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May 16, 2026Cardiovascular Research

The TRPM4 mutation p.I377T is a direct cause of electrophysiological alterations and increases arrhythmia sensitivity in mouse cardiac muscle

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Key result

TRPM4 mutation p.I377T increases Ca2+ sensitivity ~2.6-fold and drives VT susceptibility in aged mice.

  • 2.61x increase

Why the study?

Multiple mutations in TRPM4 have been associated with progressive cardiac conduction disease, but whether such mutations directly cause electrophysiological alterations in cardiac muscle cells was unclear.

Population

HEK-293T cells, ventricular cardiomyocytes, and young and aged wildtype and mutant (Trpm4I377T/I377T) mice

Comparison

TRPM4 mutant (p.I376T / murine p.I377T) vs wildtype

Design

In vitro, ex vivo, and in vivo preclinical electrophysiological study

Authors

APA PironetGMG M MarchalSSS L Sacconi

Discussion

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Overview

Does not yet support TRPM4-targeted therapy in PCCD; extends mechanistic insight in animal models but leaves human causality open.

Key Points

  • This research aims to determine if the TRPM4 mutation p.I377T directly causes electrophysiological changes in cardiac muscle cells and increases arrhythmia sensitivity.
  • Conducted in vitro electrophysiology and calcium imaging on HEK-293T cells and ventricular cardiomyocytes.
  • Performed optical mapping and intracardiac electrocardiogram measurements in wildtype and Trpm4I377T/I377T mutant mice.
  • Analyzed both young (20-40 weeks) and aged (50+ weeks) mice for differences in electrophysiological parameters.
  • The p.I376T mutation showed a 2.61x increase in Ca2+ sensitivity in whole-cell patch clamp studies on HEK-293T cells.
  • Optical mapping revealed significant slowing of conduction velocity in mutant mice compared to wildtype.
  • Aged mutant mice were more prone to sustained ventricular tachycardia during high-frequency intracardiac pacing.

Structured PICO

P
Population
Transiently-transfected HEK-293T cells, ventricular cardiomyocytes, and young (20-40 weeks) and aged (50+ weeks) wildtype and mutant (Trpm4I377T/I377T) mice
I
Intervention
TRPM4 mutation p.I377T (murine) and p.I376T (human)
C
Comparator
Wildtype (WT) littermates and unmutated cells
O
Outcome
In vitro and in vivo electrophysiological parameters including TRPM4 activity, Ca2+ sensitivity, conduction velocity, effective refractory period, and arrhythmia susceptibilitysurrogate

Main Result

Effect estimate: 2.61x increase

The TRPM4 mutation p.I377T causes a progressive cardiac conduction disease-like phenotype and increases arrhythmia susceptibility in mice, strongly indicating the human p.I376T mutation is disease-causing.

Limitations

  • Additional, unidentified genes may also contribute to the disease-trigger mechanism of a more severe PCCD-associated phenotype

Cite This Study

Pironet et al. (2026) studied Progressive cardiac conduction disease (PCCD). TRPM4 mutation p.I377T vs. Wildtype was evaluated on Electrophysiological alterations and arrhythmia sensitivity (2.61x increase). The TRPM4 mutation p.I377T caused a 2.61-fold increase in Ca2+ sensitivity and increased susceptibility to self-sustaining ventricular tachycardia in aged mutant mice compared to wildtype.

synapsesocial.com/papers/6a080af2a487c87a6a40d004https://doi.org/10.1093/cvr/cvag092.102
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Also Consider

Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context:

  1. 1Glycosylation of the murine cardiac channel TRPM4 is altered by the pathogenic p.I376T variant.2026
  2. 2Gain-of-Function Mutations in <i>TRPM4</i> Cause Autosomal Dominant Isolated Cardiac Conduction Disease2010 · 222 citations
  3. 3The Role of TRPM4 Gene Mutations in Causing Familial Progressive Cardiac Conduction Disease: A Further Contribution2022 · 18 citations
  4. 4Four TRPM4 Cation Channel Mutations Found in Cardiac Conduction Diseases Lead to Altered Protein Stability2018 · 50 citations
  5. 5Deletion of Trpm4 Alters the Function of the Nav1.5 Channel in Murine Cardiac Myocytes2021 · 25 citations