Abstract
Abstract Fri081: SIRT5 Dysfunction Evokes Arrhythmias and Na+ and Ca2+ Mishandling in mouse heart
Circulation research, Vol.137(Suppl_1)
08/01/2025
DOI: 10.1161/res.137.suppl_1.Fri081
Abstract
Background: The cardiac Na+ channel NaV1.5 (encoded by SCN5A) governs inward Na+ current (INa), playing a crucial role in the fast upstroke and plateau phases of the cardiac action potential. Mutations in SCN5A are implicated in inherited and acquired arrhythmias, including ~20% of Brugada Syndrome (BrS) cases. Altered INa impact Ca2+ handling and excitation-contraction coupling. Previously, we demonstrated that SIRT1-mediated deacetylation of NaV1.5 at K1479 enhances peak INa. Recently, potential mutations in SIRT5-including P114T-were identified in small families with BrS. SIRT5, another NAD+-dependent deACYLase from the Sirtuin family, is primarily localized to mitochondria.
Hypothesis: Sirt5 dysfunction leads to arrhythmogenesis through Na+ and Ca2+ mishandling in an oxidative stress- dependent manner in mouse hearts.
Aims: To investigate SIRT5's role in BrS using heterologous expression systems, homozygous P114T-Sirt5 knock-in (P114T-KI) and Sirt5-/- mice.
Methods: Protein expression and physical interactions were assessed by immunoprecipitation and immunoblot. Patch-clamp electrophysiology in HEK cells and mouse ventricular cardiac myocytes evaluated INa. Reactive oxygen species (ROS) levels and Ca2+ imaging were measured by confocal microscopy.
Results: Both WT and P114T-SIRT5 co-immunoprecipitate with NaV1.5, but only WT enhanced peak INa in K1479-NaV1.5 dependent manner in HEK cells. P114T-SIRT5 failed to do so. The late INa of cardiomyocytes was elevated (Figure, A), and QTc was prolonged in both Sirt5-/- and P114T mice. P114T-KI hearts showed increased Na+/Ca2+ exchanger (NCX1) expression, elevated phosphorylation of phospholamban at Thr17 (p-PLN-Thr17, Figure, B). Live-cell staining using DCFDA or mitoSOX revealed that ROS levels were higher in P114T-KI hearts at baseline compared to WT littermates and were further exacerbated by H2O2. Aberrant Ca2+ handling and arrhythmias in Langendorff-perfused hearts of P114T mice were mitigated by the mitochondrial ROS scavenger MitoTEMPO (Figure, C).
Conclusion: SIRT5 dysfunction in P114T-SIRT5 disrupts Na+ and Ca2+ homeostasis and induces arrhythmias in a ROS-dependent manner, suggesting potential mechanisms underlying BrS. These findings highlight SIRT5 as a promising therapeutic target for BrS.
Details
- Title: Subtitle
- Abstract Fri081: SIRT5 Dysfunction Evokes Arrhythmias and Na+ and Ca2+ Mishandling in mouse heart
- Creators
- Jin-Young Yoon - University of IowaHannah Choi - University of IowaBiyi Chen - University of IowaLong-Sheng Song - University of IowaBarry London - University of Iowa
- Resource Type
- Abstract
- Publication Details
- Circulation research, Vol.137(Suppl_1)
- DOI
- 10.1161/res.137.suppl_1.Fri081
- ISSN
- 0009-7330
- eISSN
- 1524-4571
- Publisher
- Lippincott Williams & Wilkins
- Language
- English
- Date published
- 08/01/2025
- Academic Unit
- Molecular Physiology and Biophysics; Cardiovascular Medicine; Fraternal Order of Eagles Diabetes Research Center; Biochemistry and Molecular Biology; Internal Medicine
- Record Identifier
- 9985014895502771
Metrics
2 Record Views