Inhibition of p300-HAT results in a reduced histone acetylation and down-regulation of gene expression in cardiac myocytes

Fine particulate matter‑induced cardiac developmental toxicity (Review)

Fine particulate matter (PM2.5) has become an important risk factor threatening human health. Epidemiological and toxicological investigations have revealed that PM2.5 not only leads to cardiovascular dysfunction, but it also gives rise to various adverse health effects on the human body, such as cardiovascular and cerebrovascular diseases, cancers, neurodevelopmental disorders, depression and autism. PM2.5 is able to penetrate both respiratory and placental barriers, thereby resulting in negative effects on fetal development. A large body of epidemiological evidences has suggested that gestational exposure to PM2.5 increases the incidence of congenital diseases in offspring, including congenital heart defects. In addition, animal model studies have revealed that gestational exposure to PM2.5 can disrupt normal heart development in offspring, although the potential molecular mechanisms have yet to be fully elucidated. The aim of the present review was to provide a brief overview of what is currently known regarding the molecular mechanisms underlying cardiac developmental toxicity in offspring induced by gestational exposure to PM2.5.

HDAC6 inhibition disrupts HDAC6-P300 interaction reshaping the cancer chromatin landscape

BACKGROUND

Histone deacetylases (HDACs) are crucial regulators of gene expression, DNA synthesis, and cellular processes, making them essential targets in cancer research. HDAC6, specifically, influences protein stability and chromatin dynamics. Despite HDAC6's potential therapeutic value, its exact role in gene regulation and chromatin remodeling needs further clarification. This study examines how HDAC6 inactivation influences lysine acetyltransferase P300 stabilization and subsequent effects on chromatin structure and function in cancer cells.

METHODS AND RESULTS

We employed the HDAC6 inhibitor ITF3756, siRNA, or CRISPR/Cas9 gene editing to inactivate HDAC6 in different epigenomic backgrounds. Constantly, this inactivation led to significant changes in chromatin accessibility, particularly increased acetylation of histone H3 lysines 9, 14, and 27 (ATAC-seq and H3K27Ac ChIP-seq analysis). Transcriptomics, proteomics, and gene ontology analysis revealed gene changes in cell proliferation, adhesion, migration, and apoptosis. Significantly, HDAC6 inactivation altered P300 ubiquitination, stabilizing P300 and leading to downregulating genes critical for cancer cell survival.

CONCLUSIONS

Our study highlights the substantial impact of HDAC6 inactivation on the chromatin landscape of cancer cells and suggests a role for P300 in contributing to the anticancer effects. The stabilization of P300 with HDAC6 inhibition proposes a potential shift in therapeutic focus from HDAC6 itself to its interaction with P300. This finding opens new avenues for developing targeted cancer therapies, improving our understanding of epigenetic mechanisms in cancer cells.

Molecular changes in endometrium origin stromal cells during initiation of cardiomyogenic differentiation induced with Decitabine, Angiotensin II and TGF- β1

Stem cells' differentiation toward cardiac lineage is a complex process dependent on various alterations in molecular basis and regulation pathways. The aim of the study is to show that endometrium-derived stromal cells - menstrual, endometrial and endometriotic, could be an attractive source for examination of the mechanisms underlying cardiomyogenesis. After treatment with Decitabine, Angiotensin II and TGF-β1, cells demonstrated morphological dedifferentiation into early cardiomyocyte-like cells and expressed CD36, CD106, CD172a typically used to sort for human pluripotent stem cell-derived cardiomyocytes. RT-qPCR revealed changed cells' genetic profiles, as majority of cardiac lineage differentiation related genes and cardiac ion channels (calcium, sodium, potassium) coding genes were upregulated after 6 and 13 days of exposure. Additionally, analysis of expression of various signaling proteins (FOXO1, PDGFB, TGFBR1, mTOR, VEGFA, WNT4, Notch1) coding genes showed differences between cell cultures as they seem to employ distinct signaling pathways through differentiation initiation. Early stages of differentiation had biggest impact on cardiomyogenesis related proteins (Nkx-2.5, EZH2, FOXO3a, H3K9Ac) levels, as we noticed after conducting Western blot and as expected, early cardiac transcription factor Nkx-2.5 was highly expressed and localized in nucleus of differentiating cells. These findings led us to assess endometrium origin stromal cells' potential to differentiate towards cardiomyogenic lineage and better understand the regulation of complex differentiation processes in ex vivo model systems.

Epigenetic Regulation of Mammalian Cardiomyocyte Development

The heart is the first organ formed during mammalian development and functions to distribute nutrients and oxygen to other parts of the developing embryo. Cardiomyocytes are the major cell types of the heart and provide both structural support and contractile function to the heart. The successful differentiation of cardiomyocytes during early development is under tight regulation by physical and molecular factors. We have reviewed current studies on epigenetic factors critical for cardiomyocyte differentiation, including DNA methylation, histone modifications, chromatin remodelers, and noncoding RNAs. This review also provides comprehensive details on structural and morphological changes associated with the differentiation of fetal and postnatal cardiomyocytes and highlights their differences. A holistic understanding of all aspects of cardiomyocyte development is critical for the successful in vitro differentiation of cardiomyocytes for therapeutic purposes.

Epigenetic Modification Factors and microRNAs Network Associated with Differentiation of Embryonic Stem Cells and Induced Pluripotent Stem Cells toward Cardiomyocytes: A Review

More research is being conducted on myocardial cell treatments utilizing stem cell lines that can develop into cardiomyocytes. All of the forms of cardiac illnesses have shown to be quite amenable to treatments using embryonic (ESCs) and induced pluripotent stem cells (iPSCs). In the present study, we reviewed the differentiation of these cell types into cardiomyocytes from an epigenetic standpoint. We also provided a miRNA network that is devoted to the epigenetic commitment of stem cells toward cardiomyocyte cells and related diseases, such as congenital heart defects, comprehensively. Histone acetylation, methylation, DNA alterations, N6-methyladenosine (m⁶a) RNA methylation, and cardiac mitochondrial mutations are explored as potential tools for precise stem cell differentiation.

Targeting Epigenetic Regulation of Cardiomyocytes through Development for Therapeutic Cardiac Regeneration after Heart Failure

Cardiovascular diseases are the leading cause of death globally, with no cure currently. Therefore, there is a dire need to further understand the mechanisms that arise during heart failure. Notoriously, the adult mammalian heart has a very limited ability to regenerate its functional cardiac cells, cardiomyocytes, after injury. However, the neonatal mammalian heart has a window of regeneration that allows for the repair and renewal of cardiomyocytes after injury. This specific timeline has been of interest in the field of cardiovascular and regenerative biology as a potential target for adult cardiomyocyte repair. Recently, many of the neonatal cardiomyocyte regeneration mechanisms have been associated with epigenetic regulation within the heart. This review summarizes the current and most promising epigenetic mechanisms in neonatal cardiomyocyte regeneration, with a specific emphasis on the potential for targeting these mechanisms in adult cardiac models for repair after injury.

