Polycomb家族基因Nspc1在斑马鱼早期发育的表达

目的探讨Polycomb家族基因Nspc1在模式生物斑马鱼发育早期的表达模式。方法根据GenBank中斑马鱼Nspc1的cDNA序列设计Nspc1原位杂交探针片断,并制备地高辛标记的探针。收取单细胞期、双细胞期、胚芽期及不同时间点的体节期斑马鱼胚胎,用制备好的探针作原位杂交,显微镜下拍照,获得信号适当的杂交结果。结果在斑马鱼体节期前,Nspc1在全身表达;从体节期开始,其表达逐渐表现出特异性,主要在头部的神经系统中表达。结论Nspc1在模式生物斑马鱼的早期发育、尤其是神经系统发育的过程中可能扮演重要角色。

Polycomb蛋白复合体对细胞衰老的表观遗传学调控

细胞衰老在表观遗传学上的调控越来越受到人们的关注.Polycomb蛋白复合体(polycombgroup proteins)通过对组蛋白的修饰,尤其是甲基化修饰发挥对靶基因的沉默作用,并因此广泛参与到发育、增殖、分化以及肿瘤发生等重要生命过程.目前,有一系列的研究报道了polycomb的各组份参与了细胞衰老的调控.本文对polycomb发挥基因沉默作用机制的最新研究进展进行了归纳总结,并以衰老过程中的重要分子p16为重点,详细介绍了polycomb调节p16表达,影响细胞衰老进程的机制.研究表明,多种polycomb成员同时结合在p16INK4a基因座,它们的结合表现出相互依赖的同时又有各自的作用.这为进一步深入理解细胞衰老提供了表观遗传学的证据.

Polycomb Group蛋白复合体与干细胞的发育调控

Polycomb group(PcG)蛋白是表观遗传调控因子中一个非常重要的家族,参与维持特定基因的沉默,在调控干细胞增殖与分化的过程中起着非常重要的作用。PcG蛋白可通过形成不同的蛋白复合物引起不同的染色质修饰来调控干细胞的生命活动,其复合物主要包括两个重要的表观遗传调控因子:PRC1(polycomb repressive complex 1)和PRC2(polycomb repressive complex 2)。为了阐明PcG蛋白在干细胞增殖与分化中的调控作用,本文分别从PcG蛋白复合体的组成、在靶基因中的定位、募集和在干细胞发育中的调控等方面进行了综述,旨在为进一步研究干细胞的发育调控机制提供理论依据。

Polycomb Group蛋白复合体与植物春化作用

Polycomb Group(PcG)蛋白能形成Polycomb Repressive Complex 1(PRC1)和PRC2等复合体,通过一个保守且表观遗传的机制调节基因表达并控制动植物的发育。拟南芥中由VERNALIZATION2参与形成的PRC2复合体(VRN2-PRC2)在春化过程中能对主要开花抑制基因FLOWER LOCUS C(FLC)的染色质进行组蛋白甲基化修饰,形成H3K27me3(组蛋白H3第27位赖氨酸三甲基化)等转录抑制标记,从而抑制FLC转录,促进开花。虽然麦类作物的春化机理与拟南芥有较大差异,但最近的研究表明麦类作物春化过程也受PcG蛋白调控。文章对拟南芥PcG蛋白介导的春化调节机制进行综述,期望能对植物尤其是麦类作物的春化机理研究提供资料。

家蚕Polycomb家族基因BmEsc功能结构域编码序列的克隆及表达分析

Polycomb蛋白（polycomb group proteins,PcG）主要包含PRC1和PRC2 2个核心蛋白质复合体,其中PRC2在靶基因转录抑制起始阶段发挥作用,ESC作为PRC2的一个关键蛋白质,通过参与组蛋白H3K27me3的修饰来抑制基因转录。为了研究家蚕PcG蛋白的功能,克隆了长度为876 bp的家蚕Esc基因（BmEsc）WD40功能结构域编码序列,构建重组表达载体转化大肠杆菌BL21（DE3）感受态细胞后,成功表达并纯化了目的蛋白质,可用于进一步的抗体制备和功能研究。利用实时荧光定量PCR检测BmEsc基因在家蚕不同发育时期的表达特征：非滞育卵中该基因的表达水平在卵期1~5 d相对较高,而滞育卵中该基因在卵期1~2 d的表达量低于非滞育卵,卵期6~9 d的表达量却高于非滞育卵,并保持较稳定水平;该基因在各龄幼虫龄中期的表达量较低,在5龄1~3 d和化蛹前的一段时期表达量较高,在蛹期的表达水平变化不大。初步推测BmEsc可能在家蚕早期胚胎发育、滞育卵中的靶基因沉默以及在幼虫蜕皮前后和化蛹变态前的组织分化过程中发挥重要作用。

