小鼠垂体瘤细胞内表达人酪氨酸羟化酶诱导产生内源性多巴胺的细胞毒性作用

目的:观察人酪氨酸羟化酶转染小鼠垂体瘤细胞产生的内源性多巴胺对细胞生存能力的影响,同时观察转染细胞对体外实验中证实可诱导多巴胺能神经元凋亡具有细胞毒性作用的选择性植物源鱼藤酮敏感性的变化(多巴胺含量越多,对鱼藤酮越敏感,鱼藤酮处理后死亡细胞越多),进一步证实多巴胺的毒性作用。方法:实验于2002-06/2003-06在美国匹兹堡大学神经生物实验室进行。将野生型和变异型人酪氨酸羟化酶表达质粒hTH-wt/pcDNA3.1和hTH-RREE/pcDNA3.1(Arg37Glu及Arg38Glu,具有持续活性)转染小鼠垂体瘤细胞细胞。将细胞随机分为hTH-wt/pcDNA3.1转染组和hTH-RREE/pcDNA3.1转染组及用相同转染方法处理,但不加入表达质粒的对照组。用Westernblot和高效液相色谱法检测人酪氨酸羟化酶、内源性多巴胺的含量;用四唑盐比色法检测转染细胞生存率;用新型细胞核萤光染料,不能透过细胞膜的SYTOXgreen试验检测死亡细胞数量及对鱼藤酮的敏感性;再用半胱氨酸天冬氨酸蛋白酶3免疫染色结合Hoechst核染色检测转染细胞凋亡情况。结果:①细胞生存率:小鼠垂体瘤细胞转染3d后,hTH-wt/pcD-NA3.1和hTH-RREE/pcDNA3.转染组分别是对照组的80.3%和81.4%(P<0.05),但两组间无差异(P>0.05)。②细胞死亡率:hTH-wt/pcDNA3.1转染细胞经鱼藤酮处理后,是未经鱼藤酮处理的1.57倍(P<0.05),hTH-RREE/pcDNA3.1转染细胞用鱼藤酮处理后,是未经鱼藤酮处理的1.88倍,但两组间无差异(P>0.05)。③凋亡细胞比率:转染hTH-wt/pcDNA3.1和hTH-RREE/pcDNA3.1后,分别是对照组的4.84和4.24倍(P<0.05)。④多巴胺、二羟苯乙酸含量:转染hTH-RREE的细胞多巴胺含量是转染hTH-wt者的4.5倍(P=0.027),但两种细胞内的二羟苯乙酸含量无明显差异。结论:小鼠垂体瘤细胞转染人酪氨酸羟化酶后可产生内源性多巴胺,可导致细胞死亡,可增加小鼠垂体瘤细胞对鱼藤酮的敏感性,同时产生的细胞凋亡参与转染细胞的死亡过程。     

酪氨酸羟化酶修饰人脐血间充质干细胞移植帕金森病大鼠纹状体内的多巴胺含量

背景：研究表明,干细胞治疗比药物治疗更接近于恢复患者的生理模式,细胞移植治疗已逐渐成为一种趋势。目的：观察酪氨酸羟化酶修饰的脐血间充质干细胞移植后帕金森病大鼠纹状体内多巴胺含量的变化。 方法：将酶切鉴定后的新构建质粒pEGFP-C2-TH经电穿孔法转染第3代脐血间充质干细胞,注射到帕金森病大鼠右侧脑室,对照组注入PBS。观察移植细胞在大鼠脑组织内的迁移情况,高效液相色谱仪检测大鼠纹状体内多巴胺的含量。 结果与结论：质粒pEGFP-C2-TH转染的脐血间充质干细胞移植后8周,细胞逐渐向脑室转移,12周时迁移至皮质,可表达酪氨酸羟化酶抗原,且实验组多巴胺含量明显高于对照组（P＜0.05）。结果表明酪氨酸羟化酶修饰的脐血间充质干细胞经脑室移植对帕金森病大鼠具有明显的治疗作用。     

