Overproduction of Biologically-active Human Nerve Growth Factor in Escherichia coli

A gene coding for human nerve growth factor (hNGF) was constructed for expression under control of the trp promoter in E. coli. The plasmid pTRSNGF contained a synthetic hNGF gene fused, in frame, to the region encoding the β-lactamase signal peptide. The plasmid pTRLNGF contained the same coding sequence as hNGF attached downstream from the N-terminal fragment of the trp L gene. E. coli cells harboring pTRSNGF produced an amount of hNGF constituting 4% of the total cellular protein, and removed the β-lactamase signal peptide. The mature protein hNGF was biologically active in the PC12h bioassay for neurite outgrowth. This biological activity was comparable to that of authentic mouse NGF. E. coli cells harboring pTRLNGF produced an amount of fusion protein hNGF constituting 25% of the total cellular protein. Although the fusion protein hNGF formed inclusion bodies in cells, dissolved fusion protein hNGF was active in neurite outgrowth from PC12h cells.     

人sTNFR1基因的克隆以及在NIH3T3细胞中的稳定表达

以He1a细胞的总RNA为模板,用RT—PCR方法扩增sTNFR1全编码区基因片段,构建含有目的片段的T载体克隆及真核表达载体pcDNA3．1（-）重组质粒亚克隆,将重组质粒和脂质体共同转染NIH3T3细胞系,G418筛选稳定转染细胞株．经核苷酸序列测序和酶切鉴定,成功构建了pcDNA3．1（-）-sTNFR1真核表达质粒,脂质体法建立了高效表达sTNFRI的稳定转染细胞系,并经RT—PCR和Western Blotting鉴定．人sTNFR1基因能在NIH3T3细胞系中稳定表达,为今后的研究打下了基础．     

hK1-L-Fc融合蛋白在CHO细胞中的表达及其活性研究

为进一步改造重组人激肽释放酶1(hK1),以期提高其生物活性,制备了通过柔性接头相连接的重组人激肽释放酶1-L-IgG1 Fc融合蛋白(hK1-L-Fc)。采用重叠延伸PCR技术构建hK1-L-Fc融合基因,克隆至表达载体pcDNA3.1,在中国仓鼠卵巢细胞(CHO-S)中表达。利用Protein A 亲和层析柱纯化融合蛋白,SDS-PAGE、Western blotting、飞行时间质谱(MALDI-TOF-MS)、HPLC检测表达产物,底物法检测融合蛋白的体外活性。结果显示:成功构建pcDNA3.1-hK1-L-Fc重组表达载体;获得稳定表达融合蛋白的细胞株;无血清悬浮批式培养的表达量在0.7 mg/L以上;纯化的蛋白其纯度在95%以上,分子量约60 kDa;活性检测显示其比活性在9.2 U/mg以上,较hK1-Fc蛋白提高了18%以上。     

Overproduction of biologically-active human nerve growth factor in Escherichia coli.

A gene coding for human nerve growth factor (hNGF) was constructed for expression under control of the trp promoter in E. coli. The plasmid pTRSNGF contained a synthetic hNGF gene fused, in frame, to the region encoding the beta-lactamase signal peptide. The plasmid pTRLNGF contained the same coding sequence as hNGF attached downstream from the N-terminal fragment of the trp L gene. E. coli cells harboring pTRSNGF produced an amount of hNGF constituting 4% of the total cellular protein, and removed the beta-lactamase signal peptide. The mature protein hNGF was biologically active in the PC12h bioassay for neurite outgrowth. This biological activity was comparable to that of authentic mouse NGF. E. coli cells harboring pTRLNGF produced an amount of fusion protein hNGF constituting 25% of the total cellular protein. Although the fusion protein hNGF formed inclusion bodies in cells, dissolved fusion protein hNGF was active in neurite outgrowth from PC12h cells.     