Polycomb基因家族在大鼠精子发生过程中的表达

目的检测大鼠精子发生不同阶段细胞中Polycomb-group(Pc-G)家族在mRNA水平上表达是否有差异。方法提纯大鼠精子发生过程中的精原细胞、精母细胞、圆形精子细胞以及支持细胞,用荧光定量PCR方法检测Pc-G家族基因mRNA表达量。结果Pc-G基因家族中Ezh2、Eed、Bmi-1在精子发生中后期高表达;在各生精细胞中,YY1基因表达量低于支持细胞。结论Pc-G基因家族在精子发生各阶段细胞中特征性表达,与精子发生具有相关性,可能对精子发生分化和维持遗传稳定性都有重要的作用。

植物Polycomb Group功能研究进展

Polycomb Group(PcG)是一类高度保守的表观调控因子,在动植物中普遍存在,并发挥着非常重要生物学功能。研究发现PcG蛋白不仅调控生物个体正确的生长发育模式,而且与细胞增殖、分化、胚胎发育、植物形态建成和植物对环境的响应等有密切关系。综述了PcG因子在植物中的组成、作用机制及其功能,并对PcG未来的研究方向进行了展望。

人Polycomb家族成员NSPc1蛋白的原核表达纯化及多克隆抗体制备

目的Polycomb家族成员NSPc1多克隆抗体的制备与检测。方法应用PCR技术扩增人NSPc1编码区全长序列并插入到pET-43.1a(+)载体中,在大肠杆菌BL21中表达融合蛋白HIS-NSPc1。利用所表达的融合蛋白中含有的6×His标签进行亲和纯化。用所获得的纯化蛋白免疫新西兰大白兔,获得兔抗人NSPc1多克隆抗体。用Western blot检测抗体免疫反应的特异性。结果在大肠杆菌中表达并纯化了人NSPc1重组蛋白,纯度达95%,用其免疫新西兰大白兔,成功制备了相应兔源多克隆抗体,Western blot实验中该抗体可以特异识别内源及外源性NSPc1蛋白。结论原核表达的NSPc1融合蛋白可以被纯化,并具有足够的蛋白免疫原性,所制备的相应多克隆抗体具有良好的特异性,可以运用于NSPc1基因的功能研究。

Polycomb家族基因BmSu(z)12在家蚕幼虫中的表达研究

[目的]研究家蚕Polycomb蛋白家族基因BmSu（z）12在家蚕幼虫中的表达情况.[方法]根据家蚕基因组预测的BmSu（z）12基因序列,设计特异引物,利用qRT-PCR对该基因在家蚕不同龄期幼虫中的表达进行研究.[结果]BmSu（z）12基因在5龄幼虫蜕皮后2d和变态前2d有较高表达,而在1～5龄取食中期表达量较低,表达特征具有一定的规律性.[结论]BmSu（z）12基因在家蚕幼虫生长发育中具有重要作用,该研究为进一步研究家蚕SU（Z）12蛋白的功能奠定基础.

Expression of the polycomb group gene <i>Bmi</i>1 does not affect the prognosis of pediatric acute lymphoblastic leukemia

The Polycomb group protein Bmi1 is a constituent of the Polycomb repressive complex 1, and it is an important molecule for the regulation of the self-renewal of hematopoietic stem cells. In the field of clinical hematology, there are reports that the level of Bmi1 expression in blast cells is related to the prognosis of acute myeloid leukemia, chronic myeloid leukemia, and myelodysplastic syndrome. We investigated whether the level of Bmi1 expression in leukemic cells is related to the prognosis and the characteristics of childhood acute lymphoblastic leukemia. In all the leukemic blast cells, Bmi1 gene expression was lower value than that in normal B cells. There were no correlations between the level of Bmi1 gene expression in leukemic blast cells and other parameters, including prognosis. Here, we report that the level of Bmi1 expression in blast cells is not related to the prognosis of pediatric acute lymphoblastic leukemia.

