中国人促红细胞生成素cDNA的克隆及其在COS-7细胞中的表达

利用PCR技术。以中国人促红细胞生成素(EPO)次全基因组为模板,进行了基因修补和重组．克隆出EPO cDNA全序列。同时发现中国人EPO cDNA与国外的克隆比较有一个核苷酸的差异,导致第62位氨基酸是丝氨酸．不是亮氨酸。将人EPO cDNA基因插入表达载体pSV2-dhfr中的不同克隆位点,构建了6种不同的转移载体质粒,即psV2 dhfr／F1,pSV2／F2,pSV2 dbfT／F3,pSV2 dhfr／F4,pSV2-dhfr／G1和psV2 dhfr／G3。将它们分别转染导人COS-7细胞,结果表明6种转移载体质粒转染的细胞上清液都有明显的EPO活性。人EPO cDNA基因转移载体质粒在COS-7细胞中的表达水平高于人次全EPO基因组转移载体质粒。     

通用真核质粒表达载体的构建

利用真核基因表达调控的原理,以pSV2-dhfr为起始材料,构建了两个通用的真核质粒表达载体pMAML1-dhfr和pMAML2-dhfr,它们包含人巨细胞病毒立即早期启动子/增强子调控元件,由两个转录方向相同或相反的表达单元组成.以荧火虫荧光素酶基因为报道基因,β-半乳苷酶基因为内对照,借助COS-7短暂表达系统,研究了它们对荧光素酶表达的影响,并比较了它们与出发载体pSV2-dhfr的相对强弱.     

小鼠白细胞介素33真核表达质粒的构建及表达

克隆小鼠IL-33基因构建其真核表达质粒,并转染COS-7细胞检测其表达。提取C57BL/6小鼠肺组织总RNA,经反转录聚合酶链式反应（RT-PCR）扩增小鼠IL-33基因,酶切后插入pcDNA^TM3.1/myc HisA构建其真核表达质粒pcDNA-3.1-IL-33,重组质粒转染COS-7细胞,RT-PCR和免疫印迹法（western blotting）检测目的基因表达。结果显示,pcDNA3.1-IL-33中插入的片段序列测定结果与小鼠IL-33cDNA序列一致,重组质粒转染COS-7细胞后检测到相应mRNA及蛋白表达。成功克隆了小鼠IL-33基因cDNA,并构建其真核表达质粒。     

红细胞生成素cDNA在中国仓鼠卵巢细胞中的稳定表达

将(?)红细胞生成素(EPO)cDNA构建的重组表达质粒用电穿孔法引入COS-7细胞,ELISA和红系集落测活结果表明,该重组质粒在哺乳动物细胞中能够表达有生物活性的红细胞生成素。进一步将其转染CHO-dhfr~-细胞,经氨甲喋呤(MTX)加压扩增,混合细胞中各克隆表达水平比较一致,细胞的平均表达水平为2-3μg/10~6 Cells/24hr。细胞冻存后复苏其表达水平与冻存前一致,表明外源基因整合稳定。     

结核分枝杆菌Rv3586结构域基因真核表达载体的构建及鉴定

目的:构建结核分枝杆菌(Mycobacterium tuberculosis,Mtb)环二腺苷酸(cyclic diadenosine monophosphate,c-di-AMP)合成酶Rv3586结构域基因的真核表达载体,并在COS-7细胞中表达。方法:以Mtb基因组为模板PCR扩增Rv3586三个结构域基因,分别克隆入pEGFP-N3真核表达质粒,用菌落PCR、质粒酶切和测序方法对插入序列进行鉴定。通过脂质体将重组质粒转染COS-7细胞,间接免疫荧光法检测目的基因在COS-7细胞内的表达。结果:PCR成功扩增出Rv3586三个结构域基因,菌落PCR、质粒酶切和质粒测序鉴定结果表明成功插入目的片段,包含Rv3586的三个结构域基因的真核表达载体构建成功。间接免疫荧光法结果显示,Rv3586三个结构域蛋白在COS-7细胞中表达成功。结论:成功构建Rv3586三个结构域基因的真核表达载体,并在COS-7细胞中表达成功,为后续Mtb Rv3586结构域的功能和应用研究奠定了基础。     