Epigenetic Regulation of Cardiomyocyte Differentiation from Embryonic and Induced Pluripotent Stem Cells

With the intent to achieve the best modalities for myocardial cell therapy, different cell types are being evaluated as potent sources for differentiation into cardiomyocytes. Embryonic stem cells and induced pluripotent stem cells have great potential for future progress in the treatment of myocardial diseases. We reviewed aspects of epigenetic mechanisms that play a role in the differentiation of these cells into cardiomyocytes. Cardiomyocytes proliferate during fetal life, and after birth, they undergo permanent terminal differentiation. Upregulation of cardiac-specific genes in adults induces hypertrophy due to terminal differentiation. The repression or expression of these genes is controlled by chromatin structural and epigenetic changes. However, few studies have reviewed and analyzed the epigenetic aspects of the differentiation of embryonic stem cells and induced pluripotent stem cells into cardiac lineage cells. In this review, we focus on the current knowledge of epigenetic regulation of cardiomyocyte proliferation and differentiation from embryonic and induced pluripotent stem cells through histone modification and microRNAs, the maintenance of pluripotency, and its alteration during cardiac lineage differentiation.

Epigenetics and Heart Development

Epigenetic control of gene expression during cardiac development and disease has been a topic of intense research in recent years. Advances in experimental methods to study DNA accessibility, transcription factor occupancy, and chromatin conformation capture technologies have helped identify regions of chromatin structure that play a role in regulating access of transcription factors to the promoter elements of genes, thereby modulating expression. These chromatin structures facilitate enhancer contacts across large genomic distances and function to insulate genes from cis-regulatory elements that lie outside the boundaries for the gene of interest. Changes in transcription factor occupancy due to changes in chromatin accessibility have been implicated in congenital heart disease. However, the factors controlling this process and their role in changing gene expression during development or disease remain unclear. In this review, we focus on recent advances in the understanding of epigenetic factors controlling cardiac morphogenesis and their role in diseases.

The Anti-Inflammatory Properties of Phytochemicals and Their Effects on Epigenetic Mechanisms Involved in TLR4/NF-κB-Mediated Inflammation

Innate immune response induces positive inflammatory transducers and regulators in order to attack pathogens, while simultaneously negative signaling regulators are transcribed to maintain innate immune homeostasis and to avoid persistent inflammatory immune responses. The gene expression of many of these regulators is controlled by different epigenetic modifications. The remarkable impact of epigenetic changes in inducing or suppressing inflammatory signaling is being increasingly recognized. Several studies have highlighted the interplay of histone modification, DNA methylation, and post-transcriptional miRNA-mediated modifications in inflammatory diseases, and inflammation-mediated tumorigenesis. Targeting these epigenetic alterations affords the opportunity of attenuating different inflammatory dysregulations. In this regard, many studies have identified the significant anti-inflammatory properties of distinct naturally-derived phytochemicals, and revealed their regulatory capacity. In the current review, we demonstrate the signaling cascade during the immune response and the epigenetic modifications that take place during inflammation. Moreover, we also provide an updated overview of phytochemicals that target these mechanisms in macrophages and other experimental models, and go on to illustrate the effects of these phytochemicals in regulating epigenetic mechanisms and attenuating aberrant inflammation.

Transcriptional Regulation of Postnatal Cardiomyocyte Maturation and Regeneration

During the postnatal period, mammalian cardiomyocytes undergo numerous maturational changes associated with increased cardiac function and output, including hypertrophic growth, cell cycle exit, sarcomeric protein isoform switching, and mitochondrial maturation. These changes come at the expense of loss of regenerative capacity of the heart, contributing to heart failure after cardiac injury in adults. While most studies focus on the transcriptional regulation of embryonic or adult cardiomyocytes, the transcriptional changes that occur during the postnatal period are relatively unknown. In this review, we focus on the transcriptional regulators responsible for these aspects of cardiomyocyte maturation during the postnatal period in mammals. By specifically highlighting this transitional period, we draw attention to critical processes in cardiomyocyte maturation with potential therapeutic implications in cardiovascular disease.

Effects of PM2.5 exposure in utero on heart injury, histone acetylation and GATA4 expression in offspring mice

Atmospheric fine particulate matter exposure (PM_2.5) can increase the incidence and mortality of heart disease, and raise the risk of fetal congenital heart defect, which have recently drawn much attention. In this study, C57BL/6 mice were exposed to PM_2.5 (approximately equivalent to 174 μg/m³) by intratracheal instillation during the gestation. After birth, 10 weeks old offspring mice were divided into four groups: male exposed group (ME), female exposed group (FE), male control group (MC), female control group (FC). The pathological injury, pro-inflammatory cytokines, histone acetylation levels, and expressions of GATA-binding protein 4 (GATA4) and downstream genes were investigated. The results showed that exposure to PM_2.5 in utero increased pathological damage and TNF-α and IL-6 levels in hearts of offspring mice, and effects in ME were more serious than FE. Notably, GATA4 protein levels in hearts in ME were significantly lower than that of MC, accompanied by down-regulation of histone acetyltransferase (HAT)-p300 and up-regulation of histone deacetylase-SIRT3. As GATA4 downstream genes, ratios of β-MHC gene expression to α-MHC significantly raised in ME relative to the MC. Results of chromatin immunoprecipitation (ChIP)-qPCR assay found that binding levels of acetylated histone 3 lysine 9 (H3K9ac) in GATA4 promoter region in the hearts of ME or FE were markedly decreased compared with their corresponding control groups. It suggested that maternal exposure to PM_2.5 may cause cardiac injury in the offspring, heart damage of male mice was worse than female mice, in which process HAT-p300, H3K9ac, transcription factor GATA4 may play an important regulation role.

Dietary natural products as epigenetic modifiers in aging-associated inflammation and disease

Covering: up to 2020Chronic, low-grade inflammation is linked to aging and has been termed "inflammaging". Inflammaging is considered a key contributor to the development of metabolic dysfunction and a broad spectrum of diseases or disorders including declines in brain and heart function. Genome-wide association studies (GWAS) coupled with epigenome-wide association studies (EWAS) have shown the importance of diet in the development of chronic and age-related diseases. Moreover, dietary interventions e.g. caloric restriction can attenuate inflammation to delay and/or prevent these diseases. Common themes in these studies entail the use of phytochemicals (plant-derived compounds) or the production of short chain fatty acids (SCFAs) as epigenetic modifiers of DNA and histone proteins. Epigenetic modifications are dynamically regulated and as such, serve as potential therapeutic targets for the treatment or prevention of age-related disease. In this review, we will focus on the role for natural products that include phytochemicals and short chain fatty acids (SCFAs) as regulators of these epigenetic adaptations. Specifically, we discuss regulators of methylation, acetylation and acylation, in the protection from chronic inflammation driven metabolic dysfunction and deterioration of neurocognitive and cardiac function.

