Histone Deacetylase Inhibition Reduces Pulmonary Vein Arrhythmogenesis through Calcium Regulation

doi:10.1016/j.ijcard.2014.09.175

International Journal of Cardiology

Volume 177, Issue 3, 20 December 2014, Pages 982-989

https://doi.org/10.1016/j.ijcard.2014.09.175 Get rights and content

Highlights

•
We studied the electrical effects of HDAC inhibitors on PV cardiomyocytes and AF inducibility in vivo.
•
MPT0E014 (a pan HDAC inhibitor) reduced PV (but not SAN) cardiomyocytes spontaneous activity and AF inducibility.
•
MPT0E014 changed PV arrhythmogenesis through class I HDAC inhibition.
•
MPT0E014 decreased Ca^2 + sparks and Ca^2 + transients with reduced RyR2 and NCX protein expression.
•
HDAC inhibition plays a critical role in PV arrhythmogenesis, which contributes to AF genesis.

Abstract

Pulmonary veins (PVs) play a critical role in the pathophysiology of atrial fibrillation (AF). Histone deacetylases (HDACs) are vital to calcium homeostasis and AF genesis. However, the electrophysiological effects of HDAC inhibition were unclear. This study evaluated whether HDAC inhibition can regulate PV electrical activity through calcium modulation.

Whole-cell patch-clamp, confocal microscopic with fluorescence, and Western blot were used to evaluate electrophysiological characteristics and Ca^2 + dynamics in isolated rabbit PV cardiomyocytes with and without MPT0E014 (a pan HDAC inhibitor), MS-275 (HDAC1 and 3 inhibitor), and MC-1568 (HDAC4 and 6 inhibitor) for 5 ~ 8 h. Atrial electrical activity and induced-AF (rapid atrial pacing and acetylcholine infusion) were measured in rabbits with and without MPT0E014 (10 mg/kg treated for 5 hours) in vivo.

MPT0E014 (1 μM)-treated PV cardiomyocytes (n = 12) had slower beating rates (2.1 ± 0.2 vs. 2.8 ± 0.1 Hz, p < 0.05) than control PV cardiomyocytes. However, control (n = 11) and MPT0E014 (1 μM)-treated (n = 12) SAN cardiomyocytes had similar beating rates (3.2 ± 0.2 vs. 2.9 ± 0.3 Hz). MS-275-treated PV cardiomyocytes (n = 12, 2.3 ± 0.2 Hz), but not MC-1568-treated PV cardiomyocytes (n = 14, 3.1 ± 0.3 Hz) had slower beating rates than control PV cardiomocytes. MPT0E014-treated PV cardiomyocytes (n = 14) had a lower frequency (2.4 ± 0.6 vs. 0.3 ± 0.1 spark/mm/s, p < 0.05) of Ca^2 + sparks than control PV (n = 17) cardiomyocytes. As compared to control, MPT0E014-treated PV cardiomyocytes had reduced Ca^2 + transient amplitudes, sodium-calcium exchanger currents, and ryanodine receptor expressions. Moreover, MPT0E014-treated rabbits had less AF and shorter AF duration than control rabbits.

In conclusions, HDAC inhibition reduced PV arrhythmogenesis and AF inducibility with modulation on calcium homeostasis.

Introduction

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia seen in clinical practice, and contributes to morbidity and mortality in the general population [1]. However, the pathophysiology underlying AF is not fully elucidated, and the current treatment of AF is unsatisfactory [2], [3]. Histone deacetylases (HDACs), which are epigenetic regulators, play critical roles in altering gene expressions during the progression of remodeling processes of cardiovascular diseases [4]. Reversible acetylation of histone and non-histone nuclear and cytosolic proteins was implicated in multiple cellular regulatory processes of cardiovascular diseases [5]. HDAC inhibitors can reduce cardiac hypertrophy and fibrosis [4], [6], [7], [8]. Our previous study has shown that a novel pan HDAC inhibitor (3-(1-Benzenesulfonyl-1H-indol-5-yl)-N-hydroxyacrylamide, MPT0E014) can improve heart failure with modulation on calcium regulation proteins [6]. Moreover, HDAC inhibitors were also shown to reduce AF induction in genetically modified mice with increased HDAC activity [9]. Activation of HDAC6 can enhance the occurrence of AF with contractile dysfunction, and AF patients had increased HDAC6 activities [10]. These findings suggest the potential role of inhibiting HDACs to treat AF. However, knowledge of the electrophysiological effects and calcium regulatory mechanisms of HDAC inhibition is limited.

