Cloning, Characterization and Transformation of Methyltransferase 2a Gene (Zmet2a) in Maize (Zea mays L.)

DNA methylation is an important epigenetic regulatory mechanism,it regulates gene expression by recruiting proteins involved in gene repression or by inhibiting the binding of transcription factor(s)to DNA.In this study,a novel methyltransferase 2a gene(Zmet2a)was cloned in maize and identified by polymerase chain reaction-base(PCR-base)using a bioinformatics strategy.The Zmet2a cDNA sequence is 2739 bp long and translates to 912 amino acid peptides.The Zmet2a protein revealed that it contains BAH and CHROMO structural domains,is a non-transmembrane protein that is hydrophilically unstable,and has no signal peptide structure.Meanwhile,we verified the biological roles of Zmet2a using transgenic Arabidopsis overexpressing Zmet2a and Zmet2a-knockout maize.Transgenic Zmet2a Arabidopsis thaliana showed highly significant advancement inflowering time,and Zmet2a-knockout maize showed advancement inflowering time,with significant changes in several traits.Altogether,these report the role of Zmet2a in the regulation offlowering time,which will lay a foundation for revealing the biological function and epigenetic regulation mechanism of Zmet2a in the growth,development andflowering of maize.

Distinct functions of Dnmt3a and Dnmt3b de novo DNA methyltransferases in ES cell proliferation and differentiation

Two de novo DNA methyltransferases, Dnmt3a and Dnmt3b, have been identified in humans and mice to contribute to the methylation of unmodified DNA. We recently showed a transition of de novo DNA methyltransferase expression from Dnmt3b to Dnmt3a during mouse embryogenesis and in tissue-specific stem cells, suggesting distinct functions of Dnmt3a and Dnmt3b during these processes. In this study, to characterize the functions of Dnmt3a and Dnmt3b in pluripotent stem cells, we exogenously transfected ES cells with Dnmt3a and Dnmt3b cDNAs linked to an internal ribosome entry site-green fluorescent protein gene, and then analyzed the effects of expression of these de novo DNA methyltransferases on ES cell growth and differentiation. ES cells expressing Dnmt3b showed specific downregulation of pluripotency marker genes such as Nanog and Oct 3/4. In addition, Dnmt3a-transfected ES cells showed a specific increase in mitotic index, while Dnmt3b-transfected ES cells showed a decrease in mitotic index. These results suggest that Dnmt3b has important physiological roles in the initial process of stem cell differentiation and that Dnmt3a has a function in stem cell proliferation.

DNA methyltransferase (DNMTs) expression in cervical cancer tissues and its relationship with HPV infection and tumor malignancy

Objective:To study the DNA methyltransferase (DNMTs) expression in cervical cancer tissues and its relationship with human papilloma virus (HPV) infection and tumor malignancy. Methods:The cervical cancer tissues and normal cervical tissues surgically removed in Department of Obstetrics and Gynecology of our hospital between July 2013 and March 2016 were collected, the fluorescent quantitative PCR method was used to determine the mRNA expression of DNMTs in the tissues, and enzyme-linked immunosorbent assay kits were used to determine the protein expression of DNMTs molecules and pro-apoptotic molecules in the tissues. Results:DNMT1, DNMT2, DNMT3a, DNMT3b and DNMT3l mRNA expression and protein expression in cervical cancer tissues were significantly higher than those in normal cervical tissues (P<0.05) while Fas, FasL, Bax and Caspase-3 protein expression were significantly lower than those in normal cervical tissues (P<0.05);DNMT1, DNMT2, DNMT3a, DNMT3b and DNMT3l protein expression in cervical cancer tissues with high-risk HPV infection (+) were significantly higher than those in cervical cancer tissues with high-risk HPV infection (-) (P<0.05);Fas, FasL, Bax and Caspase-3 protein expression were negatively correlated with DNMT1, DNMT2, DNMT3a, DNMT3b and DNMT3l protein expression. Conclusions:Elevated DNMTs expression in cervical cancer tissues is associated with high-risk HPV infection, and highly expressed DNMTs can inhibit the expression of pro-apoptotic molecules.