Maternal Exposure to High-Fat Diet Induces Long-Term Derepressive Chromatin Marks in the Heart

Heart diseases are a leading cause of death. While the link between early exposure to nutritional excess and heart disease risk is clear, the molecular mechanisms involved are poorly understood. In the developmental programming field, increasing evidence is pointing out the critical role of epigenetic mechanisms. Among them, polycomb repressive complex 2 (PRC2) and DNA methylation play a critical role in heart development and pathogenesis. In this context, we aimed at evaluating the role of these epigenetic marks in the long-term cardiac alterations induced by early dietary challenge. Using a model of rats exposed to maternal high-fat diet during gestation and lactation, we evaluated cardiac alterations at adulthood. Expression levels of PRC2 components, its histone marks di- and trimethylated histone H3 (H3K27me2/3), associated histone mark (ubiquitinated histone H2A, H2AK119ub1) and target genes were measured by Western blot. Global DNA methylation level and DNA methyl transferase 3B (DNMT3B) protein levels were measured. Maternal high-fat diet decreased H3K27me3, H2Ak119ub1 and DNA methylation levels, down-regulated the enhancer of zeste homolog 2 (EZH2), and DNMT3B expression. The levels of the target genes, isl lim homeobox 1 (Isl1), six homeobox 1 (Six1) and mads box transcription enhancer factor 2, polypeptide C (Mef2c), involved in cardiac pathogenesis were up regulated. Overall, our data suggest that the programming of cardiac alterations by maternal exposure to high-fat diet involves the derepression of pro-fibrotic and pro-hypertrophic genes through the induction of EZH2 and DNMT3B deficiency.

p300 mediates the histone acetylation of ORMDL3 to affect airway inflammation and remodeling in asthma

BACKGROUND

Bronchial asthma is affected by both environmental and genetic factors. The orosomucoid 1-like protein 3 (ORMDL3) gene is related to childhood asthma and is involved in airway inflammation and airway remodeling. The ORMDL3 promoter contains binding sites for the histone acetylase p300. Gene expression can be affected by epigenetic modifications. This study aimed to investigate whether the p300-mediated histone acetylation (HAT) of ORMDL3 gene affects airway inflammation and remodeling in asthma.

METHODS

16HBE14o- cells were transfected with various concentrations of a wild-type p300 plasmid or p300HAT-deletion plasmids. A dual luciferase reporter assay was used to examine the effect of p300-mediated HAT on the ORMDL3 promoter. Thirty BALB/c mice were randomly divided into a control group, an ovalbumin (OVA)-induced asthma group and an asthma + C646 (a selective inhibitor of p300) group. Noninvasive lung function tests were conducted to examine airway hyperreactivity (AHR) in the different groups. HE and Masson's trichrome staining was performed to examine airway remodeling and inflammation. Immunohistochemistry, western blotting and real-time PCR were used to analyze ORMDL3 expression in lung tissues. ELISA and western blotting were used to evaluate the HAT status in lung tissue. The ChIP assay was used to determine the relationship of the ORMDL3 promoter to p300 or acetylated histone H3 (aceH3).

RESULTS

p300 activated transcription from the ORMDL3 promoter, resulting in an increase in endogenous ORMDL3 mRNA levels. ORMDL3 promoter activity was reduced when the HAT activity of p300 was lost. ORMDL3 expression was elevated, and HAT activity was high in the lung tissues of asthmatic mice. p300 and aceH3 bound to the promoter region of ORMDL3. In the asthma group, the amounts of p300 and aceH3 recruited to the ORMDL3 promoter were increased. C646 inhibited p300 expression and reduced HAT activity and aceH3 levels in asthmatic mice, thereby reducing ORMDL3 expression and relieving AHR and airway remodeling.

CONCLUSION

p300-mediated HAT modulates the expression of the asthma susceptibility gene ORMDL3, thereby improving the process of airway inflammation and remodeling in asthma.

Curcuminoids: Implication for inflammation and oxidative stress in cardiovascular diseases

It has been extensively verified that inflammation and oxidative stress play important roles in the pathogenesis of cardiovascular diseases (CVDs). Curcuminoids, from the plant Curcuma longa, have three major active ingredients, which include curcumin (curcumin I), demethoxycurcumin, and bisdemethoxycurcumin. Curcuminoids have been used in traditional medicine for CVDs' management and other comorbidities for centuries. Numerous studies had delineated their anti-inflammatory, antioxidative, and other medicinally relevant properties. Animal experiments and clinical trials have also demonstrated that turmeric and curcuminoids can effectively reduce atherosclerosis, cardiac hypertrophy, hypertension, ischemia/reperfusion injury, and diabetic cardiovascular complications. In this review, we introduce and summarize curcuminoids' molecular and biological significance, while focusing on their mechanistic anti-inflammatory/antioxidative involvements in CVDs and preventive effects against CVDs, and, finally, discuss relevant clinical applications.

Genetic and epigenetic regulation of cardiomyocytes in development, regeneration and disease

Embryonic and postnatal life depend on the uninterrupted function of cardiac muscle cells. These cells, termed cardiomyocytes, display many fascinating behaviors, including complex morphogenic movements, interactions with other cell types of the heart, persistent contractility and quiescence after birth. Each of these behaviors depends on complex interactions between both cardiac-restricted and widely expressed transcription factors, as well as on epigenetic modifications. Here, we review recent advances in our understanding of the genetic and epigenetic control of cardiomyocyte differentiation and proliferation during heart development, regeneration and disease. We focus on those regulators that are required for both heart development and disease, and highlight the regenerative principles that might be manipulated to restore function to the injured adult heart.

Acetylation of H3K4, H3K9, and H3K27 mediated by p300 regulates the expression of GATA4 in cardiocytes

GATA4 is a particularly important cardiogenic transcription factor and serves as a potent driver of cardiogenesis. Recent progress in the field has made it clear that histone acetylation can influence gene expression through changing the structure of chromatin. Our previous research had revealed that hypo-acetylation could repress gata4 expression in cardiocytes, however the underlying mechanism by which this occurred was still unclear. To reveal the mechanism of histone acetylation involved in the regulation of gata4 transcription, we concentrated on P300, one of the important histone acetyltransferase associated with cardiogenesis. We found that P300 participated in gata4 expression through regulating histone acetylation in embryonic mouse hearts. RNAi-mediated downregulation of P300 modulated the global acetylation of H3 and the acetylation of H3K4, H3K9, and H3K27 in gata4 and Tbx5 promoters. Interestingly, there was an obvious inhibition of gata4 transcription, whereas Tbx5 was not influenced. Furthermore, SGC-CBP30, the selective inhibitor of the bromodomain in CBP/P300, downregulated gata4 transcription by repressing the acetylation of H3K4, H3K9, and H3K27 in the gata4 promoters. Taken together, our results identified that acetylation of H3K4, H3K9, and H3K27 mediated by P300 plays an important role in regulation of gata4 expression in cardiogenesis.

An inhibitor screen identifies histone-modifying enzymes as mediators of polymer-mediated transgene expression from plasmid DNA

Effective transgene expression in mammalian cells relies on successful delivery, cytoplasmic trafficking, and nuclear translocation of the delivered vector, but delivery is impeded by several formidable physicochemical barriers on the surface of and within the target cell. Although methods to overcome cellular exclusion and endosomal entrapment have been studied extensively, strategies to overcome inefficient nuclear entry and subsequent intranuclear barriers to effective transient gene expression have only been sparsely explored. In particular, the role of nuclear packaging of DNA with histone proteins, which governs endogenous gene expression, has not been extensively elucidated in the case of exogenously delivered plasmids. In this work, a parallel screen of small molecule inhibitors of chromatin-modifying enzymes resulted in the identification of class I/II HDACs, sirtuins, LSD1, HATs, and the methyltransferases EZH2 and MLL as targets whose inhibition led to the enhancement of transgene expression following polymer-mediated delivery of plasmid DNA. Quantitative PCR studies revealed that HDAC inhibition enhances the amount of plasmid DNA delivered to the nucleus in UMUC3 human bladder cancer cells. Native chromatin immunoprecipitation (N-ChIP)-qPCR experiments in CHO-K1 cells indicated that plasmids indeed interact with intracellular core Histone H3, and inhibitors of HDAC and LSD1 proteins are able to modulate this interaction. Pair-wise treatments of effective inhibitors led to synergistic enhancement of transgene expression to varying extents in both cell types. Our results demonstrate that the ability to modulate enzymes that play a role in epigenetic processes can enhance the efficacy of non-viral gene delivery, resulting in significant implications for gene therapy and industrial biotechnology.