As2O3诱导K562细胞凋亡过程中酪氨酸蛋白激酶活性的变化

目的：阐明Ａｓ２Ｏ３诱导Ｋ５６２细胞凋亡的可能机制，为Ａｓ２Ｏ３治疗白血病的推广应用提供一定的理论基础。方法：采用免疫沉淀、Ｗｅｓｔｅｒｎｂｌｏｔ及生物化学等方法，观察在Ａｓ２Ｏ３诱导Ｋ５６２细胞凋亡过程中，细胞胞浆和胞膜蛋白及ＡＢＬ蛋白酪氨酸激酶（ＰＴＫ）活性及某些内源性蛋白酪氨酸磷酸化的变化。结果：在Ａｓ２Ｏ３诱导Ｋ５６２细胞凋亡过程中，细胞胞浆和胞膜蛋白及ＡＢＬ蛋白ＰＴＫ活性降低，分子量为１８万和１２．５万的蛋白酪氨酸磷酸化减少。结论：Ａｓ２Ｏ３可能通过降低细胞内某些蛋白，尤其ＢＣＲ／ＡＢＬ蛋白的ＰＴＫ活性，减少蛋白酪氨酸磷酸化，从而阻断ＢＣＲ／ＡＢＬ抗凋亡信号的传导，诱导Ｋ５６２细胞凋亡     

内源性Nurrl对胚胎中脑及前脑前体细胞体外分化的诱导作用

目的：多巴胺神经元的发育是人们较为关注的问题，目前发现的蛋白可能在其发育机制中起着重要作用，研究内源性Nurrl基因表达变化对体外培养大鼠胚胎神经前体细胞分化的诱导作用。方法：实验于2003-05／2004-08在首都医科大学北京神经科学研究所完成；分离13．5d大鼠胚胎中脑及前脑神经前体细胞并进行体外培养，培养基中加入视黄酸及毛喉素诱导3d，采用RT-PCR，Western Blot及免疫荧光染色的方法观察Nurrl表达的变化及细胞分化；同时，用反义寡核苷酸转染技术阻断细胞Nurrl表达后再进行诱导，并进行同样观察。结果：视黄酸及毛喉素可诱导前体细胞的Nurrl表达，增加约60％，中脑来源神经前体细胞中(tyrosine hydrixylase，TH)阳性细胞占β-tublin-Ⅲ阳性细胞的比例由原来的(5．32&;#177;1．20)％增至(9．01&;#177;3．20)％。前脑来源神经前体细胞中TH阳性细胞占β-tublin-Ⅲ阳性细胞的比例由原来的(1．27&;#177;1．20)％增至(5．01&;#177;1．50)％。Nurrl反义寡核苷酸作用12h后前体细胞的Nurrl表达被阻断，至72h后重新表达。Nurrl被阻断后，只有少量的前体细胞被诱导为TH阳性细胞。结论：内源性Nurrl的过表达可促进胚胎神经前体细胞向多巴胺能神经元分化。     

N-乙酰半胱氨酸拮抗6-羟基多巴胺对骨髓基质细胞的毒性作用

背景：内源性6-羟基多巴胺能参与氧化应激,N-乙酰半胱氨酸能有效抗氧化和清除自由基。目的：探讨6-羟基多巴胺对骨髓基质细胞的毒性作用及N-乙酰半胱氨酸对其的拮抗作用。方法：在体外培养SD大鼠骨髓基质细胞,取第3代骨髓基质细胞分别加入终浓度为0,0.05,0.1g/L的6-羟基多巴胺和终浓度为0,0.075,0.3,1.2,4.8g/L的N-乙酰半胱氨酸。结果与结论：MTT检测发现0.05和0.1g/L6-羟基多巴胺可以明显降低骨髓基质细胞的细胞活性,而加入6-羟基多巴胺的同时加入0.3g/LN-乙酰半胱氨酸可以显著抑制6-羟基多巴胺的毒性作用。提示抗氧化剂N-乙酰半胱氨酸可以影响6-羟基多巴胺的作用。     

