title: Mutation-linked defective interdomain interactions within ryanodine receptor cause aberrant Ca²⁺release leading to catecholaminergic polymorphic ventricular tachycardia.
abstract: BACKGROUND
  The molecular mechanism by which catecholaminergic polymorphic ventricular tachycardia is induced by single amino acid mutations within the cardiac ryanodine receptor (RyR2) remains elusive. In the present study, we investigated mutation-induced conformational defects of RyR2 using a knockin mouse model expressing the human catecholaminergic polymorphic ventricular tachycardia-associated RyR2 mutant (S2246L; serine to leucine mutation at the residue 2246).
  
  
  RESULTS
  All knockin mice we examined produced ventricular tachycardia after exercise on a treadmill. cAMP-dependent increase in the frequency of Ca²⁺ sparks was more pronounced in saponin-permeabilized knockin cardiomyocytes than in wild-type cardiomyocytes. Site-directed fluorescent labeling and quartz microbalance assays of the specific binding of DP2246 (a peptide corresponding to the 2232 to 2266 region: the 2246 domain) showed that DP2246 binds with the K201-binding sequence of RyR2 (1741 to 2270). Introduction of S2246L mutation into the DP2246 increased the affinity of peptide binding. Fluorescence quench assays of interdomain interactions within RyR2 showed that tight interaction of the 2246 domain/K201-binding domain is coupled with domain unzipping of the N-terminal (1 to 600)/central (2000 to 2500) domain pair in an allosteric manner. Dantrolene corrected the mutation-caused domain unzipping of the domain switch and stopped the exercise-induced ventricular tachycardia.
  
  
  CONCLUSIONS
  The catecholaminergic polymorphic ventricular tachycardia-linked mutation of RyR2, S2246L, causes an abnormally tight local subdomain-subdomain interaction within the central domain involving the mutation site, which induces defective interaction between the N-terminal and central domains. This results in an erroneous activation of Ca²⁺ channel in a diastolic state reflecting on the increased Ca²⁺ spark frequency, which then leads to lethal arrhythmia.
authors.affiliation: Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Yamaguchi, 755-8505, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Suetomi
authors.forename: Masafumi
authors.initials: M
authors.lastname: Yano
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Uchinoumi
authors.forename: Masakazu
authors.initials: M
authors.lastname: Fukuda
authors.forename: Akihiro
authors.initials: A
authors.lastname: Hino
authors.forename: Makoto
authors.initials: M
authors.lastname: Ono
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Xu
authors.forename: Hiroki
authors.initials: H
authors.lastname: Tateishi
authors.forename: Shinichi
authors.initials: S
authors.lastname: Okuda
authors.forename: Masahiro
authors.initials: M
authors.lastname: Doi
authors.forename: Shigeki
authors.initials: S
authors.lastname: Kobayashi
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Ikeda
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Noriaki
authors.initials: N
authors.lastname: Ikemoto
authors.forename: Masunori
authors.initials: M
authors.lastname: Matsuzaki
mesh_terms: D000495:Allosteric Site; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003620:Dantrolene / Q000627:therapeutic use; D003971:Diastole; D004837:Epinephrine / Q000633:toxicity; D055879:Gene Knock-In Techniques; D006801:Humans; D015640:Ion Channel Gating / Q000235:genetics* / Q000502:physiology; D051379:Mice; D008822:Mice, Transgenic; D008955:Models, Cardiovascular; D008969:Molecular Sequence Data; D009125:Muscle Relaxants, Central / Q000627:therapeutic use; D020125:Mutation, Missense; D032383:Myocytes, Cardiac / Q000378:metabolism; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism; D017354:Point Mutation; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000502:physiology; D012420:Running; D019837:Ryanodine Receptor Calcium Release Channel / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D017180:Tachycardia, Ventricular / Q000139:chemically induced / Q000209:etiology* / Q000235:genetics / Q000503:physiopathology / Q000517:prevention & control
chemical_list: D009125:Muscle Relaxants, Central; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D019837:Ryanodine Receptor Calcium Release Channel; D003620:Dantrolene; D002118:Calcium; D004837:Epinephrine