沉默FNBP1基因对人HL-7702细胞体外增殖及迁移能力的影响

为了研究沉默FNBP1(formin-binding protem1)基因对细胞体外增殖以及对细胞迁移能力的影响,设计并构建了3个靶向FNBP1 siRNA干扰载体(Si-1,Si-2,Si-3),经酶切和DNA测序鉴定后转染人正常的肝细胞HL-7702。RT-PCR和Western blot检测瞬时转染细胞中FNBP1基因的干扰效率,筛选出特异高效的RNAi靶点。并用G418筛选稳定表达了RNAi的细胞株,用XTT法检测细胞体外增殖率,划痕法检测细胞的迁移能力。结果显示:酶切和测序结果证明干扰质粒构建正确;转染特异性的干扰质粒(Si-1、Si-2、Si-3)细胞的FNBP1基因表达量与对照组相比均有所降低,在蛋白质水平表达也明显受到抑制,且重组干扰质粒Si-2的干扰效应较强。XTT检测结果表明,构建的沉默FNBP1重组质粒Si-2能显著抑制HL-7702细胞的体外增殖能力,但并不直接影响HL-7702细胞的迁移能力。     

RNA干扰抑制nm23-M1基因表达对骨髓瘤SP2/0细胞增殖的影响

建立RNA干扰 (RNA interference, RNAi)抑制nm23-M1基因表达的骨髓瘤SP2/0细胞株, 初步探讨nm23-M1基因对小鼠骨髓瘤细胞增殖的影响.针对 nm23-M1 mRNA序列设计3个小干扰RNA (small interfering RNA, siRNA)序列, 分别构建表达这3个序列及阴性对照序列的pGenesil-1重组质粒, 再转染小鼠骨髓瘤SP2/0细胞并经G418抗性筛选稳定表达细胞株.采用半定量RT-PCR及Western 印迹检测3个重组质粒对nm23-M1 mRNA及蛋白质表达的抑制效果, 然后用MTT法观察抑制nm23-M1表达对SP2/0细胞增殖的影响.结果显示, 设计的3条siRNA不同程度地特异抑制骨髓瘤SP2/0细胞nm23-M1 mRNA及蛋白质的表达, 其中siRNA-2抑制作用最强, 其对nm23-M1 mRNA和蛋白质的抑制率分别为74.4%和62.1%; 且siRNA-2抑制nm23-M1基因表达后SP2/0 细胞增殖受到明显抑制 (P < 0.05).本研究成功构建了pGenesil-1-nm23-M1 siRNA重组质粒, 筛选出稳定抑制nm23-M1基因表达的SP2/0细胞株, 提示抑制nm23-M1基因表达有抑制骨髓瘤细胞增殖的作用; 为进一步研究nm23基因的生物学功能及临床应用打下了基础.     

利用小干涉RNA抑制肿瘤细胞MCF-7中NF-IL6的表达

RNA干扰被证明是-项能有效而特异地抑制基因表达的新技术。转录因子NF-IL6特异地在肿瘤组织中过量表达,许多报道表明抑制它的功能对肿瘤治疗有利。构建能够沉默转录因子NF-IL6表达的小干涉RNA（siRNA）质粒,转染肿瘤MCF-7细胞后,用Western印迹法和荧光酶活性实验检测NF-IL6表达水平和转录活性的改变。结果发现NF-IL6的表达水平被下调80％,转录激活能力降低了60％,转染细胞内部出现大量空洞,细胞增殖停滞。     

hHO-1结构预测及突变体的构建、表达、纯化和活性检测

人血红素加氧酶-1(human heme oxygenase-1,hHO-1)是血红素代谢的限速酶,直接调节体内胆红素水平。利用软件Spdbv程序对hHO-1进行结构模拟预测,以Ala取代第25位His残基,hHO-1活性部位的结构有较明显的改变,但据模拟推测突变后hHO-1与血红素仍然具有结合性。依据模拟结果,构建野生型和突变体表达载体pBHO-1和pBHO-1(M),并分别转化大肠杆菌DH5α,IPTG诱导表达目的蛋白。表达产物经30％-60％(NH4)2SO4盐析后纯度提高3.6倍,再经两次Q-Sepharose Fast Flow阴离子交换树脂分离则表达产物的纯度提高30倍。酶活性测定显示,突变体hHO-1(△hHO-1)较野生型hHO-1(whHO-1)活性下降了91．21％。本研究显示hHO-1的第25位His在酶与底物血红素氧化反应中起着重要作用,为有效调控酶活性发挥其生物学作用提供依据。     