STK15的表达对NIH3T3细胞的影响

目的构建pcDNA3.1-STK15表达质粒,探讨STK15基因对小鼠成纤维细胞（NIH3T3）的影响。方法构建pcDNA3.1-STK15质粒,将其转染NIH3T3,应用RT-PCR、免疫细胞化学和Western印迹方法检测STK15的表达;MTT法检测细胞增殖能力;Transwell检测细胞侵袭能力。结果转染pcDNA3.1-STK15质粒的NIH3T3细胞在48 h有STK15的表达,而且该细胞的增殖速度和穿透Matrigel胶的细胞数均明显高于对照组（P〈0.05）。结论STK15基因具有增加细胞增殖和细胞侵袭力的功能,进而形成肿瘤。     

High-Level Expression and Purification of a Recombinant Human α-1,3-Fucosyltransferase in Baculovirus-Infected Insect Cells

A human α-1,3-fucosyltransferase (Fuc-TVII) was expressed by recombinant baculovirus-infected insect Sf9 cells as a secretory fusion protein. The fusion protein consisted of the human granulocyte colony-stimulating factor signal peptide followed by an IgG-binding domain of protein A, a Fuc-TVI-derived peptide, and the putative catalytic domain of Fuc-TVII. The signal peptide was correctly cleaved and the recombinant Fuc-TVII was secreted into the culture medium at a concentration of 10 μg/ml. The recombinant Fuc-TVII could be highly purified in a single-step purification procedure, i.e., IgG–Sepharose column chromatography. The enzymatic properties of the Sf9-produced Fuc-TVII were compared with the properties of that expressed by a human B-cell line, Namalwa KJM-1, transfected with an episomal plasmid carrying the fusion Fuc-TVII cDNA. Both recombinant proteins showed α-1,3-fucosyltransferase activity toward a type II oligosaccharide with a terminal α-2,3-linked sialic acid among various acceptors. The apparentK_mvalues of Sf9-produced Fuc-TVII for GDP-fucose and its acceptor substrate were slightly lower than those of the Fuc-TVII produced by Namalwa KJM-1 cells. Sf9-produced Fuc-TVII has N-linked carbohydrate chains whose molecular weights are lower than those linked to Namalwa KJM-1-produced Fuc-TVII. This difference in carbohydrate structure hardly affects the thermal stability of Fuc-TVII. The baculovirus expression system is available for high-level expression of stable and enzymatically active secretory Fuc-TVII.     

pcDNA3.1(+)-CTGF真核表达质粒构建及其在人成骨样细胞SaOS-2细胞中的表达*

目的:构建结缔组织生长因子(CTGF)的pcDNA3.1(+)真核表达质粒(pcDNA3.1(+)-CTGF),并检测其在人成骨样细胞SaOS-2中的表达,为进一步研究CTGF基因在骨发育和骨修复中的机制提供技术支撑。方法:采用PCR方法体外克隆CTGF基因全序列,将其用同源重组技术连接到线性pcDNA3.1(+)载体上,构建pcDNA3.1(+)-CTGF真核表达质粒,并对该质粒进行测序鉴定;鉴定无误后转染至SaOS-2细胞中,观察其48 h的表达情况。结果:基因测序证实pcDNA3.1(+)-CTGF真核表达重组质粒构建成功,与对照组相比,转染SaOS-2细胞48 h后的CTGF表达水平显著上调,达到对照组的4.8×10⁵倍(P＜0.01)。结论:成功构建了pcDNA3.1(+)-CTGF真核表达质粒,并能在人成骨样细胞SaOS-2中稳定表达,为深入研究CTGF基因对骨生成的调控机制奠定了基础。     

Molecular cloning and expression of glycoprotein IIIa<Superscript>T1565C</Superscript>