Are targeted therapies for diabetic cardiomyopathy on the horizon?

Diabetes increases the risk of heart failure approximately 2.5-fold, independent of coronary artery disease and other comorbidities. This process, termed diabetic cardiomyopathy, is characterized by initial impairment of left ventricular (LV) relaxation followed by LV contractile dysfunction. Post-mortem examination reveals that human diastolic dysfunction is closely associated with LV damage, including cardiomyocyte hypertrophy, apoptosis and fibrosis, with impaired coronary microvascular perfusion. The pathophysiological mechanisms underpinning the characteristic features of diabetic cardiomyopathy remain poorly understood, although multiple factors including altered lipid metabolism, mitochondrial dysfunction, oxidative stress, endoplasmic reticulum (ER) stress, inflammation, as well as epigenetic changes, are implicated. Despite a recent rise in research interrogating these mechanisms and an increased understanding of the clinical importance of diabetic cardiomyopathy, there remains a lack of specific treatment strategies. How the chronic metabolic disturbances observed in diabetes lead to structural and functional changes remains a pertinent question, and it is hoped that recent advances, particularly in the area of epigenetics, among others, may provide some answers. This review hence explores the temporal onset of the pathological features of diabetic cardiomyopathy, and their relative contribution to the resultant disease phenotype, as well as both current and potential therapeutic options. The emergence of glucose-optimizing agents, namely glucagon-like peptide-1 (GLP-1) agonists and sodium/glucose co-transporter (SGLT)2 inhibitors that confer benefits on cardiovascular outcomes, together with novel experimental approaches, highlight a new and exciting era in diabetes research, which is likely to result in major clinical impact.

Curcumin as a potential protective compound against cardiac diseases

Curcumin, which was first used 3000 years ago as an anti-inflammatory agent, is a well-known bioactive compound derived from the active ingredient of turmeric (Curcuma longa). Previous research has demonstrated that curcumin has immense therapeutic potential in a variety of diseases via anti-oxidative, anti-apoptotic, and anti-inflammatory pathways. Cardiac diseases are the leading cause of mortality worldwide and cause considerable harm to human beings. Numerous studies have suggested that curcumin exerts a protective role in the human body whereas its actions in cardiac diseases remain elusive and poorly understood. On the basis of the current evidence, we first give a brief introduction of cardiac diseases and curcumin, especially regarding the effects of curcumin in embryonic heart development. Secondly, we analyze the basic roles of curcumin in pathways that are dysregulated in cardiac diseases, including oxidative stress, apoptosis, and inflammation. Thirdly, actions of curcumin in different cardiac diseases will be discussed, as will relevant clinical trials. Eventually, we would like to discuss the existing controversial opinions and provide a detailed analysis followed by the remaining obstacles, advancement, and further prospects of the clinical application of curcumin. The information compiled here may serve as a comprehensive reference of the protective effects of curcumin in the heart, which is significant to the further research and design of curcumin analogs as therapeutic options for cardiac diseases.

Sodium Butyrate Protects -Against High Fat Diet-Induced Cardiac Dysfunction and Metabolic Disorders in Type II Diabetic Mice

Histone deacetylases are recently identified to act as key regulators for cardiac pathophysiology and metabolic disorders. However, the function of histone deacetylase (HDAC) in controlling cardiac performance in Type II diabetes and obesity remains unknown. Here, we determine whether HDAC inhibition attenuates high fat diet (HFD)-induced cardiac dysfunction and improves metabolic features. Adult mice were fed with either HFD or standard chow food for 24 weeks. Starting at 12 weeks, mice were divided into four groups randomly, in which sodium butyrate (1%), a potent HDAC inhibitor, was provided to chow and HFD-fed mice in drinking water, respectively. Glucose intolerance, metabolic parameters, cardiac function, and remodeling were assessed. Histological analysis and cellular signaling were examined at 24 weeks following euthanization of mice. HFD-fed mice demonstrated myocardial dysfunction and profound interstitial fibrosis, which were attenuated by HDAC inhibition. HFD-induced metabolic syndrome features insulin resistance, obesity, hyperinsulinemia, hyperglycemia, lipid accumulations, and cardiac hypertrophy, these effects were prevented by HDAC inhibition. Furthermore, HDAC inhibition attenuated myocyte apoptosis, reduced production of reactive oxygen species, and increased angiogenesis in the HFD-fed myocardium. Notably, HFD induced decreases in MKK3, p38, p38 regulated/activated protein kinase (PRAK), and Akt-1, but not p44/42 phosphorylation, which were prevented by HDAC inhibition. These results suggest that HDAC inhibition plays a critical role to preserve cardiac performance and mitigate metabolic disorders in obesity and diabetes, which is associated with MKK3/p38/PRAK pathway. The study holds promise in developing a new therapeutic strategy in the treatment of Type II diabetic-induced heart failure and metabolic disorders. J. Cell. Biochem. 118: 2395-2408, 2017. © 2017 Wiley Periodicals, Inc.

Inhibition of histone acetylation by curcumin reduces alcohol-induced fetal cardiac apoptosis

Background

Prenatal alcohol exposure may cause cardiac development defects, however, the underlying mechanisms are not yet clear. In the present study we have investigated the roles of histone modification by curcumin on alcohol induced fetal cardiac abnormalities during the development.

Methods and results

Q-PCR and Western blot results showed that alcohol exposure increased gene and active forms of caspase-3 and caspase-8, while decreased gene and protein of bcl-2. ChIP assay results showed that, alcohol exposure increased the acetylation of histone H3K9 near the promoter region of caspase-3 and caspase-8, and decreased the acetylation of histone H3K9 near the promoter region of bcl-2. TUNEL assay data revealed that alcohol exposure increased the apoptosis levels in the embryonic hearts. In vitro experiments demonstrated that curcumin treatment could reverse the up-regulation of active forms of caspase-3 and caspase-8, and down-regulation of bcl-2 induced by alcohol treatment. In addition, curcumin also corrected the high level of histone H3K9 acetylation induced by alcohol. Moreover, the high apoptosis level induced by alcohol was reversed after curcumin treatment in cardiac cells.

Conclusions

These findings indicate that histone modification may play an important role in mediating alcohol induced fetal cardiac apoptosis, possibly through the up-regulation of H3K9 acetylation near the promoter regions of apoptotic genes. Curcumin treatment may correct alcohol-mediated fetal cardiac apoptosis, suggesting that curcumin may play a protective role against alcohol abuse caused cardiac damage during pregnancy.