人β干挠素基因在SV40晚期启动子控制下在小鼠骨髓瘤细胞中表达

人成纤维细胞干挠素(Hu-IFN-β)基因的HindⅡ片段,插入载体pSV2-dhfr质粒中SV40晚期启动子(Lp)下游PvuⅡ位点处。用此重组质粒与带有黄嘌呤磷酸核糖转移酶(XGPRT)基因的质粒pSV2-gpt共转染次黄嘌吟核糖转移酶(HGPRT)基因缺陷的小鼠骨髓瘤(SP2/0)细胞。在含有霉酚酸和氨基喋呤的选择培基中,筛选出有效地组成性表达的细胞株。在未加氨甲喋呤压力倍增的条件下,Hu-IFN-β抗病毒活性为1275U/10~5细胞,1ml,48小时。     

大鼠促甲状腺激素释放激素受体1基因的克隆及其在COS-7细胞系中的表达

目的:克隆大鼠促甲状腺激素释放激素受体1(TRH-R1)基因,构建其真核表达载体,并检测该基因在非洲绿猴肾细胞系COS-7中的表达。方法:应用RT-PCR方法,以大鼠脑源RNA为模板,扩增获得TRH-R1基因,定向克隆到pDsRed2-N1中,以LipofectAMINE 2000试剂转染pDsRed2-N1-TRH-R1表达载体至COS-7细胞系中进行瞬时表达。结果:测序结果表明,从大鼠脑源总RNA中克隆到正确的TRH-R1基因全长编码序列;显微照相观察到所构建的TRH-R1表达载体质粒在COS-7细胞系中获得有效表达。结论:大鼠TRH-R1基因的克隆、真核表达载体的构建及在COS-7细胞系中表达获得成功,为进一步研究其功能奠定了基础。     

重组人红细胞生成素二聚体不同真核表达载体的构建及表达

为构建重组人红细胞生成素(recombinant human erythropoietin,rhEPO)二聚体真核表达载体,应用PCR方法扩增EPO cDNA,PCR产物克隆入T载体后,经酶切、连接、转化等过程分别构建了3个EPO二聚体的真核表达载体pBT-1c、pBT-2s及pBT-3c,经测序序列完全正确。然后将3个真核表达载体分别转染于CCS-7细胞及CHO-dhfr-细胞中,用ELISA方法检测,它们在COS-7的瞬时表达量分别为4IU／ml、11.5IU／ml和7.2IU／ml。其中EPO二聚体真核表达载体pBTsv稳定转染CHO-dhfr-细胞后,用氨甲喋呤(MTX)逐渐加压的方法筛选到阳性克隆,表达量可达到4000IU／106cells／72h。     

利用反向遗传技术产生8基因全禽源流感病毒疫苗候选株

利用反向遗传技术将含有A/Chicken/Shanghai/F/98(H9N2)株禽流感病毒(avian influenza virus,AIV)的6个内部基因与H5N1亚型AIV的2个表面基因HA和NA共转染COS-1细胞,产生了6 2全禽源的重配AIV。将H5N1亚型AIV的HA基因经基因突变致弱,然后将A/Chicken/Shanghai/F/98(H9N2)AIV的6个内部基因的cD-NA和以上致弱的禽源HA基因及NA基因的cDNA分别克隆到转录/表达载体pHW2000中,构建成8个转录/表达质粒。将8个质粒共转染COS-1细胞,24h后收获细胞及上清接种SPF鸡胚,72~90h后鸡胚死亡,收取鸡胚尿囊液进行血凝、血凝抑制试验、序列分析、病毒致病性试验和动物免疫保护试验,最终证实产生了致弱的全禽源AIV疫苗候选株。     

