人穿孔素在sf9昆虫细胞中的表达和纯化

目的建立重组人穿孔素的表达和快速纯化方法。方法在sf9昆虫细胞内表达带His标签人穿孔素。使用人工制作简易的镍(Ni)柱装置进行蛋白质亲和层析。采用考马斯亮蓝染色、银染法及流式细胞计量术纯化的蛋白分析其理化性质;用人乳腺癌细胞MCF-7的PI染色法鉴定其生物学活性。结果纯化出的穿孔素具有在细胞膜打孔的生物学活性。与常规蛋白纯化方法如离子交换色谱、分子筛和疏水作用层析等方法相比,该方法操作简便、成本低,为人穿孔素接下来的研究以及其他蛋白质的纯化提供一定参考。结论以一种简单的方法在sf9昆虫细胞内表达并纯化出了有活性的人穿孔素。     

人N端脂多糖结合蛋白基因在sf21昆虫细胞中的表达

目的 表达重组人N端脂多糖结合蛋白（truncated lipopolysaccharide binding proten,tIBP）。方法 通过病毒鉴定、SDS-PAGE、western blot、毛细管电泳、体外结合实验、细胞活性实验对重组病毒及重组蛋白tLBP的分子量、纯度和生物学活性进行分析。结果 重组病毒空斑分析确定MOI(multiplicity of infection)为8～10,SDS-PAGE显示感染时间65～72h为最佳表达分析;凝胶扫描显示特异表达蛋白占总产物的9.8%,纯化蛋白的分子量约27000u,纯度达95%以上;毛细管电泳显示表达产物呈单一峰型;Lowry法测定约1L上清液可获9mg纯化蛋白;Western blot间接显示表达产物反应带与预期值相符;酶联体外结合实验证实该蛋白可特异结合LPS。应用U937细胞,经LPS(1ng/mL）刺激与LPS（1mg/mL）刺激加纯化蛋白细胞中获得高效表达,并观察到它在体外具有结合或中和内毒素的活性作用。     

博卡病毒VP_2基因在昆虫细胞sf9中表达及临床标本筛查

目的 表达人博卡病毒(HBoV)VP_2蛋白,用于临床标本HBoV的筛查.方法 将VP_2基因重组于杆状病毒基因组,重组的杆状病毒感染昆虫细胞sf9,用HA抗体进行Western Blot鉴定重组融合VP_2蛋白表达.通过电镜观察重组蛋白颗粒.以VP_2蛋白作为抗原对176例临床样本进行免疫印迹筛查.结果 在昆虫细胞中VP_2蛋白的表达量约占细胞总蛋白的60%以上,VP_2蛋白相对分子质量为60×10~3.电镜观察博卡病毒VP_2蛋白形成病毒样颗粒(VLP),其大小在20mm左右;采用免疫印迹技术从临床标本中筛查出4例患者HBoV阳性,阳性率达到2.28%(4/176).结论 本研究成功的在昆虫细胞中表达了博卡病毒VP_2蛋白;表达VP_2蛋白具有一定抗原性,为开展人博卡病血清学研究方法建立提供基础.     

Fungal metabolite gliotoxin targets flavocytochrome b558 in the activation of the human neutrophil NADPH oxidase

