逆转录病毒介导增强型绿色荧光蛋白基因在大鼠骨髓间充质干细胞中的表达

目的:观察逆转录病毒介导绿色荧光蛋白基因在SD大鼠骨髓间充质干细胞(bone marrow stromal cells,BMSCs)中的表达,为干细胞移植机制的研究提供基础.方法:采用密度梯度离心法分离培养BMSCs,诱导培养液诱导其向成脂肪方向分化,行细胞表面抗原鉴定,及油红O染色评价细胞成脂肪情况.在此基础上,采用逆转录病毒pLEGFP-N1对细胞进行荧光蛋白标记,观察细胞形态学改变荧光表达的时间与强度,计算转染率.结果:细胞扩增迅速,形态良好,纯度较高,经诱导后细胞内可见脂滴.逆转录病毒载体pLEGFP-N1成功标记SD大鼠骨髓间充质干细胞,并对4 wk体外培养进行了良好的标记.结论:逆转录病毒pLEGFP-N1转染效率高,转染成功的BMSCs可以长期稳定表达目的基因,是一种理想的病毒载体.     

增强型绿色荧光蛋白基因在日本血吸虫成虫体内的瞬时表达

目的探讨异源性增强型绿色荧光蛋白(EGFP)基因在日本血吸虫成虫体内表达的可能性。方法运用电穿孔技术将质粒pEGFP-C1导入日本血吸虫成虫体内,提取分离体外培养48小时成虫的基因组DNA、总RNA和全虫蛋白,分别用PCR、RT-PCR和Western blot验证转基因在成虫体内的存在、转录和翻译。同时,使用激光共聚焦扫描显微镜对EGFP在成虫体内进行定位。结果PCR和RT-PCR分别成功的扩增出760bp和276bp的预期大小的片断,Western-blot证实了EGFP基因在成虫体内的表达;激光共聚焦显微镜观察到,EGFP主要定位在成虫的皮层,口吸盘和尾部尤为明显。结论电穿孔技术成功地将异源基因引入日本血吸虫成虫体内并获得表达,为转基因血吸虫和基因功能的研究打下基础。     

Curcumin suppresses PPARδ expression and related genes in HT-29 cells

AIM： To investigate the effects of curcumin on the expression of peroxisome proliferator-activated receptorδ （PPARδ） and related genes in HT-29 cells.
METHODS： HT-29 cells were treated with curcumin （0-80 μmol/L） for 24 h. The effects of curcumin on the morphology of HT-29 cells were studied by Hoechst 33342 staining. The activity of caspase-3 was determined using DEVD-pNA as substrate. The levels of peroxisome PPARδ, 14-3-3ε and vascular endothelial growth factor （VEGF） in HT-29 cells were determined by Western blotting analysis and their mRNA expression was determined by real-time quantitative RT-PCR. RESULTS： Treatment with 10-80 μmol/L curcumin induced typical features of apoptosis and activated the caspase-3 in HT-29 cells. The expression of PPARδ, 14-3-3ε and VEGF was reduced and the activity of β-catenin/Tcf-4 signaling was inhibited by curcumin treatment.
CONCLUSION： Curcumin can induce apoptosis of HT-29 cells and down-regulate the expression of PPARδ, 14-3-3ε and VEGF in HT-29.     

Insertion of enhanced green fluorescent protein into the lysozyme gene creates mice with green fluorescent granulocytes and macrophages

Pluripotent hematopoietic stem cells have been studied extensively, but the events that occur during their differentiation remain largely uncharted. To develop a system that allows the differentiation of cultured multipotent progenitors by time-lapse fluorescence microscopy, myelomonocytic cells were labeled with green fluorescent protein (GFP) in vivo. This was achieved by knocking the enhanced GFP (EGFP) gene into the murine lysozyme M (lys) locus and using a targeting vector, which contains a neomycin resistant (neo) gene flanked by LoxP sites and "splinked" ends, to increase the frequency of homologous recombination. Analysis of the blood and bone marrow of the lys-EGFP mice revealed that most myelomonocytic cells, especially mature neutrophil granulocytes, were fluorescence-positive, while cells from other lineages were not. Removal of the neo gene through breeding of the mice with the Cre-deleter strain led to an increased fluorescence intensity. Mice with an inactivation of both copies of the lys gene developed normally and were fertile. (Blood. 2000;96:719-726)     