肿瘤坏死因子相关凋亡诱导配体对骨髓基质细胞的毒性作用

背景:已证实肿瘤坏死因子相关凋亡诱导配体(tumor necrosis factor-related apoptosis-inducing ligand,TRAIL)能选择性诱导白血病细胞凋亡,并且不影响正常造血干/祖细胞的功能。但TRAIL对作为造血微环境核心的骨髓基质细胞的毒性作用如何,据作者查新检索目前尚未见系统报道。目的:通过观察TRAIL对骨髓基质细胞的凋亡诱导效应及其造血支持功能的影响,继而评价TRAIL对骨髓基质细胞的毒性作用。设计、时间及地点:细胞学体外对照观察,于2006-03/10在解放军沈阳军区总医院中心实验室完成。材料:血常规、骨髓涂片细胞检查正常的骨髓标本11份,取自解放军沈阳军区总医院血液科。化疗药物柔红霉素为浙江海正药业股份有限公司产品,国药准字H33020925。方法:Percoll 贴壁法体外分离培养骨髓基质细胞,达80%融合时胰蛋白酶消化扩增,取处于对数生长期的细胞,分为4组,空白对照组不进行任何干预,柔红霉素组加入0.5μmol/L柔红霉素作用24h,TRAIL组加入200μg/L TRAIL作用18h,联合组加入0.5μmoL/L柔红霉素作用6h后再以200μg/L TRAIL作用18h。取第2代骨髓基质细胞,60Co射线照射消除内源性造血集落,接种后去除悬浮细胞,TRAIL组以200μg/L TRAIL作用基质细胞层18h,按1×105/孔将骨髓单个核细胞接种于基质细胞层,扩增5d后加入甲基纤维素培养体系,于37℃、体积分数为0.05的CO2饱和湿度条件下培养10d。主要观察指标:荧光显微镜观察诱骗受体在骨髓基质细胞的表达及定位,流式细胞仪检测柔红霉素对骨髓基质细胞诱骗受体表达的影响,AnnexinⅤ/PI标记TRAIL对骨髓基质细胞的凋亡诱导作用及对其造血支持功能的影响。结果:诱骗受体DcR1和DcR2在骨髓基质细胞中均有表达,主要定位于胞膜及胞浆。0.5μmol/L柔红霉素作用24h后,基本不影响诱骗受体DcR1和DcR2的表达水平。与空白对照组细胞凋亡率比较,TRAIL组无明显变化(t=0.973,P>0.05);柔红霉素组、联合组均显著升高(t=5.141,P=0.001;t=4.187,P=0.002),此两组间比较差异无显著性意义(t=1.222,P>0.05)。与空白对照组比较,TRAIL组骨髓单个核细胞数、粒-巨噬集落形成单位均无明显变化(t=1.313,P>0.05;t=1.172,P>0.05)结论:TRAIL的诱骗受体DcR1及DcR2在骨髓基质细胞均有表达,使骨髓基质细胞免于TRAIL的凋亡诱导效应,且TRAIL不增强柔红霉素对骨髓基质细胞的细胞毒性作用。     

人脂肪组织来源的酪氨酸羟化酶、胆碱乙酰转移酶、谷氨酸脱羧酶的表达

目的：探讨人脂肪组织来源的基质细胞（ADSCs）分化为神经细胞的神经递质关键酶TH、CHAT、GAD的表达情况。方法：分离培养人ADSCs,采用神经诱导培养基（NIM）进行诱导培养,倒置相差显微镜下连续观察细胞生长情况和形态变化,免疫组化法和免疫荧光技术检测神经递质多巴胺（DA）、乙酰胆碱（Ach）和γ-氨基丁酸（GABA）合成过程中的关键酶——酪氨酸羟化酶（TH）、胆碱乙酰转移酶（CHAT）和谷氨酸脱羧酶（GAD）的表达情况。结果：①经NIM诱导后,ADSCs可分化为神经细胞。诱导分化后,1h、5h未见TH、CHAT和GAD阳性表达。1d、5d出现TH、CHAT和GAD阳性表达。②免疫荧光单标结果：诱导后的细胞内有TH、CHAT和GAD表达。免疫荧光双标结果：GAD与TH、CHAT与TH可同时表达于同一个诱导后的细胞内。结论：ADSCs可分化为神经细胞,分化后的神经细胞具有合成神经递质DA、Ach和GABA的功能。     

