揭示TNF配体和受体家族的功能

<正>肿瘤坏死因子(TNF)是高等动物的福音。它能保护机体抵抗感染,现在还发现它能引起休克和炎症性疾病。它的近亲同源体—淋巴毒素(LT)具有与之相似的一系列生物学活性。两者的分子结构是同源的,并与两个相同的膜受体结合。     

肿瘤坏死因子受体的进展

肿瘤坏死因子(Tumor Necrosis,TNF)由活化的单核/巨噬细胞产生(称为TNF_α),也可由活化的T淋巴细胞及NK细胞产生(称为TNFβ及TNF_α)。TNF最明显的活性特征是可以在体内或体外特异地杀伤肿瘤细胞,对正常组织细胞则无明显的毒性作用。TNF的生物效应是通过TNF受体(TNFR)产生,TNF分为TNF_α及TNFβ。本文着重对TNF_αR近年来的研究进展作一综述。     

肿瘤坏死因子与临床检测

肿瘤坏死因子(Tumor Necrosis Factor,TNF)最早是从巨噬细胞中发现的仅杀伤癌细胞而不损伤正常细胞的因子,它能激活中性粒细胞并刺激其产生超氧化物,释放溶酶体酶,从而提高杀灭微生物的活性.TNF水平测定对于某些疾病的诊断、判断预后及指导用药均具有重要意义.本文就这几方面国内外研究近况综述如下:一、TNF来源、特点、生理作用TNF-α最早由Carswell等于1975年首先报道的,1984年Penica等分离表达了人的TNF-α的cDNA.目前,人们根据TNT的来源暂分为三种:一是由活化的单核或巨噬细胞分泌产生的称为TNF-α;二是由活化的T-淋巴细胞分泌产生的称为TNF-β;三是由NK细胞分泌产生的称为TNF-γ.人TNF-α是由3个分子量为17KD的单体通过1个二硫键非共价组成的,含有157个氨基酸的非糖蛋白;人TNF-β则是由171个氨基酸组成的、分子量为25KD的糖蛋白,分子内无半胱氨酸.TNF的生物学效应是:适量的TNF可调节机体的免疫及代谢功能,增强机体对入侵病原体的抵抗力,对维持机体内部的稳定状态及抵制各种致病因子的侵袭具有重要意义.但是,TNF的过量表达则与机体的炎症、感染、机体损伤等病理状态有关.TNF-α诱导的各种细胞反应是通过与细胞表面两类特异性受体相互作用而产生的,即55KD的TNF受体(TNF receptor,TNF R_1)和75KD     

活性氧在肿瘤坏死因子信号传导中的作用

肿瘤坏死因子α(TNF-α)是最强的细胞内信号诱导剂之一。它通过对半胱氨酸蛋白酶家族(caspases)、丝裂原激活的蛋白激酶(MAPK)、c-jun N端激酶(JNK)、核转录因子AP-1和NF-κB的活化,可诱导细胞凋亡、分化和基因转录。此外,TNF也可通过调节细胞的还原状态,特别是内源性活性氧的改变来介导细胞内的信号。综述了ROS在TNF所诱导细胞内信号传导的相关内容,以阐述ROS介导TNF在细胞内信号传导及调节细胞的存活和凋亡中的作用。     

肿瘤坏死因子受体相关因子2(TRAF2)在TNF信号传导中的作用

肿瘤坏死因子受体相关因子(TRAFs)是经TNF受体超家族和IL-1R/TLR超家族信号传导通路的重要成分.TNF信号传导中,TRAF2作为接头蛋白和调控因子在几乎所有分支通路中起作用,在调节TNF-R1介导的NF-κB和JNK激活过程中起重要作用.近来的研究提示,TRAF2是凋亡信号传导和抗凋亡信号传导的分支点.本文主要阐述TRAF2的分子结构及它的结构与功能的关系,TNF信号传导的分子机制及TRAF2在其中的作用,重点关注TRAF2作为凋亡途径和NF-κB介导的存活途径,即这2条相互拮抗的信号传导途径的分支点的重要性.     