SiRNA干扰HSV-1即刻早期基因α22效应的初步分析

以HSV1即刻早期基因α22为靶点,应用T7 RNA聚合酶体外合成siRNA-1和siRNA-2序列,脂质体转染法将其导入Hep-2或KMB17细胞,再接种HSV1病毒,通过细胞形态和病毒滴度的测定,初步探索了siRNA干扰α22基因的的效应.结果表明,在Hep-2中,转染siRNA的实验组与对照组的细胞病变时间相同,子代病毒的生长曲线也没有显著差异;而分别转染或共同转染siRNA-1和siRNA-2 于"限制"性细胞KMB-17中,接种病毒后,ICP22特异的siRNA对HSV1的复制则表现了相应的干扰作用,细胞病变慢,子代病毒的最高滴度峰值出现较晚.     

靶向FBXL20基因的siRNA片段的筛选及其验证

在人结肠腺癌SW480细胞株及口腔鳞癌HSC3细胞株中,筛选有效干扰fbxl 20的siRNA片段.设计合成3对靶向fbxl 20 mRNA的小干扰RNA片段,通过阳离子脂质体介导转染SW480细胞和HSC3细胞. 结果发现siRNA-1, siRNA-2, siRNA-3均能抑制SW480细胞和HSC3细胞fbxl20 mRNA的表达,siRNA-2抑制作用最明显,抑制率分别为86.8％和100%. MTT试验显示：siRNA-2转染SW480细胞和HSC3细胞后,细胞增殖能力明显降低,细胞增殖抑制率分别为29.5%和43.4%. Transwell小室迁移实验表明,HSC3细胞在转染24 h后,细胞迁移能力明显减弱,迁移抑制率高达72.4%. 流式细胞术检测细胞凋亡结果显示：转染36 h后,SW480细胞实验组细胞凋亡率为21.9%;转染24 h后,HSC3细胞实验组细胞凋亡率为44.7%. 本实验成功的筛选出了特异性的抑制fbxl 20基因的siRNA片段,并初步鉴定了fbxl 20基因的功能.     

泛素C端水解酶L1的RNA干扰载体的构建及效果评价

目的:获得抑制效果好的泛素 C 端水解酶 L1(UCH-L1)基小干扰 RNA(siRNA)干扰载体.方法:根据 Gen?Bank 中大鼠 UCH-L1基序列设计并合成4对 siRNA 寡核苷酸序列,将4对寡核苷酸序列退火成双链后分别插入siRNA 表达载体 pcDNA6.2-GW/EmGFP-miR 中构建4个 siRNA 表达质粒,测序鉴定后将4个 siRNA 表达质粒分别转染 HEK293细胞,利用 Western 印迹和 qPCR 方法检测干扰效果;将干扰效果最好的质粒包装成腺病毒,感染大鼠血管平滑肌细胞(VSMC),并采用 TNFα干预诱导 UCH-L1表达升高,Western 印迹验证干扰效果.结果:测序分析证实4对 siRNA 寡核苷酸序列分别插入 siRNA 表达载体 pcDNA6.2-GW/EmGFP-miR;qPCR 检测与 Western 印迹均表明第3号 siRNA 表达载体对 UCH-L1表达的抑制程度最高,将其包装成腺病毒并转染 VSMC 能显著抑制 TNFα诱导的UCH-L1表达升高.结论:构建并筛选出干扰效果好的 UCH-L1 siRNA 干扰载体.     

