Epigenetic modification regulates both expression of tumor-associated genes and cell cycle progressing in human colon cancer cell lines: Colo-320 and SW1116

The aim of this study is to assess the effects of DNA methylation and historic acetylation, alone or in combination, on the expression of several tumor-associated genes and cell cycle progression in two established human colon cancer cell lines: Colo-320 and SW1116. Treatments with 5-aza-2'-deoxycytidine (5-aza-dC) and trichostatin A, alone or in combination, were applied respectively. The methylation status of the CDKN2A promoter was determined by methyla-tion-specific PCR, and the acetylated status of the histones associated with the p21WAF1 and CDKN2A genes was examined by chromatin immunoprecipitation. The expression of the CDKN2A, p21WAF1, p53, p73, APC, c-myc, c-Ki-ras and survivin genes was detected by real-time RT-PCR and RT-PCR. The cell cycle profile was established by flow cytometry. We found that along with the demethylation of the CDKN2A gene promoter in both cell lines induced by 5-aza-dC alone or in combination with TSA, the expression of both CDKN2A and APC genes increased. The treatment of TSA or sodium butyrate up-regulated the transcription of p21WAF1 significantly by inducing the acetylation of histones H4 and H3, but failed to alter the acetylation level of CDKN2A-associated histones. No changes in transcription of p53, p73, c-myc, c-Ki-ras and survivin genes were observed. In addition, TSA or sodium butyrate was shown to arrest cells at the G1 phase. However, 5-aza-dC was not able to affect the cell cycle progression. In conclusion, regulation by epigenetic modification of the transcription of tumor-associated genes and the cell cycle progression in both human colon cancer cell lines Colo-320 and SW1116 is gene-specific.

Effects of histone acetylation and DNA methylation on p21^(WAF1)regulation

Cell cycle progression is regulated by interactions between cyclins and cyclin-dependent kinases (CDKs). p21(WAF1) is one of the CIP/KIP family which inhibits CDKs activity. Increased expression of p21(WAF1) may play an important role in the growth arrest induced in transformed cells. Although the stability of the p21( WAF1) mRNA could be altered by different signals, cell differentiation and numerous influencing factors. However, recent studies suggest that two known mechanisms of epigenesis, i.e.gene inactivation by methylation in promoter region and changes to an inactive chromatin by histone deacetylation, seem to be the best candidate mechanisms for inactivation of p21( WAF1). To date, almost no coding region p21(WAF1) mutations have been found in tumor cells, despite extensive screening of hundreds of various tumors. Hypermethylation of the p21(WAF1) promoter region may represent an alternative mechanism by which the p21(WAF1/CIP1) gene can be inactivated. The reduction of cellular DNMT protein levels also induces a corresponding rapid increase in the cell cycle regulator p21(WAF1) protein demonstrating a regulatory link between DNMT and p21(WAF1) which is independent of methylation of DNA. Both histone hyperacetylation and hypoacetylation appear to be important in the carcinoma process, and induction of the p21(WAF1) gene by histone hyperacetylation may be a mechanism by which dietary fiber prevents carcinogenesis. Here, we review the influence of histone acetylation and DNA methylation on p21(WAF1) transcription, and affection of pathways or factors associated such as p 53, E2A, Sp1 as well as several histone deacetylation inhibitors.

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.

The impact of acetylation and deacetylation on the p53 pathway

The p53 tumor suppressor is a sequence-specific transcription factor that undergoes an abundance of post-translational modifications for its regulation and activation.Acetylation of p53 is an important reversible enzymatic process that occurs in response to DNA damage and genotoxic stress and is indispensible for p53 transcriptional activity.p53 was the first non-histone protein shown to be acetylated by histone acetyl transferases,and a number of more recent in vivo models have underscored the importance of this type of modification for p53 activity.Here,we review the current knowledge and recent findings of p53 acetylation and deacetylation and discuss the implications of these processes for the p53 pathway.

