人大肠癌和癌旁组织消减cDNA文库的构建和鉴定

背景：抑制消减杂交(SSH)是一种较成熟的分离差异表达基因的方法，但用该方法构建大肠癌特异性基因消减cDNA文库和筛选相关基因的研究较少。目的：构建人大肠癌和癌旁组织的消减cDNA文库。方法：应用SSH技术分离大肠癌和癌旁正常组织差异表达基因的cDNA片段，将其与pGEM-T Easy载体连接，构建消减cDNA文库。将连接产物转化大肠杆菌DH5α进行文库扩增。随机挑取200个白色克隆，以聚合酶链反应(PCR)进行鉴定。结果：进行PCR扩增的200个克隆中，176个克隆有插入片段，片段分布于200～700bp。结论：成功构建了人大肠癌组织和癌旁组织差异表达基因的消减cDNA文库，为高通量筛选、克隆大肠癌特异性基因奠定了基础。     

乙型肝炎病毒X蛋白反式激活基因克隆化的研究

目的 应用抑制性消减杂交（SSH）技术构建乙型肝炎病毒X蛋白（HBX）反式激活基因差异表达的cDNA消减文库，克隆HBX反式激活相关基因。方法 以HBX表达质粒pcDNA3.1(-)-X转染HepG2细胞，以空载体pcDNA3.1(-)转染的HepG2细胞为对照。制备转染后的细胞裂解液，提取mRNA并逆转录为cDNA，经RsaⅠ酶切后，将实验组cDNA分成两组。分别与两组不同的接头衔接，再对照组cDNA进行两次消减杂交及两次抑制聚合酶链反应（PCR），将产物与T/A载体连接，构建cDNA消减文库，并转染大肠杆菌进行文库扩增，随机挑选克隆PCR扩增后进行测序及同源性分析。结果 成功构建人HBX反式激活基因差异表达的cDNA消减文库；文库扩增后得到85个白色克隆，进行菌落PCR分析。均得以200-1000bp插入片段，挑取含有插入片段的65个克隆进行测序，并通过生物信息学分析获得19种已知基因序列。和15个未知基因。结论 应用SSH技术成功构建了HBX反式激活基因差异表达的cDNA消减文库，该文库的建立为进一步阐明HBX反式调节的靶基因及致肝细胞癌发生的分子生物学机制提供理论依据。     

人单核细胞泡沫化敏感候选基因的筛选

为克隆调控单核细胞源性泡沫细胞形成的相关基因 ,采用抑制消减杂交法筛选U937细胞经氧化型低密度脂蛋白温育形成泡沫细胞后差异表达的基因。经过正向、反向两轮消减杂交和巢式聚合酶链反应扩增 ,获得了富集的差异表达的cDNA片段 ,即表达序列标签 ,克隆化后挑选经鉴定含有插入片段的质粒测序。经Genbank数据库进行同源比较 ,获得 2 0余个差异表达的EST ,其中 2个克隆FRG4和FRG1 4只有片段同源序列而无全长同源序列 ,提示可能来自新基因。Genbank登录号为 :FRG4(BI 50 2 586)和FRG1 4 (BI 50 2 587)。     

应用抑制性消减杂交技术筛选乙型肝炎病毒DNA聚合酶末端蛋白的反式激活基因

目的 应用抑制性消减杂交(SSH)技术构建乙型肝炎病毒(HBV)DNA聚合酶末端蛋白(TP)反式激活基因的差异表达的cDNA消减文库，克隆TP反式激活相关基因。方法 以TP表达质粒pcDNA3．1(-)-TP转染HepG2细胞，以空载休peDNA3，1(-)为对照；制备转染后的细胞裂解液，提取mRNA并逆转录为cDNA，经Rsal酶切后，将实验组cDNA分成两组，分别与两种不同的接头衔接，再与对照组cDNA进行两次消减杂交及两次抑制性PCR，将产物与T／A载体连接，构建cDNA消减文库，并转染大肠杆菌进行文库扩增，随机挑选克隆PCR扩增后进行测序及同源性分析。结果 文库扩增后得到35个阳性克隆，经菌落聚合酶链反应(PCR)分析，得到34个200-1000bp插入片段。对所得片段测序，并进行同源性分析，显示14种己知基因编码蛋白和1种未加功能基因序列，可能是TP反式激活靶基因。结论 成功构建乙型肝炎病毒TP反式激活基因差异发达的cDNA消减文库，为今后进一步分析、研究病毒蛋白的致病机制奠定基础。     