乳腺癌组织中TIMP-3及DNMT1的表达与患者预后的相关性

目的:分析研究乳腺癌患者中基质金属蛋白酶组织抑制因子3(TIMP-3)及DNA甲基转移酶1(DNMT1)的表达水平与患者临床预后的相关性。方法:收集58例临床资料完整的乳腺癌手术切除标本,采用免疫组化SP法检测癌组织及相应癌旁组织中TIMP-3、DNMT1、ER、PR、HER-2、p53、Ki-67的表达,将TIMP-3、DNMT1表达水平与临床病理参数及随访生存状况进行相关性分析,所有入组患者均进行随访5年以上。结果:我们发现,在乳腺癌组织中,TIMP-3呈低表达,DNMT1呈高表达,TIMP-3及DNMT1的表达呈负相关;TIMP-3表达水平与Ki-67呈负相关,DNMT1表达水平与Ki-67呈正相关,与其他临床病理参数未见相关性。Cox风险比例模型分析显示只有临床分期和DNMT1表达水平是影响总生存期(OS)和无病生存期(DFS)的独立风险因素。TIMP-3低表达组的5年OS和DFS均显著低于高表达组,DNMT1高表达组的5年OS和DFS均显著低于低表达组。结论:研究表明乳腺癌中TIMP-3及DNMT1表达水平与肿瘤细胞恶性表型及患者生存时间有关,可能成为判断乳腺癌预后的一项重要指标,并作为治疗计划制定的依据。

Aberrant DNA methylation in 5′ regions of DNA methyltransferase genes in aborted bovine clones

High rate of abortion and developmental abnormalities is thought to be closely associated with inefficient epigenetic reprogramming of the transplanted nuclei during bovine cloning. It is known that one of the important mechanisms for epigenetic reprogramming is DNA methylation. DNA methylation is established and maintained by DNA methyltransferases （DNMTs）, therefore, it is postulated that the inefficient epigenetic reprogramming of transplanted nuclei may be due to abnormal expression of DNMTs. Since DNA methylation can strongly inhibit gene expression, aberrant DNA methylation of DNMT genes may disturb gene expression. But presently, it is not clear whether the methylation abnormality of DNMT genes is related to developmental failure of somatic cell nuclear transfer embryos. In our study, we analyzed methylation patterns of the 5＇ regions of four DNMT genes including Dnmt3a, Dnmt3b, Dnmtl and Dnmt2 in four aborted bovine clones. Using bisulfite sequencing method, we found that 3 out of 4 aborted bovine clones （AF1, AF2 and AF3） showed either hypermethylation or hypomethylation in the 5＇ regions of Dnmt3a and Dnmt3b, indicating that Dnmt3a and Dnmt3b genes are not properly reprogrammed. However, the individual AF4 exhibited similar methylation level and pattern to age-matched in vitro fertilized （IVF） fetuses. Besides, we found that the 5＇ regions of Dnmtl and Dnmt2 were nearly completely unmethylated in all normal adults, IVF fetuses, sperm and aborted clones. Together, our results suggest that the aberrant methylation of Dnmt3a and Dnmt3b 5＇ regions is probably associated with the high abortion of bovine clones.