Pulmonary veins (PVs), are the most important ectopic foci for AF initiation [11], [12]. PV cardiomyocytes contain distinctive electrophysiological characteristics with abnormally triggered activities [12], [13]. PV cardiomyocytes have increased sarcoplasmic reticulum (SR) Ca^2 + stores and Ca^2 + sparks [13], which suggests that calcium dysregulation may lead to PV arrhythmogenesis. Enhanced calmodulin-dependent protein kinase II (CaMKII) and the phosphorylated ryanodine receptor (RyR) can enhance calcium leak which produces calcium sparks and generates triggered activity [14]. In addition, increased sodium calcium exchanger (NCX) currents and CaMKII-hyperphosphorylated RyR were demonstrated in AF patients [15]. Modulating PV calcium homeostasis controls PV electrical activity, which may reduce the risk of AF [16], [17], [18]. In contrast, sinoatrial node (SAN) dysfunction may enhance the occurrences of AF [19]. HDACs and HDAC inhibitors can modulate expressions of calcium regulatory proteins [20], [21]. Therefore, the purpose of this study was to examine whether HDAC inhibition can modulate PV or SAN electrical activity through calcium modulation.

Section snippets

Isolation of PV and SAN cardiomyocytes

The investigation was approved by a local ethics review board and was conducted in accordance with the US National Institute of Health’s Guide for the Care and Use of Laboratory Animals. Male rabbits (1.5 ~ 2 kg) were intravenously injected with sodium pentobarbital (100 mg⁄kg) and heparin (2500 units). Single cardiomyocytes from rabbit PVs and SANs were enzymatically dissociated by a previously described procedure [22]. Cardiomyocytes with spontaneous activity were identified by the presence of

Effects of MPT0E014 on PV APs, electrical activity, and calcium homeostasis

As shown in Fig. 1, MPT0E014-treated PV cardiomyocytes had a slower beating rate than control PV cardiomyocytes (2.1 ± 0.2 vs. 2.8 ± 0.1 Hz, p < 0.05) at the concentration of 1 μM, but not at 0.1 μM (Fig. 1A). However, control and MPT0E014-treated (0.1 and 1 μM) SAN cardiomyocytes had similar beating rates (3.2 ± 0.2 vs. 2.9 ± 0.3 Hz) (Fig. 1B). Moreover, MS-275(1 μM)-treated PV cardiomyocytes had a slower beating rate (n = 12, 2.3 ± 0.2 Hz) than control or MC-1568 (1 μM)-treated PV cardiomyocytes (n = 14, 3.1 ± 0.3 Hz) (

Discussion

In the present study, for the first time, we showed that an HDAC inhibitor may contain anti-AF potential through modulating calcium regulation in PV cardiomyocytes. Increased HDAC activity can produce atrial fibrosis and atrial arrhythmic susceptibility in transgenic mice. Although pharmacologic inhibition of HDAC suppressed atrial fibrosis and atrial arrhythmia [9], the effects of HDAC inhibition on ion channels, calcium homeostasis, and arrhythmogenesis were not assessed [9], [27]. We found

Disclosures

The authors declare no conflict of interest.

Acknowledgements

The present work was supported by grants from Taipei Medical University, Wan Fang Hospital (103swf-10, 103-wf-eva-02 and 102-wf-eva-01), and the Ministry of Science and Technology, Taiwan (MOST 100-2628-B-038-001-MY4, 102-2628-B-038-002-MY3, and 102-2325-B-010-005).

References (35)

