Role of CaMKIIdelta phosphorylation of the cardiac ryanodine receptor in the force frequency relationship and heart failure.
The force frequency relationship (FFR), first described by Bowditch 139 years ago as the observation that myocardial contractility increases proportionally with increasing heart rate, is an important mediator of enhanced cardiac output during exercise. Individuals with heart failure have defective positive FFR that impairs their cardiac function in response to stress, and the degree of positive FFR deficiency correlates with heart failure progression. We have identified a mechanism for FFR involving heart rate dependent phosphorylation of the major cardiac sarcoplasmic reticulum calcium release channel/ryanodine receptor (RyR2), at Ser2814, by calcium/calmodulin-dependent serine/threonine kinase-delta (CaMKIIdelta). Mice engineered with an RyR2-S2814A mutation have RyR2 channels that cannot be phosphorylated by CaMKIIdelta, and exhibit a blunted positive FFR. Ex vivo hearts from RyR2-S2814A mice also have blunted positive FFR, and cardiomyocytes isolated from the RyR2-S2814A mice exhibit impaired rate-dependent enhancement of cytosolic calcium levels and fractional shortening. The cardiac RyR2 macromolecular complexes isolated from murine and human failing hearts have reduced CaMKIIdelta levels. These data indicate that CaMKIIdelta phosphorylation of RyR2 plays an important role in mediating positive FFR in the heart, and that defective regulation of RyR2 by CaMKIIdelta-mediated phosphorylation is associated with the loss of positive FFR in failing hearts.
Kushnir
Alexander
A
Department of Physiology and Cellular Biophysics, Clyde and Helen Wu Center for Molecular Cardiology, Columbia University College of Physicians and Surgeons, New York, NY 10332, USA.
Shan
Jian
J
Betzenhauser
Matthew J
MJ
Reiken
Steven
S
Marks
Andrew R
AR
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000378:metabolism*; D002302:Cardiac Output / Q000235:genetics / Q000502:physiology; D017931:DNA Primers / Q000235:genetics; D006333:Heart Failure / Q000503:physiopathology*; D006339:Heart Rate / Q000235:genetics / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D016297:Mutagenesis, Site-Directed; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D009200:Myocardial Contraction / Q000235:genetics / Q000502:physiology*; D009206:Myocardium / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000502:physiology; D010766:Phosphorylation; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D019837:Ryanodine Receptor Calcium Release Channel / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D017931:DNA Primers; D050505:Mutant Proteins; D011994:Recombinant Proteins; D019837:Ryanodine Receptor Calcium Release Channel; C517660:CAMK2D protein, human; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; C517673:Camk2d protein, mouse