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Defective domaindomain interactions within the ryanodine receptor as a critical cause of diastolic Ca2 leak in failing hearts

Defective domaindomain interactions within the ryanodine receptor as a critical cause of... AimsA domain peptide (DP) matching the Gly2460Pro2495 region of the cardiac type-2 ryanodine receptor (RyR2), DPc10, is known to mimic channel dysfunction associated with catecholaminergic polymorphic ventricular tachycardia (CPVT), owing to its interference in a normal interaction of the N-terminal (1600) and central (20002500) domains (viz. domain unzipping). Using DPc10 and two other DPs harboring different mutation sites, we investigated the underlying mechanism of abnormal Ca2 cycling in failing hearts.Methods and resultsSarcoplasmic reticulum (SR) vesicles and cardiomyocytes were isolated from dog left ventricular muscles for Ca2 leak and spark assays. The RyR2 moiety of the SR was fluorescently labelled with methylcoumarin acetate (MCA) using DPs corresponding to the 163195 and 40904123 regions of RyR2 (DP163195 and DP40904123, respectively) as site-directed carriers. Both DPs mediated a specific MCA fluorescence labelling of RyR2. Addition of either DP to the MCA-labelled SR induced domain unzipping, as evidenced by an increased accessibility of the bound MCA to a large-size fluorescence quencher. Both SR Ca2 leak and Ca2 spark frequency (SpF) were markedly increased in failing cardiomyocytes. Upon introduction of DP163195 or DP40904123 into normal SR or cardiomyocytes, both Ca2 leak and SpF increased to the levels comparable with those of failing myocytes. K201 (JTV519) suppressed all of the effects induced by DP163195 (domain unzipping and increased Ca2 leak and SpF) or those in failing cardiomyocytes, but did not suppress the effects induced by DP40904123.ConclusionDefective inter-domain interaction between N-terminal and central domains induces diastolic Ca2 leak, leading to heart failure and lethal arrhythmia. Mutation at the C-terminal region seen in CPVT does not seem to communicate with the aforementioned N-terminal and central inter-domain interaction, although spontaneous Ca2 leak is similarly induced. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Cardiovascular Research Oxford University Press

Defective domaindomain interactions within the ryanodine receptor as a critical cause of diastolic Ca2 leak in failing hearts

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References (33)

Publisher
Oxford University Press
Copyright
© Published by Oxford University Press.
Subject
ORIGINAL ARTICLES
ISSN
0008-6363
eISSN
1755-3245
DOI
10.1093/cvr/cvn303
pmid
18996969
Publisher site
See Article on Publisher Site

Abstract

AimsA domain peptide (DP) matching the Gly2460Pro2495 region of the cardiac type-2 ryanodine receptor (RyR2), DPc10, is known to mimic channel dysfunction associated with catecholaminergic polymorphic ventricular tachycardia (CPVT), owing to its interference in a normal interaction of the N-terminal (1600) and central (20002500) domains (viz. domain unzipping). Using DPc10 and two other DPs harboring different mutation sites, we investigated the underlying mechanism of abnormal Ca2 cycling in failing hearts.Methods and resultsSarcoplasmic reticulum (SR) vesicles and cardiomyocytes were isolated from dog left ventricular muscles for Ca2 leak and spark assays. The RyR2 moiety of the SR was fluorescently labelled with methylcoumarin acetate (MCA) using DPs corresponding to the 163195 and 40904123 regions of RyR2 (DP163195 and DP40904123, respectively) as site-directed carriers. Both DPs mediated a specific MCA fluorescence labelling of RyR2. Addition of either DP to the MCA-labelled SR induced domain unzipping, as evidenced by an increased accessibility of the bound MCA to a large-size fluorescence quencher. Both SR Ca2 leak and Ca2 spark frequency (SpF) were markedly increased in failing cardiomyocytes. Upon introduction of DP163195 or DP40904123 into normal SR or cardiomyocytes, both Ca2 leak and SpF increased to the levels comparable with those of failing myocytes. K201 (JTV519) suppressed all of the effects induced by DP163195 (domain unzipping and increased Ca2 leak and SpF) or those in failing cardiomyocytes, but did not suppress the effects induced by DP40904123.ConclusionDefective inter-domain interaction between N-terminal and central domains induces diastolic Ca2 leak, leading to heart failure and lethal arrhythmia. Mutation at the C-terminal region seen in CPVT does not seem to communicate with the aforementioned N-terminal and central inter-domain interaction, although spontaneous Ca2 leak is similarly induced.

Journal

Cardiovascular Research – Oxford University Press

Published: Feb 15, 2009

Keywords: Keywords Calcium (cellular) Heart failure Ion channels SR (function)

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