Unraveling the relationship between histone methylation and nonalcoholic fatty liver disease

Non-alcoholic fatty liver disease(NAFLD)poses a significant health challenge in modern societies due to shifts in lifestyle and dietary habits.Its complexity stems from genetic predisposition,environmental influences,and metabolic factors.Epigenetic processes govern various cellular functions such as transcription,chromatin structure,and cell division.In NAFLD,these epigenetic tendencies,especially the process of histone methylation,are intricately intertwined with fat accumulation in the liver.Histone methylation is regulated by different enzymes like methyltransferases and demethylases and influences the expression of genes related to adipogenesis.While early-stage NAFLD is reversible,its progression to severe stages becomes almost irreversible.Therefore,early detection and intervention in NAFLD are crucial,and understanding the precise role of histone methylation in the early stages of NAFLD could be vital in halting or potentially reversing the progression of this disease.

Role of the histone methyltransferases Ezh2 and Suv4-20h1/Suv4-20h2 in neurogenesis

Mechanisms regulating neurogenesis involve broad and complex processes that represent intriguing therapeutic targets in the field of regenerative medicine.One influential factor guiding neural stem cell proliferation and cellular differentiation during neurogenesis are epigenetic mechanisms.We present an overview of epigenetic mechanisms including chromatin structure and histone modifications;and discuss novel roles of two histone modifiers,Ezh2 and Suv4-20h1/Suv4-20h2(collectively referred to as Suv4-20h),in neurodevelopment and neurogenesis.This review will focus on broadly reviewing epigenetic regulatory components,the roles of epigenetic components during neurogenesis,and potential applications in regenerative medicine.

Genome-wide profiling of histone H3 lysine 27 trimethylation and its modification in response to chilling stress in grapevine leaves

Histone H3 lysine 27 trimethylation(H3K27me3) is a histone modification associated with transcriptional repression. However, insights into the genome-wide pattern of H3K27me3 in grapevines are limited. Here, anti-H3K27 chromatin immunoprecipitation(ChIP), high-throughput sequencing, and transcriptome analysis were performed using leaves of Vitis amurensis. The leaves were treated at 4°C for 2 h and 24 h and used to investigate changes in H3K27me3 under chilling treatment. The results show that H3K27me3 is well-distributed both in gene regions(-50%) and in the intergenic region(-50%) in the grapevine genome(Vitis vinifera ‘Pinot Noir PN40024'). H3K27me3 was found to be localized in8 368 annotated gene regions in all detected samples(leaves at normal temperature and under chilling treatments) and mainly enriched in gene bodies with the adjacent promoter and downstream areas. The short-term chilling treatments(4°C for 2 h) induced 2 793 gains and 305losses in H3K27me3 modification. Subsequently, 97.3% of the alterations were restored to original levels after 24 h treatment. The ChIP-qPCR for five differential peaks showed similar results to the data for ChIP-seq, indicating that the chilling-induced H3K27me3 modification is reliable.Integrative analysis of transcriptome and ChIP-seq results showed that the expression of H3K27me3 target genes was significantly lower than those of non-target genes, indicating transcriptional repression of H3K27me3 in grapevine leaves. Furthermore, histone methylation alterations were detected in 82 genes and were related to either repression or activation of their expression during chilling stress. The findings provide the genome-wide H3K27me3 patterns in grapevines and shed light on uncovering its regulation in chilling stress responses.

Sodium butyrate alleviates deoxynivalenol-induced hepatic cholesterol metabolic dysfunction via RORγ-mediated histone acetylation modification in weaning piglets

