Suppression subtractive hybridization: a method for generating differentially regulated or tissue-specific cDNA probes and libraries.

A new and highly effective method, termed suppression subtractive hybridization (SSH), has been developed for the generation of subtracted cDNA libraries. It is based primarily on a recently described technique called suppression PCR and combines normalization and subtraction in a single procedure. The normalization step equalizes the abundance of cDNAs within the target population and the subtraction step excludes the common sequences between the target and driver populations. In a model system, the SSH technique enriched for rare sequences over 1,000-fold in one round of subtractive hybridization. We demonstrate its usefulness by generating a testis-specific cDNA library and by using the subtracted cDNA mixture as a hybridization probe to identify homologous sequences in a human Y chromosome cosmid library. The human DNA inserts in the isolated cosmids were further confirmed to be expressed in a testis-specific manner. These results suggest that the SSH technique is applicable to many molecular genetic and positional cloning studies for the identification of disease, developmental, tissue-specific, or other differentially expressed genes.     

Identification of differentially expressed genes in normal mucosa, adenoma and adenocarcinoma of colon by SSH

Abbreviation CRC colorectal cancer.SSHsuppression subtrsctive hybridization.LD PCR longdistance polymerase chain reaction.HLA human leukocyteantigen.IGRBP insulin-like growth factor binding protein.GN guanylin,EF1 elongation factor 1AIM To construct subtracted cDNA libraries and furtheridentify differentially expressed genes that are related tothe development of colorectal carcinoma(CRC).METHODS Suppression subtractive hybridization(SSH)was done on cDNAs of normal mucosa,adenoma andadenocarcinoma tissues from the same patient.Threesubtracted cDNA libraries were constructed and thenhybridized with forward and backward subtracted probesfor differential screening.Positive clones from eachsubtracted cDNA library were selected for sequencing andBLAST analysis.Finally,virtual Northern Blot confirmedsuch differential expression.RESULTS By this way,there were about 3-4×10~2clones identified in each subtracted cDNA library,inwhich about 85% positive clones were differentiallyscreened.Sequencing and BLAST homology searchrevealed some clones containing sequences of knowngene fragments and several possibly novel genes showingfew or no sequence homologies with any knownsequences in the database.CONCLUSION All results confirmed the effectiveness andsensitivity of SSH.The differentially expressed genesduring the development of CRC can be used to shed lighton the pathogenesis of CRC and be useful genetic markersfor early diagnosis and therapy.     

伯氏疟原虫青蒿素抗性相关的消减cDNA文库构建

目的　构建伯氏疟原虫青蒿素抗性相关的消减cDNA文库。　方法　提取伯氏疟原虫K173株(NS)与青蒿素抗性株(AR)的总RNA ,superSMART法合成双链cDNA,分别以NS为消减方(driver),AR为试验方(tester)及AR为driver,AS为tester进行双向抑制性消减PCR(SSHPCR)。富集的差异表达cDNA克隆到pMD18T载体构建消减文库。　结果　NSAR和ARNS消减文库分别获得395个和506个阳性克隆,从NSAR和ARNS文库中随机挑取108个克隆PCR鉴定,分别有100个和104个含插入片段,大小在0.25～2kb之间。　结论　成功构建了伯氏疟原虫青蒿素抗性相关的消减cDNA文库。     

正常肝组织与肝癌组织差异表达基因消减cDNA文库的构建

目的 构建人正常肝组织与肝癌组织差异表达基因的消减cDNA文库。方法 采用新近建立的抑制消减杂交技术,以癌旁正常肝组织及肝癌组织作为对比材料,分离肝癌组织中不表达或低表达基因的cDNA片段,将其与T载体进行T/A连接构建文库,将连接产物用电穿孔法转化大肠杆菌进行文库扩增后,随机挑取100个白色克隆进行酶切鉴定。结果 扩增消减cDNA文库获得4000余个白色阳性克隆,随机挑取的100个白色克隆进行酶切鉴定。结果 扩增消减cDNA文库获得4000余个白色阳性克隆,随机挑取的100个白色克隆经酶切后均有200-600bp的插入片段。结论 用SSH法及T/A克隆技术成功构建了正常肝组织与肝癌组织差异表达基因的消减cDNA文库,该文库的建立为进一步筛选、克隆肝癌组织中失活或低表达的新的抑癌基因奠定了基因。     