Fungal gliotoxin (GT) is a potent inhibitor of the O(2)(-)-generating NADPH oxidase of neutrophils. We reported that GT-treated neutrophils fail to phosphorylate p47(phox), a step essential for the enzyme activation, because GT prevents the colocalization of protein kinase C betaII with p47(phox) on the membrane. However, it remains unanswered whether GT directly affects any of NADPH oxidase components. Here, we examine the effect of GT on the NADPH oxidase components in the cell-free activation assay. The O(2)(-)-generating ability of membranes obtained from GT-treated neutrophils is 40.0 and 30.6% lower, respectively, than the untreated counterparts when assayed with two distinct electron acceptors, suggesting that flavocytochrome b(558) is affected in cells by GT. In contrast, the corresponding cytosol remains competent for activation. Next, GT addition in vitro to the assay consisting of flavocytochrome b(558) and cytosolic components (native cytosol or recombinant p67(phox), p47(phox), and Rac2) causes a striking inhibition (50% inhibitory concentration = 3.3 microM) when done prior to the stimulation with myristic acid. NADPH consumption is also prevented by GT, but the in vitro assembly of p67(phox), p47(phox), and Rac2 with flavocytochrome b(558) is normal. Posterior addition of GT to the activated enzyme is ineffective. The separate treatment of membranes with GT also causes a marked loss of flavocytochrome b(558)'s ability to reconstitute O(2)(-) generation, supporting the conclusion at the cellular level. The flavocytochrome b(558) heme spectrum of the GT-treated membranes stays, however, unchanged, showing that hemes remain intact. These results suggest that GT directly harms site(s) crucial for electron transport in flavocytochrome b(558), which is accessible only before oxidase activation.     

Transfection of Lepidopteran insect cells with Baculovirus DNA

Summary Several protocols are presented for preparation and transfection of Baculovirus and plasmid DNAs into Lepidopteran insect cells using the calcium-phosphate co-precipitation technique. Important parameters for optimum efficiency include the inherent susceptibility of the recipient cell line for transfection, and the method of preparation of viral and plasmid DNAs. The protocols presented provide reproducible high efficiencies for transfection of several Lepidopteran cell lines.     

Leu505 of Nox2 is crucial for optimal p67phox-dependent activation of the flavocytochrome b558 during phagocytic NADPH oxidase assembly

The role of Leu505 of Nox2 on the NADPH oxidase activation process was investigated. An X-CGD PLB-985 cell line expressing the Leu505Arg Nox2 mutant was obtained, exactly mimicking the phenotype of a previously published X91+-CGD case. In a reconstituted cell-free system (CFS), NADPH oxidase and iodonitrotetrazolium (INT) reductase activities were partially maintained concomitantly with a partial cytosolic factors translocation to the plasma membrane. This suggests that assembly and electron transfer from NADPH occurred partially in the Leu505Arg Nox2 mutant. Moreover, in a simplified CFS using purified mutant cytochrome b558 and recombinant p67phox, p47phox, and Rac1proteins, we found that the Km for NADPH and for NADH was about three times higher than those of purified WT cytochrome b558, indicating that the Leu505Arg mutation induces a slight decrease of the affinity for NADPH and NADH. In addition, oxidase activity can be extended by increasing the amount of p67phox in the simplified CFS assay. However, the maximal reconstituted oxidase activity using WT purified cytochrome b558 could not be reached using mutant cytochrome b558. In a three-dimensional model of the C-terminal tail of Nox2, Leu505 appears to have a strategic position just at the entry of the NADPH binding site and at the end of the alpha-helical loop (residues 484-504), a potential cytosolic factor binding region. The Leu505Arg mutation seems to affect the oxidase complex activation process through alteration of cytosolic factors binding and more particularly the p67phox interaction with cytochrome b558, thus affecting NADPH access to its binding site.     

Chronic granulomatous disease with partial deficiency of cytochrome b558 and incomplete respiratory burst: variants of the X-linked, cytochrome b558-negative form of the disease.

Five male patients from four different families presented with a clinical record of chronic granulomatous disease (CGD): recurrent infections of the skin and/or respiratory tract with catalase-positive microorganisms, sometimes in combination with granulomata and/or abscesses in various organs. These patients differed from "classical" forms of the disease in that their neutrophils, although deficient in killing in vitro of Staphylococcus aureus, contained a decreased but measurable amount of cytochrome b558 (10-60% of normal on a heme basis), causing weak staining in the nitroblue tetrazolium dye test and a depressed respiratory burst after contact of the cells with fluid or particulate activators of the NADPH:O2 oxidoreductase. In the cell-free activation system, the defect in the patients' cells was localized in the membrane fraction. In each of the four families, the cellular abnormalities showed an X-linked inheritance. Fusion experiments performed with the monocytes from these patients and those from patients with classical X-linked, cytochrome b558-negative (Xb(0)) or autosomal, cytochrome b558-positive (Ab+) CGD showed complementation of NADPH:O2 oxidoreductase activity in the latter but not in the former combination. Thus, the unusual CGD patients represent variant forms of Xb(0) CGD, with mutations in the gene coding for the beta subunit of cytochrome b558 that do not cause complete loss of this protein.     