鹅源新城疫病毒ZJI株基因组cDNA克隆的序列修饰

将鹅源新城疫病毒ZJI株全基因组cDNA克隆通过酶切切下包含T7启动子区域和转录载体的片段,将其自身环化后获得约6．5kb的质粒。设计引物,利用基因定点突变技术,在此质粒上T7启动子与NDV Leader序列之间突变插入额外的3个G碱基,将此突变最终引入到原基因组cDNA克隆中。应用RT—PCR技术从尿囊液中扩增NDV基因组F／HN基因区域部分片段,利用限制性内切酶BsmBI将扩增片段连接,最终将原cDNA克隆中相应片段替换下。测序结果表明,原基因组cDNA克隆中特定位置碱基插入突变成功,F／HN基因区域碱基突变均得以纠正。以上cDNA克隆的修饰与替换为该毒株的反向遗传研究打下了基础。     

人促红细胞生成素基因组基因和cDNA的克隆及其在COS－7细胞中的表达

利用ＰＣＲ技术,从正常人胎肝染色体ＤＮＡ中克隆到长度为１５７２ｂｐ的人促红细胞生成素（ＥＰＯ）基因组基因片段,它包含除第一个外显子和第一个内含子外所有外显子及内含子。再人工合成１３ｂｐ外显子１的编码区,并与１５７２ｂｐ片段拼接,从而得到除第一个内含子的人促红细胞生成素基因组基因。将克隆得到的ＥＰＯ基因插入载体ｐＳＶ２－ｄｈｆｒ得到ｐＳＶ２－ＥＰＯ表达载体,转染ＣＯＳ－７细胞后获得高效表达。利用自行研制的小鼠抗人ＥＰＯ单抗及兔抗人ＥＰＯ多抗,对表达产物进行ＥＬＩＳＡ定量测定,细胞分泌ＥＰＯ量高达２５１±７Ｕ／ｍｌ．Ｋｒｙｓｔａｌ法测得体外生物活性２４１．５±６．５Ｕ／ｍｌ．用ＥＰＯ单抗免疫沉淀结合ＳＤＳ－ＰＡＧＥ对转染细胞的表达产物做了进一步鉴定,清晰地看到了ＥＰＯ条带。从高效表达ＥＰＯ的转染细胞中分离纯化ｍＲＮＡ,用ＲＴ－ＰＣＲ方法扩增并克隆到ＥＰＯ的ｃＤＮＡ,这为ＥＰＯ在其它系统中的表达及ＥＰＯ的功能与结构的研究打下了基础。     

Expression of a gene encoding a rabbit sperm membrane protein in mammalian cells.

A general mammalian expression vector designated pSV2-EP was reconstructed by inserting an oligonucleotide fragment into pSV2-dhfr. This vector allowed insertion of cDNAs with EcoRI cohesive ends. The pSV2-EP contains a simian virus 40 (SV40) early promoter, origin for DNA replication, SV40 poly-A site, splicing site, an initiator ATG downstream from the promoter and an EcoRI site for the insertion of cDNA fragment screened from lambda gt11 expression libraries. A recombinant plasmid (pS-VRS-1) was constructed by inserting RSD-1, a cDNA encoding a rabbit sperm tail protein, into the EcoRI site of the pSV2-EP vector. Chinese hamster ovarian (CHO) dhfr-negative cells were cotransformed with pSV2-dhfr and pSVRS-1 by the calcium phosphate method. In selective culture medium without thymidine and hypoxanthine, several cell lines were obtained containing mRNA and DNA that hybridized with RSD-1. One of these transformed cell lines stained intensely with anti-rSMP-B antibodies, demonstrating that the RSD-1 was expressed in the transformed CHO cells.     