GFP基因真核表达质粒的构建及其在人胚肾293细胞中的表达

目的 克隆绿色荧光蛋白（GFP）基因并构建真核表达载体，观察其在人胚肾293（下称293细胞）细胞中的表达和分布，为制备自行设计的以λ噬菌体为载体的人类免疫缺陷病毒（HIV）核酸疫苗的阳性对照奠定基础。方法 以克隆好的pUC18／GFP为模板，根据Genbank中GFP的核苷酸序列设计引物，并在引物的5′端分别引入BamHⅠ及XhoⅠ酶切位点，特异性扩增GFP基因。TA克隆后经双酶切、测序等鉴定重组质粒，再经双酶切、连接构建含GFP编码基因的真核表达载体，酶切鉴定分析后，将该重组质粒通过脂质体介导，转染293细胞。荧光显微镜观察GFP在细胞内的表达和分布。结果重组质粒经Barn HⅠ、XhoⅠ双酶切成5．4kb与0．7kb的片断，表明表达载体pcDNA3．1（＋）中插入了GFP基因片断，测序结果表明编码框正确，并在293细胞中获得了表达，分布均匀。结论 pcDNA3．1（＋）／GFP真核表达载体已成功构建，并可在293细胞中表达。     

High levels of lymphoid expression of enhanced green fluorescent protein in nonhuman primates transplanted with cytokine-mobilized peripheral blood CD34(+) cells

We have used a murine retrovirus vector containing an enhanced green fluorescent protein complimentary DNA (EGFP cDNA) to dynamically follow vector-expressing cells in the peripheral blood (PB) of transplanted rhesus macaques. Cytokine mobilized CD34(+) cells were transduced with an amphotropic vector that expressed EGFP and a dihydrofolate reductase cDNA under control of the murine stem cell virus promoter. The transduction protocol used the CH-296 recombinant human fibronectin fragment and relatively high concentrations of the flt-3 ligand and stem cell factor. Following transplantation of the transduced cells, up to 55% EGFP-expressing granulocytes were obtained in the peripheral circulation during the early posttransplant period. This level of myeloid marking, however, decreased to 0.1% or lower within 2 weeks. In contrast, EGFP expression in PB lymphocytes rose from 2%-5% shortly following transplantation to 10% or greater by week 5. After 10 weeks, the level of expression in PB lymphocytes continued to remain at 3%-5% as measured by both flow cytometry and Southern blot analysis, and EGFP expression was observed in CD4(+), CD8(+), CD20(+), and CD16/56(+) lymphocyte subsets. EGFP expression was only transiently detected in red blood cells and platelets soon after transplantation. Such sustained levels of lymphocyte marking may be therapeutic in a number of human gene therapy applications that require targeting of the lymphoid compartment. The transient appearance of EGFP(+) myeloid cells suggests that transduction of a lineage-restricted myeloid progenitor capable of short-term engraftment was obtained with this protocol. (Blood. 2000;95:445-452)     

Saccharomyces boulardii activates expression of peroxisome proliferator-activated receptor-gamma in HT-29 cells]

BACKGROUND/AIMS: Saccharomyces boulardii (S. boulardii) has been reported to be beneficial in the treatment of inflammatory bowel disease, however, little is known about its mechanism of action. Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) is recently found to regulate inflammation in intestinal epithelial cells. We hypothesized that the anti-inflammatory effects of S. boulardii are mediated, in part, through PPAR-gamma. To test this hypothesis, we examined the ability of S. boulardii to modulate the expression of PPAR-gamma in human colon cells. METHODS: Effects of S. boulardii on survival and proliferation of HT-29 human colon cells were assessed by MTT and [3H]thymidine incorporation assays. PPAR-gamma expression was assessed by Western blot and RT-PCR. Induction of interleukin-8 (IL-8) expression by tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), or lipopolysaccharide (LPS) was assessed by RT-PCR. RESULTS: S. boulardii did not affect viability and proliferation of HT-29 cells. S. boulardii up-regulated PPAR-gamma expression at both mRNA and protein levels. Pretreatment of HT-29 cells with S. boulardii blocked PPAR-gamma down-regulation by TNF-alpha, IL-1beta, or LPS, whereas it ameliorated IL-8 response to these proinflammatory factors. CONCLUSIONS: S. boulardii stimulates PPAR-gamma expression and reduces response of human colon cells to proinflammatory cytokines.     

