肿瘤坏死因子相关凋亡诱导配体在多种疾病中的生物学作用

肿瘤坏死因子相关凋亡诱导配体（Apo2L/TRAIL）是肿瘤坏死因子家族的一员,可以诱导表达特异性死亡受体TRAIL-R1 （DR4）或TRAIL-R2 （DR5）的细胞凋亡.TRAIL可诱导多种肿瘤细胞凋亡,对正常细胞无杀伤性,因此将其作为抗肿瘤靶向治疗候选药物之一,备受关注.近期研究发现,TRAIL既通过其受体介导细胞凋亡信号通路,又可传导非凋亡的信号通路,在自身免疫病和感染性疾病中发挥重要生物学作用.因而简单阐明TRAIL在人类多种疾病中生物学作用的研究进展,对今后TRAIL研究方向和治疗策略的选择具有指导意义.     

细胞凋亡的形态代谢特点及生物学意义

细胞凋亡的形态代谢特点及生物学意义苏长青综述龚西审校细胞凋亡（ａｐｏｐｔｏｓｉｓ）的概念最早由Ｋｅｒｒ等［１］于１９７２年提出，亦称细胞程序性死亡（ｐｒｏｇｒａｍｍｅｄｃｅｌｌｄｅａｔｈ）。长期以来，有关细胞凋亡的发生机制及生物学意义一直未受重视。近...     

病毒感染中TNF信号传导途径

肿瘤坏死因子(TNF)受体及配体超家族通过诱导细胞的生长、分化、死亡等多种生物学效应，在机体抗病毒的天然免疫和获得性免疫中发挥了重要作用。一些病毒诱导感染细胞表达死亡受体(death receptor，DR)配体后可被细胞毒性淋巴细胞(CTL)和自然杀伤(NK)细胞清除，是机体抵抗病毒侵害的防御机制之一。本文介绍了病毒诱导TNF受体与配体结合至激活细胞凋亡的信号传导途径。     

死亡受体及线粒体途径与激活诱导T细胞凋亡

免疫系统形成了一系列确保激活的淋巴细胞能被有效清除的分子及信号途径，称之为激活诱导的细胞死亡。激活诱导的细胞死亡主要负责调节免疫细胞稳态及清除自身反应性淋巴细胞。死亡受体途径及线粒体死亡途径分别是细胞凋亡的外在途径和内在途径也参与了激活诱导的T细胞凋亡，本文就外周成熟T细胞凋亡相关的死亡受体途径，线粒体死亡途径及其相关调控机制研究进展作一综述。     

病毒感染中TNF信号传导途径

肿瘤坏死因子(TNF)受体及配体超家族通过诱导细胞的生长、分化、死亡等多种生物学效应,在机体抗病毒的天然免疫和获得性免疫中发挥了重要作用.一些病毒诱导感染细胞表达死亡受体(death receptor,DR)配体后可被细胞毒性淋巴细胞(CTL)和自然杀伤(NK)细胞清除,是机体抵抗病毒侵害的防御机制之一.本文介绍了病毒诱导TNF受体与配体结合至激活细胞凋亡的信号传导途径.     

三氧化二砷对多发性骨髓瘤细胞生物学特性的影响

目的探讨三氧化二砷(As2O3)对人多发性骨髓瘤细胞系RPMI8226细胞生物学特性影响的分子机制。方法用人多发性骨髓瘤细胞系RPMI8226细胞作为体外实验对象。应用流式细胞仪检测细胞周期、凋亡峰、死亡受体DR4和DR5分子及黏附分子VLA4(CD49d)的表达;用聚合酶链反应测定靶细胞CXCR4基因表达;免疫组化染色和荧光显微镜检测DR4和DR5分子的表达情况。结果5μmol/L的As2O3可以明显上调RPMI8226细胞DR4、DR5分子的表达(P<0.01),明显下调CXCR4基因和VLA4分子表达;还可以诱导RPMI8226细胞凋亡、增加G1期细胞比例,出现明显凋亡峰。结论As2O3诱导RPMI8226细胞凋亡,可能与死亡受体DR4、DR5分子过度表达有关;As2O3抑制靶细胞CXCR4基因和黏附分子VLA4的表达,从而影响细胞的增殖、迁移与归巢能力。     

细胞凋亡的研究进展

细胞的发育、分化和成熟是发育生物学和细胞生物学研究的焦点。但长期以来，有关细胞凋亡（apoptosis）规律的研究一直未被重视。近年来，生物学家逐渐认识到细胞凋亡具有特殊的生物学意义，由此形成了新的研究热点。以下扼要介绍这一领域的研究进展。一、细胞凋亡的概念与形态特征在多细胞动物中，细胞的死亡有两种不同的形式。一种是细胞坏死（necrosis），它是由于某些外界的因素，如局部贫血、物理、化学损伤或生物的侵袭等造成细胞急速死亡。另一种称为细胞凋亡，它是指象秋天树叶凋谢一样，细胞遵循自身的程序，自己结束其生命，最后…     

