title: Enhanced Cytosolic Ca2+ Activation Underlies a Common Defect of Central Domain Cardiac Ryanodine Receptor Mutations Linked to Arrhythmias.
abstract: Recent three-dimensional structural studies reveal that the central domain of ryanodine receptor (RyR) serves as a transducer that converts long-range conformational changes into the gating of the channel pore. Interestingly, the central domain encompasses one of the mutation hotspots (corresponding to amino acid residues 3778-4201) that contains a number of cardiac RyR (RyR2) mutations associated with catecholaminergic polymorphic ventricular tachycardia (CPVT) and atrial fibrillation (AF). However, the functional consequences of these central domain RyR2 mutations are not well understood. To gain insights into the impact of the mutation and the role of the central domain in channel function, we generated and characterized eight disease-associated RyR2 mutations in the central domain. We found that all eight central domain RyR2 mutations enhanced the Ca2+-dependent activation of [3H]ryanodine binding, increased cytosolic Ca2+-induced fractional Ca2+release, and reduced the activation and termination thresholds for spontaneous Ca2+release in HEK293 cells. We also showed that racemic carvedilol and the non-beta-blocking carvedilol enantiomer, (R)-carvedilol, suppressed spontaneous Ca2+oscillations in HEK293 cells expressing the central domain RyR2 mutations associated with CPVT and AF. These data indicate that the central domain is an important determinant of cytosolic Ca2+activation of RyR2. These results also suggest that altered cytosolic Ca2+activation of RyR2 represents a common defect of RyR2 mutations associated with CPVT and AF, which could potentially be suppressed by carvedilol or (R)-carvedilol.
authors.affiliation: From the the Department of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta T2N 4N1, Canada.
authors.forename: Zhichao
authors.initials: Z
authors.lastname: Xiao
authors.affiliation: From the the Department of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta T2N 4N1, Canada.
authors.forename: Wenting
authors.initials: W
authors.lastname: Guo
authors.affiliation: From the the Department of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta T2N 4N1, Canada.
authors.forename: Bo
authors.initials: B
authors.lastname: Sun
authors.affiliation: From the the Department of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta T2N 4N1, Canada.
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Hunt
authors.affiliation: From the the Department of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta T2N 4N1, Canada.
authors.forename: Jinhong
authors.initials: J
authors.lastname: Wei
authors.affiliation: From the the Department of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta T2N 4N1, Canada.
authors.forename: Yingjie
authors.initials: Y
authors.lastname: Liu
authors.affiliation: From the the Department of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta T2N 4N1, Canada.
authors.forename: Yundi
authors.initials: Y
authors.lastname: Wang
authors.affiliation: From the the Department of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta T2N 4N1, Canada.
authors.forename: Ruiwu
authors.initials: R
authors.lastname: Wang
authors.affiliation: the Department of Physiology, Otago School of Medical Sciences and HeartOtago, University of Otago, Dunedin 9054, New Zealand, and.
authors.forename: Peter P
authors.initials: PP
authors.lastname: Jones
authors.affiliation: the Department of Chemistry, University of Calgary, Calgary, Alberta T2N 1N4, Canada.
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Back
authors.affiliation: From the the Department of Physiology and Pharmacology, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta T2N 4N1, Canada,. Electronic address: swchen@ucalgary.ca.
authors.forename: S R Wayne
authors.initials: SRW
authors.lastname: Chen
mesh_terms: D019943:Amino Acid Substitution; D001145:Arrhythmias, Cardiac / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D003600:Cytosol / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D020125:Mutation, Missense; D000072417:Protein Domains; D019837:Ryanodine Receptor Calcium Release Channel / Q000235:genetics / Q000378:metabolism*
chemical_list: D019837:Ryanodine Receptor Calcium Release Channel; D002118:Calcium
keywords: Ca2+-dependent activation; atrial fibrillation; calcium; calcium channel; calcium imaging; calcium intracellular release; cardiac ryanodine receptor; carvedilol; carvedilol enantiomer; disease mutations; endoplasmic reticulum (ER); ryanodine receptor; sarcoplasmic reticulum (SR); spontaneous Ca2+ release; ventricular tachyarrhythmia