人重组FGFR1在昆虫细胞膜上的表达

目的：将人重组成纤维细胞生长因子受体1（FGFR1）表达在昆明细胞膜表面,有作筛选成纤维细胞生长因子（FGFs）损抗肽抗针。方法：将人FGFR1 cDNA克隆入昆虫病毒的转递质粒pFastBac Ⅰ上,然后转座到昆虫病毒Bacmid上。以重组Bacmid转染昆虫细胞Sf9并表达人FGFR1,以Western印迹和ELISA对表达出的蛋白质进行鉴定。结果：FGFR1 cDNA片段2100bp,重组FGFR1表达产物分子量78kD。ELISA结果显示,人重组FGFR1高效地在昆虫细胞Sf9膜表达。结论：这个表达系统能很好地表达出人重组FGFR1,并能准确地将其定位到昆虫细胞膜的表面。     

Induction of MMP-9 mediated gelatinolytic activity in human monocytic cells by cell wall components of Mycobacterium tuberculosis

Mycobacterium tuberculosis (Mtb) infection induces the expression of host matrix metalloIproteinases (MMPs) capable of tissue degradation. We show that infection of mice with Mtb results in differential expression of MMPs in the lung. MMP-9 activity increased by week 1 post-infection, while MMP-2 activity increased after week 2. RT-PCR analysis for gene expression of gelatinases and their respective inhibitors showed: a small increase in MMP-9 by week 1, no change in TIMP-1 and MMP-2, and a significant decrease in TIMP-2 by week 4. The increase in MMP-2 could be due to a decrease in TIMP-2 expression. Addition of 4-aminophenylmercuric acid to lung extracts increased MMP-9 activity, suggesting that its regulation could be due to endogenous activation by proteases. In vitro, attenuated and virulent Mtb strains equally induced MMP-9 expression in U937 monocytes. The inducer of MMP-9 in Mtb was present in culture filtrates, and was active after paraformaldehyde fixation. LAM stimulated MMP-9 expression in THP-1 cells, but not U937 cells. However, LAM-free extracts also induced MMP-9 activity in THP-1 cells. Fractionation of Mtb extracts by chromatography revealed fractions of 17 and 156 kDa with MMP-9 inducing activity. In conclusion, LAM and other components of Mtb induce the expression of MMP-9.     

The stimulatory role of human cytochrome b5 in the bioactivation activities of human CYP1A2, 2A6 and 2E1: a new cell expression system to study cytochrome P450 mediated biotransformation

Cytochrome b₅ (b₅) is increasingly recognized to be of importancefor specific cytochrome P450 (CYP) activities. We developedhuman b₅/CYP-competent mutagenicity tester bacteria to studythe role of b₅ in the bioactivation activity of human CYP. Thesenew tester bacteria were derived from the previously engineeredhuman CYP-competent Escherichia coli K12 tester strain MTC,containing a bi-plasmid system for the co-expression of a specificCYP form (CYP1A2, 2A6 or 2E1) with human b₅, and human NADPHcytochrome P450 reductase (RED), resulting in the strain BTC-b₅-1A2,BTC-b₅-2A6 and BTC-b₅-2E1, respectively. The relative contentof b₅ with CYP and RED in these three BTC-b₅-CYP strains demonstratedphysiologically relevant co-expression levels and typical CYP-specificactivities could be determined with their specific chemicalprobes. These strains were applied in mutagenicity assays alongwith their corresponding b₅-void strains to determine the effectof b₅ on the CYP1A2-, CYP2A6- and CYP2E1-mediated bioactivationof several promutagens. For CYP1A2, of the 5 compounds tested[2-aminoanthracene (2AA), 1-aminopyrene, 6-aminochrysene, 2-amino-3-methylimidazo(4,5-f)quinolineand 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)], onlythe mutagenicity of 2AA was slightly increased (     