人B7-2和增强型绿色荧光蛋白融合基因表达载体的构建

目的构建含人B7-2与增强型绿色荧光蛋白融合基因表达载体pEGFP-N3-B7-2.方法应用逆转录聚合酶链反应(RT-PCR)方法从重症肌无力患者胸腺组织中扩增到人B7-2cDNA基因片段,经回收、纯化、酶切后,依次连接到质粒pGEM-Teasy和pEGFP-N3上.结果通过酶切和序列分析证实插入片段序列正确.结论应用基因工程技术构建成功pEGFP-N3-B7-2融合基因表达载体,为增强型绿色荧光蛋白作为人B7-2生物标记分子,转染肿瘤细胞及树突状细胞制备疫苗奠定了基础.     

Calmodulin kinase II inhibition disrupts cardiomyopathic effects of enhanced green fluorescent protein

Transgenic expression of enhanced green fluorescent protein (eGFP) in myocardium can result in cardiac dysfunction and cardiomyopathy, presumably through toxic effects that disrupt normal cellular signaling. The multifunctional Ca²⁺- and calmodulin-dependent protein kinase II (CaMKII) is widely expressed in myocardium and CaMKII activity is increased in human and animal models of cardiomyopathy, so we hypothesized that increased CaMKII activity is important for cardiomyopathy due to transgenic expression of eGFP. Here we report that cardiomyocyte-delimited eGFP over-expression causes increased CaMKII activity that predicts left ventricular dilation and dysfunction. On the other hand, transgenic co-expression of a CaMKII inhibitory peptide with eGFP prevents eGFP-mediated left ventricular dilation and dysfunction. These findings suggest that increased CaMKII activity is a critical pathological signal in transgenic cardiomyopathy due to eGFP over-expression.     

稳定高表达增强型绿色荧光蛋白基因膀胱癌细胞株的构建

目的 建立稳定高表达增强型绿色荧光蛋白(EGFP)基因的膀胱癌细胞株(KU-7/EGFP)并观察其生物特性的变化.方法 利用脂质体将EGFP真核表达质粒(pEGFP-N3)转染至人膀胱癌细胞株KU-7,经过G418筛选和克隆化培养,荧光显微镜及流式细胞仪观察转染EGFP基因的KU-7在裸鼠体内外的表达情况,分析转染细胞生物学行为变化.结果 KU-7/EGFP在荧光显微镜下发出绿色荧光,能稳定、高效和持久地表达EGFP,与未转染细胞比较,其生物学特性未改变.KU-7/EGFP接种于裸鼠皮下5 d后成瘤,14 d后肿瘤直径达到15 mm.结论 成功建立了稳定高表达EGFP的膀胱癌细胞株KU-7-EGFP,其生物学特性未变.     

Enhanced green fluorescence by the expression of an Aequorea victoria green fluorescent protein mutant in mono- and dicotyledonous plant cells.

The expression of the jellyfish green fluorescent protein (GFP) in plants was analyzed by transient expression in protoplasts from Nicotiana tabacum, Arabidopsis thaliana, Hordeum vulgare, and Zea mays. Expression of GFP was only observed with a mutated cDNA, from which a recently described cryptic splice site had been removed. However, detectable levels of green fluorescence were only emitted from a small number of protoplasts. Therefore, other mutations in the GFP cDNA leading to single-amino acid exchanges in the chromophore region, which had been previously studied in Escherichia coli, were tested in order to improve the sensitivity of this marker protein. Of the mutations tested so far, the exchange of GFP amino acid tyrosine 66 to histidine (Y66H) led to detection of blue fluorescence in plant protoplasts, while the exchange of amino acid serine 65 to cysteine (S65C) and threonine (S65T) increased the intensity of green fluorescence drastically, thereby significantly raising the detection level for GFP. For GFP S65C, the detectable number of green fluorescing tobacco (BY-2) protoplasts was raised up to 19-fold, while the fluorimetricly determined fluorescence was raised by at least 2 orders of magnitude.     

神经酰胺对结肠癌HT-29细胞凋亡和增殖细胞核抗原表达的影响

目的 探索神经酰胺(C_2-cer)影响人结肠癌HT-29细胞增殖、凋亡和增殖细胞核抗原(PCNA)表达.方法 12.5、25 μmol/L的C_2-cer处理HT-29细胞,用MTT法、流式细胞仪、激光共聚焦显微镜、Western印迹等方法检测HT-29细胞增殖、凋亡和PCNA表达.结果 以12.5、25 μmol/L的C_2-cer处理HT-29细胞,细胞增殖受到抑制,细胞凋亡明显增加,PCNA表达明显降低,并呈剂量-效应关系.结论 C_2-cer可诱导细胞凋亡,该效应可能与下调PCNA表达有关.     