Treatment of cardiovascular pathology with epigenetically active agents: Focus on natural and synthetic inhibitors of DNA methylation and histone deacetylation

Cardiovascular disease (CVD) retains a leadership as a major cause of human death worldwide. Although a substantial progress was attained in the development of cardioprotective and vasculoprotective drugs, a search for new efficient therapeutic strategies and promising targets is under way. Modulation of epigenetic CVD mechanisms through administration epigenetically active agents is one of such new approaches. Epigenetic mechanisms involve heritable changes in gene expression that are not linked to the alteration of DNA sequence. Pathogenesis of CVDs is associated with global genome-wide changes in DNA methylation and histone modifications. Epigenetically active compounds that influence activity of epigenetic modulators such as DNA methyltransferases (DNMTs), histone acetyltransferases, histone deacetylases (HDACs), etc. may correct these pathogenic changes in the epigenome and therefore be used for CVD therapy. To date, many epigenetically active natural substances (such as polyphenols and flavonoids) and synthetic compounds such as DNMT inhibitors or HDAC inhibitors are known. Both native and chemical DNMT and HDAC inhibitors possess a wide range of cytoprotective activities such as anti-inflammatory, antioxidant, anti-apoptotic, anti-anfibrotic, and anti-hypertrophic properties, which are beneficial of treatment of a variety of CVDs. However, so far, only synthetic DNMT inhibitors enter clinical trials while synthetic HDAC inhibitors are still under evaluation in preclinical studies. In this review, we consider epigenetic mechanisms such as DNA methylation and histone modifications in cardiovascular pathology and the epigenetics-based therapeutic approaches focused on the implementation of DNMT and HDAC inhibitors.

Oridonin, a novel lysine acetyltransferases inhibitor, inhibits proliferation and induces apoptosis in gastric cancer cells through p53- and caspase-3-mediated mechanisms

Lysine acetylation has been reported to involve in the pathogenesis of multiple diseases including cancer. In our screening study to identify natural compounds with lysine acetyltransferase inhibitor (KATi) activity, oridonin was found to possess acetyltransferase-inhibitory effects on multiple acetyltransferases including P300, GCN5, Tip60, and pCAF. In gastric cancer cells, oridonin treatment inhibited cell proliferation in a concentration-dependent manner and down-regulated the expression of p53 downstream genes, whereas p53 inhibition by PFT-α reversed the antiproliferative effects of oridonin. Moreover, oridonin treatment induced cell apoptosis, increased the levels of activated caspase-3 and caspase-9, and decreased the mitochondrial membrane potential in gastric cancer cells in a concentration-dependent manner. Caspase-3 inhibition by Ac-DEVD-CHO reversed the proapoptosis effect of oridonin. In conclusion, our study identified oridonin as a novel KATi and demonstrated its tumor suppressive effects in gastric cancer cells at least partially through p53-and caspase-3-mediated mechanisms.

Epigenetic regulation of cardiac myofibril gene expression during heart development

Cardiac gene expression regulation is controlled not only by genetic factors but also by environmental, i.e., epigenetic factors. Several environmental toxic effects such as oxidative stress and ischemia can result in abnormal myofibril gene expression during heart development. Troponin, one of the regulatory myofibril proteins in the heart, is a well-known model in study of cardiac gene regulation during the development. In our previous studies, we have demonstrated that fetal form troponin I (ssTnI) expression in the heart is partially regulated by hormones, such as thyroid hormone. In the present study, we have explored the epigenetic role of histone modification in the regulation of ssTnI expression. Mouse hearts were collected at different time of heart development, i.e., embryonic day 15.5, postnatal day 1, day 7, day 14 and day 21. Levels of histone H3 acetylation (acH3) and histone H3 lysine 9 trimethylation (H3K9me(3)) were detected using chromatin immunoprecipitation assays in slow upstream regulatory element (SURE) domain (TnI slow upstream regulatory element), 300-bp proximal upstream domain and the first intron of ssTnI gene, which are recognized as critical regions for ssTnI regulation. We found that the levels of acH3 on the SURE region were gradually decreased, corresponding to a similar decrease of ssTnI expression in the heart, whereas the levels of H3K9me(3) in the first intron of ssTnI gene were gradually increased. Our results indicate that both histone acetylation and methylation are involved in the epigenetic regulation of ssTnI expression in the heart during the development, which are the targets for environmental factors.

Curcumin-mediated cardiac defects in mouse is associated with a reduced histone H3 acetylation and reduced expression of cardiac transcription factors

Histone acetylation plays an important role in heart development. However, the mechanism(s) remains unclear. This study was designed to evaluate the effect of curcumin-caused histone hypo-acetylation on the development of mouse embryonic heart and the expression of cardiac transcription factors in vivo. The results showed that curcumin treatment significantly decreased histone acetylase activity and histone acetylation level in mouse embryonic heart. In curcumin-treated mice, the hearts on E11.5 were smaller with thinner ventricular wall and a delayed development of trabeculae and ventricular septum compared with the controls. The ventricular septum was complete on E14.5; however, the ventricular wall and septum were thinner with fewer trabeculae than those in the controls. On E17.5, the cardiac structure appeared normal, but the ventricular wall and septum were thinner. The expression of GATA4, Nkx2.5 and Mef2c in the heart on E11.5 and E14.5 was decreased significantly as compared to the controls. There was no significant difference in Mef2c expression on E17.5 between curcumin-treated group and the controls, while GATA4 and Nkx2.5 expression remained significantly reduced. These results indicate that inhibition of histone acetylation by curcumin can reduce the expression of the cardiac transcription factors resulting in an abnormal heart development in mice.

Novel curcumin analog C66 prevents diabetic nephropathy via JNK pathway with the involvement of p300/CBP-mediated histone acetylation

Glomerulosclerosis and interstitial fibrosis represent the key events in development of diabetic nephropathy (DN), with connective tissue growth factor (CTGF), plasminogen activator inhibitor-1 (PAI-1) and fibronectin 1 (FN-1) playing important roles in these pathogenic processes. To investigate whether the plant metabolite curcumin, which exerts epigenetic modulatory properties when applied as a pharmacological agent, may prevent DN via inhibition of the JNK pathway and epigenetic histone acetylation, diabetic and age-matched non-diabetic control mice were administered a 3-month course of curcumin analogue (C66), c-Jun N-terminal kinase inhibitor (JNKi, sp600125), or vehicle alone. At treatment end, half of the mice were sacrificed for analysis and the other half were maintained without treatment for an additional 3 months. Renal JNK phosphorylation was found to be significantly increased in the vehicle-treated diabetic mice, but not the C66- and JNKi-treated diabetic mice, at both the 3-month and 6-month time points. C66 and JNKi treatment also significantly prevented diabetes-induced renal fibrosis and dysfunction. Diabetes-related increases in histone acetylation, histone acetyl transferases' (HATs) activity, and the p300/CBP HAT expression were also significantly attenuated by C66 or JNKi treatment. Chromatin immunoprecipitation assays showed that C66 and JNKi treatments decreased H3-lysine9/14-acetylation (H3K9/14Ac) level and p300/CBP occupancy at the CTGF, PAI-1 and FN-1 gene promoters. Thus, C66 may significantly and persistently prevent renal injury and dysfunction in diabetic mice via down-regulation of diabetes-related JNK activation and consequent suppression of the diabetes-related increases in HAT activity, p300/CBP expression, and histone acetylation.

Knock-down of p300 decreases the proliferation and odontogenic differentiation potentiality of HDPCs

AIM

To investigate the role of p300 in the regulation of proliferation and odontogenic differentiation of human dental pulp cells (HDPCs).