A domesticated Harbinger transposase forms a complex with HDA6 and promotes histone H3 deacetylation at genes but not TEs in Arabidopsis

In eukaryotes,histone acetylation is a major modification on histone N-terminal tails that is tightly connected to transcriptional activation.HDA6 is a histone deacetylase involved in the transcriptional regulation of genes and transposable elements(TEs)in Arabidopsis thaliana.HDA6 has been shown to participate in several complexes in plants,including a conserved SIN3 complex.Here,we uncover a novel protein complex containing HDA6,several Harbinger transposon-derived proteins(HHP1,SANT1,SANT2,SANT3,and SANT4),and MBD domain-containing proteins(MBD1,MBD2,and MBD4).We show that mutations of all four SANT genes in the sant-null mutant cause increased expression of the flowering repressors FLC,MAF4,and MAF5,resulting in a late flowering phenotype.Transcriptome deep sequencing reveals that while the SANT proteins and HDA6 regulate the expression of largely overlapping sets of genes,TE silencing is unaffected in sant-null mutants.Our global histone H3 acetylation profiling shows that SANT proteins and HDA6 modulate gene expression through deacetylation.Collectively,our findings suggest that Harbinger transposon-derived SANT domain-containing proteins are required for histone deacetylation and flowering time control in plants.

Reversible histone acetylation/ deacetylation modification by p300 and HDAC3 is involved in the regulation of IL-18 promoter activity

Interleukin-18 (IL-18) is a pleiotropic cytokine involved in the development of T helper type 1 (Thl) cells, and it plays important roles in regulation of both the innate and acquired immune responses. The aim of this study was to elucidate whether the reversible histone acetylation/ deacetylation modification participates in the regulation of IL-18 transcription expression. The transcription coactivator p300 containing the histone acetyltransferase (HAT) activity, and the histone deacetylase 3 (HDAC3) were used in this study to analyze the effect of this modification in the regula-tion of mouse IL-18 gene. The results demonstrate that transfection of p300-expression plasmid promotes the en-dogenous IL-18 mRNA synthesis in J774 cells, and stimulates the activation of IL-18 promoter. It has been found that this stimulating effect of p300 was reversed by HDAC3, indicat-ing the involvement of the reversible histone acetyla-tion/deacetylation modification in IL-18 regulation. Fur-thermore, the data show that the HAT activity of p300 was essential to its function in activating IL-18 promoter. In ad-dition, p300 was shown to be able to work synergistically with the transcription factor c-Fos on activation of IL-18 promoter and this effect could also be impaired by HDAC3. Results presented in this paper indicate that the reversible histone acetylation/deacetylation modification plays an im-portant role in the transcriptional regulation of IL-18.

An Alternative Method for Anomeric Deacetylation of Per-acetylated Carbohydrates

An alternative method for anomeric deacetylation of fully acetylated carbohydrates has been developed using imidazole in methanol.

Relationship between histone acetylation/deacetylation and gene transcription

In eukaryotes, nucleosome is the basic unit of chromatin. Nucleosome is composed of an octamer of histone proteins (two molecules each of histones H 2A , H 2B , H 3 and H 4) and DNA strand wound around the octamer. Some data show that core histone octamer can affect gene transcription both \%in vitro\% and \%in vivo.\% Recent results indicate that histone acetylation/deacetylation is a key step to regulate activity of genes. This article summarizes some coactivators, such as GCN5p, P300/CBP and TAF Ⅱ 250, which are recently found to have histone acetyltransferase activity. The relationship between these coactivators and gene activation is also described. Besides, this article concerns some corepressors which have histone deacetylase activity, such as Rpd3p, HDAC2. These corepressors combine with other protein complex and then repress transcription. Finally, some problems to be solved and the future direction in this active field are discussed.