TAK1siRNA对C2C12细胞内TAK1基因表达的影响

目的:高效下调TAK1基因表达的小干扰RNA(siRNA)分子的获得.方法:采用脂质体转染方法,将3对(siRNA ID#94455、siRNA ID # 94549、siRNA ID # 189006)人工合成的TAK1基因特异的小干扰RNA(siRNA)分子分别导入小鼠成肌细胞C2C12中,采用实时荧光定量PCR方法分析细胞内TAK1基因的相对表达.结果:和对照组相比,siRNA ID # 94455、siRNA ID # 94549和siRNA ID # 189006分别下调了细胞内TAK1基因的mRNA表达水平33.34%、46.73%和79.97%.结论:实验获得了能够高效下调TAK1基因表达的siRNA.     

siRNA介导的MKK4表达抑制研究

采用脂质体转染方法,将3对(siRNA ID#64447、siRNA ID#64539和siRNA ID#186583)人工合成的MKK4基因特异的小分子干扰RNA(siRNA)分别导入小鼠成肌细胞C2C12中.实时荧光定量PCR结果表明,转染了siRNA ID#64447的细胞,其MKK4 mRNA的表达水平下调得最多,约为85%.试验获得了能够高效下调MKK4基因表达的siRNA.     

维甲酸受体β基因RNAi表达质粒的构建及其对A549细胞增殖和分化的影响

目的：利用RNA干扰（RNAi）技术,构建针对维甲酸受体（RAR）β基因的小干扰RNA（siRNA）表达质粒,诱导RARβ基因沉默,并观察其对肺癌细胞A549株的细胞周期和增殖的影响。方法：依据设计siRNA的原则。针对人RARβ的mRNA序列,设计并合成编码siRNA的2条寡核苷酸序列,经退火成互补双链,再克隆到pSUPER-NEO-GFP真核表达载体中构建重组体pSUPER-RAR[β转染至A549细胞中,以空质粒和RARβ高表达质粒转染为对照,用Western印迹检测RARβ基因的表达,并采用M1Tr试验检测转染后细胞株的增殖和细胞分化情况。结果：表达人类RARβ基因的siRNA重组表达质粒构建成功;MTT试验结果表明,转染的A549-RARβ-si细胞增殖能力降低。结论：采用RNAi技术特异阻断RARB基因表达,通过转染A549细胞,可使其细胞形态发生变化,并抑制其细胞生长。     

沉默FNBP1基因对人HL-7702细胞 体外增殖及迁移能力的影响

为了研究沉默FNBP1（formin-binding protein 1）基因对细胞体外增殖以及对细胞迁移能力的影响,设计并构建了3个靶向FNBP1siRNA干扰载体(Si-1,Si-2,Si-3),经酶切和DNA测序鉴定后转染人正常的肝细胞HL-7702.RT-PCR和Western blot检测瞬时转染细胞中FNB...     

人血红素加氧酶-1的原核表达、纯化及其中和抗体的制备

目的确定人血红素加氧酶-1（human heme oxygenase-1,hHO-1）在大肠埃希菌中的表达条件与纯化方法,利用纯化的蛋白制备具有中和活性的hHO—1多克隆抗体。方法将hHO-1原核表达质粒pMW172／hHO-1转人大肠埃希菌菌株BL21,通过改变摇床转速、诱导剂IPTG浓度和培养时间确定hHO-1蛋白的最佳可溶性表达条件;利用超声破碎、高速离心、分级盐析、分子筛层析等方法纯化hHO-1蛋白,建立体外HO-1活性测定方法检测hHO-1蛋白的活性;利用纯化的hHO-1活性蛋白作为抗原免疫新西兰兔,制备多克隆抗体;利用ELISA方法和Western印迹技术分别测定抗体的效价和特异性,通过HO-1活性测定检测抗体的中和活性。结果确定hHO-1最佳可溶性表达条件为：37℃、200r／min培养3h后,0．1 mmoL／LIPTG诱导培养4h。超声破碎菌体,上清经30％～40％盐析纯化及分子筛层析纯化,获得活性hHO-1蛋白,收得率为30．3％,纯化倍数为2．83倍,纯度为90％。制备的抗hHO-1的兔血清效价达到10^6,并能中和掉46％hHO-1的催化活性。结论为hHO-1蛋白的表达和纯化以及多克隆抗体制备确立了可行的技术方案;获得了高纯度活性hHO-1蛋白及hHO-1多克隆抗体,为HO-1功能、结构研究,以及相关疾病研究奠定了基础。     