Background:Cholesterol is an essential component of lipid rafts in cell plasma membrane,which exerts a hepatoprotective role against mycotoxin exposure in pigs,and cholesterol metabolism is vulnerable to epigenetic histone acetylation.Therefore,our present study aimed to investigate whether a histone deacetylase inhibitor(sodium butyrate [NaBu]) could protect the porcine liver from deoxynivalenol(DON) exposure by modulating cholesterol metabolism.Herein,we randomly divided 28 pigs into four groups,which were fed an uncontaminated basal diet,contaminated diet(4 mg DON/kg),uncontaminated diet supplemented with 0.2% NaBu or 4 mg/kg DON contaminated diet(4 mg DON/kg) supplemented with 0.2% NaBu for 28 d.Results:We found that the serum alanine transaminase(ALT),aspartate transaminase(AST),and alkaline phosphatase(ALP) were all increased in pigs exposed to DON,indicative of significant liver injury.Furthermore,the cholesterol content in the serum of DON-exposed pigs was significantly reduced,compared to the healthy Vehicle group.Transcriptome analysis of porcine liver tissues revealed that the cholesterol homeostasis pathway was highly enriched due to DON exposure.In which we validated by qRT-PCR and western blotting that the cholesterol program was markedly activated.Importantly,NaBu effectively restored parameters associated with liver injury,along with the cholesterol content and the expression of key genes involved in the cholesterol biosynthesis pathway.Mechanistically,we performed a ChIP-seq analysis of H3K27ac and showed that NaBu strongly diminished DON-increased H3K27ac genome-wide enrichment.We further validated that the elevated H3K27ac and H3K9ac occupancies on cholesterol biosynthesis genes were both decreased by NaBu,as determined by ChIP-qPCR analysis.Notably,nuclear receptor RORγ,a novel regulator of cholesterol biosynthesis,was found in the hyperacetylated regions.Again,a remarkable increase of RORγ at both mRNA and protein levels in DON-exposed porcine livers was drastically reduced by NaBu.Consistent with RORγ expression,NaBu also hindered RORγ transcriptional binding enrichments on these activated cholesterol biosynthesis genes like HMGCR,SQLE,and DHCR24.Furthermore,we conducted an in vitro luciferase reporter assay to verify that porcine RORγ directly bonds to the promoters of the above target genes.Conclusions:Collectively,our results demonstrate the utility of the natural product Na Bu as a potential anti-mycotoxin nutritional strategy for regulating cholesterol metabolism via RORγ-mediated histone acetylation modification.

Novel insights into histone lysine methyltransferases in cancer therapy:From epigenetic regulation to selective drugs

The reversible and precise temporal and spatial regulation of histone lysine methyltransferases(KMTs)is essential for epigenome homeostasis.The dysregulation of KMTs is associated with tumor initiation,metastasis,chemoresistance,invasiveness,and the immune microenvironment.Therapeutically,their promising effects are being evaluated in diversified preclinical and clinical trials,demonstrating encouraging outcomes in multiple malignancies.In this review,we have updated recent understandings of KMTs'functions and the development of their targeted inhibitors.First,we provide an updated overview of the regulatory roles of several KMT activities in oncogenesis,tumor suppression,and immune regulation.In addition,we summarize the current targeting strategies in different cancer types and multiple ongoing clinical trials of combination therapies with KMT inhibitors.In summary,we endeavor to depict the regulation of KMT-mediated epigenetic landscape and provide potential epigenetic targets in the treatment of cancers.

Upregulation of histone H3 caused by CRYAA may contribute to the development of age-related cataract

Objective:Age-relate cataract(ARC)is a disease of the eyes with no effective drugs to prevent or treat patients.The aim of the present study is to determine whether histone H3,αA-crystallin(CRYAA),β-galactosidase(GLB1),and p53 are involved in the pathogenesis of ARC.Methods:A total of 99 anterior lens capsules(ALCs)of patients with ARC of various nuclear grades,ultraviolet models of ALCs,and two human lens epithelial cell lines(FHL-124 and SRA01/04)were used,and the expression of histone H3,CRYAA,GLB1,and p53 were detected by immunoblotting and reverse transcription and real time-quantitative polymerase chain reaction.The association between CRYAA with histone H3,GLB1,and p53 was assessed in FHL-124 and SRA01/04 cells following CRYAA overexpression.Results:Histone H3 and p53 in ALCs of patients with ARC were up-regulated in a grade-dependent manner,and the expression of CRYAA showed a positive association with histone H3,p53,and GLB1.In UV models of ALCs and human lens epithelial cell lines,the expression levels of histone H3,cell apoptosis factors(Bax/Bcl-2,cleaved caspase-3),and inflammation factors(interleukin-6,tumor necrosis factor-α)were all up-regulated.Furthermore,transfection of CRYAA in FHL-124 cells induced overexpression of histone H3.Conclusion:CRYAA-mediated upregulation of histone H3 may be involved in the pathogenesis of ARC.p53 may also have a role in ARC development,but not via the CRYAA-histone H3 axis.The results of the present study may assist in improving our understanding of the pathogenesis of ARC and in identifying potential targets for treatment.