Objective To construct the eukaryotic expression vectors of mutant GPIIIa, establish CHO cell lines stably expressing mutant GPIIIa. Methods Total RNA were extracted from HEL cells. Mutant GPIIIa cDNA was synthesized by RT-PCR using the specific primers designed according to Genbank by Primer 5, then leaded to T1565C. The expression vector pcDNA3.1(+) and PCR products were respectively digested by NheI and HindIII, the specific cDNA fragments were directly inserted to the pcDNA3.1(+) because of having the same adhesive ends. Then wild type pcDNA3.1(+)IIIa and mutant pcDNA3.1(+)IIIa were respectively transfected into CHO cells using Lipofectamine 2000 reagent. The cell lines expressing GPIIIa and GPIIIa^T1565C were screened by G418. Expression of GPIIIa and GPIIIa^T1565C on transfected CHO cell surface were evaluated by flow cytometry and by RT-PCR to substantiate mRNA. Results The cDNAs of GPIIIa and GPIIIa^T1565C were amplified by RT-PCR, and the recombinant of mutant pcDNA3.1(+)IIIa were constructed. By sequencing and enzyme digestion, it was be confirmed that there is a mutant of GPIIIa on 1565(T → C). The result of flow cytometric analysis showed fluorescence intensity in the CHO cells transfected by recombinant is much higher than that by pcDNA3.1(+)IIIa. Conclusions (1) Succeeded in constructing recombinants pcDNA3.1(+)IIIa^T1565C. (2) Succeeded in getting the cell lines expressing GPIIIa^T1565C Supported by Heilongjiang Science & Technology bereau found GB06C40303.     

脑源性神经营养因子受体trkB在NIH 3T3细胞上的表达

构建了克隆有大鼠脑源性神经营养因子（BDNF）受体trkB全长基因的真核表达载体pcDNA3.1( )-rat trkB.用脂质体介导法将重组载体转入小鼠NIH3T3细胞,在mRNA和蛋白质水平检测到了trkB基因在用G418筛选到的抗性NIH 3T3细胞中的表达,表达的trkB蛋白定位于细胞膜上。BDNF能够剂量依赖性地促进NIH 3T3－trkB细胞的增殖,说明表达的trkB是有功能的。该表达trkB和NIH3T3细胞为研究BDNF的生理功能、活性测定和从噬菌体展示肽库中筛选BDNF肽提供了一个简便的细胞模型。     

人同源盒基因NKX3.1对前列腺癌细胞的诱导凋亡作用

构建人同源盒基因NKX3.1 cDNA真核表达载体,研究其在前列腺癌细胞PC-3、LNCaP 中的表达及对细胞的促凋亡作用.以人前列腺癌细胞LNCaP细胞中的总RNA为模板,RT-PCR扩增NKX3.1基因全长编码片段,将NKX3.1 cDNA重组到真核表达载体pcDNA3.1（+）中; 将pcDNA3.1-NKX3.1表达载体瞬时转染前列腺癌细胞PC-3和LNCaP 细胞,用RT-PCR和Western印迹检测NKX3.1 cDNA在转录水平和蛋白水平的表达;绘制细胞生长曲线,观察NKX3.1对前列腺癌细胞增殖的抑制作用;用DNA/ladder和流式细胞术检测NKX3.1对前列腺癌细胞凋亡的影响,进一步用RT PCR检测凋亡相关基因caspase3、caspase8、caspase9、Apaf1、survivin和Bcl2表达的变化.人同源盒基因NKX3.1 cDNA真核表达载体pcDNA3.1-NKX3.1经酶切及测序鉴定正确. pcDNA3.1-NKX3.1转染PC-3和LNCaP细胞后,经RT-PCR和Western印迹证明能有效表达NKX3.1.生长曲线显示,前列腺癌细胞转染NKX3.1 cDNA后细胞增殖受到抑制;前列腺癌细胞转染NKX3.1 cDNA 48 h后,DNA电泳呈现具有凋亡特征的DNA ladder;流式细胞术检测出现明显凋亡峰;RT-PCR检测凋亡相关基因.结果显示,caspase3、caspase8、caspase9基因表达明显增加,Bcl2基因表达明显减少.本研究成功构建了真核表达载体pcDNA3.1 NKX3.1, 转染PC3和LNCaP细胞后能有效表达,并对细胞具有诱导凋亡作用     