Leptin Signaling Modulates Expression of Polycomb and Trithorax Complexes in the Brain of Fat Tissue Implanted Polycystic Ovarian Sindrome Mice

The Polycystic Ovary Syndrome (PCOS) is the most common androgenic disorder in women during reproductive life. PCOS may also be accompanied by metabolic syndrome and recent studies point to leptin as playing a role in disrupting infertility and in changing the energy balance in obese mice through its action on the hypothalamus. The aim is to assess the expression of the Polycomb & Trithorax Complexes genes in brain of mice transplanted with fat tissue from normal mice, in order to better understand the neuronal mechanisms underlying the reversion of PCOS. Three B6 V-Lepob/J mouse groups: Normal weight, obese and seven-day-treatment obese had their brain RNA extracted and submitted to an 84 Polycomb & Trithorax Complexes genes PCR Array plate and MetacoreTM pathways localization. Genomic profiles obtained were compared to the ones of the normal-weight-mice group. Differentially expressed genes were 13% and 26% respectively to control and treatment. Major changes were in genes: Snai1/31;Smarca1/?17;Dnmt3b/4.7;Ezh1/ 15. Altered genes were associated to canonical pathways and provided 3 networks related to epigenetics. Underlying neuronal changes caused by leptin in obese mice brain, there is an important role being played by the histone code. Here there is evidence that leptin drives the chromatin packing to a more condensed pattern. Upregulation of methyltransferase genes, like Ezh1, favors this thought. In summary the Polycomb & Trithorax complexes might answer for the silencing of some downregulated genes in the obese mice brain when exposed to leptin.

Polycomb Repressive Complex 2-Mediated H3K27 Trimethylation Is Required for Pathogenicity in Magnaporthe oryzae

Polycomb repressive complex 2(PRC2)contributes to catalyze the methylation of histone H3 at lysine 27 and plays vital roles in transcriptional silencing and growth development in various organisms.In Magnaporthe oryzae,histone H3K27 is found to associate with altered transcription of in planta induced genes.However,it is still unknown whether and how H3K27me3 modification is involved in pathogenicity to rice and stress response.In this study,we found that core subunits of PRC2,Kmt6-Suz12-Eed,were required for fungal pathogenicity to rice in M.oryzae.Kmt6-Suz12-Eed localized in the nuclei and was necessary for the establishment of H3K27me3 modification.With ChIP-seq analysis,9.0%of genome regions enriched with H3K27me3 occupancy,which corresponded to 1033 genes in M.oryzae.Furthermore,deletion of Kmt6,Suz12 or Eed altered genome-wide transcriptional expression,while the de-repression genes in theΔkmt6 strain were highly associated with H3K27me3 occupancy.Notably,plenty of genes which encode effectors and secreted enzymes,secondary metabolite synthesis genes,and cell wall stress-responsive genes were directly occupied with H3K27me3 modification and de-repression in theΔkmt6 strain.These results elaborately explained how PRC2 was required for pathogenicity,which is closely related to effector modulated host immunity and host environment adaption.

Epigenetic Repression of SATB1 by Polycomb Group Protein EZH2 in Epithelial Cells

Objective To study the regulatory mechanism of SATB1 repression in cells other than T cells or erythroid cells, which have high expression level of SATB1. Methods HeLa epithelial cells were treated with either histone deacetylase inhibitor (HDACi) trichostatin A (TSA) or DNA methylation inhibitor 5-Aza-C before detecting SATB1 expression. Luciferase reporter system was applied to measure effects of EZH2 on SATB1 promoter activity. Over-expression or knockdown of EZH2 and subsequent quantitative reverse transcription-polymerase chain reaction were performed to determine the effect of this Polycomb group protein on SATB1 transcription. Chromatin immunoprecipitation (ChIP) assay was applied to measure enrichment of EZH2 and trimethylated H3K27 (H3K27me3) at SATB1 promoter in HeLa cells. K562 cells and Jurkat cells, both having high-level expression of SATB1, were used in the ChIP experiment as controls. Results Both TSA and 5-Aza-C increased SATB1 expression in HeLa cells. Over-expression of EZH2 reduced promoter activity as well as the mRNA level of SATB1, while knockdown of EZH2 apparently enhanced SATB1 expression in HeLa cells but not in K562 cells and Jurkat cells. ChIP assay results suggested that epigenetic silencing of SATB1 by EZH2 in HeLa cells was mediated by trimethylation modification of H3K27. In contrast, enrichment of EZH2 and H3K27me3 was not detected within proximal promoter region of SATB1 in either K562 or Jurkat cells. Conclusion SATB1 is a bona fide EZH2 target gene in HeLa cells and the repression of SATB1 by EZH2 may be mediated by trimethylation modification on H3K27.