Expression and characterization of full-length human heme oxygenase-1: the presence of intact membrane-binding region leads to increased binding affinity for NADPH cytochrome P450 reductase

Heme oxygenase-1 (HO-1) is the chief regulatory enzyme in the oxidative degradation of heme to biliverdin. In the process of heme degradation, HO-1 receives the electrons necessary for catalysis from the flavoprotein NADPH cytochrome P450 reductase (CPR), releasing free iron and carbon monoxide. Much of the recent research involving heme oxygenase has been done using a 30 kDa soluble form of the enzyme, which lacks the membrane binding region (C-terminal 23 amino acids). The goal of this study was to express and purify a full-length human HO-1 (hHO-1) protein; however, due to the lability of the full-length form, a rapid purification procedure was required. This was accomplished by use of a glutathione-s-transferase (GST)-tagged hHO-1 construct. Although the procedure permitted the generation of a full-length HO-1, this form was contaminated with a 30 kDa degradation product that could not be eliminated. Therefore, attempts were made to remove a putative secondary thrombin cleavage site by a conservative mutation of amino acid 254, which replaces arginine with lysine. This mutation allowed the expression and purification of a full-length hHO-1 protein. Unlike wild type (WT) HO-1, the R254K mutant could be purified to a single 32 kDa protein capable of degrading heme at the same rate as the WT enzyme. The R254K full-length form had a specific activity of approximately 200-225 nmol of bilirubin h-1 nmol-1 HO-1 as compared to approximately 140-150 nmol of bilirubin h-1 nmol-1 for the WT form, which contains the 30 kDa contaminant. This is a 2-3-fold increase from the previously reported soluble 30 kDa HO-1, suggesting that the C-terminal 23 amino acids are essential for maximal catalytic activity. Because the membrane-spanning domain is present, the full-length hHO-1 has the potential to incorporate into phospholipid membranes, which can be reconstituted at known concentrations, in combination with other endoplasmic reticulum resident enzymes.     

针对2B区域的短双链RNA抑制柯萨奇B3病毒感染HeLa细胞的特性研究

为了研究短双链RNA(Small interfering RNA,siRNA)对柯萨奇B组3型病毒(CVB3)复制的影响及其作用特性,合成针对CVB3基因组2B区的siRNA-2B,脂质体法转染HeLa细胞后感染CVB3病毒,观测转染效率及存留时间、毒性作用、病毒致细胞病变效应、病毒滴度、病毒RNA含量、siRNA-2B对重组基因的特异性降解及培养上清有限稀释后再感染情况.结果发现siRNA-2B能高效转染入HeLa细胞并存留长达48h,高剂量的siRNA-2B对培养细胞无明显毒性,siRNA-2B能特异性针对2B区有效地降解病毒RNA,能明显抑制病毒RNA的复制.随着转染浓度的增加,siRNA-2B的抗病毒作用逐渐增强.siRNA-2B还能明显降低CVB3的再感染能力.这些结果提示,针对基因组2B区的siRNA-2B可以明显抑制CVB3基因复制,有效控制病毒再感染,并具有高效性、特异性和量效关系等特点.为siRNA可能成为预防和治疗CVB3感染的新途径奠定基础.     

