathy, independent of hypertrophy, induced by prolonged β-AR stimulation.

KEYWORDS:

Beta-adrenergic; CaMKII; Fibrosis; Hypertrophy; Phosphorylation

PMID:
26080362
PMCID:
PMC4530053
DOI:
10.1016/j.yjmcc.2015.06.007
[Indexed for MEDLINE]
Free PMC Article

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