D Dobrev et al.
New antiarrhythmic drugs for treatment of atrial fibrillation
Lancet
(2010)
Y.H. Kao et al.
Histone deacetylase inhibition improved cardiac functions with direct antifibrotic activity in heart failure
Int J Cardiol
(2013)
F. Liu et al.
Histone-deacetylase inhibition reverses atrial arrhythmia inducibility and fibrosis in cardiac hypertrophy independent of angiotensin
J Mol Cell Cardiol
(2008)
S. Nattel
Paroxysmal atrial fibrillation and pulmonary veins: relationships between clinical forms and automatic versus re-entrant mechanisms
Can J Cardiol
(2013)
S.H. Chang et al.
Increased Ca(2 +) sparks and sarcoplasmic reticulum Ca(2 +) stores potentially determine the spontaneous activity of pulmonary vein cardiomyocytes
Life Sci
(2008)
S.L. Chang et al.
Heat shock protein inducer modifies arrhythmogenic substrate and inhibits atrial fibrillation in the failing heart
Int J Cardiol
(2013)
TA. McKinsey et al.
MEF2 a calcium-dependent regulator of cell division, differentiation and death
Trends Biochem Sci
(2002)
S.L. Chang et al.
Electrophysiological characteristics of complex fractionated electrograms and high frequency activity in atrial fibrillation
Int J Cardiol
(2013)
S.M. Williams et al.
Class I HDACs regulate angiotensin II-dependent cardiac fibrosis via fibroblasts and circulating fibrocytes
J Mol Cell Cardiol
(2014)
A.S. Go et al.
Heart disease and stroke statistics-2013 update: a report from the American Heart Association
Circulation
(2013)

D Dobrev et al.

Novel molecular targets for atrial fibrillation therapy

Nat Rev Drug Discov

(2012)

T.A. McKinsey

Therapeutic potential for HDAC inhibitors in the heart

Annu Rev Pharmacol Toxicol

(2012)

M. Haberland et al.

The many roles of histone deacetylases in development and physiology: implications for disease and therapy

Nat Rev Genet

(2009)

T.A. McKinsey

Targeting inflammation in heart failure with histone deacetylase inhibitors

Mol Med

(2011)

H. Tao et al.

Histone deacetylases in cardiac fibrosis: Current perspectives for therapy

Cell Signal

(2013)

D. Zhang et al.

Activation of Histone Deacetylase-6 Induces Contractile Dysfunction Through Derailment of alpha-Tubulin Proteostasis in Experimental and Human Atrial Fibrillation

Circulation

(2014)

Y.J. Chen et al.

Electrophysiology of Pulmonary Veins

J Cardiovasc Electrophysiol

(2006)

Cited by (22)