TNF基因治疗肿瘤的研究进展

肿瘤坏死因子 (TNF)是一种既能直接杀死肿瘤细胞 ,又能通过激活免疫系统发挥抗肿瘤作用的细胞因子 .其基因工程药品临床应用后 ,具有严重的毒副作用 ,因此 ,人们开始了TNF基因冶疗的研究 .TNF基因治疗为TNF在肿瘤治疗中的应用开拓了新的途径     

高内涵筛选NF-κB信号通路的技术体系建立

NF-κB是参与免疫调节、炎症反应、肿瘤发生等过程重要的转录因子,在TNFα、IL-1β、LPS等因子诱导下NF-κB发生核转位并激活其转录活性。尝试利用高内涵筛选(High Content Screening,HCS)和RNA干扰(RNAinterference,RNAi)技术建立NF-κB核转位高通量筛选体系,该体系的应用将有助于发现新的NF-κB信号通路调节因子,为免疫与肿瘤的机制研究提供线索。     

原发性骨质疏松症的发病机制和治疗研究

该项目采用了组织培养、动物实验、组织形态计量、骨密度测定、生化分析、扫描电镜和透射电镜等技术，研究了原发性骨质疏松症(POP)患者骨组织中的肿瘤坏死因子(TNF)和白细胞介素-6(1L-6)的活性变化、阿仑膦酸钠和雌激素对骨质疏松症的治疗作用比较，以及羟乙二膦酸二钠和左旋多巴复合治疗POP等。     

抗肿瘤生物制品项目——恶性肿瘤基因治疗

基因治疗是当今肿瘤治疗研究的最前沿，它为从基因水平上根治癌症开辟了全新途径。随着分子生物学技术的迅速发展，多种淋巴因子的基因已在体外获得克隆及高效表达，重组肿瘤坏死因子(TNF)已应用于人体肿瘤过继免疫治疗。然而，由于TNF半衰期短，迫使应用大剂量冲击，结果导致机体难以耐受的毒副作用，严重影响疗效。     

基于网络药理学和分子对接探讨蛹虫草对糖尿病作用机制研究

目的:以网络药理学和分子对接分析的方法，系统研究蛹虫草在治疗糖尿病中的机制，为开发治疗糖尿病的新药提供理论依据。方法:采用TCMSP数据库对蛹虫草的活性成分和治疗靶点进行预测和筛选。Cytoscape3.9.0绘制了活性组分和靶标网络，STRING数据库分析了蛋白-蛋白相互作用(PPI),利用DAVID数据库对交叉靶标进行了GO生物富集及KEGG富集分析。分子对接研究由SYBYL-X 2.0软件进行验证完成。结果:得到蛹虫草的活性成分有120个，取交集基因得到96个，蛋白互作分析发现IL6、TNF和TP53治疗糖尿病的作用，KEGG富集结果发现，蛹虫草治疗糖尿病主要通过Pathways in cancer、TNF signaling pathway、HIF-1 signaling pathway、African trypanosomiasis等信号通路进行调控。分子对接结果表明，蛹虫草中的活性成分Kushenol, t、Leachianone, g、Cis-Dihydroquercetin等成分与IL6、TNF和TP53具有较好的结合能力。结论:蛹虫草的活性成分Kushenol, t、...     

Induction by E1A oncogene expression of cellular susceptibility to lysis by TNF

Tumour necrosis factor alpha (ref. 1), synthesized primarily by monocytes in response to various invasive agents, induces a wide variety of biological effects relevant to regulating cell growth and differentiation, including the selective killing of some tumour cells and the growth stimulation of some normal fibroblasts. As tumour necrosis factor (TNF) appears to kill tumour cells preferentially, we asked whether TNF sensitivity correlates with the expression of specific oncogene(s). If so, by examining the cellular target(s) of the oncogene product, it might be possible to identify specific factor(s) which mediate TNF action. By using an in vitro cytotoxicity assay with NIH 3T3 and Fisher BRK-derived cells expressing exogenously introduced oncogenes, we found that adenovirus E1A proteins induce susceptibility to TNF killing.     