十八烯酸对人肾癌A498细胞毒性作用的实验研究

目的探讨十八烯酸对人肾癌细胞A498细胞的毒性作用。方法从甘肃地产猫儿眼（Euphorbia kansui L）提取并制备十八烯酸。给予人A498细胞0．3、0．6、3．0mg／L十八烯酸培养,分别采用MTT法、克隆形成和流式细胞技术对十八烯酸对人A498细胞的毒性作用进行检测。结果给予人A498细胞0．3、0．6、3．0mg／L十八烯酸,细胞增殖抑制率随给药浓度增加而增加（分别为53．20％、66．26％、87．42％）,半数抑制浓度（IC50）为0．29mg／L;克隆形成抑制率随给药浓度增加而增加（分别为46．43％、61．31％、71．42％）,IC50为0．31mg/L;人A498细胞凋亡率别为11．16％、17．31％、26．22％。结论十八烯酸对人A498细胞具有明显的增殖抑制作用,能促进人A498细胞凋亡。     

重组表达的猪溶素及其突变体诱导小鼠巨噬细胞的细胞毒性和IL-1β释放

目的观察猪溶素(Suilysin,SLY)及其无溶血活性的突变体诱导小鼠腹腔巨噬细胞(peritoneal macrophage,PM)释放IL-1β和细胞毒的差异,为进一步研究SLY诱导炎性体激活通路奠定基础。方法重组表达纯化SLY及第353氨基酸位点突变体rSLY353L,体外和小鼠PM相互作用,用乳酸脱氢酶释放法检测细胞毒作用,用酶联免疫吸附试验(ELISA)检测IL-1β的水平。结果不同浓度rSLY(0.1~10μg)诱导小鼠PM细胞毒性呈现明显的剂量效应,rSLY(1μg/ml)诱导产生750 pg/ml的IL-1β同时细胞毒20%;rSLY(5μg/ml)可引起最大量的IL-1β释放但细胞毒高达90%。相同剂量的rSLY353L不能诱导可检测到的IL-1β和细胞毒性。rSLY与PM共孵育20 h IL-1β产量最高,20 h后IL-1β产量下降但细胞毒性随孵育时间延长而增大。结论 1μg/ml SLY和PM作用20 h可诱导较高的IL-1β产生同时细胞毒性较低,该实验条件适用于进一步进行SLY激活PM炎性体信号通路的机制研究。     

淋巴因子诱导的细胞毒细胞小鼠体内外抗肿瘤作用的研究

采用Ｃ５７ＢＬ／６或ＤＢＡ／２小鼠脾脏制备淋巴因子诱导的细胞毒细胞（ＬＩＣＣ）并其肿瘤活性，实验结果表明ＬＩＣＣ在体外对小鼠黑色素瘤Ｂ１６和白血病Ｌ１２１０耐药株（ＭＴＸ）细胞杀伤活性比对照组显著增强（Ｐ〈０．０１），且具有逆转耐药株（ＭＴＸ）的作用，我们建立了小鼠黑色素瘤Ｂ１６细胞肺转移的模型，并给荷瘤小鼠尾静脉注射ＬＩＣＣ，发现治疗组小鼠肺表现肿瘤转移结节数显著减少（Ｐ〈０．０１）。本文又将２     

Expression of transgenes in midbrain dopamine neurons using the tyrosine hydroxylase promoter