Ras protein participated in histone acetylation-mediated cell cycle control in Physarum polycephalum

In this paper, we demonstrate that in Physarum polycephalum, a naturally synchronized slime mold, histone deacetylase (HDAC) inhibitor Trichostatin A (TSA), arrestes the cell cycle at the checkpoints of S/G2, G2/M and mitosis exit, and influences the transcription of two ras genes Ppras1 and Pprap1, as well as the Ras protein level. Antibody neu-tralization experiment using anti-Ras antibody treatment showed that Ras protein played an important role in cell cycle checkpoint control through regulation of the level of Cyclin B1, suggesting that Ras protein might be a key factor for histone acetylation-mediated cell cycle regulation in P. polycephalum.

组蛋白乙酰化/甲基化在口腔疾病中的研究进展

组蛋白乙酰化和甲基化能影响染色质构象,进而调控多种生物学活动。异常的组蛋白乙酰化和甲基化修饰与多种口腔疾病的发生发展有关。在牙的发育过程中,组蛋白乙酰化和甲基化修饰有序地升高或降低,调控牙的发育,氟离子能够破坏组蛋白乙酰化和甲基化修饰的平衡,这可能与氟牙症的发生有关。此外,组蛋白乙酰化和甲基化修饰也参与调控了口腔的炎症性疾病,炎症微环境下,组蛋白乙酰转移酶GCN5表达下降,使Dickkopf 1(DKK1)表达下降,从而激活Wnt/β⁃catenin通路,最终抑制牙周膜干细胞的成骨分化。Zeste增强子同源物2(enhancer of zeste homolog 2,EZH2)与H3K27me3在炎症牙髓组织和牙髓细胞中下降,抑制EZH2可抑制炎症刺激导致的人牙髓细胞中白细胞介素⁃1b、白细胞介素⁃6和白细胞介素⁃8的表达。组蛋白乙酰化/甲基化修饰能够与多条信号通路相互作用,促进口腔肿瘤的发生发展,并与唾液腺肿瘤的高侵袭性有关。靶向组蛋白乙酰化和甲基化相关酶的小分子药物能调控组蛋白甲基化/乙酰化修饰水平,在口腔颌面部疾病治疗中展现出应用潜能,例如组蛋白去乙酰化酶抑制剂——伏立诺他,其既能够抑制炎症的相关细胞因子的分泌,还能促进成牙本质细胞分化并形成牙本质相关基质,展现出了在保髓治疗中的潜力。了解组蛋白乙酰化/甲基化修饰在口腔疾病发生发展中的作用,有助于推进表观遗传修饰在口腔疾病的研究深入,提供新的疾病诊疗视角。

乙酰辅酶A羧化酶2通过调控细胞周期促进肝癌细胞增殖

目的:研究乙酰辅酶A羧化酶2(acetyl-co carboxylase 2,ACC2)对肝癌细胞增殖、迁移能力的影响以及其潜在的作用机制。方法:通过TCGA、GEO、CPTAC数据库对ACC2在肝癌(hepatocellular carcinoma,HCC)患者肝脏组织中的表达和预后价值进行分析。采用CRISPR-Cas9系统构建了ACC2敲低肝癌细胞系,观察肝癌细胞增殖、迁移能力以及细胞周期的变化,Western blot实验检测细胞周期相关蛋白的表达。结果:ACC2在肝癌组织中低表达(P<0.05)且与预后不良相关(P<0.05)。体外细胞功能学实验表明降低ACC2表达显著促进肝癌细胞增殖、迁移能力(P<0.05)。细胞周期流式分析显示敲低ACC2促进肝癌细胞周期G1/S期的转变(P<0.05),细胞周期相关蛋白中CyclinE2和p21的表达降低,而CyclinA2和p-RB的表达升高。结论:ACC2可以促进肝癌细胞增殖和迁移的能力,对细胞增殖的促进作用是通过加速肝癌细胞周期G1向S期的转化实现的。