Down-regulation of histone deacetylase 7 reduces biological activities of retinal microvascular endothelial cells under high glucose condition and related mechanism

AIM:To investigate the expression and effect of histone deacetylase 7(HDAC7)in human retinal microvascular endothelial cells(HRMECs)under high glucose condition and related mechanism,and the expression of HDAC7 in the retinal tissue in diabetic rats.METHODS:The expression of HDAC7 in HRMECs under high glucose and the retinal tissue from normal or diabetic rats were detected with immunohistochemistry and Western blot.LV-shHDAC7 HRMECs were used to study the effect of HDAC7 on cell activities.Cell count kit-8(CCK-8),5-ethynyl2’-deoxyuridine(EdU),flow cytometry,scratch test,Transwell test and tube formation assay were used to examine the ability of cell proliferation,migration,and angiogenesis.Finally,a preliminary exploration of its mechanism was performed by Western blot.RESULTS:The expression of HDAC7 was both upregulated in retinal tissues of diabetic rats and high glucosetreated HRMECs.Down-regulation of HDAC7 expression significantly reduced the ability of proliferation,migration,and tube formation,and reversed the high glucose-induced high expression of CDK1/Cyclin B1 and vascular endothelial growth factor in high glucose-treated HRMECs.CONCLUSION:High glucose can up-regulate the expression of HDAC7 in HRMECs.Down-regulation of HDAC7 can inhibit HRMECs activities.HDAC7 is proposed to be involved in pathogenesis of diabetic retinopathy and a therapeutic target.

Histone methyltransferases and demethylases:regulators in balancing osteogenic and adipogenic differentiation of mesenchymal stem cells

Mesenchymal stem cells （MSCs） are characterized by their self-renewing capacity and differentiation potential into multiple tissues. Thus, management of the differentiation capacities of MSCs is important for MSC-based regenerative medicine, such as craniofacial bone regeneration, and in new treatments for metabolic bone diseases, such as osteoporosis. In recent years, histone modification has been a growing topic in the field of MSC lineage specification, in which the Su（var）3-9, enhancer-of-zeste, trithorax （SET） domain-containing family and the Jumonji C （JmjC） domain-containing family represent the major histone lysine methyltransferases （KMTs） and histone lysine demethylases （KDMs）, respectively. In this review, we summarize the current understanding of the epigenetic mechanisms by which SET domain-containine KMTs and JmiC domain-containinlz KDMs balance the osteogenic and adipogenic differentiation of MSCs.

Effects of DNA Methylation and Histone Modification on Differentiation-associated Gene Expression in ES,NIH3T3,and NIT-1

The effects of epigenetic modification on the differentiation of islet cells and the expression of associated genes（Pdx-1,Pax4,MafA,and Nkx6.1,etc） were investigated.The promoter methylation status of islet differentiation-associated genes（Pdx-1,Pax4,MafA and Nkx6.1）,Oct4 and MLH1 genes of mouse embryonic stem cells,NIH3T3 cells and NIT-1 cells were profiled by methylated DNA immunoprecipitation,real-time quantitative PCR（MeDIP-qPCR） techniques.The histone modification status of these genes promoter region in different cell types was also measured by using chromatin immunoprecipitation real-time quantitative PCR methods.The expression of these genes in these cells was detected by using real-time quantitative PCR.The relationship between the epigenetic modification（DNA methylation,H3 acetylation,H3K4m3 and H3K9m3） of these genes and their expression was analyzed.The results showed that：（1） the transcription-initiation-sites of Pdx-1,MafA and Nkx6.1 were highly methylated in NIH3T3 cells; （2） NIH3T3 cells showed a significantly higher level of DNA methylation modification in the transcription-initiation-site of Pdx-1,Pax4,MafA and Nkx6.1 genes than that in mES cells and NIT-1 cells（P〈0.05）; （3） NIT-1 cells had a significantly higher level of H3K4m3 modification in the transcription-initiation-site of Pdx-1,Pax4,MafA and Nkx6.1 genes than that in mES cells and NIH3T3 cells（P〈0.05）,with significantly increased level of gene expression; （4） NIH3T3 cell had a significantly higher level of H3K9m3 modification in the transcription-initiation-site of Pdx-1,Pax4,MafA and Nkx6.1 genes than that in mES cells and with NIT-1 cell（P〈0.05）,with no detectable mRNA expression of these genes.It was concluded that histone modification（H3K4m3 and H3K9m3） and DNA methylation might have an intimate communication between each other in the differentiation process from embryonic stem cells into islet cells.