METHODOLOGY

The recombinant lentiviral vector pshRNA-copGFP was used to knock-down p300 expression in HDPCs. Protein level of acetylated H3 was detected. The proliferation of HDPCs was measured using the CCK8 assay. The cell cycle and apoptosis were analysed using flow cytometry and TUNEL staining, respectively. The expression levels of Cdc25A, p21(waf1) and the cleaved products of caspase 3 and caspase 7 were determined utilizing real-time quantitative polymerase chain reaction and Western blotting analysis. The alkaline phosphatase (ALP) activity was measured, and the formation of mineralized nodules was assessed using alizarin red staining after the induction of odontogenic differentiation of HDPCs. The expression levels of the odontogenic differentiation markers DMP-1, DSPP and DSP were detected utilizing real-time quantitative polymerase chain reaction and Western blotting analysis.

RESULTS

After p300 was knocked down in HDPCs, p300 was significantly down-regulated at both the mRNA and protein levels, and histone H3 acetylation was reduced. The proliferation capacity of HDPCs was suppressed in p300 knock-down groups. The cells were arrested in the G0/G1 phase of the cell cycle, and cell apoptosis was triggered. ALP activity, the formation of mineralized nodules and the expression levels of DMP-1, DSPP and DSP were all decreased in p300-knock-down HDPCs undergoing odontogenic differentiation.

CONCLUSION

Knocking down p300 restrains the proliferation and odontogenic differentiation potentiality of HDPCs.

Epigenetic regulation of cardiac myocyte differentiation

Cardiac myocytes (CMs) proliferate robustly during fetal life but withdraw permanently from the cell cycle soon after birth and undergo terminal differentiation. This cell cycle exit is associated with the upregulation of a host of adult cardiac-specific genes. The vast majority of adult CMs (ACMs) do not reenter cell cycle even if subjected to mitogenic stimuli. The basis for this irreversible cell cycle exit is related to the stable silencing of cell cycle genes specifically involved in the progression of G2/M transition and cytokinesis. Studies have begun to clarify the molecular basis for this stable gene repression and have identified epigenetic and chromatin structural changes in this process. In this review, we summarize the current understanding of epigenetic regulation of CM cell cycle and cardiac-specific gene expression with a focus on histone modifications and the role of retinoblastoma family members.

Histone acetyltransferase p300 mediates histone acetylation of PS1 and BACE1 in a cellular model of Alzheimer's disease

Epigenetic modifications, particularly histone acetylation, have been implicated in Alzheimer's disease (AD). While previous studies have suggested that histone hypoacetylation may regulate the expression of genes associated with memory and learning in AD, little is known about histone regulation of AD-related genes such as Presenilin 1(PS1) and beta-site amyloid precursor protein cleaving enzyme 1(BACE1). By utilizing neuroblastoma N2a cells transfected with Swedish mutated human amyloid precursor protein (APP) (N2a/APPswe) and wild-type APP (N2a/APPwt) as cellular models of AD, we examined the alterations of histone acetylation at the promoter regions of PS1 and BACE1 in these cells. Our results revealed that histone H3 acetylation in PS1 and BACE1 promoters is markedly increased in N2a/APPswe cells when compared to N2a/APPwt cells and control cells (vector-transfected), respectively, causing the elevated expression of PS1 and BACE1. In addition, expression of histone acetyltransferase (HAT) adenoviral E1A-associated 300-kDa protein (p300) is dramatically enhanced in N2a/APPswe cells compared to N2a/APPwt and control cells. We have further demonstrated the direct binding of p300 protein to the PS1 and BACE1 promoters in N2a/APPswe cells. The expression levels of H3 acetylation of the PS1 and BACE1 promoters and p300 protein, however, were found to be not significantly different in N2a/APPwt cells when compared to controls in our studies. Furthermore, curcumin, a natural selective inhibitor of p300 in HATs, significantly suppressed the expression of PS1 and BACE1 through inhibition of H3 acetylation in their promoter regions in N2a/APPswe cells. These findings indicated that histone acetyltransferase p300 plays a critical role in controlling the expression of AD-related genes through regulating the acetylation of their promoter regions, suggesting that p300 may represent a novel potential therapeutic target for AD.

The histone acetyltransferase p300 regulates the expression of pluripotency factors and odontogenic differentiation of human dental pulp cells

p300 is a well-known histone acetyltransferase (HAT) and coactivator that plays vital roles in many physiological processes. Despite extensive research on the involvement of p300 in the regulation of transcription in numerous cell lines, the roles of this protein in regulating pluripotency genes and odontogenic differentiation in human dental pulp cells (HDPCs) are poorly understood. To address this issue, we investigated the expression of OCT4, NANOG and SOX2 and the proliferation and odontogenic differentiation capacity of HDPCs following p300 overexpression. We found that p300 overexpression did not overtly affect the ability of HDPCs to proliferate. The overexpression of p300 upregulated the promoter activity and the mRNA and protein expression of NANOG and SOX2. The HAT activity of p300 appeared to partially mediate the regulation of these factors; indeed, when a mutant form of p300 lacking the HAT domain was overexpressed, the promoter activity and expression of NANOG and SOX2 decreased relative to p300 overexpression but was greater than in the control. Furthermore, we demonstrated that the mRNA levels of the odontogenic marker genes dentine matrix protein-1 (DMP-1), dentin sialophosphoprotein (DSPP), dentin sialoprotein (DSP), osteopontin (OPN) and osteocalcin (OCN) were significantly decreased in HDPCs overexpressing p300 cultured under normal culture conditions and increased in HDPCs inducted to undergo odontogenic differentiation. This finding was further confirmed by measuring levels of alkaline phosphatase (ALP) activity and assessing the formation of mineralized nodules. The HAT activity of p300 had no significant effect on odontogenic differentiation. p300 was recruited to the promoter regions of OCN and DSPP and might be acting as a coactivator to increase the acetylation of lysine 9 of histone H3 of OCN and DSPP. Collectively, our results show that p300 plays an important role in regulating the expression of key pluripotency genes in HDPCs and modifying odontogenic differentiation.

Prenatal alcohol exposure causes the over-expression of DHAND and EHAND by increasing histone H3K14 acetylation in C57 BL/6 mice

Prenatal alcohol exposure leads to congenital heart abnormal development, its mechanisms are still unknown. Recent reports have associated alcohol exposure with histone H3 acetylation. In the present study, we have performed the experiments to test the hypothesis that histone H3K14 acetylation is the key role in the fetal heart leads to over-expression of cardiac specific genes DHAND and EHAND caused by prenatal alcohol exposure. Seventy pregnant C57BL/6 mice were divided randomly into seven groups (n=10). They were the untreated group, dimethyl sulfoxide group, alcohol exposure group, curcumin treatment group, both alcohol and curcumin treatment group, SAHA treatment group, both alcohol and SAHA treatment group. Fetal mouse hearts were collected on embryonic day 14.5. The changes of HATs activities, the acetylation levels of histone H3K14 (H3K14ac), the expression levels of cardiac specific genes DHAND and EHAND, and structure of chromatin were determined. Our data indicates that curcumin and SAHA significantly reduces and increases the activities of HATs and the levels of histone H3K14ac in fetal hearts, respectively. The expression of DHAND and EHAND is significantly down-regulated and up-regulated in the groups treated with curcumin and SAHA. Furthermore, our results from ChIP assays have shown that the histone H3K14ac connects with the DHAND and EHAND genes are significantly inhibited by curcumin and simulated by SAHA. Our study suggests that prenatal alcohol exposure causes the over-expression of DHAND and EHAND by increasing H3K14ac in mice.