死亡受体及线粒体途径与激活诱导T细胞凋亡

免疫系统形成了一系列确保激活的淋巴细胞能被有效清除的分子及信号途径 ,称之为激活诱导的细胞死亡。激活诱导的细胞死亡主要负责调节免疫细胞稳态及清除自身反应性淋巴细胞。死亡受体途径及线粒体死亡途径分别是细胞凋亡的外在途径和内在途径 ,也参与了激活诱导的T细胞凋亡 ,本文就外周成熟T细胞凋亡相关的死亡受体途径、线粒体死亡途径及其相关调控机制研究进展作一综述。     

Apo—1／Fas受体及其配体在诱导淋巴细胞凋亡中的作用

本文介绍了Ａｐｏ－１／Ｆａｓ受体及其配体的结构及其分布，阐述了Ａｐｏ－１／Ｆａｓ受体及其配体在免疫生物学方面的效应：诱导ＴＣＲ＾ｉｍ／Ａｐｏ－１＾ｈｉ胸腺细胞的阴性选择；清除外周自身反应Ｔ细胞克隆；诱导某些活化Ｔ，Ｂ细胞凋亡；介导某些白血病细胞凋亡，并阐述了Ａｐｏ－１／Ｆａｓ受体及其配体在诱导细胞凋亡中的作用机理。     

Fas死亡信号激发域cDNA的克隆、表达及体外生物学效应

目的：克隆及表达Fas死亡信号激发域(Fas Activation Domain，FasAD)片段，获得具有生物学活性的FasAD多肽。方法：应用半巢式逆转录-多聚酶链反应(RT-PCR)扩增Fas死亡信号激发域cDNA片段，构建Intein表达型原核表达载体FasAD-pTYB12，应用IMPACT^TM-CN系统表达及进行一步法亲合层析分离、纯化FasAD多肽。结果：DNA序列测定显示克隆的FasAD cDNA碱基排列顺序与Genebank(M67454)所示完全一致。重组表达载体FasAD-pTYB12经IPTG诱导，成功表达可溶性融合蛋白，进一步分离、纯化获得分子量约5000的FasAD多肽，Westem blot显示FasAD多肽能被兔抗人Fas多抗识别。初步的生物学活性鉴定显示，该FasAD多肽抑制rhFasL诱导的细胞凋亡的生物学活性最高可达70％。结论：可利用IMPACT^TM-CN系统制备Fas死亡信号激发域的小分子量多肽，为深入研究Fas结构与功能的关系及与配体的相互作用提供了相关的实验基础，为进一步开发相关的生物免疫调节剂提供了实验依据。     

肿瘤坏死因子受体超家族成员死亡受体在病毒感染中的作用

死亡受体是一组具有死亡结构域的膜受体,属于肿瘤坏死因子受体超家族成员.表达死亡受体的细胞与其相应的配体结合后可引发细胞凋亡,因此死亡受体参与机体的多种生理和病理过程,特别是在多种病毒感染中发挥着双重作用,本文就最新发现的死亡受体在肝炎病毒、HIV以及巨细胞病毒等多种病毒感染中的作用作一综述.     

Both intrinsic and extrinsic apoptotic pathways are involved in Toll-like receptor 4 (TLR4)-induced cell death in monocytic THP-1 cells

Our previous study showed that TLR3 induces apoptosis via both death receptors and mitochondial in human endothelial cells. We report here that the activation of TLR4 induced dose- and time-dependent cell death in moncytic THP-1 cells. LPS treatment of THP-1 cells induced the activation of both caspase 8 and 9, suggesting the involvement of intrinsic and extrinsic apoptosis pathways. TNFα was induced by TLR4 activation at both mRNA and protein levels, but its neutralization did not down-regulated TLR4-induced cell death. TLR4 activation also induced the up-regulation of TRAIL and its receptors DR4 and DR5, and the neutralization of TRAIL ameliorated TLR4 induced apoptosis, suggesting the involvement of TRAIL and its receptors DR4 and DR5 in LPS-induced cell death. Meanwhile, LPS treatment down-regulated the expression of FLICE inhibitory protein (FLIP), a suppressor of death receptor-induced cell death. In addition, TLR4 activation down-regulated the anti-apoptotic protein bcl-2, and up-regulated the pro-apoptotic proteins Noxa and Puma, suggesting that mitochondrial apoptotic pathway was also involved in LPS-induced cell death. Furthermore, we found that TAP63α might confer to the activation of intrinsic and extrinsic apoptotic pathways. The treatment of THP-1 cells with LPS induced the translocation of TAP63α from cytoplasm to nucleus. Taken together, our study suggested that both death receptors and mitochondial were involved in TLR4-induced cell death, and TAP63α may be a target for the prevention of LPS-induced cell death.     