Tumour necrosis factors alpha and beta inhibit virus replication and synergize with interferons

Tumour necrosis factor (TNF) and lymphotoxin were initially described as tumoricidal proteins that are produced by activated macrophages and lymphocytes, respectively. Since TNF and lymphotoxin are structurally related, bind to the same cell surface receptor and have indistinguishable biological activities, they have been designated as TNF-alpha and TNF-beta, respectively. The multiple activities of these molecules indicate their importance in immunoregulative responses. Here we report that both TNF-alpha and TNF-beta have antiviral activity and synergize with interferons (IFNs) in the induction of resistance to both RNA and DNA virus infection in diverse cell types. These effects of TNFs are not due to the induction of IFN synthesis. Virus-infected cells are selectively killed by TNFs and this activity is accelerated by IFN-gamma. The production of TNFs is induced by viruses, further suggesting the importance of TNFs in the physiological antiviral response.     

Tumour necrosis factor and lymphotoxin genes map close to H-2D in the mouse major histocompatibility complex

Tumour necrosis factor (TNF-alpha) and lymphotoxin (TNF-beta) are related proteins, secreted by macrophages and lymphocytes respectively, which play a role in destruction of tumour cells and virally infected cells (for reviews see refs 1,2). TNF-alpha is a non-glycosylated protein of relative molecular mass 17,000 (Mr 17 K), whereas TNF-beta is a glycoprotein of Mr 25 K. Both TNF-alpha and TNF-beta aggregate into multimers and act through the same receptor molecule on target cells. Genes encoding these two TNF proteins have been cloned from mouse and man and in both are closely linked, being separated by approximately 1 kilobase (kb) of DNA. In the mouse these genes are located on chromosome 17, but in man they are on the short arm of chromosome 6. This segment of chromosome 6 also contains the genes of the major histocompatibility complex (MHC), as does chromosome 17 in the mouse. To find out whether the TNF genes are located within the MHC, we used polymorphic restriction sites to analyse a panel of MHC congeneic and intra-MHC recombinant mouse strains. Initially, we mapped the TNF genes the D or Qa region in the distal half of the mouse MHC. We then studied a gene cluster encompassing part of the D and Qa regions and found the TNF genes are located 70 kb proximal to the D gene.     

Requirement of tumour necrosis factor for development of silica-induced pulmonary fibrosis

The deposition of silica particles in the lung of man or experimental animals leads to silicosis, a disease of progressive respiratory failure caused by a fibrotic reaction. It has long been suspected that the phagocytosis of silica by pulmonary macrophages induces the secretion of fibrogenic factors. Several potentially fibrogenic cytokines released by macrophages have been identified, including interleukin-1 (IL-1), tumour necrosis factor-alpha (TNF), platelet-derived growth factor, basic fibroblast growth factor and transforming growth factor-beta (TGF-beta). Here we show that TNF plays an important part in silica-induced pulmonary fibrosis in mice in that (1) a single instillation of silica leads to a marked increase in the level of lung TNF messenger RNA which lasts for greater than 70 days, while there are no obvious changes in the amounts of IL-1 alpha or TGF-beta mRNAs; and (2) silica-induced collagen deposition is almost completely prevented by anti-TNF antibody, but is significantly increased by continuous infusion of mouse recombinant TNF.     

Tumour necrosis factor as immunomodulator and mediator of monocyte cytotoxicity induced by itself, gamma-interferon and interleukin-1

Activated monocytes or macrophages can release soluble cytotoxic molecules capable of lysing tumour cells in vitro and thus represent an important component of the host defence mechanisms against malignancy. The recent availability of pure recombinant or natural human lymphokines and monokines and their respective polyclonal or monoclonal antibodies now makes it possible to dissect the interactions of these factors in the induction and performance of the cytotoxic event by the monocytes. Our studies indicate that pretreatment of monocytes with alpha-IFN or gamma-IFN, and also interleukin (IL)-1 or tumour necrosis factor (TNF) results in enhanced monocyte cytotoxicity. Although all these substances induce the production of IL-1 by monocytes, TNF mediates the enhanced cytotoxicity induced in monocytes by gamma-IFN, IL-1 and, in an autocrine manner, by TNF itself. Neither TNF, IL-1, gamma-IFN nor alpha-IFN mediate spontaneous monocyte cytotoxicity or that induced by alpha-IFN. Our studies thus reveal new interactions between the two monokines IL-1 and TNF and provide a dual role for TNF, as immunomodulator and mediator of monocyte cytotoxicity induced by certain specific lymphokine and monokine molecules.     