脂质体介导转染的绿色荧光蛋白基因在骨髓基质细胞内的表达

目的研究脂质体转染法对骨髓基质细胞进行基因修饰的可行性。方法在体外分离和扩增大鼠骨髓基质细胞,用脂质体转染法介导绿色荧光蛋白基因进入到骨髓基质细胞内,荧光显微镜下检测荧光蛋白的表达,台盼兰排斥试验检测转染细胞的活力。结果绿色荧光蛋白可以在大鼠骨髓基质细胞内表达,转染效率为(28.9±3.6)%;脂质体法转染后的细胞活力为(93.6±4.8)%。结论脂质体转染法可以介导外源基因进入到骨髓基质细胞内表达。     

Ultra-fast excited state dynamics in green fluorescent protein: multiple states and proton transfer.

The green fluorescent protein (GFP) of the jellyfish Aequorea Victoria has attracted widespread interest since the discovery that its chromophore is generated by the autocatalytic, posttranslational cyclization and oxidation of a hexapeptide unit. This permits fusion of the DNA sequence of GFP with that of any protein whose expression or transport can then be readily monitored by sensitive fluorescence methods without the need to add exogenous fluorescent dyes. The excited state dynamics of GFP were studied following photo-excitation of each of its two strong absorption bands in the visible using fluorescence upconversion spectroscopy (about 100 fs time resolution). It is shown that excitation of the higher energy feature leads very rapidly to a form of the lower energy species, and that the excited state interconversion rate can be markedly slowed by replacing exchangeable protons with deuterons. This observation and others lead to a model in which the two visible absorption bands correspond to GFP in two ground-state conformations. These conformations can be slowly interconverted in the ground state, but the process is much faster in the excited state. The observed isotope effect suggests that the initial excited state process involves a proton transfer reaction that is followed by additional structural changes. These observations may help to rationalize and motivate mutations that alter the absorption properties and improve the photo stability of GFP.     

Type and position of promoter elements in retroviral vectors have substantial effects on the expression level of an enhanced green fluorescent protein reporter gene

Purpose: Although gene transfer with retroviral vectors has already been applied to patients as part of clinical protocols, low expression of transgenes in target cells still remains a problem. Therefore, we compared various retroviral vectors using different promoters and backbones for expression of the enhanced green fluorescent protein (EGFP) reporter gene in fibroblasts and CD34⁺ cells. Methods: The N2A retroviral vector was used to test expression from the herpes simplex virus thymidine kinase promoter (vector N2A-TK-EGFP), a human phosphoglycerate kinase promoter (vector N2A-PGK-EGFP), and the SV40 promoter (vector N2A-SV-EGFP). Additional constructs used the spleen focus-forming virus (SFFV) long terminal repeat (LTR) as promoter and expressed EGFP alone (vector SFβ1-EGFP) or EGFP and a downstream (vector SFβ1-EGFP-IRES) or upstream (vector SFβ1-IRES-EGFP) internal ribosomal entry site. Results: For NIH 3T3 cells the fluorescence-activated cell sorting analysis revealed that the most active internal promoter was the SV40 promoter in the vector N2A-SV-EGFP (mean fluorescence intensity, MFI, 66.7 ± 0.4), followed by N2A-PGK-EGFP (26.3 ± 1.8 MFI), and N2A-TK-EGFP (4.8 ± 0.1 MFI). Expression from the SFβ1-EGFP vector (82.6 ± 6.7 MFI) and the SFβ1-EGFP-IRES vector (102.8 ± 6.2 MFI) was higher than from SFβ1-IRES-EGFP vector (15.5 ± 1.8 MFI). In human CD34-positive cells, the EGFP expression from all vectors was considerably lower than in fibroblasts with the SFβ1-EGFP vector still being four- to fivefold more active than the internal promoters tested. Conclusion: The SFFV LTR seems to allow a high expression of transgenes, as long as the transgene is not expressed downstream of an internal ribosomal entry site. Internal promoters may be useful for targeted gene expression in specific cell types, but the reduced level of expression from some internal promoters has to be taken into consideration. Received: 7 January 2000 / Accepted: 1 February 2000