Atrial fibrillation-associated minK38G/S polymorphism modulates delayed rectifier current and membrane localization.

Area of Science:

• Cardiovascular Physiology
• Molecular Cardiology
• Genetic Basis of Arrhythmias

Background:

• Atrial fibrillation (AF) is a common arrhythmia with complex causes.
• A specific single nucleotide polymorphism (SNP) in the KCNE1 gene (minK38G) is associated with increased AF risk.
• The functional impact of this KCNE1 SNP on cardiac ion channel function remains unclear.

Purpose of the Study:

• To investigate the functional consequences of the minK38G SNP on cardiac ion channel function.
• To determine the effect of the minK38G SNP on delayed-rectifier potassium currents.
• To explore the molecular mechanisms underlying the SNP's impact on channel expression and function.

Main Methods:

• Patch clamp electrophysiology to measure ion currents.
• Confocal microscopy and protein biochemistry to assess protein expression and localization.
• Mathematical modeling of cardiac action potentials to simulate functional consequences.

Main Results:

• The minK38G SNP significantly reduced the slow delayed rectifier current (I(Ks)) density compared to the wild-type minK38S.
• Reduced I(Ks) was attributed to decreased KvLQT1 membrane and surface expression.
• Mathematical simulations predicted that minK38G prolongs atrial action potential and promotes arrhythmogenic behaviors like alternans and afterdepolarizations.

Conclusions:

• The minK38G variant impairs I(Ks) function, likely via reduced KvLQT1 membrane trafficking.
• This study identifies a novel amino acid determinant of minK-KvLQT1 interaction.
• The findings suggest potential mechanistic heterogeneity in the genetic underpinnings of atrial fibrillation.