茶树冷胁迫诱导H1-histone基因的克隆与序列分析

利用cDNA-AFLP技术对茶树不同低温胁迫处理下的基因表达差异进行了分析,获得一低温诱导后特异表达片段TDF8(transcript derived fragment,TDF)。BLAST比对结果显示,该片段与其它物种的逆境诱导特异表达的H1-histone基因有很高的相似性。通过RACE分别扩增出其3′和5′末端序列,成功获得该基因cDNA全长序列(GenBank登录号EU716314)。所得序列全长916 bp,其开放阅读框共编码207氨基酸,蛋白分子量约为30.77 kD。该基因氨基酸序列分析表明,与烟草的胁迫诱导H1-histone基因的氨基酸序列一致性达79%。可以认为,该基因应该属于逆境诱导条件下表达的H1-histone基因家族成员之一。

融合模糊Histon阈值和FCM的Lab空间色彩分割算法

提出了一种简单有效的自适应无监督方法。在CIELab空间中利用模糊Histon阈值技术获得图像中所有可能的均匀区域,即通过寻找峰值,区域初始分割和区域颜色相似性合并,获得由聚类中心标注的均匀区域,提出自适应FCM聚类算法以提高均匀区域之间的紧密度,最终完成色彩分割。该算法已成功应用到伯克利图像库,相比当前一些无监督色彩分割算法,例如:Mean-Shift、NCuts取得了合理更好的划分,视觉上有效提取目标物体,具有一定鲁棒性。

栽培四倍体棉种及其二倍体祖先种的Histone3基因片段序列分析

组蛋白是植物基因组的重要组成部分。根据Genebank中登录的Histone3基因的全长cD NA序列,设计PCR引物,进行了异源四倍体栽培陆地棉、海岛棉及其二倍体祖先种非洲棉和雷蒙德氏棉中Histone3基因片段序列分析。不同物种中获得的基因片段分别由2个内含子、部分外显子区和3'端非翻译区组成。共存在77个单核苷酸多态性位点,其中外显子区9个,内含子Ⅰ区22个,内含子Ⅱ区21个,3'端非翻译区25个。外显子的SNP变化不影响Histone3基因的转录和翻译。分子聚类结果表明,不同物种A、D基因组的序列定向进化同源性明显,其中AvsD序列相似性为91.6%,AvsATB序列相似性为95.8%,AvsATH序列相似性为95.2%,DvsDTB序列相似性为98.5%,DvsDTH序列相似性为98.0%。A、D染色体组基因序列部分同源性分析表明,陆地棉中ATHvsDTH序列相似性为91.0%,海岛棉中ATBvsDTB序列相似性为92.5%。聚类结果再现了A、D基因组多倍体化后其基因序列与二倍体祖先种平行演化的特点以及A、D染色体组间进化速率在四倍体棉种中与二倍体祖先种中表现的一致性。本文也讨论了基因序列在不同物种中的相似性比较不仅是研究进化的有效方法,也可用于发现基因在不同物种中SNP序列及应用前景。

Histone acetylation of the htr3a gene in the prefrontal cortex of Wistar rats regulates ethanol-seeking behavior

Previous reports showed that decreased histone deacetylase activity significantly potentiated the rewarding effects of psychostimulants, and that encoding of the 5-HT3 receptor by the htr3a gene was related to ethanol-seeking behavior. However, the effects of a histone deacetylase inhibitor on ethanol-seeking behavior and epigenetic regulation of htr3a mRNA expression after chronic ethanol exposure are not fully understood. Using quantitative reverse transcription-polymerase chain reaction and chromatin immunoprecipitation analysis, we investigated the effects of chronic ethanol exposure and its interaction with a histone deacetylase inhibitor on histone-acetylation-mediated changes in htr3a mRNA expression in the htr3a promoter region. The conditioned place preference procedure was used to evaluate ethanol-seeking behavior. Chronic exposure to ethanol effectively elicited place conditioning. In the prefrontal cortex, the acetylation of H3K9 and htr3a mRNA expression in the htr3a promoter region were significantly higher in the ethanol group than in the saline group. The histone deacetylase inhibitor sodium butyrate potentiated the effects of ethanol on htr3a mRNA expression and enhanced ethanol-induced conditioned place preferences. These results suggest that ethanol upregulates htr3a levels through mechanisms involving H3K9 acetylation, and that histone acetylation may be a therapeutic target for treating ethanol abuse.

