Cardiovascular Research Advance Access [Accepted Manuscript] published online on October 15, 2007
Cardiovascular Research, doi:10.1093/cvr/cvm038
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MODULATION OF RYANODINE RECEPTOR BY LUMINAL CALCIUM AND ACCESSORY PROTEINS IN HEALTH AND CARDIAC DISEASE
Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH
* Corresponding Author: Sandor Gyorke, Department of Physiology and Cell Biology, 505 Davis Heart and Lung Research Institute, The Ohio State University, 473 W 12th Ave, Columbus, OH 43210. Phone: 614-292-3969, FAX: 614-247-7799, E-mail: Sandor.Gyorke{at}osumc.edu
The cardiac ryanodine receptor (RyR2) is the sarcoplasmic reticulum (SR) Ca2+ release channel which is responsible for generation of the cytosolic Ca2+ transient required for activation of cardiac contraction. RyR2 functional activity is governed by changes in [Ca2+] on both the cytosolic and luminal phase of the RyR2 channel. Activation of RyR2 by cytosolic Ca2+ results in Ca2+-induced Ca2+ release (CICR) from the SR. The decline in luminal [Ca2+] following release contributes to termination of CICR and Ca2+ signaling refractoriness through the process of luminal Ca2+-dependent deactivation of RyR2s. The control of RyR2s by luminal Ca2+ involves coordinated interaction of the channel with several SR proteins, including the Ca2+-binding protein calsequestrin (CASQ2), and the integral proteins triadin 1 (TRD) and junctin (JCN). CASQ2 in addition to serving as a Ca2+ storage site and a luminal Ca2+ buffer modulates RyR2 function more directly as a putative luminal Ca2+ sensor. TRD and JCN, stimulatory by themselves, mediate the interactions between CASQ2 and RyR2. Acquired and genetic defects in proteins of this junctional Ca2+ signaling complex lead to disease states such as cardiac arrhythmia and heart failure by impairing luminal Ca2+regulation of RyR2.
KEYWORDS sarcoplasmic reticulum; ryanodine receptor; calsequestrin; calcium-induced calcium release
Time for primary review: 20 days
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