伪狂犬病病毒感染猪脾淋巴细胞的转录组学分析

旨在探究伪狂犬病病毒(PRV)体外感染猪脾淋巴细胞基因组转录水平的变化,通过检测PRV感染猪脾淋巴细胞组蛋白乙酰化酶(HATs)、组蛋白去乙酰化酶(HDACs)的基因表达水平,筛选感染关键时间点进行PRV感染细胞的高通量测序,分析PRV感染后基因表达层面的变化。结果表明,PRV感染后共筛选出2293个差异基因(DEGs),其中有726个基因表达上调,1567个基因表达下调。GO富集分析显示DEGs广泛分布于细胞膜、细胞核和细胞质中,参与调节细胞膜受体活性、信号转导和免疫等生物学进程。KEGG分析发现差异基因主要富集到免疫相关信号通路,如Toll样受体信号通路、NOD样受体信号通路等,提示PRV致病机制可能与炎症反应和细胞凋亡有关,研究结果可为进一步了解PRV感染猪免疫系统的分子机制提供重要参考。

Functions and mechanisms of non-histone protein acetylation in plants^(∞)

Lysine acetylation, an evolutionarily conserved post-translational protein modification, is reversibly catalyzed by lysine acetyltransferases and lysine deacetylases. Lysine acetylation, which was first discovered on histones, mainly functions to configure the structure of chromatin and regulate gene transcriptional activity. Over the past decade, with advances in high-resolution mass spectrometry, a vast and growing number of non-histone proteins modified by acetylation in various plant species have been identified.Lysine acetylation of non-histone proteins is widely involved in regulating biological processes in plants such as photosynthesis, energy metabolism, hormone signal transduction and stress responses. Moreover, in plants, lysine acetylation plays crucial roles in regulating enzyme activity,protein stability, protein interaction and subcellular localization. This review summarizes recent progress in our understanding of the biological functions and mechanisms of non-histone protein acetylation in plants. Research prospects in this field are also noted.

N-乙酰化壳聚糖的FTIR和XRD研究

壳聚糖分子的脱乙酰度(DD)是影响壳聚糖性质的主要因素之一。文章通过壳聚糖的N-乙酰化反应制备了不同脱乙酰度的壳聚糖。采用傅里叶变换红外光谱(FTIR)和X射线衍射(XRD)分别研究了由N-乙酰化反应得到的不同脱乙酰度的壳聚糖的红外光谱特性和晶体结构,并由此分别计算确定了样品的脱乙酰度和结晶度,探讨了N-乙酰化程度对壳聚糖脱乙酰度以及结晶度的影响。由FTIR可知,随N-乙酰程度的增加,壳聚糖分子中剩余氨基的反应速度变慢。另外XRD也表明,伴随N-乙酰反应,壳聚糖分子的结晶区被破坏,规整度下降,并逐渐形成新的结晶区。

姜黄素诱导Raji、HL-60和K562组蛋白乙酰化的研究

目的研究姜黄素对淋巴瘤细胞系Raji细胞的抑制增殖作用,并在组蛋白乙酰化/去乙酰化水平对其抗肿瘤机制进行探讨。方法MTT法检测不同浓度姜黄素、TSA作用于Raji细胞的抑制增殖率。以TSA处理后的细胞为阳性对照,免疫组化法定量分析及免疫荧光流式细胞化学定量检测姜黄素作用后Raji、HL-60、K562细胞的组蛋白乙酰化H3水平。结果姜黄素抑制Raji细胞增殖,并呈时间剂量依赖性;25μmol.L-1姜黄素可致Raji、HL-60、K562细胞的乙酰化H3水平增加(P<0.05),50μmol.L-1姜黄素的诱导作用增强(P<0.01)。结论姜黄素可以选择性地抑制Raji细胞增殖;且类似于TSA诱导Raji,HL-60,K562细胞组蛋白乙酰化增加。