Histone deacetylase inhibitor pre-treatment enhances the efficacy of DNA-interacting chemotherapeutic drugs in gastric cancer

BACKGROUND The prognosis of gastric cancer continues to remain poor,and epigenetic drugs like histone deacetylase inhibitors(HDACi)have been envisaged as potential therapeutic agents.Nevertheless,clinical trials are facing issues with toxicity and efficacy against solid tumors,which may be partly due to the lack of patient stratification for effective treatments.To study the need of patient stratification before HDACi treatment,and the efficacy of pre-treatment of HDACi as a chemotherapeutic drug sensitizer.METHODS The expression activity of class 1 HDACs and histone acetylation was examined in human gastric cancer cells and tissues.The potential combinatorial regime of HDACi and chemotherapy drugs was defined on the basis of observed drug binding assays,chromatin remodeling and cell death.RESULTS In the present study,the data suggest that the differential increase in HDAC activity and the expression of class 1 HDACs are associated with hypoacetylation of histone proteins in tumors compared to normal adjacent mucosa tissue samples of gastric cancer.The data highlights for the first time that pretreatment of HDACi results in an increased amount of DNA-bound drugs associated with enhanced histone acetylation,chromatin relaxation and cell cycle arrest.Fraction-affected plots and combination index-based analysis show that pre-HDACi chemo drug combinatorial regimes,including valproic acid with cisplatin or oxaliplatin and trichostatin A with epirubicin,exhibit synergism with maximum cytotoxic potential due to higher cell death at low combined doses in gastric cancer cell lines.CONCLUSION Expression or activity of class 1 HDACs among gastric cancer patients present an effective approach for patient stratification.Furthermore,HDACi therapy in pretreatment regimes is more effective with chemotherapy drugs,and may aid in predicting individual patient prognosis.

Curcumin-induced Histone Acetylation in Malignant Hematologic Cells

This study investigated the inhibitory effects of curcumin on proliferation of hematological malignant cells in vitro and the anti-tumor mechanism at histone acetylation/histone deacetylation levels. The effects of curcumin and histone deacetylase inhibitor trichostatin A （TSA） on the growth of Raji cells were tested by MTT assay. The expression of acetylated histone-3 （H3） in Raji, HL60 and K562 cells, and peripheral blood mononuclear cells （PBMCs） treated with curcumin or TSA was detected by immunohistochemistry and FACS. The results showed curcumin inhibited pro- liferation of Raji cells significantly in a time- and dose-dependent fashion, while exhibited low toxicity in PBMCs. Curcumin induced up-regulation of the expression of acetylated H3 dose-dependently in all malignant cell lines tested. In conclusion, curcumin inhibited proliferation of Raji cells selectively, enhanced the level of acetylated H3 in Raji, HL60, and K562 cells, which acted as a histone deacetylase inhibitor like TSA. Furthermore, up-regulation of H3 acetylation may play an important role in regulating the proliferation of Raji cells.

Fusion Wheat Histone H4 Protein Increases Transfection Efficiency of Non-viral DNA Vector

The lack of efficient and non-toxic gene delivery, preferably with non-viral DNA vectors, is generally regarded as a major limitation for gene therapy. In this study, a wheat histone H4 gene was cloned from Triticum aestivum, sequenced, modified and expressed in E. coli. The wheat histone H4 gene and reconstructed H4TL gene encoded wheat histone H4 and a recombinant protein of 141 amino acids with an approximate molecular weight of 15500. Gel electrophoresis mobility shift assays demonstrated that the purified protein had high affinity for DNA. Most significantly, the complex of plasmid pEGFP/C1 with H4TL was transfected with increased efficiency into MCF-7, HO8910, LNCap, A549 and HeLa cells in vitro. These results demonstrate that the targeting of non-viral vectors to tumor-specific receptors provides a cheap, simple and highly efficient tool for gene delivery.