抑制性消减杂交技术克隆和筛选丙型肝炎病毒F蛋白的反式调节基因

目的 构建丙型肝炎病毒（HCV）F蛋白反式激活相关基因差异表达的差异cDNA，克隆HCV-F蛋白反式激活相关基因。方法 以HCV-F表达质粒pcDNA3．1（-）-F转染HepG2细胞，以空载体pcDNA3．1（-）为对照；制备转染后的细胞裂解液，从中提取mRNA并合成cDNA，经RsaI酶切后将实验组cDNA分成两组，分别与两种不同的接头衔接，再与对照组cDNA进行两次消减杂交及两次抑制性聚合酶链反应，将产物与T／A载体连接，构建cDNA消减文库，并转染大肠杆菌进行文库扩增，随机挑选克隆聚合酶链反应后进行测序及同源性分析。结果 成功构建人HcVF蛋白反式激活相关基因差异表达的cDNA。扩增后得到56个200～1000bP插入片段的克隆，随机挑选其中28个插入片段测序，并通过生物信息学分析获得其全长基因序列，结果共获得19种编码基因，其中2个为未知功能的新基因。结论 筛选到的cDNA全长序列，包括一些与细胞生长调节、物质代谢和细胞凋亡密切相关的蛋白编码基因。     

高血压大鼠重塑血管差异表达基因的克隆及表达

为从基因水平研究高血压病大鼠血管重塑机制，采用抑制消减杂交性筛选两肾一夹肾血管性高血压大鼠重塑大血管（胸主动脉）差异表达基因。经过两轮消减杂交和巢式聚合酶链反应扩增，获得了富集的差异表达cDNA片段，经Genbank等数据库进行同源比较，获得10余个差异表达的表达序列标签；采用Western blot方法对其中2个已知基因编码蛋白细胞色素C和Bcl-2的表达进行检测。结果发现细胞色素C在高血压大鼠重塑大血管组织中表达增高，而Bcl-2在高血压大鼠重塑大血管组织中表达减少。研究结果提示氧化应激导致细胞凋亡机制尤其是Bcl-2／细胞色素C－半胱天冬酶途径在大血管重塑过程中具有重要作用。     

一个新的家兔高脂血症相关基因的筛选、克隆和序列分析

目的 寻找新的高脂血症相关基因，探讨其分子机理。方法用高脂饲料复制家兔高胆固醇血症模型，采用抑制性消减杂交技术克隆高脂血症相关基因，快速扩增cDNA末端技术扩增全长，用基因芯片和荧光半定量聚合酶链反应技术检测其表达，并用逆转录一聚合酶链反应法观察该基因的组织分布。结果获得一个新的家兔高脂血症相关基因，GenBank登录号为AY24719，长1386bp，编码321个氨基酸，与人类G蛋白α亚基同源性达92％。该基因在家兔心、肝、骨骼肌等组织中广泛表达，其中以胰腺的表达最强。结论对AY248719基因的研究有助于进一步揭示高脂血症的分子机理。     

抑制性消减杂交技术原理及应用

0 引言抑制性消减杂交(suppression subtractive hybridization, SSH)技术是一种鉴定、分离组织细胞中选择性表达基因的技术。其原理是以抑制性多聚酶链反应(PCR)反应为基础的cDNA消减杂交技术。通过合成两个不同的接头,连接于测试cDNA片段的5’末端,达到选择性扩增差异性表达的cDNA片段,抑制非目的cDNA的扩增。该技术与其他消减杂交技术相比具有假阳性率低、敏感性高、效率高等优点而得到广泛应用, 1 抑制性消减杂交技术产生的背景高等真核生物细胞中约含有4-10万个不同的基因,但在生物体的发育过程中只有15％的基因得以表达。这     