利用同源蛋白的信号肽和前肽序列在CHO细胞中表达重组人BMP6

BMP6属于TGF-β超家族,具有较强的骨诱导作用。主要利用BMP6自身的信号肽、前肽与成熟肽基因序列构建了表达质粒pcDNA-BMP6;同时利用BMP2的信号肽、前肽与BMP6的成熟肽基因序列构建了表达质粒pcDNA-BMP2/6。将两种质粒分别瞬时转染Cos7细胞,发现质粒pcDNA-BMP2/6表达rhBMP6的效率高于质粒pcDNA-BMP6。然后将质粒pcDNA-BMP2/6与含二氢叶酸还原酶基因(dhfr)的表达质粒共转染dhfr缺陷型的中华仓鼠卵巢(CHO)细胞,经G418筛选、氨甲蝶呤(MTX)介导目的基因扩增、亚克隆后得到表达rhBMP6成熟肽的单克隆细胞株。将表达产物rhBMP6初步纯化后,能诱导前成肌细胞系C2C12向成骨细胞方向转化,显示其具有骨诱导作用。     

Active human erythropoietin expressed in insect cells using a baculovirus vector: a role for N-linked oligosaccharide

Biologically active recombinant human erythropoietin has been expressed at high levels in an insect cell background. Expression involved the preparation of a human erythropoietin cDNA, the transfer of this cDNA to the Autographa californica nuclear polyhedrosis virus (AcNPV) genome under the polyhedrin gene promoter, and the subsequent infection of Spodoptera frugiperda cells with recombinant AcNPV. Erythropoietin cDNA was prepared through the expression of the human erythropoietin gene in COS cells using pSV2 and the construction of a COS cell cDNA library in bacteriophage Lambda GT10. Prior to transfer to the AcNPV genome, erythropoietin cDNA isolated from this library was modified at the 3'-terminus in order to replace genomic erythropoietin for SV40 cDNA derived from pSV2. Transfer of this cDNA to AcNPV and the infection of S. frugiperda cells with cloned recombinant virus led to the secretion of erythropoietin: based on bioassay, rates of hormone secretion (over 40 U/ml per h) were 50-fold greater than observed for COS cells. The purified recombinant product possessed full biological activity (at least 200,000 U/mg), but was of lower Mr (23,000) than human erythropoietin produced in COS cells (30,000) or purified from urine (30,000 to 38,000). This difference was attributed to the glycosylation of erythropoietin in S. frugiperda cells with oligosaccharides of only limited size. Further removal of N-linked oligosaccharides from this Mr 23,000 hormone using N-Glycanase yielded an apo-erythropoietin (Mr 18,000) which possessed substantially reduced biological activity. These results indicate that glycosylation, but not the normal processing of oligosaccharides to complex types, is required for the full hormonal activity of human erythropoietin during red cell development.     

Active human erythropoietin expressed in insect cells using a baculovirus vector: A role for N-linked oligosaccharide

Biologically active recombinant human erythropoietin has been expressed at high levels in an insect cell background. Expression involved the preparation of a human erythropoietin cDNA, the transfer of this cDNA to the Autographa californica nuclear polyhedrosis virus (AcNPV) genome under the polyhedrin gene promoter, and the subsequent infection of Spodoptera frugiperda cells with recombinant AcNPV. Erythropoietin cDNA was prepared through the expression of the human erythropoietin gene in COS cells using pSV2 and the construction of a COS cell cDNA library in bacteriophage Lambda GT10. Prior to transfer to the AcNPV genome, erythropoietin cDNA isolated from this library was modified at the 3′-terminus in order to replace genomic erythropoietin for SV40 cDNA derived from pSV2. Transfer of this cDNA to AcNPV and the infection of S. frugiperda cells with cloned recombinant virus led to the secretion of erythropoietin: based on bioassay, rates of hormone secretion (over 40 U/ml per h) were 50-fold greater than observed for COS cells. The purified recombinant product possessed full biological activity (at least 200000 U/mg), but was of lower M_r (23000) than human erythropoietin produced in COS cells (30000) or purified from urine (30000 to 38000). This difference was attributed to the glycosylation of erythropoietin in S. frugiperda cells with oligosaccharides of only limited size. Further removal of N-linked oligosac-charides from this M_r 23000 hormone using N-Glycanase yielded an apo-erythropoietin (M_r 18000) which possessed substantially reduced biological activity. These results indicate that glycosylation, but not the normal processing of oligosaccharides to complex types, is required for the full hormonal activity of human erythropoietin during red cell development.     

