抑制肿瘤小G蛋白ARHI研究进展

小GTP结合蛋白在细胞的整个生命活动中起着重要的作用.人类ARHI基因是小GTP结合蛋白中Ras亚家族的一个成员.系母系印迹基因,定位于染色体lp31.ARHI基因含有两个外显子和一个内含子,启动子区域有转录抑制因子E2F结合位点、3'末端有Au-rich区域.在ARHI基因中存在三个CpG岛,其中第一个CpG岛位于该基因的启动子区域,第二个CpG岛跨越了启动子和第一个外显子区.第三个CpV岛处于第二个外显子之内.与正常细胞相比,ARHI基因在肿瘤细胞中表达受到抑制,其原因为ARHI基因的杂合缺失,CpG岛的异常甲基化,转录抑制因子增多和多聚组蛋白脱乙酰化酶表达加强等.ARHI通过需钙蛋白酶途径诱导细胞凋亡;通过与STAT3(信号转导与转录激活因子3)的结合阻滞癌变.     

HDAC抑制剂SAHA抑制人乳腺癌细胞MCF-7的迁移和增殖

用组蛋白去乙酰化酶(histone deacetylase complex,HDAC)抑制剂SAHA对人乳腺癌细胞MCF-7进行处理,抑制组蛋白的去乙酰化,进而检测SAHA对MCF-7的影响.体外划痕实验与Transwell实验表明SAHA可以抑制MCF-7细胞的迁移;免疫印迹(Western blot)实验表明SAHA可以抑制迁移相关基因MYL9蛋白水平的表达.MTT实验和克隆形成实验表明SAHA可以抑制MCF-7细胞的增殖;Western blot实验与逆转录实时荧光定量PCR(RT-qPCR)实验表明SAHA能够抑制细胞周期蛋白标志基因CyclinD1、CDK4的表达,促进周期蛋白激酶抑制剂p21的表达.     

阿司匹林乙酰化修饰HDAC1抑制人结肠癌细胞HCT116增殖

大量研究表明阿司匹林具有重要的抗肿瘤作用。阿司匹林的乙酰基可以乙酰化大量蛋白质，从而影响体内的乙酰化水平，但其乙酰化作用在抗肿瘤上的具体机制还不清楚。组蛋白去乙酰化酶抑制剂(HDACi)已用于肿瘤治疗或处于临床研究，通过抑制组蛋白去乙酰化酶(Histone Deacetylases, HDACs)的去乙酰化酶活发挥抗癌作用。组蛋白去乙酰化酶1(Histone Deacetylase1, HDAC1)是Zn²⁺依赖的Ⅰ类HDAC家族成员，在多种癌症中表达上调，是组蛋白去乙酰化酶抑制剂(Histone Deacetylase Inhibitors, HDACi)发挥抗癌作用最关键的靶点之一。在抗肿瘤的过程中，阿司匹林是否乙酰化调控HDAC1尚未见报道。在本文中，我们发现阿司匹林可以乙酰化HDAC1并抑制其去乙酰化酶活，赖氨酸(K)200位点是阿司匹林乙酰化HDAC1的关键位点。有趣的是，HDAC1可以对自身去乙酰化，但不能发生在K200上。沉默信息调节因子2相关酶1(SIRT1),而不是HDAC1,可以对HDAC1的K200位点去乙酰化。进一步细胞学实验发现，在敲除H...     

EBNA1和Vav1共同调控Bim表达影响细胞凋亡的研究

Burkitt's淋巴瘤是一种具有高度侵袭性的恶性肿瘤,主要发生在非洲赤道地区,病理特征表现为颌部或腹部肿大成瘤.在我国广东地区发病率较高,目前治疗效果较差.发现在Burkitt's淋巴瘤细胞Raji中EBNA1和Vav1蛋白可以影响Bim的表达和细胞凋亡.组蛋白去乙酰化酶抑制剂丁酸钠(NaB)刺激Burkitt's 淋巴瘤Raji 发现促凋亡蛋白Bim表达上调.进一步实验发现病毒蛋白EBNA1和细胞蛋白Vav1的共表达可以抵消NaB对Bim启动子转录活性的影响. 因此,认为EBNA1 和Vav1 蛋白具有协同作用,共同调控组蛋白的乙酰化水平影响细胞凋亡.     

组蛋白去乙酰化抑制剂对拟南芥根尖干细胞微环境的影响

根系发育是植物生长的重要组成部分,该过程由多种信号转导途径共同调节。组蛋白乙酰化和去乙酰化的动态变化对基因表达具有关键的调控作用,而对其在根发育中功能的研究还不深入。本研究通过组蛋白去乙酰化酶抑制剂Trichostatin A（TSA）处理拟南芥,发现其主根生长受到抑制,分生区细胞数目变少。显微观察的结果表明TSA影响了根尖干细胞微环境。根尖微环境调控相关因子SCR和SHR的表达受TSA处理的影响并不明显,而PLT1/PLT2的表达受TSA强烈抑制。我们对生长素运输途径的分析发现在TSA处理条件下,PIN1表达只受轻微影响,而PIN2表达量明显下调。pDR5:GFP的结果表明TSA可能引起生长素在根尖的积累和分布变化。综上所述,TSA影响了拟南芥根尖干细胞微环境的维持,表明组蛋白的去乙酰化在根发育过程中发挥着重要作用。     