人胰腺癌抑制消减cDNA文库的构建

目的应用抑制消减杂交技术(SSH)构建胰腺癌和正常胰腺组织间差异表达的抑制消减cDNA文库。方法分别提取胰腺癌(tester)和癌旁正常胰腺组织(driver)中的总RNA和mRNA．合成双链cDNA，经RsaI酶切后，将胰腺癌双链cDNA分为两组，分别加上不同的接头，再与正常胰腺组织cDNA进行两次消减杂交及两次抑制性PCR，分离出胰腺癌差异表达基因的cDNA片段。将该差异表达片段克隆至T／A载体，并转化大肠杆菌TOP10F’，经蓝白斑筛选后，再用PcR方法筛选阳性克隆，从而构建胰腺癌抑制消减cDNA文库。结果文库扩增后得到257个白色克隆，随机挑取50个阳性克隆进行PCR扩增分析，其中47个克隆有插入片段．克隆阳性率为94％，片段大小主要集中在300～600bp之间。结论成功构建了人胰腺癌抑制消减cDNA文库，为进一步筛选、克隆胰腺癌特异性表达基因奠定了基础。     

应用抑制性消减杂交技术克隆丙型肝炎病毒 E2蛋白反式调节基因

目的应用抑制性消减杂交(SSH)技术构建丙型肝炎病毒(HCV)E2蛋白反式调节基因差异表达的cDNA消减文库,克隆HCVE2蛋白反式调节相关基因。方法以HCVE2表达质粒pcDNA3.1(-)_E2转染HepG2细胞,以空载体pcDNA3.1(-)为对照,制备转染后的细胞裂解液,从中提取mRNA并逆转录为cDNA,经RsaI酶切后将实验组cDNA分成两组,分别与两种不同的接头衔接,再与对照组cDNA进行两次消减杂交及两次抑制性聚合酶链反应(PCR)扩增,将产物与T/A载体连接,构建cDNA消减文库,并转染大肠杆菌进行文库扩增,随机挑选克隆PCR扩增后进行测序及同源性分析。结果成功构建人HCVE2蛋白反式调节基因差异表达的cDNA消减文库。文库扩增后得到78个阳性克隆,进行菌落PCR分析,均得到100～1000bp插入片段。挑取38个含有插入片段的阳性克隆测序分析,获得35个已知基因序列和3个未知基因。通过生物信息学分析获得其全长序列,其功能正在研究中。结论应用SSH技术成功构建了HCVE2反式调节基因差异表达的cDNA消减文库。该文库的建立为进一步阐明HCVE2反式调节的靶基因及致慢性肝脏疾病发生的分子生物学机制提供理论依据。     

Identification of differentially expressed genes in mouse hepatocarcinoma ascites cell line with low potential of lymphogenous metastasis

INTRODUCTION Tumor metastasis is an incident involving multiple genes. However, the number of metastasis related genes available nowadays is very limited to elucidate the puzzling process of metastasis. Therefore, more attentions have been paid to screen …     

Differential display of vincristine-resistance-related genes in gastric cancer SGC7901 cell

