G9α-dependent histone H3K9me3 hypomethylation promotes overexpression of cardiomyogenesis-related genes in foetal mice.

Alcohol consumption during pregnancy can cause foetal alcohol syndrome and congenital heart disease. Nonetheless, the underlying mechanism of alcohol-induced cardiac dysplasia remains unknown. We previously reported that alcohol exposure during pregnancy can cause abnormal expression of cardiomyogenesis-related genes, and histone H3K9me3 hypomethylation was observed in alcohol-treated foetal mouse heart. Hence, an imbalance in histone methylation may be involved in alcohol-induced cardiac dysplasia. In this study, we investigated the involvement of G9α histone methyltransferase in alcohol-induced cardiac dysplasia in vivo and in vitro using heart tissues of foetal mice and primary cardiomyocytes of neonatal mice. Western blotting revealed that alcohol caused histone H3K9me3 hypomethylation by altering G9α histone methyltransferase expression in cardiomyocytes. Moreover, overexpression of cardiomyogenesis-related genes (MEF2C, Cx43, ANP and ß-MHC) was observed in alcohol-exposed foetal mouse heart. Additionally, we demonstrated that G9α histone methyltransferase directly interacted with histone H3K9me3 and altered its methylation. Notably, alcohol did not down-regulate H3K9me3 methylation after G9α suppression by short hairpin RNA in primary mouse cardiomyocytes, preventing MEF2C, Cx43, ANP and ß-MHC overexpression. These findings suggest that G9α histone methyltransferase-mediated imbalance in histone H3K9me3 methylation plays a critical role in alcohol-induced abnormal expression cardiomyogenesis-related genes during pregnancy. Therefore, G9α histone methyltransferase may be an intervention target for congenital heart disease.

Anacardic acid attenuates pressure-overload cardiac hypertrophy through inhibiting histone acetylases.

Cardiac hypertrophy has become a major cardiovascular problem wordwide and is considered the early stage of heart failure. Treatment and prevention strategies are needed due to the suboptimal efficacy of current treatment methods. Recently, many studies have demonstrated the important role of histone acetylation in myocardium remodelling along with cardiac hypertrophy. A Chinese herbal extract containing anacardic acid (AA) is known to possess strong histone acetylation inhibitory effects. In previous studies, we demonstrated that AA could reverse alcohol-induced cardiac hypertrophy in an animal model at the foetal stage. Here, we investigated whether AA could attenuate cardiac hypertrophy through the modulation of histone acetylation and explored its potential mechanisms in the hearts of transverse aortic constriction (TAC) mice. This study showed that AA attenuated hyperacetylation of acetylated lysine 9 on histone H3 (H3K9ac) by inhibiting the expression of p300 and p300/CBP-associated factor (PCAF) in TAC mice. Moreover, AA normalized the transcriptional activity of the heart nuclear transcription factor MEF2A. The high expression of cardiac hypertrophy-linked genes (ANP, ß-MHC) was reversed through AA treatment in the hearts of TAC mice. Additionally, we found that AA improved cardiac function and survival rate in TAC mice. The current results further highlight the mechanism by which histone acetylation is controlled by AA treatment, which may help prevent and treat hypertrophic cardiomyopathy.

[Interactive regulatory effect of histone H3K9ac acetylation and histone H3K9me3 methylation on cardiomyogenesis in mice].

OBJECTIVE: To study the interactive regulatory effect of histone acetylation and methylation on cardiomyogenesis, and to provide a theoretical basis for the prevention and treatment of congenital heart disease. METHODS: A total of 24 Kunming mice were randomly divided into embryo day 14.5 (ED 14.5) group, embryo day 16.5 (ED 16.5) group, postnatal day 0.5 (PND 0.5) group, and postnatal day 7 (PND 7) group, with 6 mice in each group, and the heart tissue of fetal and neonatal mice was collected. Colorimetry was used to measure the activities of histone acetylases (HATs) and histone methyltransferases (HMTs) in the myocardium. Western blot was used to measure the expression of H3K9ac and H3K9me3 in the myocardium. RESULTS: Colorimetry showed that the activities of HATs and HMTs were higher before birth and were lower after birth. There was a significant difference in the activity of HATs in the myocardium between the PND 0.5 and PND 7 groups and the ED 14.5 group (P<0.05), as well as between the PND 7 group and the ED 16.5 group (P<0.05). There was also a significant difference in the activity of HMTs in the myocardium between the PND 7 group and the ED 14.5 and ED 16.5 groups (P<0.05). Western blot showed higher expression of H3K9ac and H3K9me3 before birth and lower expression of H3K9ac and H3K9me3 after birth, and there were significant differences in the expression H3K9ac and H3K9me3 in the myocardium between the PND 0.5 and PND 7 groups and the ED 14.5 and ED 16.5 groups (P<0.05). CONCLUSIONS: The dynamic expression of HATs, HMTs, H3K9ac, and H3K9me3 is observed during cardiomyogenesis, suggesting that histone H3K9ac acetylation and histone H3K9me3 methylation mediated by HATs and HMTs may play a role in interactive regulation during cardiomyogenesis.

