SUMOylation of the cardiac sodium channel NaV1.5 modifies inward current and cardiac excitability

Heart Rhythm. 2023 Nov;20(11):1548-1557. doi: 10.1016/j.hrthm.2023.07.067. Epub 2023 Aug 3.

Abstract

Background: Decreased peak sodium current (INa) and increased late sodium current (INa,L), through the cardiac sodium channel NaV1.5 encoded by SCN5A, cause arrhythmias. Many NaV1.5 posttranslational modifications have been reported. A recent report concluded that acute hypoxia increases INa,L by increasing a small ubiquitin-like modifier (SUMOylation) at K442-NaV1.5.

Objective: The purpose of this study was to determine whether and by what mechanisms SUMOylation alters INa, INa,L, and cardiac electrophysiology.

Methods: SUMOylation of NaV1.5 was detected by immunoprecipitation and immunoblotting. INa was measured by patch clamp with/without SUMO1 overexpression in HEK293 cells expressing wild-type (WT) or K442R-NaV1.5 and in neonatal rat cardiac myocytes (NRCMs). SUMOylation effects were studied in vivo by electrocardiograms and ambulatory telemetry using Scn5a heterozygous knockout (SCN5A+/-) mice and the de-SUMOylating protein SENP2 (AAV9-SENP2), AAV9-SUMO1, or the SUMOylation inhibitor anacardic acid. NaV1.5 trafficking was detected by immunofluorescence.

Results: NaV1.5 was SUMOylated in HEK293 cells, NRCMs, and human heart tissue. HyperSUMOylation at NaV1.5-K442 increased INa in NRCMs and in HEK cells overexpressing WT but not K442R-Nav1.5. SUMOylation did not alter other channel properties including INa,L. AAV9-SENP2 or anacardic acid decreased INa, prolonged QRS duration, and produced heart block and arrhythmias in SCN5A+/- mice, whereas AAV9-SUMO1 increased INa and shortened QRS duration. SUMO1 overexpression enhanced membrane localization of NaV1.5.

Conclusion: SUMOylation of K442-Nav1.5 increases peak INa without changing INa,L, at least in part by altering membrane abundance. Our findings do not support SUMOylation as a mechanism for changes in INa,L. Nav1.5 SUMOylation may modify arrhythmic risk in disease states and represents a potential target for pharmacologic manipulation.

Keywords: Arrhythmia; Na(V)1.5; SENP; SUMOylation; Sodium current.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Arrhythmias, Cardiac / genetics
  • Arrhythmias, Cardiac / metabolism
  • HEK293 Cells
  • Humans
  • Mice
  • Myocytes, Cardiac* / metabolism
  • NAV1.5 Voltage-Gated Sodium Channel / genetics
  • NAV1.5 Voltage-Gated Sodium Channel / metabolism
  • Rats
  • Sodium / metabolism
  • Sodium Channels / metabolism
  • Sumoylation*

Substances

  • anacardic acid
  • NAV1.5 Voltage-Gated Sodium Channel
  • Sodium
  • Sodium Channels
  • Scn5a protein, mouse