Bmi-1,a Polycomb Group Protein,Plays an Essential Role in Tumorigenesis and Metastasis

Dysregulation of polycomb group protein Bmi-1 expression has been linked with an invasive phenotype of certain human cancers and poor prognosis of patients; however, the underlying mechanisms are

Polycomb Group Genes as the Key Regulators in Gene Silencing

The Polycomb group （PcG） genes repress gene expression mainly through chromatin modifications and regulation of chromatin structure. At present, at/east four protein complexes of PcG proteins are identified, including Polycomb repressive complex 1 （PRC1）, Polycomb repressive complex 2 （PRC2）, PHO-repressive complex （PhoRC） and Polycomb repressive deubiquitinase （PR-DUB）. In this review, the recent discoveries of the composition of the above complexes, as well as their roles in regulating histone modifications and gene silencing are discussed. We mainly focus on the composition of PRC1 and PRC2 complex and recruitment of PcG to target genes and mechanisms of PRC1 and PRC2-mediated gene silencing. Although much progress has been made in understanding gene silencing mediated by PcG proteins, we also discuss several important questions that still remained unanswered, such as the inheritance of histone modifications during cell division.

Polycomb-group proteins in the initiation and progression of cancer

The Polycomb group(PcG) proteins are a family of chromatin regulators and critical for the maintenance of cellular identity. The PcG machinery can be categorized into at least three multi-protein complexes, namely Polycomb Repressive Complex 1(PRC1), PRC2, and Polycomb Repressive De UBiquitinase(PR-DUB).Their deregulation has been associated with human cancer initiation and progression. Here we review the updated understanding for Pc G proteins in transcription regulation and DNA damage repair and highlight increasing links to the hallmarks in cancer. Accordingly, we discuss some of the recent advances in drug development or strategies against cancers caused by the gain or loss of PcG functions.

Polycomb与心脏发育

心脏作为维持血液循环的"泵",在人体发挥重要作用.而心脏发育的正常进行则是维持其功能的基础.因此,对心脏发育及其调节的研究一直为科学家们所关注.Polycomb复合体是一组抑制基因转录的蛋白,参与调节多种组织器官发育相关基因的表达.越来越多的证据表明,Polycomb在心脏发育中起重要的调节作用.因此,进一步了解其调节作用的机制,将为解析先天性心脏病的发病机制提供有益线索.本文主要从表观遗传的角度,重点阐述了Polycomb蛋白复合体与心脏发育的关系.

Expression, Imprinting, and Evolution of Rice Homologs of the Polycomb Group Genes

Polycomb group proteins （PcG） play important roles in epigenetic regulation of gene expression. Some core PeG proteins, such as Enhancer of Zeste （E（z））, Suppressor of Zeste （12） （Su（z）12）, and Extra Sex Combs （ESC）, are conserved in plants. The rice genome contains two E（z）-Iike genes, OsiEZ1 and OsCLF, two homologs of Su（z）12, OsEMF2a and OsEMF2b, and two ESC-like genes, OsFIE1 and OsFIE2. OsFIE1 is expressed only in endosperm; the maternal copy is expressed while the paternal copy is not active. Other rice PcG genes are expressed in a wide range of tissues and are not imprinted in the endosperm. The two E（z）-Iike genes appear to have duplicated before the separation of the dicots and monocots; the two homologs of Su（z）12 possibly duplicated during the evolution of the Gramineae and the two ESC- like genes are likely to have duplicated in the ancestor of the grasses. No homologs of the Arabidopsis seed-expressed PcG genes MEA and FIS2 were identified in the rice genome. We have isolated T-DNA insertion lines in the rice homologs of three PcG genes. There is no autonomous endosperm development in these T-DNA insertion lines. One line with a T-DNA insertion in OsEMF2b displays pleiotropic phenotypes including altered flowering time and abnormal flower organs, suggesting important roles in rice development for this gene.