Aberrant DNA methyltransferase 1 expression in clear cell renal cell carcinoma development and progression

Objective： To better understand the contribution of dysregulated DNA methyltransferase 1 （DNMT1） expression to the progression and biology of clear cell renal cell carcinoma （ccRCC）. Methods： We examined the differences in the expression of DNMT1 in 89 ecRCC and 22 normal tissue samples by immunohistochemistry. In addition, changes in cell viability, apoptosis, colony formation and invading ability of ccRCC cell lines （786-0 and Caki-1） were assessed after transfection with DNMT1 siRNA. Results： We found DNMT1 protein was significantly higher expressed in ccRCC than that of in no-tumor tissues （56.2% and 27.3%, respectively, P=0.018）. The expression of DNMT1 was strongly associated with ccRCC tumor size, tumor pathology stage, histological grading, lymph node metastasis, vascular invasion, recurrence and prognosis. Moreover, knockdown of DNMT1 expression significantly inhibited ccRCC cell viability, induced apoptosis, decreased colony formation and invading ability. Conclusions： Expression of DNMTI protein is increased in ccRCC tissues, and DNMT1 expression is associated with poor prognosis of patients. Experiments in vitro further showed DNMT1 played an essential role in proliferation and invasion of renal cancer cells. Moreover, targeting this enzyme could be a promising strategy for treating ccRCC, as evidenced by inhibited cell viability, increased apoptosis, decreased colony formation and invading ability.

DNA methyltransferase3a expression is an independent poor prognostic indicator in gastric cancer

AIM: To explore the alteration of DNA methyltransferase expression in gastric cancer and to assess its prognostic value.

Single nucleotide polymorphism in DNA methyltransferase 3B promoter and its association with gastric cardiac adenocarcinoma in North China

AIM:To investigate the association between single nucleotide polymorphism (SNP) in promoter of the DNA methyltrans-ferase 3B(DNMT3B) gene and risk for development and lymphatic metastasis of gastric cardiac adenocarcinoma (GCA). METHODS: The hospital based case-control study included 212 GCA patients and 294 control subjects without overt cancer. The DNMT3B SNP was genotyped by PCR and restriction fragment length polymorphism (RFLP) analysis. RESULTS: The C/C genotype was not detected in both GCA patients and controls. In control subjects, the frequency of T/T and C/T genotypes was 94.9% and 5.1% respectively, and that of T and C alleles was 97.4% and 2.6%, respectively. The genotype and allelotype distribution in the GCA patients was not significantly different from that in controls (P=0.34 and 0.33, respectively). When stratified by smoking status and family history of upper gastrointestinal cancer, significant difference in the genotype distribution was not observed between GCA patients and controls. The distribution of DNMT3B genotypes in GCA patents with or without lymphatic metastasis did not show significant difference (P= 0.42). CONCLUSION: The distribution of DNMT3B SNP in North China is distinct from that in Caucasians. Although this SNP has been associated with susceptibility to lung, head, neck and breast cancer, it may not be used as a stratification marker to predict susceptibility and lymphatic metastasis of GCA, at least in the population of North China.

放射治疗对宫颈癌DNA甲基转移酶表达的影响

目的:研究放射治疗对宫颈癌(cervical cancer,CIN)组织中DNA甲基转移酶(DNA methyltransferase,DNMT)1、3A和3B表达的影响,探讨其在放射治疗耐受中的作用。方法:选用12例宫颈癌患者放射治疗前、中、后三个时期的组织,应用qPCR检测宫颈癌组织在放射治疗前期、中期和后期的DNMT1、DNMT3A和DNMT3B mRNA的表达变化。结果:宫颈癌放射治疗前、中、后三个时期DNMT1对β-actin mRNA的相对表达量分别是(0.1229±0.0217)、(0.5696±0.0217)和(0.1620±0.0352);放射治疗期间和放射治疗之前宫颈癌组织中DNMT1 mRNA的表达差异有统计学意义(P<0.05),放射治疗期间和放射治疗之后宫颈癌组织中DNMT1 mRNA的表达差异有统计学意义(P<0.05),放射治疗之前和放射治疗之后宫颈癌组织中DNMT1 mRNA的表达差异有统计学意义(P<0.05);DNMT3A对β-actin mRNA的相对表达量分别是(0.0012±0.0001)、(0.0021±0.0001)和(0.0014±0.0001),放射治疗期间和放射治疗之前宫颈癌组织中DNMT3A mRNA的表达差异有统计学意义(P<0.05),放射治疗期间和放射治疗之后宫颈癌组织中DNMT3A mRNA的表达差异有统计学意义(P<0.05),放射治疗之前和放射治疗之后宫颈癌组织中DNMT3A mRNA的表达差异无统计学意义(P>0.05);DNMT3B对β-actin mRNA的相对表达量分别是(0.6627±0.0348)、(0.8104±0.0845)和(0.2391±0.0470),放射治疗期间和放射治疗之前宫颈癌组织中DNMT3B mRNA的表达差异有统计学意义(P<0.05),放射治疗期间和放射治疗之后宫颈癌组织中DNMT3B mRNA的表达差异有统计学意义(P<0.05),放射治疗之前和放射治疗之后宫颈癌组织中DNMT3B mRNA的表达差异有统计学意义(P<0.05)。结论:放射治疗使宫颈癌组织中DNMT1,DNMT3A和DNMT3B表达发生变化,其可能在放射耐受中起到了作用。