应用抑制消减杂交技术筛选大肠癌新相关基因

目的利用抑制消减杂交技术（Suppression Subtractive Hybridization，SSH）构建人大肠癌差异表达cDNA文序，分离并克隆出大肠癌发病的相关新基因。方法运用抑制消减杂交技术分离大肠癌组织及癌旁正常黏膜差异表达基因的cDNA片断，将其与T载体连接构建文库，从库中随机挑取200个白色菌落．使用PCR方法鉴定阳性克隆并对其中50个克隆进行测序，将测序结果登录GenBank进行卜司源性对比分析，并对部分有意义的差异表达片断进行Virtual Northern Blot分析。结果成功构建人源性大肠癌消减cDNA文库，通过筛选获得20个差异表达的基因，其中有2个片断未检测到同源性序列，根据杂交结果考虑可能是存大肠肿瘤中差异表达的新基因。结论运用SSH技术成功构建了人大肠癌的差异表达的cDNA消减杂交文库，并筛选出2个存大肠肿瘤中差异表达的新基因。     

Construction and selection of subtracted cDNA library of mouse hepatocarcinoma cell lines with different lymphatic metastasis potential

AIM: In order to elucidate the molecular mechanism of lymphatic metastasis of hepatocarcinoma, we detected the difference of gene expression between mouse hepatocarcinoma cell lines Hca-F and Hca-P with different lymphatic metastasis potential.METHODS: cDNA of Hca-F cells was used as a tester and cDNA of Hca-P cells was used as a driver, cDNAs highly expressed in Hca-F cells were isolated by the suppression subtractive hybridization (SSH) method. The isolated cDNA was cloned into T/A cloning vector. The ligation products were transformed into DH5 α competent cells. Individual dories were randomly selected and used for PCR amplification.Vector DNA from positive clones was isolated for sequencing.RESULTS: There were 800 positive clones in amplified subtracted cDNA library. Random analysis of 160 clones with PCR showed that 95% of the clones contained 100-700 bp inserts. Analysis of 20 sequenced cDNA clones randomly picked from the SSH library revealed 4 known genes(mouse heat shock protein 84 ku, DNA helicase, ribosomal protein S13 ,ethanol induced 6 gene) and 3 expressed sequence tags (ESTs). Four cDNAs showed no homology and presumably represent novel genes.CONCLUSION: A subtracted cDNA library of differentially expressed genes in mouse heptocarcinoma cell lines with different lymphatic metastasis potential was successfully constructed with SSH and T/A cloning techniques. The library is efficient and lays a solid foundation for searching new lymphatic metastasis related genes. The expression of mouse heat shock protein gene, DNA helicase and other 4 novel gene may be different between mouse heptocarcinoma cell lines with different lymphatic metastasis potential.     

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。     

SSH技术筛选家蝇抗感染差异基因

目的 为了解家蝇抗菌分子免疫机制及效应免疫分子的表达情况,运用ssh、real-time PCR,构建家蝇差异表达消减文库.方法 以金黄色葡萄球菌（S.aureus）、大肠杆菌（E.coli）和球孢白僵菌（Beauvoir bassinet bacteria）,感染家蝇幼虫构建金黄色葡萄球菌、大肠杆菌和球孢白僵菌感染的差减文库,成功构建了家蝇抗感染差异表达cDNA文库.结果 文库的阳性克隆进行PCR鉴定主要分布在250～750 bp之间,随机挑取252个白斑进行测序和同源性分析,应用反向Northern斑点杂交技术鉴定了35个基因,其中32个为真阳性,包括抗菌肽、酶、核糖体蛋白,以及一些功能不明的蛋白.结论 运用real-time PCR技术分析了三种蛋白基因的表达情况,结果显示诱导后不同时间点,不同发育阶段抗菌肽均普遍表达,但表达水平存在着明显的差异,诱导后表达明显升高.     

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.     

Efficient screening of retroviral cDNA expression libraries.

Expression cloning of cDNAs was first described a decade ago and was based on transient expression of cDNA libraries in COS cells. In contrast to transient transfection of plasmids, retroviral gene transfer delivers genes stably into a wide range of target cells. We utilize a simple packaging system for production of high-titer retrovirus stock from cDNA libraries to establish a cDNA expression cloning system. In two model experiments, murine interleukin (IL)-3-dependent Ba/F3 cells were infected with libraries of retrovirally expressed cDNA derived from human T-cell mRNA or human IL-3-dependent TF-1 cell line mRNA. These infected Ba/F3 cells were selected for the expression of CD2 by flow cytometry or for the alpha subunit of the human IL-3 receptor (hIL-3R alpha) by factor-dependent growth. CD2 (frequency, 1 in 10(4)) and hIL-3R alpha (frequency, 1 in 1.5 x 10(5)) cDNAs were readily detected in small-scale experiments, indicating this retroviral expression cloning system is efficient enough to clone low-abundance cDNAs by their expression or function.     

