14-3-3ε/YWHAE regulates the transcriptional expression of cardiac sodium channel Na1.5.

Background: Cardiac voltage-gated sodium channel alpha subunit 5 (Na1.5) encoded by SCN5A is associated with arrhythmia disorders. However, the molecular mechanism underlying Na1.5 expression remains to be fully elucidated. Previous studies have reported that the 14-3-3 family acts as an adaptor involved in regulating kinetic characteristics of cardiac ion channels.

Objective: The purpose of this study was to establish 14-3-3ε/YWHAE, a member of the 14-3-3 family, as a crucial regulator of Na1.5 and to explore the potential role of 14-3-3ε in the heart.

Methods: Western blotting, patch clamping, real-time reverse transcription-polymerase chain reaction, RNA immunoprecipitation, electrocardiogram recording, echocardiography, and histologic analysis were performed.

Results: YWHAE overexpression significantly reduced the expression level of SCN5A mRNA and sodium current density, whereas YWHAE knockdown significantly increased SCN5A mRNA expression and sodium current density in HEK293/Na1.5 and H9c2 cells. Similar results were observed in mice injected with adeno-associated virus serotype 9-mediated YWHAE knockdown. The effect of 14-3-3ε on Na1.5 expression was abrogated by knockdown of TBX5, a transcription factor of Na1.5. An interaction between 14-3-3ε protein and TBX5 mRNA was identified, and YWHAE overexpression significantly decreased TBX5 mRNA stability without affecting SCN5A mRNA stability. In addition, mice subjected to adeno-associated virus serotype 9-mediated YWHAE knockdown exhibited shorter R-R intervals and higher prevalence of premature ventricular contractions.

Conclusion: Our data unveil a novel regulatory mechanism of Na1.5 by 14-3-3ε and highlight the significance of 14-3-3ε in transcriptional regulation of Na1.5 expression and cardiac arrhythmias.