High glucose induces Smad activation via the transcriptional coregulator p300 and contributes to cardiac fibrosis and hypertrophy

BACKGROUND

Despite advances in the treatment of heart failure, mortality remains high, particularly in individuals with diabetes. Activated transforming growth factor beta (TGF-β) contributes to the pathogenesis of the fibrotic interstitium observed in diabetic cardiomyopathy. We hypothesized that high glucose enhances the activity of the transcriptional co-activator p300, leading to the activation of TGF-β via acetylation of Smad2; and that by inhibiting p300, TGF-β activity will be reduced and heart failure prevented in a clinically relevant animal model of diabetic cardiomyopathy.

METHODS

p300 activity was assessed in H9c2 cardiomyoblasts under normal glucose (5.6 mmol/L-NG) and high glucose (25 mmol/L-HG) conditions. 3H-proline incorporation in cardiac fibroblasts was also assessed as a marker of collagen synthesis. The role of p300 activity in modifying TGF-β activity was investigated with a known p300 inhibitor, curcumin or p300 siRNA in vitro, and the functional effects of p300 inhibition were assessed using curcumin in a hemodynamically validated model of diabetic cardiomyopathy - the diabetic TG m(Ren-2)27 rat.

RESULTS

In vitro, H9c2 cells exposed to HG demonstrated increased p300 activity, Smad2 acetylation and increased TGF-β activity as assessed by Smad7 induction (all p < 0.05 c/w NG). Furthermore, HG induced 3H-proline incorporation as a marker of collagen synthesis (p < 0.05 c/w NG). p300 inhibition, using either siRNA or curcumin reduced p300 activity, Smad acetylation and TGF-β activity (all p < 0.05 c/w vehicle or scrambled siRNA). Furthermore, curcumin therapy reduced 3H-proline incorporation in HG and TGF-β stimulated fibroblasts (p < 0.05 c/w NG). To determine the functional significance of p300 inhibition, diabetic Ren-2 rats were randomized to receive curcumin or vehicle for 6 weeks. Curcumin treatment reduced cardiac hypertrophy, improved diastolic function and reduced extracellular matrix production, without affecting glycemic control, along with a reduction in TGF-β activity as assessed by Smad7 activation (all p < 0.05 c/w vehicle treated diabetic animals).

CONCLUSIONS

These findings suggest that high glucose increases the activity of the transcriptional co-regulator p300, which increases TGF-β activity via Smad2 acetylation. Modulation of p300 may be a novel strategy to treat diabetes induced heart failure.

Islet-1 may function as an assistant factor for histone acetylation and regulation of cardiac development-related transcription factor Mef2c expression

Objective

Islet-1 is an important transcription factor for cardiac development through mediating extensive interactions between DNA and proteins. The present study was to investigate the role of Islet-1 in regulating the expression of cardiac development-related transcription factors and mechanism.

Methods and Results

The expression of Islet-1 and histone acetylases (HATs) subtype p300 was determined in newborn mouse hearts and mouse embryonic hearts at different development stages using Western blot. The expression of Islet-1 and cardiac development-related transcription factors Mef2c, GATA4 and Tbx5 as well as histone H3 acetylation level were determined in cardiac progenitor cells with and without transfection of Islet-1 interference RNA (RNAi) in lentivirus using PCR and Western blot. Islet-1 peak expression occurred on day E14.5 in mouse embryonic heart, and was present in the promoter regions of Mef2c, GATA4 and Tbx5 that were precipitated with p300 antibody. When Islet-1 was inhibited with specific RNAi in cardiac progenitor cells, the expression of Mef2c and Tbx5, but not GATA4, was significantly suppressed along with selective reduction in histone H3 acetylation in the promoter region of Mef2c, but not GATA4 and Tbx5. The level of Mef2c DNA, not GATA4 and Tbx5, in the complex associated with p300 was significantly decreased in the cells with Islet-1 knockdown.

Conclusions

These data suggested that Islet-1 might function as an assistant factor that was involved in the regulation of histone acetylation and Mef2c expression via assisting p300 on specifically targeting the promoter of Mef2c.

Dilated cardiomyopathy and mitochondrial dysfunction in Sirt1-deficient mice: a role for Sirt1-Mef2 in adult heart

The deacetylase Sirtuin-1 (Sirt1) is involved in the cardiac hypertrophic responses and cardiac embryo morphogenesis. However, the physiological function of Sirt1 deficiency in the postnatal development of the heart remains to be characterized. The aim of the study was to investigate the relevance of Sirt1 in the development and function of the myocardium. Hearts from Sirt1-deficient mice partially or totally lacking Sirt1 protein activity were analyzed. Loss of Sirt1 activity led to dilated cardiomyopathy in adult hearts, a phenotype accompanied by reduced cardiomyocyte size and the absence of fibrosis. Morphological and functional mitochondrial abnormalities were observed in the adult hearts lacking Sirt1, suggesting that mitochondrial dysfunction contributes to the progression of the observed cardiomyopathy. Moreover, gene expression analyses revealed that mitochondrial genes were the most affected in Sirt1-deficient mice, showing a reduction in their expression. No overt cardiac dilatation was observed in neonates lacking Sirt1 activity, but first signs of mitochondrial alterations were already present. Immunoblot analyses revealed that Sirt1 is highly expressed in the heart after birth, indicating the importance of Sirt1 in the neonatal period. Finally, Sirt1 deficiency affected the acetylation pattern of the myocyte enhancer factor 2 (Mef2) transcription factors, which are critical for normal heart development and mitochondrial integrity. Collectively, our findings indicate that Sirt1 is essential for the maintenance of cardiac mitochondrial integrity and normal postnatal myocardium development.

Bone morphogenetic protein‑2 enhances the expression of cardiac transcription factors by increasing histone H3 acetylation in H9c2 cells

Bone morphogenetic protein (BMP)‑2 induces the expression of cardiac transcription factors during early heart development, however, the underlying mechanisms for this are not clear. Our previous studies indicated that histone acetylation is critical in the regulation of cardiac gene expression. In the present study, the hypothesis that BMP2 enhances the expression of cardiac transcription factors by increasing histone H3 acetylation was tested. Cultured H9c2 rat embryonic cardiac myocytes were transfected with adenoviruses expressing human BMP2 (AdBMP2). Real‑time RT‑PCR, western blotting, chromatin immunoprecipitation (ChIP) and colorimetric assays were employed to determine gene expression, histone H3 acetylation levels and histone acetylase (HAT) activities. The mRNA expression levels of BMP2, GATA4, MEF2C and p300, but not of Tbx5 and GCN5, were significantly upregulated following transfection with AdBMP2. Similarly, the histone H3 acetylation levels were enhanced in the whole chromatin and in the promoter regions of GATA4 and MEF2C, but not Tbx5, in the transfected cells. The HAT activities were also enhanced. These results indicate that BMP2 is able to upregulate the expression of the cardiac transcription factors GATA4 and MEF2C, in part by increasing histone H3 acetylation in the promoter regions of these genes.