Death receptor signaling and autoimmunity

In recent years, it has become clear that self-nonself discrimination by the immune system is driven not so much by the specificities of the antigen receptors themselves, but by ligand-receptor systems that sense the presence of foreign pathogens (toll-like receptors) and those that regulate the balance between cellular proliferation and programmed cell death (tumor necrosis factor [TNF] family ligands and receptors). Interestingly, these two receptor families share a number of common signaling pathways, mediated by the cytoplasmic proteins containing death domains and TRAF domains, which trigger the complementary processes of programmed cell death and inflammation. Both humans and mice with genetic defects in the TNF-receptor family member Fas accumulate abnormal lymphocytes and develop systemic autoimmunity. These findings high-lighted the importance of this TNF-receptor family member in the homeostasis of the immune system. In particular, the Fas receptor has been shown to be important in immunoreceptor-mediated apoptosis of activated T and B lymphocytes. Six members of the TNF-receptor superfamily share a common signaling domain with Fas, termed the death domain, that directly links these receptors to the apoptotic machinery of the cell, and, collectively, these receptors have been designated as “death receptors”. We are currently investigating a number of important unresolved issues in this field, including: (1) how susceptibility to apoptosis through death receptors is regulated, (2) how Fas and related death receptors function in the maintenance of self-tolerance and homeostasis in the major cell types of the immune system, and (3) recently described nonapoptotic lymphocyte activation signals that use components of death receptor signaling.     

The caspase-8 modulator c-FLIP

Death receptors belong to the tumor necrosis factor receptor superfamily and can induce apoptosis through activation of procaspase-8. The cellular FLICE-inhibitory protein (c-FLIP) is able to modulate activation of procaspase-8 and thereby prevents induction of apoptosis mediated by death receptors. As an important modulator of caspase-8, c-FLIP regulates life and death in various types of normal cells and tissues, such as lymphoid cells, and renders resistance to death receptor-mediated apoptosis in many types of cancer cells. In addition to an apoptosis modulator, c-FLIP has been shown to exert other physiological functions related to cell proliferation and tumorigenesis. Dysregulation of c-FLIP expression has been shown to be associated with various diseases, such as cancer and autoimmune diseases, and c-FLIP might be a critical target for therapeutic intervention. This review focuses on recent findings about the physiological function and intracellular regulation of c-FLIP.     

Caspase-8: regulating life and death

Roles for cell death in development, homeostasis, and the control of infections and cancer have long been recognized. Although excessive cell damage results in passive necrosis, cells can be triggered to engage molecular programs that result in cell death. Such triggers include cellular stress, oncogenic signals that engage tumor suppressor mechanisms, pathogen insults, and immune mechanisms. The best-known forms of programmed cell death are apoptosis and a recently recognized regulated necrosis termed necroptosis. Of the two best understood pathways of apoptosis, the extrinsic and intrinsic (mitochondrial) pathways, the former is induced by the ligation of death receptors, a subset of the TNF receptor (TNFR) superfamily. Ligation of these death receptors can also induce necroptosis. The extrinsic apoptosis and necroptosis pathways regulate each other and their balance determines whether cells live. Integral in the regulation and initiation of death receptor-mediated activation of programmed cell death is the aspartate-specific cysteine protease (caspase)-8. This review describes the role of caspase-8 in the initiation of extrinsic apoptosis execution and the mechanism by which caspase-8 inhibits necroptosis. The importance of caspase-8 in the development and homeostasis and the way that dysfunctional caspase-8 may contribute to the development of malignancies in mice and humans are also explored.     

Life and death decisions: secondary complexes and lipid rafts in TNF receptor family signal transduction

Signaling by receptors in the TNF receptor (TNFR) superfamily mediate biological outcomes ranging from inflammation to apoptosis and other forms of programmed cell death. How receptor signaling mediates these divergent responses is just beginning to be understood. Here, we discuss how receptor submembrane localization and the formation of alternate signaling complexes can alter the fate of cells stimulated through TNFRs with a death domain, also known as "death receptors."     

电离辐射与细胞凋亡

电离辐射所致细胞死亡的主要形式为细胞凋亡。细胞凋亡的基因调控机制精密而复杂 ,P53、bcl- 2家族、Fas系统、c- myc、P34 cdc2、caspases等均参与辐射性细胞凋亡的调控。细胞凋亡是细胞内一系列凋亡蛋白酶激活的级联反应和细胞表面死亡接受外部信号调节的结果。辐射性细胞凋亡的滞后期因细胞种类而异 ,线性能量传递 ( L ET)及辐射剂量影响细胞凋亡率     

Autoimmunity as a consequence of retrovirus-mediated expression of C-FLIP in lymphocytes

The induction of apoptosis by death receptors serves to regulate immune responses by eliminating unwanted and harmful cells. Mature lymphocytes express FLICE inhibitory proteins (FLIPs) that block death receptor-induced cell death. Here, we show that both B and T cells downregulate c-FLIP upon activation in vitro. Retrovirus-mediated expression of c-FLIP blocks Fas-induced apoptosis of activated lymphocytes but does not affect cell death resulting from cytokine withdrawal. In vivo, c-FLIP expression results in defective superantigen-mediated elimination of T cells, the accumulation of activated B cells, the production of autoantibodies, and the development of autoimmune disease. No effect was seen on negative selection of thyomocytes. These results suggest that activation-dependent downregulation of c-FLIP renders mature lymphocytes sensitive to death receptor-mediated apoptosis and is required to maintain self-tolerance.