MMP-7基因真核表达载体的构建及其在HeLa细胞中的表达与鉴定

目的：构建MMP-7基因真核重组质粒,检测并鉴定MMP-7在人宫颈癌HeLa细胞中的表达。方法：提取宫颈癌组织总RNA,通过基因克隆构建MMP-7基因真核表达重组质粒pcDNA3.1（＋）/MMP-7,酶切、PCR及基因测序鉴定,用阳离子脂质体介导采用基因转染技术转染人宫颈癌Hela细胞,RT-PCR检测外源基因的表达、间接免疫荧光法检测对表达产物进行鉴定。结果：成功构建了重组表达质粒pcDNA3.1（＋）/MMP-7并转染了人宫颈癌Hela细胞,通过RT-PCR可以检测到MMP-7 mRNA在Hela细胞中的表达,经间接免疫荧光反应可检测到明显的阳性反应,而转染空载体组表达阴性。结论：构建的重组质粒pcDNA3.1（＋）/MMP-7能在Hela细胞中表达,为该蛋白在人子宫癌后续的功能研究奠定了基础。     

研究报告重组人GPx7的原核表达、纯化及其抗肿瘤活性检测

研究大肠杆菌表达重组人谷胱甘肽过氧化物酶7（glutathione peroxidase 7,GPx7）,并对纯化精制的重组人GPx7进行体内抗肿瘤活性检测。以质粒pCDNA3.1（-）-GPx7为模板,PCR 扩增获得N-端去除信号肽的 GPx7 基因片段,构建的重组质粒pET24A-GPx7在E.coli BL21（DE3）中诱导表达。采用Sulfopropyl强阳离子交换层析和Superdex 75分子排阻层析纯化精制获得原核表达的重组人GPx7蛋白。该蛋白的体外催化活性微弱,但S180荷瘤小鼠连续14d注射GPx7蛋白后,肿瘤生长受到抑制,抑制率为29.26%,与对照组相比具有显著差异。实验结果表明,采用阳离子交换和分子排阻层析两步法可纯化精制原核表达的重组人GPx,重组人GPx7蛋白在荷瘤小鼠模型中表现出体内抗肿瘤活性。     

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。     

小鼠IL-27真核表达载体的构建及其在RAW264.7 细胞中的表达

目的:构建小鼠白介素27(Interleukin 27,IL-27)单链融合基因的真核表达载体并检验其在RAW264.7细胞中的表达情况。方法:提取小鼠脾细胞总RNA,通过RT-PCR扩增出小鼠EBI3和p28 c DNA。采用重叠延伸PCR(splicing by overlap extension PCR,SOE PCR)通过编码疏水性多肽接头(Gly4Ser)3的DNA序列连接小鼠EBI3和p28基因片段,构建小鼠IL-27单链融合基因(mouse single chain IL-27,msc IL-27),并将其克隆至pc DNA3.1(+)载体。通过酶切和测序鉴定阳性重组载体,将重组质粒pc DNA3.1-IL-27通过脂质体转染法转染小鼠巨噬细胞株RAW264.7,通过RT-PCR方法检测目的基因的表达。结果:测序分析表明,小鼠IL-27单链融合基因中EBI3、linker和p28的连接顺序、方向及碱基序列与预期相符。在转染后的RAW264.7细胞中检测到了小鼠IL-27 m RNA的表达。结论:成功构建了小鼠IL-27单链融合基因及其真核表达载体,并在RAW264.7细胞中实现表达,为进一步探讨IL-27的生物学功能奠定了基础。     