Atrial fibrillation: Epigenetic aspects and role of sodium-glucose cotransporter 2 inhibitors
2023, Pharmacological Research
Atrial fibrillation (AF) is the most frequent arrhythmia and is associated with substantial morbidity and mortality. Pathophysiological aspects consist in the activation of pro-fibrotic signaling and Ca²⁺ handling abnormalities at atrial level. Structural and electrical remodeling creates a substrate for AF by triggering conduction abnormalities and cardiac arrhythmias. The care of AF patients focuses predominantly on anticoagulation, symptoms control and the management of risk factors and comorbidities. The goal of AF therapy points to restore sinus rhythm, re-establish atrioventricular synchrony and improve atrial contribution to the stroke volume. New layer of information to better comprehend AF pathophysiology, and identify targets for novel pharmacological interventions consists of the epigenetic phenomena including, among others, DNA methylation, histone modifications and noncoding RNAs. Moreover, the benefits of sodium-glucose cotransporter 2 inhibitors (SGLT2i) in diabetic and non-diabetic patients at cardiovascular risk as well as emerging evidence on the ability of SGLT2i to modify epigenetic signature in cardiovascular diseases provide a solid background to investigate a possible role of this drug class in the onset and progression of AF.
In this review, following a summary of pathophysiology and management, epigenetic mechanisms in AF and the potential of sodium-glucose SGLT2i in AF patients are discussed.
Histone deacetylase 2-dependent ventricular electrical remodeling in a porcine model of early heart failure
2021, Life Sciences
Citation Excerpt :
Pan-HDAC inhibition by TSA or SAHA produces dose-dependent reductions in Gja1 transcription in ventricular cardiomyocytes [26]. Preclinical studies in murine models revealed positive effects of HDAC inhibition by small-molecule compounds [11,27,28] on atrial fibrillation, and recent data from humans and murine cardiomyocytes showed electrophysiological effects suggesting regulation of K+ channel expression [16,17,27,29]. Global inhibition of class I or class II HDACs result in rather broad and partially unspecific effects on ion channel expression and changes of cardiac electrophysiology.
Heart failure (HF) is linked to electrical remodeling that promotes ventricular arrhythmias. Underlying molecular signaling is insufficiently understood, in particular concerning patients with early disease stages. Previous observations suggest a key role for epigenetic mechanisms in cardiac remodeling processes. We hypothesized that histone deacetylases (HDACs) 1 and 2 contribute to cellular electrophysiological dysregulation in ventricular cardiomyocytes during HF development.
HDAC and ion channel expression was quantified in a porcine model of early HF induced by short-term atrial tachypacing, resulting in atrial fibrillation with rapid ventricular rate response. Anti-Hdac1 and anti-Hdac2 siRNA treatment was employed in neonatal murine cardiomyocytes (NMCM) to study effects of HDACs on ion channel mRNA expression and action potential duration (APD).
Early HF was characterized by mild reduction of left ventricular ejection fraction, prolonged QTc intervals, and increased ventricular effective refractory periods. Delayed repolarization was linked to significant downregulation of HDAC2 in left ventricular (LV) tissue. In addition, there was a tendency towards reduced transcript expression of KCNJ2/K_ir2.1 K⁺ channels. In NMCM, knock-down of Hdac2 recapitulated AP prolongation. Finally, siRNA-mediated suppression of Hdac2 reduced Kcnh2/K_v11.1 K⁺ channel expression.
Suppression of HDAC2 is linked to ventricular electrical remodeling of APD and ion channel expression in early stages of heart failure. This previously unrecognized mechanism may serve as basis for future approaches to prevention and treatment of ventricular arrhythmias.
Functional genomics and epigenomics of atrial fibrillation
2021, Journal of Molecular and Cellular Cardiology
Citation Excerpt :
An additional well-known example applies to histone deacetylases (HDACs) that act as proteostasis regulators in AF, by removing acetyl groups from the lysine residues of nucleosomal histone tails and various non-histone proteins. HDAC inhibition reverses atrial fibrosis and arrhythmogenesis and restore expression levels of Connexin40 in mice [117], and also in rabbit cardiomyocytes by modulating calcium homeostasis [118]. HDACs modulate the expression of relevant cardiac transcription factors such as MEF2 [119], which has a role in hypertrophy and fibrosis.
Atrial fibrillation is a progressive cardiac arrhythmia that increases the risk of hospitalization and adverse cardiovascular events. Despite years of study, we still do not have a full comprehension of the molecular mechanism responsible for the disease. The recent implementation of large-scale approaches in both patient samples, population studies and animal models has helped us to broaden our knowledge on the molecular drivers responsible for AF and on the mechanisms behind disease progression. Understanding genomic and epigenomic changes that take place during chronification of AF will prove essential to design novel treatments leading to improved patient care.
Histone deacetylase inhibition attenuates atrial arrhythmogenesis in sterile pericarditis
2018, Translational Research
Citation Excerpt :
HDAC inhibitors are known to reduce proinflammatory cytokines and attenuate inflammation and oxidative stress,31 which may contribute to the lower incidence of frequent APCs in MPT0E014-treated op rabbits and a lower incidence of burst firings in MPT0E014-treated opPVs. Our previous study showed that MPT0E014 decreased the sodium-calcium exchanger current and calcium transient.32,33 This calcium-regulatory effect could result in slower spontaneous activity in MPT0E014-treated control PVs or opPVs.
Cardiac surgery is complicated with atrial fibrillation (AF). Histone deacetylase (HDAC) inhibition reduces AF occurrence. In pericarditis, HDAC inhibition may modulate AF trigger and substrate. We recorded electrocardiograms in control and pericardiotomic (op) rabbits without and with an intraperitoneal injection of MPT0E014 (HDAC inhibitor). Conventional microelectrodes recorded action potentials (APs) in pulmonary veins (PVs), the right and left atrium (LA). Masson's trichrome was used to identify collagen fibers in PVs and the LA. Electrocardiograms showed frequent atrial premature contractions in op rabbits, but not in the other 3 groups. The beating rates in PVs and opPVs were decreased by MPT0E014 treatment. Spontaneous burst firings occurred in opPVs (36.4%), but not in control PVs. H₂O₂ induced greater burst firings in opPVs (72.7%) than in control PVs (11.1%), MPT0E014-treated PVs (16.7%), and MPT0E014-treated opPVs (12.5%). The AP duration at a repolarization extent of 90% (APD₉₀) was shorter in the opLA than that in the control LA. In the presence of isoproterenol (1 μM), rapid atrial pacing (RAP, 20 Hz) induced a higher incidence of burst firings in the opLA (90%) than in the other groups. In contrast, acetylcholine (5 mM) and RAP induced a lower incidence of burst firing in the MPT0E014-treated LA (33.3%) than in the other groups. Fibrosis prevailed in opPVs and the opLA compared to the respective control PVs and LA, which was attenuated in those that received MPT0E014. In conclusion, a pericardiotomy increased fibrosis and arrhythmogenesis in PVs and the LA, which were prevented by HDAC inhibition.
Targeting histone deacetylases: A novel therapeutic strategy for atrial fibrillation
2016, European Journal of Pharmacology
Citation Excerpt :
MS-275 (which selectively inhibits HDAC1, -2, and -3), but not MC-1568 (which selectively inhibits class II HDACs), showed similar effects as MPT0E014 on PV cardiomyocytes. These findings suggest that class I HDAC inhibition is more likely to contribute to anti-AF potential through PV regulation (Lkhagva et al., 2014). Table 1 summarizes the experimental evidence supporting the potential anti-AF effects of HDAC inhibition via electrical or structural remodeling.
Atrial fibrillation (AF) is a common cardiac arrhythmia associated with high mortality and morbidity. Current treatments of AF have limited efficacy and considerable side effects. Histone deacetylases (HDACs) play critical roles in the pathophysiology of cardiovascular diseases and contribute to the genesis of AF. Therefore, HDAC inhibition may prove a novel therapeutic strategy for AF through upstream therapy and modifications of AF electrical and structural remodeling. In this review, we provide an update of the knowledge of the effects of HDACs and HDAC inhibitors on AF, and dissect potential underlying mechanisms.
Epigenetic mechanisms in atrial fibrillation: New insights and future directions
2016, Trends in Cardiovascular Medicine
Citation Excerpt :
As compared to control, MPT0E014-treated PV cardiomyocytes had reduced Ca(2+) transient amplitudes, sodium-calcium exchanger currents, and ryanodine receptor expressions [80]. Moreover, MPT0E014-treated rabbits had less AF and shorter AF duration than control rabbits [80]. In conclusions, HDAC inhibition reduced PV arrhythmogenesis and AF inducibility with modulation on calcium homeostasis.
Atrial fibrillation (AF) is the most common sustained arrhythmia. AF is a complex disease that results from genetic and environmental factors and their interactions. In recent years, numerous studies have shown that epigenetic mechanisms significantly participate in AF pathogenesis. Even though a poor understanding of the molecular and electrophysiologic mechanisms of AF, accumulated evidence has suggested that the relevance of epigenetic changes in the development of AF. The aim of this review is to describe the present knowledge about the epigenetic regulatory features significantly participates in AF, and look ahead on new perspectives of epigenetic mechanisms research. Epigenetic regulatory features such as DNA methylation, histone modification, and microRNA influence gene expression by epigenetic mechanisms and by directly binding to various factor response elements in the target gene promoters. Given the role of epigenetic alterations in regulating genes, there is potential for the integration of factors-induced epigenetic alterations as informative factors in the risk assessment process. In this review, new insight into the epigenetic mechanisms in AF pathogenesis is discussed, with special emphasis on DNA methylation, histone modification, and microRNA. Further studies are needed to reveal the potential targets of epigenetic mechanisms, and it can be developed as a therapeutic target for AF.