AIM: To isolate and clone the vincristine-resistance-related genes in gastric cancer SGC7901 cell line and to clarify the multidrug-resistant molecular mechanism of gastric cancer cells. METHODS: The modified differential-display polymerase chain reaction (DD-PCR) was used to examine differences in the mRNA composition of Vincristine-resistant gastric cancer SGC 7901 cells (SGC7901/VCR), induced by vincristine sulfate versus SGC7901cells. The differentially expressed cDNA fragments were confirmed by reverse Northern analysis, sequencing, BLAST analysis and Northern bolt analysis. RESULTS: The DD-PCR identified that 54 cDNA fragments were preferentially expressed in SGC 7901/VCR cells. When these cDNA fragments were analyzed by reverse Northern blot, twenty were reproducibly expressed at high level in SGC7901/VCR. Sequencing and BLAST analysis revealed that seven of the genes were known genes:ADP-ribosylation factor 4, Cytochrome oxidase subunit II, Ss-A/Ro ribonucleoprtein autoantigen 60kd subunit,ribosomal protein S13, galaectin-8 gene, oligophrenin 1 mRNA, ribosomal protein L23 mRNA; thirteen of the genes were unknown genes. The length and abundance of the four unknown genes were further confirmed by Northern blot analysis. CONCLUSION: The twenty differential known and unknown genes may be related to the vincristine-resistant mechanism in human gastric cancer SGC7901 cell line.     

Screening differentially expressed genes in mouse hepatocarcinoma ascites cell line with high potential of lymphatic metastasis

AIM: To screen genes differentially expressed in mouse hepatocarcinoma ascites cell line with high potential of lymphatic metastasis. METHODS: A subtracted cDNA library of mouse hepatocarcinoma cell line with high potential of lymphatic metastatic Hca-F and its synogenetic cell line Hca-P with a low metastatic potential was constructed by suppression subtracted hybridization(SSH) method. The screened clones of the subtracted library were sequenced and GeneBank homology search was performed. RESULTS: Fourteen differentially expressed cDNA fragments of Hca-F were obtained with two novel genes. CONCLUSION: SSH is a useful technique to detect differentially expressioned genes and an effective method to clone novel genes.     

日本血吸虫消减雌性成虫cDNA文库的建立及其特异表达基因的筛选

目的 筛选雌性日本血吸虫特异表达基因。方法 感染日本血吸虫6周的家兔,用静脉灌注法收集成虫,经核糖核酸固定液固定,分别提取雌、雄成虫总RNA,纯化后获得mRNA,并反转录为cDNA。用抑制性消减杂交技术(SSH)构建雌、雄成虫正向消减(雌虫消减雄虫)及反向消减(雄虫消减雌虫)cDNA文库。用斑点杂交法筛选差异表达基因,挑选目标基因片段(与正向消减探针杂交的信号明显高于与反向消减探针杂交信号的克隆)进行测序、同源性搜索及基因功能预测分析。以日本血吸虫肌动蛋白(actin)基因作内参照,用半定量PCR(semi-quantitative PCR)鉴定目标基因在雌、雄虫体内的表达。结果 得到正向消减及反向消减cDNA文库,斑点杂交筛选出50个雌虫特异性表达的克隆,经测序得到42个表达序列标签(EST),其中,有17个基因(占40.5%)与已知日本血吸虫卵壳蛋白基因高度同源;17个基因(占40.5%)与日本血吸虫未知基因高度同源、且有一小片段与卵壳蛋白基因高度同源;有8个基因(占19.0%)与日本血吸虫其他未知基因高度同源。半定量PCR结果,6个基因在雌虫体内的表达水平明显高于雄虫,分别与GenBank的血吸虫卵壳蛋白基因AY222885、AY222895、AB017097、AF519182、M32281及血吸虫其他基因AY813556高度同源。结论 构建了雌、雄成虫正向消减及反向消减cDNA文库。用SSH可筛选日本血吸虫雌性特异性表达基因。     

Analysis of genes dominantly expressed in rat cerebral endothelial cells using suppression subtractive hybridization

In mammals, a fully developed, highly branched vascular system specialized for each particular organ or tissue is essential for obtaining metabolic nutrients supply. The formation of a blood-brain barrier that protects against environmental insults is a distinguishing feature of the brain's vascular system. Since this is accomplished by cerebral endothelial cells (CECs), we analyzed the genes specifically and/or dominantly expressed in rat CECs using Suppression Subtractive Hybridization (SSH). We found 39 genes specifically and/or dominantly expressed in CECs. 24 genes of known function (thrombospondin-2, vimentin, etc.), 13 genes of known sequence but unknown function including 7 of ESTs (SNERG1, rat GPCR, etc.), and 2 novel genes. The physiological significance of these genes in CECs has been under investigation. SSH is useful for identifying genes regulated in an organ-specific manner in cells such as CECs to obtain clarification of their physiological roles.     