Overexpression of DNA methyltransferase 1 and its biological significance in primary hepatocellular carcinoma

AIM： To explore the relationship between DNA methyltransferase 1 （DNMT1） and hepatitis B virus （HBV）-related hepatocellular carcinoma （HCC） and its biological significance in primary HCC. METHODS： We carried out an immunohistochemical examination of DNMT1 in both HCC and paired nonneoplastic liver tissues from Chinese subjects. DNMT1 mRNA was further examined in HCC cell lines by real-time PCR. We inhibited DNMT1 using siRNA and detected the effect of depletion of DNMT1 on cell proliferation ability and cell apoptosis in the HCC celt line SMMC-7721. RESULTS： DNMT1 protein expression was increased in HCCs compared to histologically normal nonneoplastic liver tissues and the incidence of DNMT1 immunoreactivity in HCCs correlated significantly with poor tumor differentiation （P = 0.014）. There were more cases with DNMT1 overexpression in HCC with HBV （42.85%） than in HCC without HBV （28.57%）. However, no significant difference in DNMT1 expression was found in HBV-positive and HBV-negative cases in the Chinese HCC group. There was a trend that DNMT1 RNA expression increased more in HCC cell lines than in pericarcinoma cell lines and normal liver cell lines. In addition, we inhibited DNMT1 using siRNA in the SMMC-7721 HCC cell line and found depletion of DNMT1 suppressed cells growth independent of expression of proliferating cell nuclear antigen （PCNA）, even in HCC cell lines where DNMT1 was stably decreased. CONCLUSION： The findings implied that DNMT1 plays a key role in HBV-retated hepatocellular tumorigenesis. Depletion of DNMT1 mediates growth suppression in SMMC-7721 cells.

DNMT3a在肺腺癌中的表达及癌细胞迁移的影响分析

目的探讨DNA甲基转移酶3a(DNMT3a)在肺腺癌中的表达水平及影响肺腺癌细胞迁移的分子机制。方法回顾性分析2023年1~12月在安徽医科大学第一附属医院胸外科接受手术治疗的41例肺腺癌患者临床资料,使用IHC和蛋白质印迹实验(WB)检测并分析DNMT3a在41例患者肺腺癌组织及癌旁组织中的表达水平;通过分析TCGA数据库揭示DNMT3a与肺腺癌患者预后关系。慢病毒介导SK-LU-1和A549细胞系过表达或敲低DNMT3a,通过IHC、WB、实时荧光定量聚合链反应(qRT-PCR)、DNMT3a抑制剂实验观察DNMT3a对蜗牛家族转录因子(Snail)表达的影响;细胞划痕实验和Transwell细胞迁移实验检测过表达或敲低DNMT3a对肺腺癌细胞迁移的影响。结果DNMT3a高表达对比DNMT3a低表达的肺腺癌患者生存期较短,差异有统计学意义(P<0.01);DNMT3a和Snail在肺腺癌组织中较癌旁组织相比均高表达(P<0.01),且DNMT3a和Snail在肺腺癌组织中的表达呈正相关(r=0.612,P<0.01)。与对照组相比,过表达DNMT3a的SK-LU-1细胞中Snail表达上调并增加了肺腺癌细胞的迁移数量(P<0.01),敲低DNMT3a的A549细胞中Snail表达下调并减少了肺腺癌细胞的迁移数量(P<0.01)。结论DNMT3a在肺腺癌组织中高表达且与不良预后显著相关,DNMT3a通过上调Snail的表达促进肺腺癌细胞的迁移。