View all citing articles on Scopus

View full text

Histone Deacetylase Inhibition Reduces Pulmonary Vein Arrhythmogenesis through Calcium Regulation

Highlights

Abstract

Introduction

Section snippets

Isolation of PV and SAN cardiomyocytes

Effects of MPT0E014 on PV APs, electrical activity, and calcium homeostasis

Discussion

Disclosures

Acknowledgements

Lancet

Int J Cardiol

J Mol Cell Cardiol

Can J Cardiol

Life Sci

Int J Cardiol

Trends Biochem Sci

Int J Cardiol

J Mol Cell Cardiol

Heart disease and stroke statistics-2013 update: a report from the American Heart Association

Circulation

Novel molecular targets for atrial fibrillation therapy

Nat Rev Drug Discov

Therapeutic potential for HDAC inhibitors in the heart

Annu Rev Pharmacol Toxicol

The many roles of histone deacetylases in development and physiology: implications for disease and therapy

Nat Rev Genet

Targeting inflammation in heart failure with histone deacetylase inhibitors

Mol Med

Histone deacetylases in cardiac fibrosis: Current perspectives for therapy

Cell Signal

Activation of Histone Deacetylase-6 Induces Contractile Dysfunction Through Derailment of alpha-Tubulin Proteostasis in Experimental and Human Atrial Fibrillation

Circulation

Electrophysiology of Pulmonary Veins

J Cardiovasc Electrophysiol