去乙酰化酶抑制剂TSA对间充质干细胞C3H10T1/2增殖和成脂分化的影响

采用MTT和流式细胞术分别检测不同浓度的TSA对C3H10T1/2细胞活性和细胞周期分布的影响;油红O染色检测TSA对其成脂分化的影响,实时定量PCR检测TSA对成脂分化的关键转录因子PPAR-γ,以及成脂分化标志物Fabp4和Adipoq mRNA转录的影响.研究去乙酰化酶抑制剂TSA对间充质干细胞C3H10T1/2增殖和成脂分化的影响及其可能的作用机制.结果显示TSA浓度为1、10和30 nmol/L呈浓度依赖性地抑制C3H10T1/2细胞活性,改变细胞形态,并将其细胞周期抑制在G0/G1期;TSA浓度为10nmol/L明显抑制C3H10T1/2细胞的成脂分化作用,并呈浓度依赖性地抑制PPAR-γ、Fabp4和Adipoq mRNA的转录.表明TSA呈剂量依赖性地抑制间充质干细胞C3H10T1/2的增殖和成脂分化,除转录水平调控外,非组蛋白如细胞骨架相关蛋白可能也参与TSA的抑制作用.     

一个多ON基因系统的表达动力学分析

研究了一个转录水平上的基因表达模型,它不仅考虑了启动子的复杂性,而且考虑了相互作用转录因子的调控效果.假定启动子区域有2个调控位点,启动子有1个失活态和2个激活态(即2个不同的转录出口),并考虑了绑定到不同调控位点的转录因子之间相互作用的3种代表性机制:招募机制,稳定机制和混合机制.理论分析和数值模拟结果显示:不同的转录出口能够导致mRNA分布峰的多样性; 3种机制下的平均表达水平和平均爆发频率都相同,但稳定机制诱导最大的表达噪声和平均爆发规模,而招募机制诱导最小的表达噪声和平均爆发规模.这些结果表明:细胞表型的产生源是复杂的,既与启动子结构有关也与调控机制有关.     

δEF1与雌激素受体-α和他莫昔芬耐药关系的研究

乳腺癌是常见的女性恶性肿瘤,抗雌激素耐药是成功治疗的一大障碍,雌激素受体(ER)-α的减少或消失是产生抗药性的首要机制.δ晶体蛋白增强因子1(δ-crystallin enhancer factor1,δEF1)是锌指同源结构域转录因子家族中的一员,在乳腺癌等诸多肿瘤中均证实有δEF1的异常表达.采用RT-PCR、Western blotting和细胞免疫荧光技术,分析了在δ晶体蛋白增强因子1(δEF1)功能缺失情况下雌激素受体阳性乳腺癌细胞中雌激素受体(ER)-α表达的变化及组蛋白乙酰化对ER-α的影响.同时采用细胞活力实验证实δEF1通过调控ER-α的表达影响乳腺癌细胞对抗雌激素药物他莫西芬(tamoxifen,TAM)的敏感性.结果表明:δEF1被抑制后,乳腺癌细胞中ER-α的表达水平明显升高(p0.01),细胞对他莫西芬(TAM)的反应增强,存活率降低(p0.01);而组蛋白乙酰化可以显著恢复细胞中ER-α的表达(p0.01).     

siRNA干扰p38α上调人血管eNOS基因启动子转录活性

目的:通过靶向 p38α的siRNA干扰人血管内皮细胞的 p38α信号通路,探索其对血管内皮型一氧化氮合酶(eNOS)基因启动子转录活性的调节作用.方法:利用 Western 印迹检测 siRNA-p38α干扰HUVEC-12细胞后 p38α蛋白的表达,确定 siRNA-p38α的最佳作用时间和浓度,然后通过双荧光素酶报告基因技术检测转染 siRNA-p38α后细胞裂解液的荧光强度,分析eNOS基因启动子的转录活性变化.结果:与对照组比较,siRNA-p38α干扰后 p38α蛋白表达明显减弱,而相应的 eNOS启动子转录活性上调, 以100 nmol/L 的 siRNA-p38α作用 48 h 的效果最佳.结论:siRNA干扰 p38α信号可上调人血管内皮细胞 eNOS基因的转录活性.     

山羊Agouti基因启动子活性区域探究

对前期拼接获得的12 847 bp山羊Agouti基因序列(EF587236和JN651404)进行启动子活性区域预测,确定候选启动子区为6 450~7 100 bp,得到一个长度为2 537 bp的DNA片段,在该区域发现一个典型转录因子结合位点TATA框,并预测到HSF,SYR,GATA-1,Nkx-2,ADR1等多个转录因子结合位点;山羊基因组序列(登录号:AJPT01136617.1)中有两段序列与牛的预测启动子promoter A和promoter B同源性较高,据此设计引物扩增目的片段,同时构建12个荧光素酶报告基因质粒,瞬时转染人皮肤黑素瘤细胞A375和293T细胞检测目的片段是否具有Agouti基因启动子活性。结果表明,所构建的目的片段质粒与阴性对照相比无显著差异,说明所获得的目的片段不具有启动子活性。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that