Association of DNA methylation/demethylation with the functional outcome of stroke in a hyperinflammatory state

Inflammation is closely related to stroke prognosis, and high inflammation status leads to poor functional outcome in stroke. DNA methylation is involved in the pathogenesis and prognosis of stroke. However, the effect of DNA methylation on stroke at high levels of inflammation is unclear. In this study, we constructed a hyperinflammatory cerebral ischemia mouse model and investigated the effect of hypomethylation and hypermethylation on the functional outcome. We constructed a mouse model of transient middle cerebral artery occlusion and treated the mice with lipopolysaccharide to induce a hyperinflammatory state. To investigate the effect of DNA methylation on stroke, we used small molecule inhibitors to restrain the function of key DNA methylation and demethylation enzymes. 2,3,5-Triphenyltetrazolium chloride staining, neurological function scores, neurobehavioral tests, enzyme-linked immunosorbent assay, quantitative reverse transcription PCR and western blot assay were used to evaluate the effects after stroke in mice. We assessed changes in the global methylation status by measuring DNA 5-mc and DNA 5-hmc levels in peripheral blood after the use of the inhibitor. In the group treated with the DNA methylation inhibitor, brain tissue 2,3,5-triphenyltetrazolium chloride staining showed an increase in infarct volume, which was accompanied by a decrease in neurological scores and worsening of neurobehavioral performance. The levels of inflammatory factors interleukin 6 and interleukin-1 beta in ischemic brain tissue and plasma were elevated, indicating increased inflammation. Related inflammatory pathway exploration showed significant overactivation of nuclear factor kappa B. These results suggested that inhibiting DNA methylation led to poor functional outcome in mice with high inflammation following stroke. Further, the effects were reversed by inhibition of DNA demethylation. Our findings suggest that DNA methylation regulates the inflammatory response in stroke and has an important role in the functional outcome of hyperinflammatory stroke.

Potassium bisperoxo(1,10-phenanthroline) oxovanadate suppresses proliferation of hippocampal neuronal cell lines by increasing DNA methyltransferases

Bisperoxo(1,10-phenanthroline) oxovanadate(BpV) can reportedly block the cell cycle. The present study examined whether BpV alters gene expression by affecting DNA methyltransferases(DNMTs), which would impact the cell cycle. Immortalized mouse hippocampal neuronal precursor cells(HT_(22)) were treated with 0.3 or 3 μM BpV. Proliferation, morphology, and viability of HT_(22) cells were detected with an IncuCyte real-time video imaging system or inverted microscope and 3-(4,5-dimethylthiazol-2-yl)-5(3-carboxymethonyphenol)-2-(4-sulfophenyl)-2H-tetrazolium, respectively. mRNA and protein expression of DNMTs and p21 in HT_(22) cells was detected by real-time polymerase chain reaction and immunoblotting, respectively. In addition, DNMT activity was measured with an enzyme-linked immunosorbent assay. Effects of BpV on the cell cycle were analyzed using flow cytometry. Results demonstrated that treatment with 0.3 μM BpV did not affect cell proliferation, morphology, or viability; however, treatment with 3 μM BpV decreased cell viability, increased expression of both DNMT3B mRNA and protein, and inhibited the proliferation of HT_(22) cells; and 3 μM BpV also blocked the cell cycle and increased expression of the regulatory factor p21 by increasing DNMT expression in mouse hippocampal neurons.