Local anesthetics inhibit priming of neutrophils by lipopolysaccharide for enhanced release of superoxide: suppression of cytochrome b558 expression by disparate mechanisms

Local anesthetics have anti-inflammatory effects in vivo and inhibit neutrophil functions in vitro, but how these agents act on neutrophils remains unclear. Phagocytosis and bactericidal activity of neutrophils are enhanced by exposure to bacterial components such as lipopolysaccharide (LPS); this process is termed priming, which for enhanced release of superoxide (O2-) causes mobilization of intracellular granules that contain cytochrome b558, a component of reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. We studied whether local anesthetics affected LPS priming for enhanced release of O2- in response to triggering by the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (fMLP), and we investigated which element in the LPS signaling pathway might be the target of local anesthetics. Neutrophils were incubated with 10 ng/ml LPS and 1% plasma+/-local anesthetics, washed, and triggered with fMLP. Local anesthetics all inhibited LPS priming, and 50% inhibition was at 0.1 mM tetracaine, 0.5 mM bupivacaine, 3.0 mM lidocaine, or 4.0 mM procaine. Local anesthetics inhibited LPS-induced mobilization of specific granules and secretory vesicles. Local anesthetics inhibited LPS-induced up-regulation of cytochrome b558 but not LPS-induced translocation of p47phox. Inhibition of priming by local anesthetics was reversed by washing and incubating for 5 min. Tetracaine alone, but not the other local anesthetics, inhibited LPS activation of p38 mitogen-activated protein kinase (MAPK) and MAPK kinase 3 (kinases in the LPS signaling pathway). The p38 MAPK inhibitors SB203580 and PD169316 also blocked LPS priming. Thus, tetracaine and the other local anesthetics inhibit by disparate mechanisms, but all the local anesthetics impaired up-regulation of cytochrome b558 and all impaired priming of NADPH oxidase by LPS.     

Analysis of localization and function of the COOH-terminal corresponding site of cytochrome b558 in fish neutrophils.

Using an antibody against the synthetic peptide corresponding to the COOH-terminal region of human cytochrome b558 large subunit, a broad band was specifically detected in neutrophil lysates from 6 marine fish and 2 freshwater fish by western blotting. Immunofluorescence assay showed that the antibody recognized the epitopes in eel and tilapia neutrophils permeabilized with detergent. These results suggest that the cytochrome b large subunit universally exists in fish neutrophils and that the epitopes are exposed to the cytoplasmic side of fish neutrophils as well as human neutrophils. Furthermore, a synthetic peptide corresponding to the COOH-terminus of the large subunit apparently blocked superoxide production in a specific and dose-dependent fashion in eel and tilapia neutrophils, indicating that the region equivalent to the COOH-terminus of cytochrome b large subunit is responsible for superoxide generation in fish neutrophils.     

