mTOR复合物在细胞迁移中的作用

细胞迁移是一个高度有序且多信号通路协调控制的过程,在个体发育、器官形成、伤口愈合及肿瘤恶性转移过程中具有重要作用.哺乳动物雷帕霉素靶蛋白(mammalian target of rapamycin,mTOR)广泛存在于从酵母到哺乳动物的细胞中,参与调控与细胞生长和代谢密切相关的多种生命过程,其参与形成的复合物在调控细胞迁移过程中发挥重要作用.对雷帕霉素靶蛋白复合物的组成和它们在细胞迁移中的作用的最新研究进行系统阐述.     

Cu(Ⅱ)Aβ1-40复合物的制备及其神经毒性的初步研究

目的：探索Aβ神经毒性的来源和作用机制。方法：体外制备了Cu(Ⅱ)Aβ1-40复合物，并对该复合物体内外的生物学活性进行了分析。结果：Cu(Ⅱ)Aβ1-40复合物ESR波谱呈现蛋白束缚Cu(Ⅱ)的谱线特征，提示：Cu(Ⅱ)已以某种方式与邵结合。Cu(Ⅱ)Aβ1-40复合物可利用水溶液中分子氧以及XO/X系统产生的超氧阴离子自由基形成过氧化氢；而单纯的Aβ1-40却无此作用。CD谱显示：与单纯的Aβ1-40比较，Cu(Ⅱ)Aβ1-40复合物的α-螺旋百分含量有所降低。Cu(Ⅱ)Aβ1-40复合物对原代培养海马神经元的生长抑制作用要比单纯Aβ1-40作用出现的早。大鼠脑海马微量注射Cu(Ⅱ)Aβ1-40复合物后行为学改变要比单纯Aβ1-40作用更为明显。结论：Aβ与Cu(Ⅱ)结合后启动活性氧系统进而造成神经细胞损伤，这可能是Aβ在AD脑内神经毒性的作用机制之一。     

南澳大利亚丝核菌抑病土中细菌与放线菌的分离及其对病害的生物防治作用

从南澳大利亚埃文采集的土壤样品中计数分离了细菌和放线菌,该土壤对Rhizoctonia．solani融合群8引起的小麦根腐病具有抑制作用。统计了分离物中对R.solani AG-8菌株2l有拮抗作用的百分比。热处理(60℃,10min)能够消除土壤的抑病能力,可显著减少土壤中细菌和放线菌的数量,但是并不改变对病原菌有抑制作用的分离物的总体百分比。依据对R.solani AG-8菌株21,Gaewuarunomyces graminis var．tritici(Ggt)菌株8,Fusarium graminearum菌株Fg,Verticillium dahliae菌株Vd5,Bipolaris sorokiniana菌株Bs,Pythium irregulare菌株BH40,以及引起棉花猝倒病的Rhizoctonia solani solani AG-4菌株1664的抑菌能力,自2700个菌株中筛选了9个最强拈抗菌株;其中7个菌株能够产生几丁质酶,或者产生内切葡聚糖酶,而几丁质酶活性与生物防治效果具有相关性。这9个菌株鉴定为Bacillus megaterium(菌株Ap25),B．subtilis(菌株Ap113),Streptomyces spp．(菌株Ap117),Bocillus coagulans(菌株Ap123),Streptoverticillium reticuIum(菌株Ap89),Cellulomonas flavigena(菌株ApT5),以及放线菌(菌株Ap116,Ap111和Ap139)．B．megaterium Ap25 and B．subtilis Ap113对小麦根腐病及全蚀病的防治效果以及刺激小麦生长的作用最强。这两个菌株能够在平板上抑制一种分离自同一土样的有益菌Trichoderma pseudokoningii菌株ASMH的生长,但对该木霉菌的生物防治效果及其刺激植物生长的作用没有明显削弱。     

Alzheimer氏病Aβ与Cu(II)相互作用的研究方法

大量老年斑沉积在脑神经细胞外是老年性痴呆的一个重要病理特征。现已证明老年斑的重要组成成分是一种小片段肽Aβ,另外,发现老年斑中也存在一些过渡态的金属离子如Zn(II)和Cu(II)等。近年的一些实验研究提示,Aβ与Cu(II)络合成复合物可能是Aβ神经毒性作用的机制之一。以A1β-40为例,对在体外条件下研究AβCu(Ⅱ)复合物性质及生物学活性的实验方法进行介绍,这将有利于对Aβ神经毒性作用机制更加深入和广泛的研究。     

Alzheimer氏病Aβ与Cu(Ⅱ)相互作用的研究方法

大量老年斑沉积在脑神经细胞外是老年性痴呆的一个重要病理特征.现已证明老年斑的重要组成成分是一种小片段肽Aβ,另外,发现老年斑中也存在一些过渡态的金属离子如Zn(Ⅱ)和Cu(Ⅱ)等.近年的一些实验研究提示,Aβ与Cu(Ⅱ)络合成复合物可能是Aβ神经毒性作用的机制之一.以Aβ1-40为例,对在体外条件下研究AβCu(Ⅱ)复合物性质及生物学活性的实验方法进行介绍,这将有利于对Aβ神经毒性作用机制更加深入和广泛的研究.     