RaSH, a rapid subtraction hybridization approach for identifying and cloning differentially expressed genes

Human melanoma cells growth-arrest irreversibly and terminally differentiate on treatment with a combination of fibroblast interferon and the protein kinase C activator mezerein. This experimental protocol also results in a loss of tumorigenic potential and profound changes in gene expression. Various cloning and cDNA microarray strategies are being used to determine the complete spectrum of gene expression changes underlying these alterations in human melanoma cells. An efficient approach, Rapid Subtraction Hybridization (RaSH), has been developed that is permitting the identification of genes of potential relevance to cancer growth control and terminal cell differentiation. RaSH cDNA libraries are prepared from double-stranded cDNAs that are enzymatically digested into small fragments, ligated to adapters, and PCR amplified followed by incubation of tester and driver PCR fragments. This subtraction hybridization scheme is technically simple and results in the identification of a high proportion of differentially expressed sequences, including known genes and those not described in current DNA databases. The RaSH approach represents an efficient methodology for identifying and cloning genes displaying differential expression that associate with and potentially regulate complex biological processes.     

Identification of pancreatic exocrinopathy in non-obese diabetic mice by gene subtraction analysis.

Type 1 diabetes is an immune-mediated disease with pancreatic infiltration and subsequent beta cell destruction. In this study pancreatic exocrinopathy in non-obese diabetic mice (NOD) was identified using gene subtraction methods (SSH) and macroarray analysis. Female NOD mice were treated with cyclophosphamide for acceleration and synchronization of the disease process at 70 d of age and analysed 10 d later, before the onset of overt diabetes. Extraction of total RNA of pancreas was followed by subtraction using the SSH technique. Pools of cDNA were generated using total RNA from treated and untreated NOD mice. Subtraction of cDNA pools of cyclophosphamide treated mice from cDNA pools of untreated mice resulted in a cDNA library, from which 480 clones were randomly selected. The clones were hybridized against labelled cDNA-probes generated from cyclophosphamide-treated and control NOD mice. Fifty-three clones (11 %) revealed at least twofold differential gene expression after cyclophosphamide treatment. Three of the downregulated genes (amylase, carboxypeptidase and preprotrypsin) were selected for evaluation of macroarray data by quantitative real-time PCR. Analysis of real-time PCR data confirmed suppression of gene expression with highest fold change for amylase (4.68-fold) followed by carboxypeptidase (2.79-fold) and preprotrypsin (2.14-fold). These results lead to the conclusion that inflammation in this animal model of type 1 diabetes is not restricted to pancreatic islets and that subtraction followed by macroarray analysis is capable of identifying genes responsible associated with disease progression.     

Molecular cloning of a CD28 cDNA by a high-efficiency COS cell expression system.

CD28 (Tp44) is a human T-cell-specific homodimer surface protein that may participate in T-cell activation. We have isolated a cDNA clone encoding CD28 by a simple and highly efficient cloning strategy based on transient expression in COS cells. Central to this strategy is the use of an efficient method to prepare large plasmid cDNA libraries. The libraries are introduced into COS cells, where transient expression of surface antigen allows the isolation of cDNAs by way of monoclonal antibody binding. The CD28 cDNA encodes a highly glycosylated membrane protein with homology to the immunoglobulin superfamily and directs the production of a homodimer in transfected COS cells.     

人乳头病毒16、18型与人胃腺癌关系的探讨

目的：采用ＰＣＲ法检测胃癌患者人乳头病毒（ＨＰＶ）１６，１８型ＤＮＡ序列，探讨ＨＰＶ类型与人胃腺癌的关系，为今后进行胃癌基因治疗及预防提供理论及实验依据。     

应用抑制性消减杂交技术克隆和筛选PS1TP5反式激活相关基因

目的构建乙型肝炎病毒前-S1蛋白反式激活基因5(PS1TP5)的反式激活相关基因差异表达的cDNA,克隆PS1TP5蛋白反式激活相关基因。方法以PS1TP5表达质粒pcDNA3.1(-)-myc-his(A)-PS1TP5转染HepG2细胞,以空载体pcDNA3.1(-)-myc-his(A)为对照,制备转染后的细胞裂解液,提取mRNA并合成cDNA,经RsaⅠ酶切后将实验组cDNA分成两组,分别衔接两种不同接头,再与对照组cDNA进行两次消减杂交及两次PCR反应,产物与T/A克隆载体连接,构建cDNA消减文库,并转染大肠杆菌进行文库扩增,随机挑选克隆经PCR鉴定后进行测序及同源性分析。结果成功构建人PS1TP5蛋白反式激活相关基因差异表达的cDNA。扩增后得到70个200～1 000 bp插入片段的克隆,随机挑选其中30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24种编码基因,其中1个为未知功能的新基因,电子拼接后命名为HBV PS1TP5TP1(乙型肝炎病毒前-S1蛋白反式激活蛋白5反式激活蛋白1),GenBank注册号DQ487761。结论筛选到的cDNA全长序列,包括一些与细胞...     

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)。