Key result
Kir2.1 Δ314-315 mutation causes dual channel dysfunction, driving conduction defects and abnormal calcium release.
Why the study?
Andersen-Tawil Syndrome is associated with life-threatening arrhythmias of unknown mechanism.
This study provides the first in-vivo demonstration of a dual arrhythmogenic mechanism of ATS1 defects in Kir2.1 channel function at both the sarcolemma and the sarcoplasmic reticulum.
Does not alter ATS1 management; extends mechanistic insights into Kir2.1 dual dysfunction in animal models.
Andersen-Tawil Syndrome (ATS) is associated with life threatening arrhythmias of unknown mechanism. We report on a mouse model carrying the trafficking-deficient mutant Kir2.1 Δ314-315 . The mouse recapitulates the electrophysiological phenotype of type 1 (ATS1), with slower conduction velocities in response to flecainide, QT prolongation exacerbated by isoproterenol, and increased vulnerability to calcium-mediated arrhythmias resembling catecholaminergic polymorphic ventricular tachycardia (CPVT). Kir2.1 Δ314-315 expression significantly reduced inward rectifier K + and Na + inward currents, depolarized resting membrane potential and prolonged action potential duration. Immunolocalization in wildtype cardiomyocytes and skeletal muscle cells revealed a novel sarcoplasmic reticulum (SR) microdomain of functional Kir2.1 channels contributing to intracellular Ca 2+ homeostasis. Kir2.1 Δ314-315 cardiomyocytes showed defects in SR Kir2.1 localization and function, which contributed to abnormal spontaneous Ca 2+ release events. This is the first in-vivo demonstration of a dual arrhythmogenic mechanism of ATS1 defects in Kir2.1 channel function at the sarcolemma and the SR, with overlap between ATS1 and CPVT.
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Macías et al. (2021) studied Andersen-Tawil Syndrome Type 1. Kir2.1 Δ314-315 mutation vs. Wild-type Kir2.1 was evaluated on Electrophysiological phenotype and intracellular calcium dynamics. The Kir2.1 Δ314-315 mutation caused dual dysfunction of Kir2.1 channels at the sarcolemma and sarcoplasmic reticulum, leading to conduction defects and abnormal spontaneous calcium release.
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