TRIM25通过EZH2介导巨噬细胞M2极化促进食管鳞状细胞癌细胞的增殖迁移和侵袭

目的:探讨TRIM25和EZH2在食管鳞状细胞癌(ESCC)相关巨噬细胞浸润中的作用及其可能的作用机制。方法:利用佛波酯诱导THP-1为M0巨噬细胞,将其与转染处理后的KYSE510细胞共培养,收集共培养巨噬细胞,分为Ctrl组、sh-NC组、sh-TRIM25组、sh-NC+oe-NC组、sh-TRIM25+oe-NC组、sh-NC+oe-EZH2组和sh-TRIM25+oe-EZH2组。收集共培养上清液,将其加入KYSE510细胞中,分为Ctrl组、TAM组、sh-NC+TAM组、sh-TRIM25+TAM组、sh-NC+oe-NC+TAM组、sh-TRIM25+oe-NC+TAM组、sh-NC+oe-EZH2+TAM组和sh-TRIM25+oe-EZH2+TAM组。qPCR法和WB法检测细胞中TRIM25、EZH2和Arg-1表达,放线菌酮蛋白合成抑制实验检测细胞EZH2蛋白稳定性,FCM检测F4/80+CD206+巨噬细胞比例,CCK-8法、克隆形成实验和Transwell实验分别检测细胞的增殖、迁移和侵袭能力。结果:KYSE510细胞中TRIM25和EZH2 mRNA和蛋白表达均高于人食管鳞状上皮细胞HET-1A(P<0.01)。与sh-NC组和sh-NC+oe-NC组相比,sh-TRIM25组和sh-TRIM25+oe-NC组F4/80+CD206+巨噬细胞比例和Arg-1蛋白表达均降低(P<0.05),sh-NC+oe-EZH2组则升高(P<0.05)。与sh-NC+TAM组和sh-NC+oe-NC+TAM组相比,sh-TRIM25+TAM组和sh-TRIM25+oe-NC+TAM组KYSE510细胞活力、克隆形成数、迁移和侵袭细胞数均降低(P<0.05),sh-NC+oe-EZH2+TAM组则升高(P<0.05)。敲低TRIM25可通过抑制EZH2蛋白半衰期,降低EZH2蛋白稳定性。过表达EZH2可部分逆转sh-TRIM25对巨噬细胞和KYSE510细胞的影响。结论:TRIM25通过促进EZH2蛋白稳定性诱导巨噬细胞M2极化,从而促进ESCC细胞增殖、迁移和侵袭。

JASMONATE-ZIM DOMAIN proteins engage Polycomb chromatin modifiers to modulate Jasmonate signaling in Arabidopsis

Jasmonate(JA)regulates various aspects of plant growth and development and stress responses,with prominent roles in male reproductive development and defenses against herbivores and necrotrophic pathogens.JASMONATE-ZIM DOMAIN(JAZ)proteins are key regulators in the JA signaling pathway and function to repress the expression of JA-responsive genes.Here,we show that JAZ proteins directly interact with several chromatin-associated Polycomb proteins to mediate repressive chromatin modifications at JA-responsive genes and,thus,their transcriptional repression in Arabidopsis.Genetic analyses revealed that the developmental defects,including anther and pollen abnormalities,resulting from loss or block of JA signaling were partially rescued by loss of Polycomb protein-mediated chromatin silencing(Polycomb repression).We further found that JAZ-mediated transcriptional repression during anther and pollen development requires Polycomb proteins at four key Regulatory loci.Analysis of genome-wide occupancy of a Polycomb factor and transcriptome reprogramming in response to JA revealed that Polycomb repression is involved in the repression of various JA-responsive genes.Taken together,our study reveals an important chromatin-based mechanism for JAZ-mediated transcriptional repression and JA signaling in plants.