DNMT1与T淋巴细胞因子在急性髓系白血病中的表达水平及相关性分析

目的分析DNA甲基转移酶1(DNMT1)与T淋巴细胞因子在急性髓系白血病(AML)中的表达水平及相关性。方法选取昆明医科大学第一附属医院2020年1月至2022年12月收治的初诊AML患者作为AML组(38例),另选取同期在昆明医科大学第一附属医院进行骨髓穿刺的缺铁性贫血患者作为对照组(21例)。检测并比较两组骨髓DNMT1的信使RNA(mRNA)表达水平及T淋巴细胞因子[白细胞介素(IL)-2、IL-4、IL-6、IL-10、干扰素-γ(INF-γ)、肿瘤坏死因子-α(TNF-α)、转化生长因子-β(TGF-β)]水平,以及比较不同临床特征AML患者DNMT1表达水平。采用Pearson相关分析AML患者DNMT1表达水平与T淋巴细胞因子水平的相关性。绘制受试者工作特征(ROC)曲线分析DNMT1、T淋巴细胞因子单独及联合检测对AML的诊断效能。结果AML组DNMT1 mRNA表达水平高于对照组(P<0.001)。白细胞计数(WBC)≥5.0×10^(10)/L、骨髓幼稚细胞比例≥60%、外周血幼稚细胞比例≥60%、乳酸脱氢酶(LDH)≥300 U/L、骨髓外浸润、染色体核型预后不良患者DNMT1表达水平分别高于WBC<5.0×10^(10)/L、骨髓幼稚细胞比例<60%、外周血幼稚细胞比例<60%、LDH<300 U/L、无骨髓外浸润、染色体核型预后良好患者,差异均有统计学意义(P<0.05)。AML组血清IL-2、IL-4、IL-10、INF-γ水平高于对照组,TGF-β水平低于对照组,差异均有统计学意义(P<0.05)。Pearson相关分析结果显示,DNMT1表达水平与IL-2、IL-4、IL-10、INF-γ水平呈正相关(r=0.574、0.619、0.527、0.483,P<0.05),与TGF-β水平呈负相关(r=-0.475,P<0.05)。ROC曲线分析结果显示,DNMT1联合IL-2、IL-4、IL-10、INF-γ检测诊断AML的曲线下面积分别为0.918、0.711、0.756、0.726。结论AML患者的DNMT1表达水平升高、T淋巴细胞因子表达失衡,二者存在一定相关性,DNMT1与部分T淋巴细胞因子联合检测对AML具有诊断价值。

DNA methyltransferase 3B promoter polymorphism and its susceptibility to primary hepatocellular carcinoma in the Chinese Han nationality population:A case-control study

AIM： To investigate the correlation between C/T single nucleotide polymorphism （SNP） in the promoter of the DNA methyltransferase 3B （D/VMT3B） gene and risk for development and progression of primary hepatocellular carcinoma （HCC）. METHODS： One hundred case subjects were selected consecutively from Tongji Hospital （Wuhan, China）. from March to November 2006. They did not receive radiotherapy or chemotherapy for newly diagnosed and histopathologically confirmed HCC. One hundred and forty control subjects having no history of cancerous or genetic diseases were healthy volunteers to Wuhan Blood Center in the same period. Frequency was matched for sex, age, alcohol consumption and cigarette smoking status of the case subjects. C/T polymorphism of the DNMT3B promoter was analyzed using polymerase chain reaction-restriction fragment length polymorphism （PCR-RFLP） and sequencing analysis. The association between genotypes of DNMT3B and clinicopathological parameters among cases was also studied. RESULTS： The CC genotype HCC patients and controls. was not detected in both In control subjects, the frequency of TT and CT genotypes was 99.3% and 0.7% respectively, and that of T and C alleles was 99.6% and 0.4% respectively. The frequency of CT genotype was higher in HCC （3.0%）. The frequency of T and C alleles was 98.5% and 1.5% respectively. However, the genotype and allelotype distribution in HCC patients was not significantly different from that in controls. CONCLUSION： C/T polymorphism is not associated with the increased risk of HCC. DNMT3B genetic polymorphism is variable in different races, ethnic groups or geographic areas. Further study is needed to clarify the role of DNMT3B SNP in the development of HCCamong other populations.