人Cosmc 胞外段蛋白在昆虫细胞Sf-9 中的表达与纯化研究

目的:利用昆虫细胞Bac-to-Bac 杆状病毒表达系统表达人Cosmc 胞外段蛋白,为体外研究Cosmc 蛋白的结构和功能奠定基础,同时也为O-连接糖基化及相关疾病的研究提供思路。方法:采用Bac-to-Bac 系统,构建重组转移质粒pFastBac1-Cosmc extracellular domain(pFastBac1-Cosmc ED),转化到含穿梭载体Bacmid 的感受态细胞DH10Bac 中,通过蓝白斑筛选和PCR 鉴定,获得重组转座子rBacmid-Cosmc ED。在脂质体介导下,重组病毒感染Sf-9 无血清细胞,在Sf-9 中表达Cosmc 胞外段蛋白,由于Cosmc N 端加有昆虫细胞信号肽HBM(Honey Bee Melittin)且不含有跨膜段,所以Cosmc 胞外段蛋白表达后分泌到培养基上清中,通过SDS-PAGE 和Western blot 对表达产物进行检测,并通过Ni-NTA 亲和层析柱对其进行纯化分析。结果:SDS-PAGE 和Western blot 分析显示得到一条分子量约为33 kD 的特异性条带,与目的蛋白大小相符,质谱结果进一步证明所得蛋白为Cosmc 胞外段蛋白。结论:Sf-9 细胞中可成功表达Cosmc 胞外段蛋白,为进一步研究Cosmc 的结构和功能奠定基础。     

Similar proportion of sporadic cases in cytochrome b558 negative chronic granulomatous disease and Duchenne muscular dystrophy.

We studied 12 Japanese families of cytochrome b558 (b) negative chronic granulomatous disease (13 patients and 23 family members) and 15 controls for cytochrome b content, O2-, and H2O2 production. Cytochrome b content (nmol/10(8) cells), O2- production (nmol/10(7) cells/min), and percentage of H2O2 generating cells (%) were 1) 0.45-1.19, 64.1-174.2, and 85.8-100.0 in controls (mean +/- 2 S.D.), 2) 0.13-0.38, 22.6-50.9, and 20.0-62.4 in healthy carriers, and 3) undetectable, undetectable, and 0 in patients, respectively. These findings indicate that healthy carriers and normal homozygotes are separable by these three parameters, and that 4 of the 12 families studied represent fresh gene mutation. Pooling of data by Segal et al., Ohno et al., and ours yielded the overall incidence of a fresh gene mutation to be 19.4% (7 of 36 cases). The lower fresh mutation rate than predicted from Haldane's formula suggests a higher mutation rate in males than in females, as previously suggested in Duchenne muscular dystrophy.     

Eosinophils of human colonic mucosa: C3b and Fc gamma receptor expression and phagocytic capabilities

Because little is known about eosinophils of the human intestine, we measured their C3b and Fc gamma receptor expression and phagocytic activity in mucosal suspensions from colon resections for large bowel neoplasms. Enzymatically dissociated suspensions were enriched for eosinophils by countercurrent centrifugation. C3b and Fc gamma receptors were measured by immunofluorescent assays with flow cytometry. Phagocytosis of Escherichia coli ON2 was determined by an in vitro microscopic method. Suspensions of normal tissue from neoplasm resections yielded 1.8 X 10(6) eosinophils/g mucosa, and these cells were more numerous than either macrophages or neutrophils. Fivefold enrichment was achieved by countercurrent centrifugation, and 75% of these cells expressed C3b receptors and 90% expressed Fc gamma receptors. Sixty-seven percent of mucosal eosinophils were phagocytic for E. coli ON2 and ingested a mean of 4.7 bacteria per cell. Eosinophils accounted for more overall phagocytic activity than either neutrophils or macrophages.     

转染双启动子杆状病毒表达载体在昆虫细胞共表 …

目的 通过体外表达ｒｈＩＬ－１２,以供研究其在体内外的生物学效应。方法 外周血单个核细胞（ＰＢＭＣ）、粘时细胞和人口腔表皮样癌细胞ＫＢ分别经ＳＡＣ（含Ａ蛋白的金黄色葡萄球菌ＣｏｗａｎⅠ菌株）、ＩＦＮ－γ＋ＬＰＳ和ＰＤＢｕ（１２、１３－二丁酸佛波酯）刺激,以ＧＩＴ（异硫氰酸胍）一步法提取细胞总ＲＮＡ,经ＲＴ－ＰＣＲ技术获得ＩＬ－１２ Ｐ４０和Ｐ３５ ｃＤＮＡ,将两条基因分别插入双启动子杆状病毒转染载