白介素-31参与瘙痒的研究进展

瘙痒是很多皮肤疾病的常见临床症状，包括特应性皮炎、结节性痒疹、银屑病、慢性荨麻疹等。最近的研究表明，白介素-31在皮肤疾病的瘙痒中扮演重要角色。白介素-31可由CD4⁺辅助T细胞、肥大细胞、角化细胞、巨噬细胞、树突状细胞等合成与释放，通过激活白介素-31异二聚体受体(IL-31受体A和抑瘤素受体M)产生痒觉相关信号。尽管研究发现白介素-31可通过直接或间接的作用向神经中枢传递痒觉信号，但是它的致痒机制尚不完全清楚。本文就白介素-31的基因、受体、来源以及在瘙痒相关疾病中的作用展开综述。     

PTEN和FHIT在口腔鳞癌中的表达及意义

目的：检测抑癌基因VIEN、FHIT在正常口腔黏膜上皮和口腔鳞癌中的表达情况，并探讨其与肿瘤组织学类型的关系。方法：采用SP法免疫组化方法检测62例口腔鳞癌中和12例正常口腔黏膜中FHIT、PTEN的蛋白表达。结果：在正常口腔黏膜中PTEN均为强阳性表达(12／12)，在口腔鳞癌中24．2％(15／62)表现为PTEN蛋白表达的缺乏或减少；而FHIT在正常口腔黏膜中也均为强阳性表达(12／12)；在口腔鳞癌中17．7％(11／62)表现为FHIT蛋白表达缺乏或减少。结论：PTEN、FHIT在口腔鳞癌的发生过程中起着一定的作用。     

茶氟香酰胺对人肝癌细胞生长和迁移的抑制作用

茶氟香酰胺(Ethyl 6-fluorocoumarin-3-carboxylyl L-theanine,TFC)是对茶氨酸进行结构优化后的产物,通过实验研究其对人肝癌细胞(SMMC7721)生长和迁移的抑制作用,并了解其作用机制.MTT和Transwell chamber法分别检测不同浓度的TFC对SMMC7721细胞生长和迁移的影响,流式细胞术分析不同浓度的TFC对SMMC7721细胞凋亡的影响,Western blotting检测不同浓度的TFC组对与SMMC7721细胞中与肿瘤细胞生长、迁移和凋亡密切相关蛋白表达的影响.实验结果显示,TFC能够显著抑制SMMC7721细胞生长、迁移并诱导癌细胞凋亡,TFC药物分子作用机制可能与下调SMMC7721细胞中血管内皮生长因子受体VEGFR1、磷酸化蛋白激酶B(phosphorylated protein kinase B,p AKT)、核转录因子NF-κB、抗凋亡蛋白(BCL2,apoptosis regulator,BCL2)、细胞周期蛋白(cyclin D1,CCND1)表达和上调促凋亡蛋白(BCL2 associated X,apoptosis regulator,BAX)、细胞色素c(cytochrome c,somatic,CYCS)、人体抑癌基因蛋白(tumor protein p53,TP53)、半胱天冬酶3(caspase,CASP3)和E-cadherin蛋白表达有关,TFC抑制人肝癌SMMC7721细胞生长和迁移作用的重要信号通路涉及到VEGFR/AKT/NF-κB.     

异硫氰酸异丁酯抑制肝癌细胞HepG2生长的效应与机理

为了探究异硫氰酸异丁酯(isobutyl isothiocyanate)对肝癌细胞HepG2的生长抑制效应及其分子机制，该研究通过MTT实验检测化合物对细胞的生长抑制率，计算出IC50值为3.5 μg·mL－1；通过流式细胞技术检测发现0.437 μg·mL－1以上浓度的化合物能诱导HepG2细胞凋亡；通过划痕实验检测发现0.875 μg·mL－1以上浓度的化合物能抑制细胞迁移；进一步通过生物信息学分析表明异硫氰酸异丁酯的靶蛋白可能为巨噬细胞迁移抑制因子(MIF)，且HepG2细胞中MIF表达量高于低敏感株.免疫印迹实验也进一步发现化合物不仅能够抑制蛋白酪氨酸激酶2/信号转导子和转录激活子3(JAK2/STAT3)信号通路的激活，还能下调p53蛋白表达.研究结果表明，异硫氰酸异丁酯可能通过靶向HepG2细胞中的MIF蛋白，影响MIF与其受体CD74相互作用，从而下调p53蛋白表达，阻滞细胞周期的正常进行，诱导细胞凋亡，对肝癌具有特异性的抑癌潜力.     