Nitric oxide and histone deacetylases modulate cocaine-induced mu-opioid receptor levels in PC12 cells

Background

Cocaine exposure has been reported to alter central μ-opioid receptor (MOR) expression in vivo. The present study employed an in vitro cellular model to explore possible mechanisms that may be involved in this action of cocaine.

Methods

To assess the effects of cocaine on MOR levels, two treatment regimens were tested in PC12 cells: single continuous or multiple intermittent. MOR protein levels were assessed by western blot analysis and quantitative PCR was used to determine relative MOR mRNA expression levels. To evaluate the role of nitric oxide (NO) and histone acetylation in cocaine-induced MOR expression, cells were pre-treated with the NO synthase inhibitor N^ω-nitro-L-arginine methylester (L-NAME) or the non-selective histone acetyltransferase inhibitor curcumin.

Results

Both cocaine treatment regimens significantly increased MOR protein levels and protein stability, but only multiple intermittent treatments increased MOR mRNA levels as well as c-fos mRNA levels and activator protein 1 binding activity. Both regimens increased NO production, and pre-treatment with L-NAME prevented cocaine-induced increases in MOR protein and mRNA levels. Single and multiple cocaine treatment regimens inhibited histone deacetylase activity, and pre-treatment with curcumin prevented cocaine-induced up-regulation of MOR protein expression.

Conclusions

In the PC12 cell model, both NO and histone deacetylase activity regulate cocaine-induced MOR expression at both the transcriptional and post-transcriptional levels. Based on these novel findings, it is hypothesized that epigenetic mechanisms are implicated in cocaine’s action on MOR expression in neurons.

Melatonin suppresses proinflammatory mediators in lipopolysaccharide-stimulated CRL1999 cells via targeting MAPK, NF-κB, c/EBPβ, and p300 signaling

Melatonin is an indoleamine secreted by the pineal gland as well as a plant-derived product that exerts potential anti-inflammatory properties, but the mechanisms of action remain unclear. Here, we investigated the roles of melatonin in regulation of proinflammatory mediators and identified the underlying mechanisms in human vascular smooth muscle (VSM) cell line CRL1999 stimulated by lipopolysaccharide (LPS). We found that treatment with melatonin significantly inhibited the production and expression of TNF-α and interleukin (IL)-1β, cyclooxygenase-2 (COX-2), inducible nitric oxide synthase, prostaglandin E(2) (PGE2), and nitric oxide (NO) in a dose-dependent manner. Moreover, we also found that the suppression of proinflammatory mediators by melatonin was mediated through inhibition of MAPK, NF-κB, c/EBPβ, and p300 signaling in LPS-stimulated CRL1999 cells. Treatment with melatonin markedly inhibited phosphorylation of ERK1/2, JNK, p38 MAPK, IκB-α, and c/EBPβ, blocked binding of NF-κB and c/EBPβ to promoters, and suppressed p300 histone acetyltransferase (HAT) activity and p300 HAT-mediated NF-κB acetylation. Transfection with an ERK-, IκB-, or c/EBPβ-specific siRNA or pretreatment with an ERK-, p38 MAPK-, or p300-selective inhibitor considerably abrogated the melatonin-mediated inhibition of proinflammatory mediators. Conversely, exogenous overexpression of a constitutively active p300, but not its HAT mutant, effectively reversed the melatonin-mediated inhibitions. Collectively, these results indicate that melatonin suppresses proinflammatory mediators by simultaneously targeting the multiple signaling such as ERK/p38 MAPK, c/EBPβ, NF-κB, and p300, in LPS-stimulated VSM cell line CRL1999, and suggest that melatonin is a potential candidate compound for the treatment of proinflammatory disorders.

Phytochemical antioxidants modulate mammalian cellular epigenome: implications in health and disease

In living systems, the mechanisms of inheritance involving gene expression are operated by (i) the traditional model of genetics where the deoxyribonucleic acid (DNA) transcription and messenger ribonucleic acid stability are influenced by the DNA sequences and any aberrations in the primary DNA sequences and (ii) the epigenetic (above genetics) model in which the gene expression is regulated by mechanisms other than the changes in DNA sequences. The widely studied epigenetic alterations include DNA methylation, covalent modification of chromatin structure, state of histone acetylation, and involvement of microribonucleic acids.

SIGNIFICANCE

Currently, the role of cellular epigenome in health and disease is rapidly emerging. Several factors are known to modulate the epigenome-regulated gene expression that is crucial in several pathophysiological states and diseases in animals and humans. Phytochemicals have occupied prominent roles in human diet and nutrition as protective antioxidants in prevention/protection against several disorders and diseases in humans.

RECENT ADVANCES

However, it is beginning to surface that the phytochemical phenolic antioxidants such as polyphenols, flavonoids, and nonflavonoid phenols function as potent modulators of the mammalian epigenome-regulated gene expression through regulation of DNA methylation, histone acetylation, and histone deacetylation in experimental models.

CRITICAL ISSUES AND FUTURE DIRECTIONS

The antioxidant or pro-oxidant actions and their involvement in the epigenome regulation by the phytochemical phenolic antioxidants should be at least established in the cellular models under normal and pathophysiological states. The current review discusses the mechanisms of modulation of the mammalian cellular epigenome by the phytochemical phenolic antioxidants with implications in human diseases.

Curcumin loaded NLC induces histone hypoacetylation in the CNS after intraperitoneal administration in mice

The natural p300-specific histone acetyltransferase (HAT) inhibitor, curcumin (CUR), has been widely investigated for its potential therapeutic effect as an anticancer and anti-inflammatory agent. Notwithstanding this interesting pharmacological profile, CUR shows some drawbacks, such as poor absorption and a very fast metabolism and elimination, that limit its clinical use. Aim of the present study was to formulate CUR loaded nanostructured lipid carriers (NLC-CUR) in order to improve the bioavailability and stability of this compound after systemic administration with increased effects in the central nervous system (CNS). NLC-CUR were prepared and characterized on their physicochemical properties by PCS and DSC analyses. Thus, NLC-CUR were systemically injected and the effects in the CNS were compared with a CUR control formulation containing 0.05% DMSO (DMSO-CUR). Our results demonstrate that CUR is able to decrease histone acetylation in the CNS when included in NLCs. Western blot analysis shows that intraperitoneal injection of NLC-CUR (100mg/kg) in mice induces a marked hypoacetylation of histone 4 (H4) at lysine 12 (K12) in the spinal cord compared with control group. Notably, DMSO-CUR (100mg/kg) did not change the H4K12 acetylation level in the CNS. Our study suggests a novel approach to ameliorate the pharmacokinetics of CUR that allows a better permeation in the CNS.

Epigenetics and diabetic cardiomyopathy

Cardiovascular complications are a chief cause of mortality and morbidity in diabetic patients. Recent studies suggest that epigenetic changes which may arise as a consequence of environmental factors play an important role in predisposition to disease. Epigenetic mechanisms such as DNA methylation, chromatin remodeling and histone modifications regulate the gene expression in response to environmental signals. Role of epigenetics has been recognized in the pathology of diabetes, however its role in diabetic associated cardiomyopathy remains largely unexplored. In this article, we review current literature on the epigenetic mechanisms involved in diabetes and discuss recent evidence of epigenetic changes that may play an important role in pathophysiology of DCM.