Inhibition of Histone Deacetylases Induces K+ Channel Remodeling and Action Potential Prolongation in HL-1 Atrial Cardiomyocytes

Abstract

Background/Aims: Cardiac arrhythmias are triggered by environmental stimuli that may modulate expression of cardiac ion channels. Underlying epigenetic regulation of cardiac electrophysiology remains incompletely understood. Histone deacetylases (HDACs) control gene expression and cardiac integrity. We hypothesized that class I/II HDACs transcriptionally regulate ion channel expression and determine action potential duration (APD) in cardiac myocytes. Methods: Global class I/II HDAC inhibition was achieved by administration of trichostatin A (TSA). HDAC-mediated effects on K⁺ channel expression and electrophysiological function were evaluated in murine atrial cardiomyocytes (HL-1 cells) using real-time PCR, Western blot, and patch clamp analyses. Electrical tachypacing was employed to recapitulate arrhythmia-related effects on ion channel remodeling in the absence and presence of HDAC inhibition. Results: Global HDAC inhibition increased histone acetylation and prolonged APD₉₀ in atrial cardiomyocytes compared to untreated control cells. Transcript levels of voltage-gated or inwardly rectifying K⁺ channels Kcnq1, Kcnj3 and Kcnj5 were significantly reduced, whereas Kcnk2, Kcnj2 and Kcnd3 mRNAs were upregulated. Ion channel remodeling was similarly observed at protein level. Short-term tachypacing did not induce significant transcriptional K⁺ channel remodeling. Conclusion: The present findings link class I/II HDAC activity to regulation of ion channel expression and action potential duration in atrial cardiomyocytes. Clinical implications for HDAC-based antiarrhythmic therapy and cardiac safety of HDAC inhibitors require further investigation.

HDAC (Histone Deacetylase) Inhibitor Valproic Acid Attenuates Atrial Remodeling and Delays the Onset of Atrial Fibrillation in Mice

“…This is in line with an unaltered H4-acetylation in atria from WT VPA mice, which might point to a possible long-term compensatory mechanism because H4-acetylation was increased acutely in WT atria by VPA. Recently, Lugenbiel et al 70 reported AP prolongation in HL-1 cardiomyocytes after 12-hour treatment with the pan-HDAC inhibitor TSA. Such an effect seems not to be present after prolonged treatment with VPA in mice, which might depend on VPAs HDAC inhibitory profile or efficacy.…”

Trigger-Specific Remodeling of KCa2 Potassium Channels in Models of Atrial Fibrillation

“…Cells were subjected to electrical stimulation as reported using the C-Pace EP system (IonOptix, Westwood, MA, USA). 25 The cells were stimulated with 10 V/10 ms pulses at 5 Hz stimulation rate. Following rapid electrical stimulation for 24 h, cell viability was visually assessed by microscopic examination and TUNEL assays.…”

“…Protein immunodetection was performed using sodium dodecyl sulfate (SDS) gel electrophoresis and Western blotting as described previously. 25 Equal amounts of protein were separated on 10% SDS polyacrylamide gels and transferred onto polyvinylidene difluoride membranes. Membranes were blocked with 5% milk in PBS-T for 2 hours at room temperature and developed using primary antibodies directed against K Ca 2.1 (1:1000, APC-039), K Ca 2.2 (1:1000, APC-028) and K Ca 2.3 (1:1000, APC-025, all from Alomone Lab, Jerusalem, Israel).…”

Differential regulation of K Ca 2.1 ( KCNN1 ) K + channel expression by histone deacetylases in atrial fibrillation with concomitant heart failure

“…Gelatin-/fibronectin-coated six-well dishes were seeded with 4-5 × 10 6 HL-1 cells. Cells were ≥90% confluent after 24 h incubation and subjected to electrical stimulation as described (Lugenbiel et al, 2018) using the C-Pace EP system (IonOptix). Stimulation was performed with 10 V/10 ms pulses at 4 Hz rates.…”

“…To date, histone deacetylase (HDAC) effects on cardiac K + currents have been almost exclusively investigated using broad range inhibitors. In vitro, APD prolongation and reduced expression of K + channels were observed in atrial cardiomyocytes after application of broad‐spectrum inhibitors of HDACs (Lugenbiel et al, 2018). Furthermore, inhibition of class I HDACs resulted in AF suppression in animal models (Seki et al, 2016; Skibsbye et al, 2018, Scholz et al 2019).…”