JNK signaling-dependent regulation of histone acetylation are involved in anacardic acid alleviates cardiomyocyte hypertrophy induced by phenylephrine.

Cardiac hypertrophy is a complex process induced by the activation of multiple signaling pathways. We previously reported that anacardic acid (AA), a histone acetyltransferase (HAT) inhibitor, attenuates phenylephrine (PE)-induced cardiac hypertrophy by downregulating histone H3 acetylation at lysine 9 (H3K9ac). Unfortunately, the related upstream signaling events remained unknown. The mitogen-activated protein kinase (MAPK) pathway is an important regulator of cardiac hypertrophy. In this study, we explored the role of JNK/MAPK signaling pathway in cardiac hypertrophy induced by PE. The mice cardiomyocyte hypertrophy model was successfully established by treating cells with PE in vitro. This study showed that p-JNK directly interacts with HATs (P300 and P300/CBP-associated factor, PCAF) and alters H3K9ac. In addition, both the JNK inhibitor SP600125 and the HAT inhibitor AA attenuated p-JNK overexpression and H3K9ac hyperacetylation by inhibiting P300 and PCAF during PE-induced cardiomyocyte hypertrophy. Moreover, we demonstrated that both SP600125 and AA attenuate the overexpression of cardiac hypertrophy-related genes (MEF2A, ANP, BNP, and ß-MHC), preventing cardiomyocyte hypertrophy and dysfunction. These results revealed a novel mechanism through which AA might protect mice from PE-induced cardiomyocyte hypertrophy. In particular, AA inhibits the effects of JNK signaling on HATs-mediated histone acetylation, and could therefore be used to prevent and treat pathological cardiac hypertrophy.

Interactions between the ERK1/2 signaling pathway and PCAF play a key role in PE­induced cardiomyocyte hypertrophy.

Cardiomyocyte hypertrophy is a compensatory phase of chronic heart failure that is induced by the activation of multiple signaling pathways. The extracellular signal­regulated protein kinase (ERK) signaling pathway is an important regulator of cardiomyocyte hypertrophy. In our previous study, it was demonstrated that phenylephrine (PE)­induced cardiomyocyte hypertrophy involves the hyperacetylation of histone H3K9ac by P300/CBP­associated factor (PCAF). However, the upstream signaling pathway has yet to be fully identified. In the present study, the role of the extracellular signal­regulated protein kinase (ERK)1/2 signaling pathway in PE­induced cardiomyocyte hypertrophy was investigated. The mice cardiomyocyte hypertrophy model was successfully established by treating cells with PE in vitro. The results showed that phospho­(p­)ERK1/2 interacted with PCAF and modified the pattern of histone H3K9ac acetylation. An ERK inhibitor (U0126) and/or a histone acetylase inhibitor (anacardic acid; AA) attenuated the overexpression of phospho­ERK1/2 and H3K9ac hyperacetylation by inhibiting the expression of PCAF in PE­induced cardiomyocyte hypertrophy. Moreover, U0126 and/or AA could attenuate the overexpression of several biomarker genes related to cardiac hypertrophy (myocyte enhancer factor 2C, atrial natriuretic peptide, brain natriuretic peptide and ß­myosin heavy chain) and prevented cardiomyocyte hypertrophy. These results revealed a novel mechanism in that AA protects against PE­induced cardiomyocyte hypertrophy in mice via the ERK1/2 signaling pathway, and by modifying the acetylation of H3K9ac. These findings may assist in the development of novel methods for preventing and treating hypertrophic cardiomyopathy.