14-3-3ε/YWHAE regulates the transcriptional expression of cardiac sodium channel NaV1.5

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.