Modulation of cGMP by human HO-1 retrovirus gene transfer in pulmonary microvessel endothelial cells

Carbon monoxide (CO) stimulates guanylate cyclase (GC) and increases guanosine 3',5'-cyclic monophosphate (cGMP) levels. We transfected rat-lung pulmonary endothelial cells with a retrovirus-mediated human heme oxygenase (hHO)-1 gene. Pulmonary cells that expressed hHO-1 exhibited a fourfold increase in HO activity associated with decreases in the steady-state levels of heme and cGMP without changes in soluble GC (sGC) and endothelial nitric oxide synthase (NOS) proteins or basal nitrite production. Heme elicited significant increases in CO production and intracellular cGMP levels in both pulmonary endothelial and pulmonary hHO-1-expressing cells. N(omega)-nitro-L-arginine methyl ester (L-NAME), an inhibitor of NOS, significantly decreased cGMP levels in heme-treated pulmonary endothelial cells but not heme-treated hHO-1-expressing cells. In the presence of exogenous heme, CO and cGMP levels in hHO-1-expressing cells exceeded the corresponding levels in pulmonary endothelial cells. Acute exposure of endothelial cells to SnCl2, which is an inducer of HO-1, increased cGMP levels, whereas chronic exposure decreased heme and cGMP levels. These results indicate that prolonged overexpression of HO-1 ultimately decreases sGC activity by limiting the availability of cellular heme. Heme activates sGC and enhances cGMP levels via a mechanism that is largely insensitive to NOS inhibition.     

Role of heme oxygenase-1 in hypoxia-reoxygenation: requirement of substrate heme to promote cardioprotection

Heme oxygenase-1 (HO-1) catalyzes the enzymatic degradation of heme to carbon monoxide, bilirubin, and iron. All three products possess biological functions; bilirubin, in particular, is a potent free radical scavenger of which its antioxidant property is enhanced at low oxygen tension. Here, we investigated the effect of severe hypoxia and reoxygenation on HO-1 expression in cardiomyocytes and determined whether HO-1 and its product, bilirubin, have a protective role against reoxygenation damage. Hypoxia caused a time-dependent increase in both HO-1 expression and heme oxygenase activity, which gradually declined during reoxygenation. Reoxygenation of hypoxic cardiomyocytes produced marked injury; however, incubation with hemin or bilirubin during hypoxia considerably reduced the damage at reoxygenation. The protective effect of hemin is attributable to increased availability of substrate for heme oxygenase activity, because hypoxic cardiomyocytes generated very little bilirubin when incubated with medium alone but produced substantial bile pigment in the presence of hemin. Interestingly, incubation with hemin also maintained high heme oxygenase activity levels during the reoxygenation period. Reactive oxygen species generation was enhanced after hypoxia, and hemin and bilirubin were capable once again to attenuate this effect. These results indicate that the HO-1-bilirubin pathway can effectively defend hypoxic cardiomyocytes against reoxygenation injury and highlight the issue of heme availability in the cytoprotective action afforded by HO-1.     

Effect of heme and heme oxygenase-1 on vascular endothelial growth factor synthesis and angiogenic potency of human keratinocytes

BACKGROUND: Skin injury leads to the release of heme, a potent prooxidant which is degraded by heme oxygenase-1 (HO-1) to carbon monoxide, iron, and biliverdin, subsequently reduced to bilirubin. Recently the involvement of HO-1 in angiogenesis has been shown; however, the role of heme and HO-1 in wound healing angiogenesis has not been yet investigated. RESULTS: Treatment of HaCaT keratinocytes with hemin (heme chloride) induced HO-1 expression and activity. The effect of heme on vascular endothelial growth factor (VEGF) synthesis is variable: induction is significant after a short, 6 h treatment with heme, while longer stimulation may attenuate its production. The involvement of HO-1 in VEGF synthesis was confirmed by inhibition of VEGF expression by SnPPIX, a blocker of HO activity and by attenuation of HO-1 mRNA expression with specific siRNA. Importantly, induction of HO-1 by hemin was able to overcome the inhibitory effect of high glucose on VEGF synthesis. Moreover, HO-1 expression was also induced in keratinocytes cultured in hypoxia, with concomitant augmentation of VEGF production, which was further potentiated by hemin stimulation. Accordingly, conditioned media from keratinocytes overexpressing HO-1 enhanced endothelial cell proliferation and augmented formation of capillaries in angiogenic assay in vitro. CONCLUSIONS: HO-1 is involved in hemin-induced VEGF expression in HaCaT and may play a role in hypoxic regulation of this protein. HO-1 overexpression may be beneficial in restoring the proper synthesis of VEGF disturbed in diabetic conditions.