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J Mol Cell Cardiol. 2014 Sep;74:274-83. doi: 10.1016/j.yjmcc.2014.06.004. Epub 2014 Jun 17.

CaMKII-dependent phosphorylation of cardiac ryanodine receptors regulates cell death in cardiac ischemia/reperfusion injury.

Author information

1
Centro de Investigaciones Cardiovasculares, CCT, La Plata, Facultad de Ciencias Médicas, 60 y 120, 1900 La Plata, Argentina.
2
Department of Pharmacology, University of California, San Diego, 9500 Gilman Dr, La Jolla, CA 92093-0636, USA.
3
Cardiovascular Research Institute, Department of Molecular Physiology and Biophysics, Department of Medicine (in Cardiology), Baylor College of Medicine, Houston, TX 77030, USA.
4
Centro de Investigaciones Cardiovasculares, CCT, La Plata, Facultad de Ciencias Médicas, 60 y 120, 1900 La Plata, Argentina. Electronic address: msalas@med.unlp.edu.ar.
5
Centro de Investigaciones Cardiovasculares, CCT, La Plata, Facultad de Ciencias Médicas, 60 y 120, 1900 La Plata, Argentina. Electronic address: aliciamattiazzi@gmail.com.

Abstract

Ca(2+)-calmodulin kinase II (CaMKII) activation is deleterious in cardiac ischemia/reperfusion (I/R). Moreover, inhibition of CaMKII-dependent phosphorylations at the sarcoplasmic reticulum (SR) prevents CaMKII-induced I/R damage. However, the downstream targets of CaMKII at the SR level, responsible for this detrimental effect, remain unclear. In the present study we aimed to dissect the role of the two main substrates of CaMKII at the SR level, phospholamban (PLN) and ryanodine receptors (RyR2), in CaMKII-dependent I/R injury. In mouse hearts subjected to global I/R (45/120min), phosphorylation of the primary CaMKII sites, S2814 on cardiac RyR2 and of T17 on PLN, significantly increased at the onset of reperfusion whereas PKA-dependent phosphorylation of RyR2 and PLN did not change. Similar results were obtained in vivo, in mice subjected to regional myocardial I/R (1/24h). Knock-in mice with an inactivated serine 2814 phosphorylation site on RyR2 (S2814A) significantly improved post-ischemic mechanical recovery, reduced infarct size and decreased apoptosis. Conversely, knock-in mice, in which CaMKII site of RyR2 is constitutively activated (S2814D), significantly increased infarct size and exacerbated apoptosis. In S2814A and S2814D mice subjected to regional myocardial ischemia, infarct size was also decreased and increased respectively. Transgenic mice with double-mutant non-phosphorylatable PLN (S16A/T17A) in the PLN knockout background (PLNDM) also showed significantly increased post-ischemic cardiac damage. This effect cannot be attributed to PKA-dependent PLN phosphorylation and was not due to the enhanced L-type Ca(2+) current, present in these mice. Our results reveal a major role for the phosphorylation of S2814 site on RyR2 in CaMKII-dependent I/R cardiac damage. In contrast, they showed that CaMKII-dependent increase in PLN phosphorylation during reperfusion opposes rather than contributes to I/R damage.

KEYWORDS:

Apoptosis; CaMKII; Ischemia/reperfusion injury; Myocardium; Necrosis; RyR2 PLN

PMID:
24949568
PMCID:
PMC4131282
DOI:
10.1016/j.yjmcc.2014.06.004
[Indexed for MEDLINE]
Free PMC Article

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