P33INGlb蛋白的结构及其基因分子生物学

生长抑制因子-1(Inhibitor of growth 1,INGI)是最近发现的一种Ⅱ型抑癌基因,其中P33INGlb是ING1基因的主要转录产物以及重要的抑癌基因,将P33INGlb基因正义表达载体转染入正常双倍体成纤维细胞,可抑制细胞生长,而P33INGlb的反义表达载体可促进细胞的恶性转化,P33INGlb的这些生物学特性与其特殊结构关系很大,本文就P33INGlb蛋白及其各种结构的基因生物学机制进行综述。     

FHIT在肺癌中的表达与细胞凋亡相关性的研究

目的:探讨脆性组氨酸三联体基因(FHIT)在肺癌中表达情况以及与肺癌细胞凋亡相关性.方法: 利用组织芯片和免疫组织化学技术,检测110例肺癌及25例良性病变的肺组织标本FHIT基因蛋白表达, 并运用脱氧核糖核苷酸末端转移酶介导的缺口末端标记技术(TUNEL)检测肺癌细胞凋亡.结果:1 良性病( ) 变的肺组织FHIT基因异常表达率为16%,肺癌组织异常表达率为85.5%,二者比较,差异有极显著性( =49.390,2P = 0.000); 2 肺癌FHIT基因表达与肺癌细胞凋亡指数(AI)存在显著性差异2= 23.326, = 0.006),且FHIT P基因表达与AI正相关( =0.452, P = 0.000).结论:FHIT基因可能参与肿瘤细胞凋亡的调节, FHIT基因表达下 降可能与肺癌的发生密切相关.     

FHIT和Survivin基因在大肠癌中的表达及意义

应用免疫组织化学S-P法检测59例大肠癌和40例正常大肠粘膜组织FHIT和Survivin基因的表达。结果表明：大肠癌组织FHIT和Survivin表达的阳性率分别为49．2％，45．8％，正常大肠粘膜组织FHIT和Survivin表达的阳性率分别为77．5％，12．5％，二者FHIT和Survivin阳性表达的差异均有显著意义（P〈0．05）；FHIT表达与大肠癌临床分级（P％0．001）、Dukes分期（P％0．001）和淋巴结转移均有关（P〈0．001）。Survivin表达均与大肠癌临床分级、Dukes分期和淋巴结转移无关；在大肠癌中，FHIT和Survivin表达之间呈显著负相关（P〈0．001）。     

Anchoring mechanisms for LFA-3 cell adhesion glycoprotein at membrane surface

The manner in which a membrane protein is anchored to the lipid bilayer may have a profound influence on its function. Most cell surface membrane proteins are anchored by a membrane-spanning segment(s) of the polypeptide chain, but another type of anchor has been described for several proteins: a phosphatidyl inositol glycan moiety, attached to the protein C terminus. This type of linkage has been identified on membrane proteins involved in adhesion and transmembrane signalling and could be important in the execution of these functions. We report here that an immunologically important adhesion glycoprotein, lymphocyte function-associated antigen 3 (LFA-3), can be anchored to the membrane by both types of mechanism. These two distinct cell-surface forms of LFA-3 are derived from different biosynthetic precursors. The existence of a phosphatidyl-inositol-linked and a transmembrane anchored form of LFA-3 has important implications for adhesion and transmembrane signalling by LFA-3.     

Inhibition of PKB/Akt activity involved in apigenininduced apoptosis in human gastric carcinoma cells

Apigenin is a flavonoid widely distributed in fruits and vegetables. It possesses growth inhibitory properties against numerous cancer cell lines. However,the molecular mechanism(s) by which api-genin elicits its effects have not been fully elucidated. Here we studied whether apigenin inhibits growth and induces apoptosis in human gastric carcinoma cells. We showed that the flavonoid inhibited growth of the cells and caused apoptosis,as evidenced by DNA Ladder,cleavage of pro-caspase-3 in a time-dependent manner. Induction of apoptosis was dependent on inhibition of the PKB/Akt activity. We found that while apigenin had no effect on the expression of Akt and Bad,it inhibited specific phosphorylation of the two proteins that are associated with pro-survival mechanisms. We propose that this important flavonoid induces apoptosis in gastric cancer cells by inhibiting Akt activity. Since Akt is often activated in cancers,our findings may have clinical implications.     

