Background: Cardiac sodium channel NaV1.5 encoded by SCN5A is associated with arrhythmia disorders. However, the molecular mechanism underlying NaV1.5 expression remains to be fully elucidated. Previous studies have reported that 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 14-3-3 family, as a crucial regulator of NaV1.5 and explore the potential role of 14-3-3ε in the heart.
Methods: Western blotting, patch-clamping, real-time RT-PCR, RNA immunoprecipitation, electrocardiogram recording, echocardiography and histological 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/NaV1.5 and H9c2 cells. Similar results were observed in mice injected with adeno-associated virus serotype 9 (AAV9)-mediated YWHAE knockdown. The effect of 14-3-3ε on NaV1.5 expression was abrogated by knockdown of TBX5, a transcription factor of NaV1.5. 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. Additionally, mice subjected to AAV9-mediated YWHAE knockdown exhibited shorter R-R intervals and higher prevalence of premature ventricular contractions.
Conclusion: Our data unveil a novel regulatory mechanism of NaV1.5 by 14-3-3ε, and highlight the significance of 14-3-3ε in transcriptional regulation of NaV1.5 expression and cardiac arrhythmias.
Keywords: 14-3-3ε/YWHAE; Na(V)1.5/SCN5A; TBX5; cardiac arrhythmias; transcriptional regulation.
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