The expression of the rare caveolin-3 variant T78M alters cardiac ion channels function and membrane excitability

Giulia Campostrini, Mattia Bonzanni, Alessio Lissoni, Claudia Bazzini, Raffaella Milanesi, Elena Vezzoli, Maura Francolini, Mirko Baruscotti, Annalisa Bucchi, Ilaria Rivolta, Matteo Fantini, Stefano Severi, Riccardo Cappato, Lia Crotti, Peter J. Schwartz, Dario DiFrancesco, Andrea Barbuti

Research output: Contribution to journalArticlepeer-review

Abstract

Aims Caveolinopathies are a family of genetic disorders arising from alterations of the caveolin-3 (cav-3) gene. The T78M cav-3 variant has been associated with both skeletal and cardiac muscle pathologies but its functional contribution, especially to cardiac diseases, is still controversial. Here, we evaluated the effect of the T78M cav-3 variant on cardiac ion channel function and membrane excitability. Methods and results We transfected either the wild type (WT) or T78M cav-3 in caveolin-1 knock-out mouse embryonic fibroblasts and found by immunofluorescence and electron microscopy that both are expressed at the plasma membrane and form caveolae. Two ion channels known to interact and co-immunoprecipitate with the cav-3, hKv1.5 and hHCN4, interact also with T78M cav-3 and reside in lipid rafts. Electrophysiological analysis showed that the T78M cav-3 causes hKv1.5 channels to activate and inactivate at more hyperpolarized potentials and the hHCN4 channels to activate at more depolarized potentials, in a dominant way. In spontaneously beating neonatal cardiomyocytes, the expression of the T78M cav-3 significantly increased action potential peak-to-peak variability without altering neither the mean rate nor the maximum diastolic potential. We also found that in a small cohort of patients with supraventricular arrhythmias, the T78M cav-3 variant is more frequent than in the general population. Finally, in silico analysis of both sinoatrial and atrial cell models confirmed that the T78M-dependent changes are compatible with a pro-arrhythmic effect. Conclusion This study demonstrates that the T78M cav-3 induces complex modifications in ion channel function that ultimately alter membrane excitability. The presence of the T78M cav-3 can thus generate a susceptible substrate that, in concert with other structural alterations and/or genetic mutations, may become arrhythmogenic.

Original languageEnglish
Pages (from-to)1256-1265
Number of pages10
JournalCardiovascular Research
Volume113
Issue number10
DOIs
Publication statusPublished - Aug 1 2017

Keywords

  • Arrhythmia
  • Caveolin
  • Electrophysiology
  • Genetic diseases
  • Ion channels

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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