Billions of neurons are interconnected in the central nervous system (CNS). Identification of specific neuronal circuit is indispensable for understanding the relationship between structure and function in the CNS. The midbrain dopamine (DA) neuron system consists of the retrorubral area (A8), the substantia nigra (SN; A9) and the ventral tegmental area (VTA; A10). We hypothesized that genetic methods using cell-type-specific promoters may offer the possibility to express tracer molecules in DA neurons to facilitate neuronal tracing. To address this, we used the 2.5 kb rat tyrosine hydroxylase (TH) promoter in adenovirus or adeno-associated virus (AAV) to express tracers specifically in DA neurons. We found that stereotaxic injection of TH promoter containing adenoviral construct resulted in cell-type-specific transgene expression in the noradrenaline (NA) neurons of the locus coeruleus (LC). However, it caused a significant toxicity to DA neurons in the SN. In contrast, stereotaxic injection of TH promoter containing AAV to the SN resulted in cell-type-specific transgene expression in DA neurons with no detectable toxicity. Taken together, our results demonstrate that it is possible to selectively trace DA neuronal circuits in rodent brains using the TH promoter in the context of AAV.     

Susceptibility to tumors induced by polyoma virus is conferred by an endogenous mouse mammary tumor virus superantigen

A dominant gene carried in certain inbred mouse strains confers susceptibility to tumors induced by polyoma virus. This gene, designated Pyvs, was defined in crosses between the highly susceptible C3H/BiDa strain and the highly resistant but H-2k-identical C57BR/cdJ strain. The resistance of C57BR/cdJ mice is overcome by irradiation, indicating an immunological basis. In F1 x C57BR/cdJ backcross mice, tumor susceptibility cosegregates with Mtv-7, a mouse mammary tumor provirus carried by the C3H/BiDa strain. This suggests that Pyvs might encode the Mtv-7 superantigen (SAG) and abrogate polyoma tumor immunosurveillance through elimination of T cells bearing specific V beta domains. DNA typing of 110 backcross mice showed no evidence of recombination between Pyvs and Mtv-7. Strongly biased usage of V beta 6 by polyoma virus-specific CD8+ cytotoxic T lymphocytes in C57BR/cdJ mice implicates T cells bearing this Mtv-7 SAG-reactive V beta domain as critical anti-polyoma tumor effector cells in vivo. These results indicate identity between Pyvs and Mtv-7 sag, and demonstrate a novel mechanism of inherited susceptibility to virus-induced tumors based on effects of an endogenous superantigen on the host's T cell repertoire.     

Expression of endogenous xenotropic retrovirus by methylcholanthrene- induced squamous cell carcinoma of the mouse respiratory tract

As a model for human lung cancer, squamous cell carcinomas were induced by 3-methylcholanthrene in mouse tracheas which had been explanted to a subcutaneous site. The tumors that developed were examined for both ecotropic and xenotropic infectious murine leukemia virus (MuLV). From all squamous carcinomas--six out of six--a xenotropic MuLV was isolated. From some of the fibrosarcomas that occurred incidentally in our induction system, ecotropic MuLV was isolated. However, in the fibrosarcomas, no xenotropic MuLV at all was found.     

Correlation between tyrosine hydroxylase activity,melanogenesis, and estradiol binding in human melanoma cells

Cytosols fractions from human mammary carcinoma, or malignant melanoma cells, and tyrosine hydroxylase (TH) bind 3H-estradiol (3H.E) with strong affinity. Monoclonal antibodies secreted by cloned cell hybrids which were formed by the fusion of murine myeloma cells with spleen cells from BALB/c mice pre-immunized with purified TH were used to differentiate between 3H.E-binding protein in the cytosols of various neoplastic cells. These monoclonal TH-antibodies inhibited the enzymic activity and the binding of 3H.e to TH or to cytosol fractions of melanotic melanoma cells, but had no effect on 3H.E binding to cytosol fractions from various mammary epithelial or carcinoma cell lines. Cultivation of estradiol-responsive melanotic melanoma cells in media supplemented with the TH-antibodies, caused loss of pigmentation, the cells became amelanotic and non-responsive to 17 beta-estradiol. The results indicate that the estrogen does not bind to melanoma cells via a receptor as for mammary carcinoma cells but to tyrosine hydroxylase.     