SirT3调节氧化应激作用

依赖于烟酰胺腺嘌呤二核苷酸的去乙酰化酶Sirtuin-3(SirT3)是在进化上高度保守的Sirtuin家族成员之一,能对线粒体内相关的乙酰化蛋白脱乙酰基,通过增加活性氧自由基(ROS)清除酶活性和稳定线粒体功能来抑制线粒体内ROS的蓄积。该文综述了SirT3调节因氧化应激诱发的功能性及器质性损伤的作用和机制,为SirT3在相关病理及生理机制的研究提供有益的参考。

α-乙酰基二硫缩烯酮的新合成方法

The α-acetyl ketene dithioacetals 2, which bear various alkylthio groups, are a kind of important intermediates in organic synthesis. In this paper, dithioacetals 2 were prepared in very high yields (90%—100%) via the deacetylation reaction of the corresponding α,α-diacetyl ketene dithioacetals 1 in the presence of concentrated sulfuric acid. This reaction involves an %in-situ% electrophilic addition-deacetylation mechanism and shows the nucleophilicity of the α-carbon atom in α-oxo ketenedithioacetals. Meanwhile, when the reaction time was prolonged to 22—25 h, the β-keto thiolesters 3a and 3c were produced in good yields.

乙酰基转移酶Tip60(KAT5)的功能研究进展

Tip60(KAT5)属于MYST乙酰基转移酶家族,同时它也是进化上非常保守的Nu A4蛋白质复合体的重要成员.过去十几年的研究证实,Tip60一方面可以作为转录调控因子结合核受体(如雄激素受体,AR)或c-MYC、AICD/Fe65、NCo R、E2F等转录因子来激活或抑制下游基因的表达,另一方面,KAT5可以乙酰化一系列蛋白来调控这些蛋白质的活性及稳定性,进而调控DNA损伤修复反应、细胞周期进程、细胞周期检查点的激活、凋亡、代谢及自噬等重要细胞功能.此外,Tip60在肿瘤的发生发展及转移、胚胎发育等过程中也发挥着至关重要的作用.本文将主要对Tip60近几年的研究进展做一个综述.

DADS体内诱导人胃癌细胞分化作用中组蛋白乙酰化的变化

目的观察二烯丙基二硫(DADS)在体内诱导胃癌细胞分化的作用及对人胃癌细胞移植瘤组蛋白乙酰化的影响。方法裸鼠皮下注入人胃癌细胞MGC803建立人胃癌异种移植模型,采用光学显微镜观察移植瘤细胞形态变化,流式细胞光度术和W estern b lot分析DADS对MGC803细胞移植瘤细胞周期分布的影响及瘤组织中p21WAF1蛋白、组蛋白H3、H4乙酰化的表达情况。结果腹腔注射DADS剂量为100、200 mg.kg-1时对移植瘤有明显生长抑制作用;光学显微镜显示经DADS处理后瘤细胞密度及异型性明显减小。流式细胞仪分析结果显示DADS呈浓度依赖性将移植瘤细胞阻滞在G2/M期。DADS浓度为100 mg.kg-1和200 mg.kg-1作用瘤细胞后,与对照组相比分别可使G2/M期细胞增加2.22和3.37倍。W estern b lot分析表明在G2/M期阻滞同时有组蛋白H3乙酰化表达增加,但组蛋白H4乙酰化表达水平不受DADS作用的影响;瘤组织中的p21WAF1蛋白表达量也随DADS浓度升高而上升。结论DADS对胃癌细胞裸鼠移植瘤的生长有明显抑制和诱导分化作用,这种抑制可能与其阻滞移植瘤细胞周期、上调瘤细胞组蛋白乙酰化及p21WAF1蛋白水平有关。

组蛋白乙酰化/去乙酰化与白血病的研究进展

组蛋白乙酰化/去乙酰化与基因调控密切相关。组蛋白乙酰化水平的异常在白血病的发展、增殖和分化中起着很重要的作用。随着对组蛋白乙酰化的深入研究,组蛋白去乙酰化酶抑制剂在白血病中的作用机制越来越受到人们的关注。