急性低氧后小胶质细胞中DNA甲基转移酶的表达变化

目的:探究小胶质细胞在急性低氧后DNA甲基转移酶的变化情况。方法:以BV2细胞为研究对象,将其分为对照组(control)、H-0组(低氧12 h不进行复氧)、H-2组(低氧12 h复氧2 h)、H-4组(低氧12 h复氧4 h)、H-8组(低氧12 h复氧8 h)、H-12组(低氧12 h复氧12 h)、H-24组(低氧12 h复氧24 h)。将BV2细胞低氧12 h,在不同的时间点进行复氧构建模型,通过荧光倒置显微镜明场观察细胞形态;采用Real-time PCR检测DNMT1、DNMT 3A、DNMT 3B在mRNA水平上的表达变化;采用Western blot检测DNMT1、DNMT 3A、DNMT 3B在蛋白水平上的表达变化。结果:与control组相比,H-0组的细胞数量减少,细胞形态皱缩,大部分细胞触角伸长,细胞暗淡无光,折光度降低。随着复氧时间的增加(H-2、H-4、H-8、H-12、H-24),贴壁细胞逐渐减少。与control组相比,DNMT1在H-0组中蛋白的表达水平显著上升(P<0.05),H-8、H-12、H-24组DNMT1的mRNA和蛋白水平表达显著降低(P<0.05)。DNMT 3A在H-8、H-12组中的mRNA和蛋白水平表达显著降低(P<0.05)。DNMT 3B在H-0、H-4、H-8、H-12、H-24组细胞中的mRNA和蛋白水平无显著变化。结论:在低氧后小胶质细胞中DNMT1、DNMT 3A发挥了重要作用。

Dnmt3b对髁突纤维软骨干细胞多向分化调控作用的实验研究

目的:探究DNA甲基转移酶3b(DNA methyltransferase 3b enzyme,Dnmt3b)对大鼠髁突纤维软骨干细胞(fibrocartilage stem cells,FCSCs)成脂、成骨、成软骨向分化能力的影响。方法:体外分离培养大鼠髁突FCSCs,构建Dnmt3b过表达慢病毒,感染FCSCs建立过表达Dnmt3b的FCSCs细胞模型,并对其进行成脂、成骨、成软骨诱导培养,检测Dnmt3b过表达对大鼠髁突FCSCs成脂、成骨、成软骨相关基因表达的影响。结果:大鼠髁突纤维软骨干细胞具有间充质干细胞特性。与对照组相比,Dnmt3b过表达组成脂相关基因过氧化物酶体增殖物激活受体γ(peroxisome proliferator-activated receptorγ,Ppar-γ)的表达显著降低,成骨相关基因Runt相关转录因子2(runt-related transcription factor 2,Runx2)、碱性磷酸酶(alkaline phosphatase,ALP)的表达显著升高,成软骨相关基因SRY相关转录因子9(SRY-related high mobility group-box gene 9,Sox9)、聚集蛋白聚糖(aggrecan,ACAN)的表达显著升高。结论:Dnmt3b能促进大鼠髁突纤维软骨干细胞成软骨向分化和成骨向分化,抑制其成脂向分化。