Cloning and expression in Escherichia coli of the gene for human tumour necrosis factor

Tumour necrosis factor (TNF) was found originally in mouse serum after intravenous injection of bacterial endotoxin into mice primed with viable Mycobacterium bovis, strain Bacillus Calmette-Guerin (BCG). TNF-containing serum from mice is cytotoxic or cytostatic to a number of mouse and human transformed cell lines, but less or not toxic to normal cells in vitro. It causes necrosis of transplantable tumours in mice. TNF also occurs in serum of rat, rabbit and guinea pig. Rabbit TNF has been purified recently to give a single band on SDS-polyacrylamide gel electrophoresis (PAGE). The purified TNF had a relative molecular mass (Mr) 40,000 +/- 5,000 measured by gel filtration, and 17,000 by SDS-PAGE. Its isoelectric point is 5.0 +/- 0.3. The necrotic activity in vivo and the cytotoxicity in vitro are produced by the same substance. The gene encoding TNF has been identified in a human genomic DNA library using as a probe a cloned cDNA encoding a portion of rabbit TNF. The regions of this gene encoding an amino-acid sequence corresponding to mature TNF have been expressed in Escherichia coli and the product of this expression isolated in pure form and shown to produce necrosis of murine tumours in vivo.     

Identity of differentiation inducing factor and tumour necrosis factor

Human myelogenous leukaemic cells can be induced to differentiate into the monocyte/macrophage pathway by protein inducers called differentiation inducing factors (DIF) in conditioned media of mitogen-stimulated human peripheral blood leukocytes. However, human DIF has not yet been well characterized. DIF is known to be a T-cell lymphokine, as it can be obtained from the T-cell line HUT-102 and can be partially purified from medium conditioned by phytohaemagglutinin (PHA)-stimulated lymphocytes. We found that monocytes also produce factor(s) that induce differentiation of human myelogenous leukaemia cell lines to cells with macrophage-like characteristics. This factor(s) has activity different from that of colony-stimulating factor(s) or interferons. We have now purified a DIF to homogeneity from medium conditioned by PHA-stimulated leukocytes using a human myeloblastic leukemia cell line, ML-1, as target cells. The purified DIF has a relative molecular mass (Mr) of approximately 17,000, with an NH2-terminal sequence the same as that of human tumour necrosis factor (TNF). Recombinant human TNF (rHuTNF) induces differentiation of ML-1 cells and an anti-pDIF monoclonal antibody can neutralize both differentiation inducing activity and cytotoxic activity of DIF and rHuTNF. The findings indicate that one of the DIF(s) produced by leukocytes is probably TNF.     

Recombinant human TNF induces production of granulocyte-monocyte colony-stimulating factor

Tumor necrosis factor (TNF) is synthesized by macrophages exposed to endotoxin. It produces haemorrhagic necrosis of a variety of tumours in mice and is cytostatic or cytocidal against various transformed cell lines in vitro, but viability of normal human or rodent cells is unaffected. The role of TNF is unlikely to be restricted to the rejection of tumours. Colony-stimulating factors (CSFs) are required for survival, proliferation and differentiation of haematopoietic progenitor cells. The haematopoietic growth factor known as granulocyte-monocyte colony-stimulating factor (GM-CSF) has the ability to stimulate proliferation and differentiation of normal granulocyte-monocyte and eosinophil stem cells and enhance the proliferation of pluripotent, megakaryocyte and erythroid stem cells. In addition, GM-CSF stimulates a variety of functional activities in mature granulocytes and macrophages, for example inhibition of migration, phagocytosis of microbes, oxidative metabolism, and antibody-dependent cytotoxic killing of tumour cells. We show here that TNF markedly stimulates production of GM-CSF messenger RNA and protein in normal human lung fibroblasts and vascular endothelial cells, and in cells of several malignant tissues.