Impaired Binding to Junctophilin-2 and Nanostructural Alteration in CPVT Mutation
Date
2021-07-23Author
Yin, LihengJr, Alexandra Zahradnikova
Rizzetto, Riccardo
Boncompagni, Simona
Meritens, Camille Rabesahala de
Zhang, Yadan
Joanne, Pierre
Marqués-Sulé, Elena
Aguilar-Sánchez, Yuriana
Fernández-Tenorio, Miguel
Villejoubert, Olivier
Li, Linwei
Wang, Yue Yi
Mateo, Philippe
Nicolas, Valérie
Gerbaud, Pascale
Lai, F. Anthony
Perrier, Romain
Álvarez, Julio L.
Niggli, Ernst
Valdivia, Héctor H.
Valdivia, Carmen R.
Ramos-Franco, Josefina
Zorio, Esther
Zissimopoulos, Spyros
Protasi, Feliciano
Benitah, Jean-Pierre
Gómez, Ana M.
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Show full item recordAbstract
RATIONALE: Catecholaminergic polymorphic ventricular tachycardia is a rare disease, manifested by syncope or sudden death
in children or young adults under stress conditions. Mutations in the Ca2+ release channel/type 2 ryanodine receptor (RyR2)
gene account for about 60% of the identified mutations. Recently, we found and described a mutation in RyR2 N-terminal
domain, RyR2R420Q.
OBJECTIVE: To determine the arrhythmogenic mechanisms of this mutation.
METHODS AND RESULTS: Ventricular tachycardias under stress conditions were observed in both patients with catecholaminergic
polymorphic ventricular tachycardia and knock-in mice. During action potential recording (by patch-clamp in knock-in mouse
cardiomyocytes and by microelectrodes in mutant human induced pluripotent stem cell-derived cardiomyocytes), we observed
an increased occurrence of delayed afterdepolarizations under isoproterenol stimulation, associated with increased Ca2+ waves
during confocal Ca2+ recording in both mouse and human RyR2R420Q cardiomyocytes. In addition, Ca2+-induced Ca2+-release,
as well as a rough indicator of fractional Ca2+ release, were higher and Ca2+ sparks longer in the RyR2R420Q-expressing cells.
At the ultrastructural nanodomain level, we observed smaller RyR2 clusters and widened junctional sarcoplasmic reticulum
measured by gated stimulated emission depletion super-resolution and electronic microscopy, respectively. The increase in
junctional sarcoplasmic reticulum width might be due to the impairment of RyR2R420Q binding to junctophilin-2, as there were
less junctophilin-2 coimmunoprecipitated with RyR2R420Q. At the single current level, the RyR2R420Q channel dwells longer in
the open state at low intracellular Ca2+ ([Ca2+]i), but there is predominance of a subconductance state. The latter might be
correlated with an enhanced interaction between the N terminus and the core solenoid, a RyR2 interdomain association that
has not been previously implicated in the pathogenesis of arrhythmias and sudden cardiac death.
CONCLUSIONS: The RyR2R420Q catecholaminergic polymorphic ventricular tachycardia mutation modifies the interdomain
interaction of the channel and weakens its association with junctophillin-2. These defects may underlie both nanoscale
disarrangement of the dyad and channel dysfunction.
GRAPHIC ABSTRACT: An online graphic abstract is available for this article.
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