Construction of a metastasis-associated gene subtracted cDNA library of human colorectal carcinoma by suppression subtraction hybridization

AIM: To construct a differentially-expressed gene subtracted cDNA library from two colorectal carcinoma (CRC) cell lines with different metastatic phenotypes by suppression subtractive hybridization. METHODS: Two cell lines of human CRC from the same patient were used. SW620 cell line showing highly metastatic potential was regarded as tester in the forward subtractive hybridization, while SW480 cell line with lowly metastatic potential was treated as tester in the reverse hybridization. Suppression subtractive hybridization (SSH) was employed to obtain cDNA fragments of differentially expressed genes for the metastasis of CRC. These fragments were ligated with T vectors, screened through the blue-white screening system to establish cDNA library. RESULTS: After the blue-white screening, 235 white clones were picked out from the positive-going hybridization and 232 from the reverse. PCR results showed that 200-700 bp inserts were seen in 98% and 91% clones from the forward and reverse hybridizations, respectively. CONCLUSIONS: A subtractive cDNA library of differentially expressed genes specific for metastasis of CRC can be constructed with SSH and T/A cloning techniques.     

Construction of a metastasis-associated gene subtracted cDNA library of human colorectal carcinoma by suppression subtraction hybridization

AIM:To construct a differentially-expressed gene subtractedcDNA library from two colorectal carcinoma (CRC) cell lineswith different metastatic phenotypes by suppressionsubtractive hybridization.METHODS:Two cell lines of human CRC from the samepatient were used.SW620 cell line showing highlymetastatic potential was regarded as tester in the forwardsubtractive hybridization,while SW480 cell line with lowlymetastatic potential was treated as tester in the reversehybridization.Suppression subtractive hybridization (SSH)was employed to obtain cDNA fragments of differentiallyexpressed genes for the metastasis of CRC.These fragmentswere ligated with T vectors,screened through the blue-white screening system to establish cDNA library.RESULTS:After the blue-white screening,235 white cloneswere picked out from the positive-going hybridization and232 from the reverse.PCR results showed that 200-700 bpinserts were seen in 98% and 91% clones from the forwardand reverse hybridizations,respectively.CONCLUSIONS:A subtractive cDNA library of differentiallyexpressed genes specific for metastasis of CRC can beconstructed with SSH and T/A cloning techniques.     

Changes in gene expression in atherosclerotic plaques analyzed using DNA array

A better understanding of atherogenesis at the level of gene expression could lead to the identification of new therapeutic strategies for vascular diseases. With DNA array technology, it is possible to identify multiple, simultaneous changes in gene expression in small tissue samples from atherosclerotic arteries. We analyzed gene expression in normal arteries and in immunohistologically characterized human advanced atherosclerotic lesions using an array of 18376 cDNA fragments. The array method was first validated by detecting a group of genes (n=17) that were already known to be connected to atherogenesis. These genes included e.g. Apolipoprotein E, CD68, TIMP and phospholipase D. Next we detected 75 differentially expressed genes that were previously not connected to atherogenesis. A subgroup of genes involved in cell signaling and proliferation was selected for further analyzes with in situ hybridization and RT-PCR which confirmed array results by showing induction in advanced lesions of Janus kinase 1 (JAK-1) which is an important signaling molecule in activated macrophages; VEGF receptor-2 which mediates angiogenic and vasculoprotective effects of VEGF; and an unknown gene, which mapped on chromosome 19. It is concluded that DNA array technology enables fast screening of gene expression in small samples of atherosclerotic lesions. The technique will be useful for the identification of new factors, such as JAK-1 and VEGF receptor-2, which may play an important role in atherogenesis.