人促红细胞生成素基因组基因的克隆及全序列分析

为了克隆到全长的人促红细胞生成素基因,从而在真核系统中及转基因动物乳腺中进行表达,从一个中国人的血细胞中提取基因组ＤＮＡ,构建了不完全基因组噬菌体文库,文库效价为５×１０４．这种文库的构建方法是用ＢａｍＨⅠ对基因组ＤＮＡ进行完全酶切,回收１０．５ｋｂ左右的酶切片段,插入到λ－噬菌体ＥＭＢＬ３载体中．筛选文库所使用的探针是用ＰＣＲ方法从基因组ＤＮＡ模板中扩增的５５６ｂｐ的ＥＰＯ基因片段．从该文库中筛选到了一个含有完整ＥＰＯ基因的插入片段长度为１２．５ｋｂ的阳性克隆．经全序列分析证实,所克隆的ＥＰＯ基因编码正确,但在５′－侧翼及第一内含子处与国外发表的序列相比较,发现两处核苷酸差异,这两个核苷酸的差异改变了５′－调控区的两个小的开放阅读框——ＯＲＦ１和ＯＲＦ３,其在基因表达调探方面的作用值得进一步探讨．     

In vitro and in vivo transfection and expression of plasmid-based non-viral vector for erythropoietin gene therapy

A non-viral gene therapy vector, pcDNA3-EPO, was constructed by subcloning erythropoietin (EPO) cDNA into plasmid pcDNA3. After liposome-mediated transfection of the NIH 3T3 cells in vitro, EPO expression in the culture medium was detected by ELISA and amounted to 1.25 ± 0.3 IU ml^–1. The biological activity of this EPO in the medium was detected after intramuscular injection of BALB/c mice. PCR of genomic DNA and RT-PCR of total RNA also confirmed that the plasmid pcDNA3-EPO had been transfected into the cells. A pool of pcDNA3-EPO transfectants, which stably expressed EPO, was obtained by G418 selection. When pcDNA3-EPO was combined into liposomes and intramuscularly injected into BALB/c mice, the reticulocyte ratio in the positive mice was three times higher than that in the control mice. In vivo expression was maintained in mice for at least one month.     

重组人骨形态发生蛋白2在CHO细胞中的表达、鉴定及活性分析

构建真核表达载体pCDNA3.1( )-hBMP-2,与质粒pSV2-dhfr共转染CHO-dhfr-细胞,以含有700μg/mLG418的IMDM进行选择性培养,筛选抗性克隆,并用MTX扩增,提高rhBMP-2的表达量。收集的rhBMP-2蛋白进行Westernblot检测,还原蛋白样品电泳产生一条大小约为18kD的特异性条带,非还原蛋白样品电泳产生一条大小约为30kD的特异性条带,提示表达的rhBMP-2是经过糖基化修饰的,且以同源二聚体形式分泌表达。单细胞分离培养得到14株rCHO(hBMP-2)单克隆细胞株,ELISA法检测rhBMP-2表达水平,最高可达7.83μg/24h/106cells。活性分析结果表明,表达的rhBMP-2具有很强的生物学活性。     

两个不同启动子在COS7细胞中转录效率的比较

 两个不同启动子在ＣＯＳ７细胞中转录效率的比较陈坚刘小萍曹韫旭陆德如（第二军医大学医学生物技术和分子遗传研究所,上海２００４３３）ＣｏｍｐａｒｉｓｏｎｏｆｔｈｅＴｒａｎｓｃｒｉｐｔｉｏｎａｌＥｆｉｃｉｅｎｃｙｏｆＴｗｏＤｉｆｆｅｒｅｎｔＰｒｏｍｏｔｅｒ...