Targeting pancreatic cancer immune evasion by inhibiting histone deacetylases

The immune system plays a vital role in maintaining the delicate balance between immune recognition and tumor development.Regardless,it is not uncommon that cancerous cells can intelligently acquire abilities to bypass the antitumor immune responses,thus allowing continuous tumor growth and development.Immune evasion has emerged as a significant factor contributing to the progression and immune resistance of pancreatic cancer.Compared with other cancers,pancreatic cancer has a tumor microenvironment that can resist most treatment modalities,including emerging immunotherapy.Sadly,the use of immunotherapy has yet to bring significant clinical breakthrough among pancreatic cancer patients,suggesting that pancreatic cancer has successfully evaded immunomodulation.In this review,we summarize the impact of genetic alteration and epigenetic modification(especially histone deacetylases,HDAC)on immune evasion in pancreatic cancer.HDAC overexpression significantly suppresses tumor suppressor genes,contributing to tumor growth and progression.We review the evidence on HDAC inhibitors in tumor eradication,improving T cells activation,restoring tumor immunogenicity,and modulating programmed death 1 interaction.We provide our perspective in targeting HDAC as a strategy to reverse immune evasion in pancreatic cancer.

DNA and histone methylation in gastric carcinogenesis

Epigenetic alterations contribute significantly to the development and progression of gastric cancer,one of the leading causes of cancer death worldwide.Epigenetics refers to the number of modifications of the chromatin structure that affect gene expression without altering the primary sequence of DNA,and these changes lead to transcriptional activation or silencing of the gene.Over the years,the study of epigenetic processes has increased,and novel therapeutic approaches that target DNA methylation and histone modifications have emerged.A greater understanding of epigenetics and the therapeutic potential of manipulating these processes is necessary for gastric cancer treatment.Here,we review recent research on the effects of aberrant DNA and histone methylation on the onset and progression of gastric tumors and the development of compounds that target enzymes that regulate the epigenome.

Current evidence for histone deacetylase inhibitors in pancreatic cancer

Pancreatic cancer is one of the most aggressive human cancers,with more than 200 000 deaths worldwide every year.Despite recent efforts,conventional treatment approaches,such as surgery and classic chemotherapy,have only slightly improved patient outcomes.More effective and well-tolerated therapies are required to reverse the current poor prognosis of this type of neoplasm.Among new agents,histone deacetylase inhibitors (HDACIs) are now being tested.HDACIs have multiple biological effects related to acetylation of histones and many non-histone proteins that are involved in regulation of gene expression,apoptosis,cell cycle progression and angiogenesis.HDACIs induce cell cycle arrest and can activate the extrinsic and intrinsic pathways of apoptosis in different cancer cell lines.In the present review,the main mechanisms by which HDACIs act in pancreatic cancer cells in vitro,as well as their antiproliferative effects in animal models are presented.HDACIs constitute a promising treatment for pancreatic cancer with encouraging anti-tumor ef-fects,at well-tolerated doses.

Curcumin inhibits hepatitis B virus infection by downregulating ccc DNA-bound histone acetylation

AIM To investigate the potential effect of curcumin on hepatitis B virus(HBV) covalently closed circular DNA(ccc DNA) and the underlying mechanism.METHODS A Hep G2.2.15 cell line stably transfected with HBV was treated with curcumin, and HBV surface antigen(HBs Ag) and e antigen(HBe Ag) expression levels were assessed by ELISA. Intracellular HBV DNA replication intermediates and ccc DNA were detected by Southern blot and real-time PCR, respectively. The acetylation levels of histones H3 and H4 were measured by Western blot. H3/H4-bound ccc DNA was detected by chromatin immunoprecipitation(Ch IP) assays. The deacetylase inhibitors trichostatin A and sodium butyrate were used to study the mechanism of action for curcumin. Additionally, short interfering RNAs(si RNAs) targeting HBV were tested along with curcumin.RESULTS Curcumin treatment led to time-and dose-dependent reductions in HBs Ag and HBe Ag expression and significant reductions in intracellular HBV DNA replication intermediates and HBV ccc DNA. After treatment with 20 μmol/L curcumin for 2 d, HBs Ag and ccc DNA levels in Hep G2.2.15 cells were reduced by up to 57.7%(P < 0.01) and 75.5%(P < 0.01), respectively, compared with levels in non-treated cells. Meanwhile, time-and dose-dependent reductions in the histone H3 acetylation levels were also detected upon treatment with curcumin, accompanied by reductions in H3-and H4-bound ccc DNA. Furthermore, the deacetylase inhibitors trichostatin A and sodium butyrate could block the effects of curcumin. Additionally, transfection of si RNAs targeting HBV enhanced the inhibitory effects of curcumin.CONCLUSION Curcumin inhibits HBV gene replication via downregulation of ccc DNA-bound histone acetylation and has the potential to be developed as a ccc DNA-targeting antiviral agent for hepatitis B.