Role of endogenous dopamine in the central serotonergic deficits induced by 3,4-methylenedioxymethamphetamine

Similar to other amphetamine analogs 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy"), a currently popular illicit drug, has been characterized recently as a serotonergic neurotoxin due to its ability to cause long-lasting deficits in markers of central serotonergic function in animals. Because the serotonergic toxicity associated with the MDMA analog methamphetamine has been linked previously to endogenous dopamine and because MDMA, like methamphetamine, elicits pronounced dopamine release in vitro, we have examined the role of endogenous dopamine in both the immediate (3 hr) and longer-term (3 days) central serotonergic deficits induced by systemic MDMA administration to rats. Depletion of central dopamine content with alpha-methyl-p-tyrosine or reserpine, or selective destruction of nigrostriatal dopamine projections with bilateral 6-hydroxydopamine-induced substantia nigral lesions, partially blocked the immediate MDMA-induced reduction in rat striatal tryptophan hydroxylase (TPH) activity. In addition, the longer-term TPH deficits caused by a high single dose of MDMA were completely prevented by prior alpha-methyl-p-tyrosine or reserpine, and attenuated significantly by inhibition of dopamine uptake with the selective dopamine-uptake blocker GBR 12909. These results implicate endogenous drug-released dopamine as a partial mediator of the initial decrease in TPH activity caused by MDMA and as an important prerequisite to the development of long-term MDMA-induced neurotoxicity. Potential mechanisms of dopamine-mediated toxicity are discussed.     

Neuroleptic drugs activate tyrosine hydroxylase of retinal amacrine cells

Tyrosine hydroxylase of retinal dopamine-containing amacrine cells exists in two states, a basal state in the dark and an activated state in the light. Treatment with haloperidol, chlorpromazine, clozapine or domperidone results in activation of tyrosine hydroxylase in the dark. With haloperidol, the magnitude of the activation was dose-related. After a single dose of haloperidol (3 mg/kg i.p.) enzyme activation persisted for at least 3 hr. By kinetic analysis, activation was characterized as a decrease in the Km for the pteridine cofactor. Activation by light induces similar kinetic changes. Apparently, the dopaminergic system of retina responds to neuroleptic drug treatment similar to that nigrostriatal dopaminergic system.     

Peripheral T cell activation and deletion induced by transfer of lymphocyte subsets expressing endogenous or exogenous mouse mammary tumor virus

Murine T cell reactivity with products of the minor lymphocyte stimulatory (Mls) locus correlates with the expression of particular variable (V) domains of the T cell receptor (TCR) beta chain. It was recently demonstrated that Mls antigens are encoded by an open reading frame (ORF) in the 3' long terminal repeat of either endogenous or exogenous mouse mammary tumor virus (MMTV). Immature thymocytes expressing reactive TCR-V beta domains are clonally deleted upon exposure to endogenous Mtv's. Mature T cells proliferate vigorously in response to Mls-1a (Mtv-7) in vivo, but induction of specific anergy and deletion after exposure to Mtv-7-expressing cells in the periphery has also been described. We show here that B cells and CD8+ (but not CD4+) T cells from Mtv-7+ mice efficiently induce peripheral deletion of reactive T cells upon transfer to Mtv-7- recipients, whereas only B cells stimulate specific T cell proliferation in vivo. In contrast to endogenous Mtv-7, transfer of B, CD4+, or CD8+ lymphocyte subsets from mice maternally infected with MMTV(SW), an infectious homologue of Mtv- 7, results in specific T cell deletion in the absence of a detectable proliferative response. Finally, we show by secondary transfers of infected cells that exogenous MMTV(SW) is transmitted multidirectionally between lymphocyte subsets and ultimately to the mammary gland. Collectively our data demonstrate heterogeneity in the expression and/or presentation of endogenous and exogenous MMTV ORF by lymphocyte subsets and emphasize the low threshold required for induction of peripheral T cell deletion by these gene products.