Mo MLV gag-pol基因在NIH3T3细胞中的表达和鉴定

目的 构建含MoMLV gag-pol基因的重组表达载体,实现其在NIH3T3细胞中稳定表达。方法 应用RT-PCR方法反转录并扩增gag-pol基因,克隆入真核表达载体pcDNA4/HisMaxA上,构建重组表达载体pcDNA4/HisMaxA-gag-pol,用脂质体法转染NIH3T3细胞,Zeocin筛选稳定表达细胞株,通过SDS-PAGE分析检测表明, gag-pol基因在NIH3T3细胞实现了表达,产物相对分子质量(kD)为194.78×103。然后,将逆转录病毒载体导入此细胞系,包装逆转录病毒。用PCR与标记基因补救分析法检测野生型辅助病毒。结果 酶切鉴定的片段大小分别为5.2-kb,与预期大小一致,经Zeocin筛选后获得稳定表达细胞株,SDS-PAGE实验表明产物融合蛋白相对分子质量(kD)为194.78×103,与预期相符。脂质体转染包装细胞,嘌呤霉素加压筛选出高病毒滴度(4.0×106CFU/ml)的细胞克隆,且未检测到辅助病毒。结论 本工作构建的融合表达载体pcDNA4/HisMaxA-gag-pol及其在NIH3T3细胞中的表达,构建成功具有靶向性的逆转录病毒包装细胞系,该细胞系能够包装出高滴度的逆转录病毒,为肝细胞的基因治疗提供了一种新的基因转移系统。     

人Nephrin—GFP融合蛋白真核表达载体的构建和鉴定

目的构建人19号染色体长臂Nephrin基因和绿色荧光蛋白（green fluorescence protein,GFP）真核表达质粒,为进一步研究肾小球裂隙隔膜分子复合物构成与功能提供基础。方法设计引物,扩增真核表达质粒pEGFPN3中的GFP基因片段,将其插入nephrin原核表达载体pcDNA3．1 nephrin V5-His,重组质粒经酶切鉴定后测序,并转染至COS-7细胞观察表达情况及生物学特性。结果成功构建pcDNA3．Inephrin—GFP重组质粒,并将Nephtin—GFP融合蛋白成功表达于COS-7细胞,进一步经交联实验证明Nephtin—GFP融合蛋白具有正确的细胞膜表达。结论利用pEGFPN3和pcDNA3．1nephtinV5-His可成功重组Nephrin—GFP表达质粒,为进一步研究肾小球裂隙隔膜分子复合物构成及其功能提供有利工具。     

人补体调节蛋白DAF、MCP在哺乳动物细胞中的共表达及协同作用研究

利用双启动子构建含人补体调节蛋白DAF和MCP cDNA的双顺反子重组表达载体pcDNA3-DAFMCP-DP, 以磷酸钙沉淀法转染NIH3T3细胞, 用G418筛选获得NIH3T3 pcDNA3-DAFMCP-DP转化细胞。PCR实验结果显示人补体调节蛋白基因DAF和MCP整合在转化的异源细胞的染色体上。RT-PCR和Western blot印迹实验分别从RNA水平和蛋白质水平证实了人补体调节蛋白分子DAF和MCP在细胞系中皆获得同步表达。检测连续传代30次的NIH3T3 pcDNA3-DAFMCP-DP结果表明人DAF和MCP基因仍稳定整合在细胞基因组中, 并未随着传代而丢失, 为稳定的转双基因细胞系。补体依赖的细胞毒反应表明, pcDNA3-DAFMCP-DP转染细胞系由于DAF和MCP的共表达获得较DAF或MCP单一表达时更强的保护能力, 能更好地抑制人补体依赖的细胞毒作用的发生, 保护宿主细胞免受人补体的攻击。以上结果表明, DAF和MCP双基因重组表达载体实现了人补体调节蛋白基因高效转移和高水平共表达, 为获得表达多种人补体调节蛋白的理想供体提供了有效策略。而且共表达的DAF和MCP具有协同效应, 能更有效地阻止补体激活造成的细胞损伤, 在克服超急性排斥反应的基因治疗中具有潜在的临床应用价值。