常见肝癌细胞系的转铁蛋白受体表达差异分析及主动靶向载体效率比较

转铁蛋白受体1(transferrin receptor 1,TfR1)可介导细胞内吞过程,从而摄取与之特异结合的纳米颗粒,因此成为许多主动靶向型纳米载体的靶点。研究表明,肝癌细胞存在TfR1高表达现象,可作为肿瘤治疗纳米药物递送系统的关键性靶点。体外评价是TfR1靶向纳米载体的重要研究环节,然而肝癌细胞模型种类繁多,其TfR1表达水平可能存在一定差异。选择了几种常见的肝癌细胞系,包括HepG2、Hep3B、MHCC97-H以及Huh-1,分别从mRNA水平以及蛋白水平测定了细胞系TfR1的表达情况,考察了转铁蛋白(Tf)以及转铁蛋白核酸适配体(transferrin nucleic acid aptamer, Tf-APT)对不同细胞的亲和效率。同时,制备了包载紫杉醇的TfR1靶向脂质体,并考察其对不同细胞系的细胞生长抑制作用。结果表明,4种肝癌细胞系在mRNA水平以及蛋白水平均存在TfR1的表达差异;同时,体外抗肿瘤结果显示,不同肝癌细胞系对紫杉醇-TfR1靶向脂质体的敏感性也存在显著不同。     

Escape from adaptive conflict after duplication in an anthocyanin pathway gene

Gene duplications have been recognized as an important source of evolutionary innovation and adaptation since at least Haldane, and their varying fates may partly explain the vast disparity in observed genome sizes. The expected fates of most gene duplications involve primarily non-adaptive substitutions leading to either non-functionalization of one duplicate copy or subfunctionalization, neither of which yields novel function. A significant evolutionary problem is thus elucidating the mechanisms of adaptive evolutionary change leading to evolutionary novelty. Currently, the most widely recognized adaptive process involving gene duplication is neo-functionalization (NEO-F), in which one copy undergoes directional selection to perform a novel function after duplication. An alternative, but understudied, adaptive fate that has been proposed is escape from adaptive conflict (EAC), in which a single-copy gene is selected to perform a novel function while maintaining its ancestral function. This gene is constrained from improving either novel or ancestral function because of detrimental pleiotropic effects on the other function. After duplication, one copy is free to improve novel function, whereas the other is selected to improve ancestral function. Here we first present two criteria that can be used to distinguish NEO-F from EAC. Using both tests for positive selection and assays of enzyme function, we then demonstrate that adaptive evolutionary change in a duplicated gene of the anthocyanin biosynthetic pathway in morning glories (Ipomoea) is best interpreted as EAC. Finally, we argue that this phenomenon likely occurs more often than has been previously believed and may thus represent an important mechanism in generating evolutionary novelty.     

Calcium-dependent phosphorylation of histone H3 in butyrate-treated HeLa cells

Ca2+ is prominant in the control of cell proliferation and function. However, the biochemical mechanism(s) mediating its effects on nuclear events is unknown. We report here that Ca2+, at physiological concentrations, stimulates the phosphorylation of histone H3 by an endogenous protein kinase in HeLa cell nuclei. Also, pretreatment of cells with Na butyrate, which increases histone acetylation, selectively increases the susceptability of histone H3 to phosphorylation by the protein kinase. Our results reveal a potential link between histone H3 acetylation and phosphorylation, modifications which are thought to have important effects on chromatin structure and function and suggest a possible mechanism whereby stimuli at the cell surface (such as hormones, mitogens and drugs) may influence biochemical events at the nuclear level; changes in the intracellular Ca2+ concentration may influence the phosphorylation of chromosomal proteins, mediated by Ca2+ -dependent kinases in th nucleus.     

The DNA sequence, annotation and analysis of human chromosome 3

After the completion of a draft human genome sequence, the International Human Genome Sequencing Consortium has proceeded to finish and annotate each of the 24 chromosomes comprising the human genome. Here we describe the sequencing and analysis of human chromosome 3, one of the largest human chromosomes. Chromosome 3 comprises just four contigs, one of which currently represents the longest unbroken stretch of finished DNA sequence known so far. The chromosome is remarkable in having the lowest rate of segmental duplication in the genome. It also includes a chemokine receptor gene cluster as well as numerous loci involved in multiple human cancers such as the gene encoding FHIT, which contains the most common constitutive fragile site in the genome, FRA3B. Using genomic sequence from chimpanzee and rhesus macaque, we were able to characterize the breakpoints defining a large pericentric inversion that occurred some time after the split of Homininae from Ponginae, and propose an evolutionary history of the inversion.     

分子序列的突变危险性与遗传密码的编码规则

定义了分子序列（碱基序更和对应的氨基酸序列）的突变危险性函数，通过危险性函数的极小化可以导出遗传密码的简并规则，终止密码子在密码表上的位置及亲－水畴排布，氨基酸在密码表上的定位接近标准密码表，各个生物类别的突变危险性函数值差别不超过５％，可看作守恒量，Ｒａｓ家庭癌基因产物具有较大的突变危险性函数值，这提示分子序列的突变危险性函数可能有重要的应用价值和理论意义。