Regulation of neuronal survival by DNA methyltransferases

The limited regenerative capacity of neuronal cells requires tight orchestration of cell death and survival regulation in the context of longevity, age-associated diseases as well as during the development of the nervous system. Subordinate to genetic networks epigenetic mechanisms like DNA methylation and histone modifications are involved in the regulation of neuronal development, function and aging. DNA methylation by DNA methyltransferases （DNMTs）, mostly correlated with gene silencing, is a dynamic and reversible process. In addition to their canonical actions performing cytosine methylation, DNMTs influence gene expression by interactions with histone modifying enzymes or complexes increasing the complexity of epigenetic transcriptional networks. DNMTs are expressed in neuronal progenitors, post-mi- totic as well as adult neurons. In this review, we discuss the role and mode of actions of DNMTs including downstream networks in the regulation of neuronal survival in the developing and aging nervous system and its relevance for associated disorders.

Influence of DNA methyltransferase 3b on FHIT expression and DNA methylation of the FHIT promoter region in hepatoma SMMC-7721 cells

BACKGROUND: Alterations in DNA methylation occur during the pathogenesis of human tumors. In this study, we investigated the influence of DNA methyltransferase 3b (DNMT3b) on fragile histidine trial (FHIT) expression and on DNA methylation of the FHIT promoter region in the hepatoma cell line SMMC-7721. METHODS: DNMT3b siRNA was used to down-regulate DNMT3b expression. DNMT3b and FHIT proteins were determined by Western blotting. Methylation-specific PCR was used to analyze the methylation status of the FHIT gene. RESULTS: After DNMT3b siRNA transfection, the expression of DNMT3b was inhibited in SMMC-7721 cells, and the expression of FHIT was significantly higher than that in the control group. There was no significant difference in methylation status between the DNMT3b siRNA transfected cells and control cells. CONCLUSION: DNMT3b may play an important role in regulation of FHIT expression in hepatoma SMMC-7721 cells, but not through methylation of the FHIT promoter. (Hepatobiliary Pancreat Dis Int 2009; 8: 273-277)

cDNA Cloning of Goat DNA Methyltransferase 1,Screening of shRNA Vectors and Influences to Development of Nuclear Transfer Embryos

This study was designed to clone cDNA of goat DNA methyltransferase 1（DNMT1） gene,to screen an effective shRNAproducing vector targeting goat DNA methyltransferase 1 and to improve the developmental competence of goat nuclear transfer embryos by decreasing the DNMT1 expression in donor cells.In this study,PCR primers were designed against regions of high homology between bovine and sheep sequences and then used to amplify the larger portions of the coding regions.Next,3 RNAi oligonucleotides were designed based on the cloned sequences and inserted into pRNAT-U6.1/Neo vector,acquiring 3 new vectors,respectively termed pRNAD1,pRNAD2 and pRNAD3.Then the positive cells were sorted by flow cytometry after transfection and detected by real-time PCR analysis and sodium bisulfite genomic sequencing.Finally,the developmental rates of nuclear transfer（NT） embryos generated using donor cells with and without the effective shRNA vector respectively,as well as in vitro fertilization（IVF） embryos were observed and recorded.The results showed that the coding regions of goat DNA methyltransferase 1 gene was successfully cloned（GenBank no.FJ617538）.Furthermore,an effective interfering shRNA（pRNAD2） was obtained,with its interference effect being 47.88%.Finally,NT embryos with shRNA vector harbored better developmental competence during morula and blastocyst stage compared to controls（P 〈 0.05）,reaching the similar rates to IVF embryos（P 〉 0.05）.In conclusion,goat DNA methyltransferase 1 gene cDNA was cloned and sequenced,an effective shRNA vector responsible for inhibiting DNA methyltransferase 1 expression was developed and the developmental competence of goat nuclear transfer morulae and blastcysts was significantly improved,which provided a feasible pathway for improving goat nuclear transfer embryo development competence by decreasing the methylation level in donor cells through RNAi-mediated manner.