TGF-β与Caspase在肿瘤细胞凋亡中的作用

TGF-β（transforming growth factor beta）是一种多功能的多肽类细胞因子,在调节细胞的生长和分化中起重要作用。从分子水平上,在不同的细胞中,TGF-β1刺激细胞凋亡是通过影响p38和ERK1/ERK-MAPK激酶的活性来介导的。Caspase半胱氨酸蛋白酶家族引发的级联反应是胞凋亡过程的中心环节,激活后的下游caspase通过切割特异性底物,导致细胞凋亡。在肿瘤细胞的凋亡过程中,TGF-β和caspase起着十分重要的作用。     

家蚕Caspase家族基因 BmCaspase-X 的克隆与功能分析

【目的】本研究旨在克隆获得家蚕 Bombyx mori Caspase家族基因,并通过RNAi技术初步分析其在家蚕细胞水平细胞凋亡中的功能。【方法】 用cDNA末端快速扩增方法（rapid amplification of cDNA ends, RACE）克隆家蚕Caspase家族一个新基因,用RNAi和流式细胞术初步分析该基因在家蚕细胞凋亡中的功能。【结果】将克隆获得的家蚕Caspase家族基因命名为 BmCaspase-X,其全长为2 105 bp,开放阅读框长为1 494 bp,编码497 aa,分子量为57.8 kDa,等电点为5.29。BmCaspase-X含有Caspase特有的结构位点。系统进化分析表明,BmCaspase-X与家蚕ICE同其他昆虫Caspase-4同源物先聚在一起,再与具有长前体结构域的昆虫其他因子聚为一类。RNAi初步结果显示该基因干扰后没有出现明显的细胞凋亡。【结论】BmCaspase-X具有典型Caspase特征,属于Caspase家族成员。目前RNAi实验结果表明 BmCaspase-X 未能引起家蚕细胞凋亡的改变。本文为进一步研究该基因的功能奠定基础。     

Caspase激活与调控的分子机制

Caspases是一类天冬氨酸特异性的半胱氨酸蛋白酶(IL-1β转化酶相关蛋白酶).迄今,在哺乳动物至少已发现13种caspase成员.Caspases在胞内通常以无活性的酶原形式存在,在其内部特定的天冬氨酸残基部位蛋白质裂解加工后可导致酶原激活,引发细胞凋亡.作为效应子的caspase在绝大多数细胞的凋亡过程中具有十分重要的作用.随着线虫死亡程序及某些死亡受体介导敏感细胞凋亡的信号机制的阐明,人们对caspase激活与调控在细胞凋亡中的机制研究已获得重大进展.     

促细胞凋亡因子Bid蛋白的研究进展

Bid蛋白是Bcl-家族中促凋亡类的蛋白。它具有可被caspase8酶切高控、高效地诱民细胞色素c从线粒体泄漏到胞浆中的功能,从而在细胞凋亡中起着重要的作用,因而倍受人们的重视。Bid蛋白的功能被发现以来,短短几年间,人们从分子生物学、细胞学、结构分析以及利用脂质体模型膜体系等各方面对Bid蛋白进行研究,取得了很大的进展。     

凋亡抑制蛋白IAP及其调控

调亡过程中关键参与者是caspase家族的多种成员,它们在凋亡过程中要受到严格调控。凋亡抑制蛋白IAP通过抑制caspase的活性从而参与对凋亡的调控,所以IAP的结构特征及其调控机制具有重要意义。     

Caspase与神经系统疾病

近年来,细胞凋亡发生机制的研究已取得众多进展。研究表明,许多神经系统疾病与caspase家族有着密切联系。现将细胞凋亡的最新研究结果及其与神经系统疾病的关系,尤其是caspase家族在神经系统疾病中的主导地位作简单综述,希望由此了解神经元细胞凋亡的内在机制并达到治疗目的。     

Caspase家族在细胞凋亡中的研究进展

半胱氨酸蛋白酶（caspase）家族成员是近两年来发现的在细胞凋亡过程中起关键作用的酶,对其深入研究有助于揭示细胞凋亡的发生机制,阐明不同疾病的发病机理。本文介绍了Caspase家族及其在细胞凋亡中的研究近况。     

p53上调凋亡调制物的促凋亡作用

p53上调凋亡调制物(p53up-regulated modulator of apoptosis,PUMA)是Bcl-2家族中BH3-only(Bcl-2 homology 3-only)蛋白质家族成员,通过其BH3结构域与所有的Bcl-2抗凋亡蛋白质结合,引发线粒体功能障碍和胱天蛋白酶(caspase)级联反应,诱导细胞凋亡。PUMA被证实在多种病理性应激介导的细胞凋亡中发挥着至关重要的作用,因而成为近年研究的热点。     

Survivin在口腔颌面部上皮性肿瘤中的研究进展

Survivin是近年发现的结构独特的凋亡抑制蛋白家族成员,具有抑制细胞凋亡、调节细胞有丝分裂的双重功能.Survivin具有肿瘤特异性,在正常成人组织中少见表达却高表达于多种肿瘤组织且与肿瘤细胞的浸润和病人的不良预后密切相关.本文对Surviviu的生物学功能及其与口腔颌面部上皮性肿瘤关系的研究进展进行综述.     

喜树碱诱导的草地贪夜蛾Sf9细胞凋亡

传统植物源杀虫剂喜树碱具有优异的抑制昆虫生长发育活性, 其诱导昆虫细胞凋亡的作用方式和机制尚不明确, 极大地限制了喜树碱在植物保护领域的应用开发。本研究以1 μmol/L喜树碱诱导草地贪夜蛾Spodoptera frugiperda Sf9细胞呈现细胞皱缩、微绒毛消失和染色质边集等典型细胞凋亡早期超微结构形态特征, 中期凋亡小体逐渐出现并急剧增多, DNA电泳分析可见清晰DNA片段化凋亡特征。流式细胞术分析表明1 μmol/L喜树碱诱导Sf9细胞12 h凋亡率达到最大值39.67%, 是对照的13.13倍, 随后减小。喜树碱诱导Sf9细胞凋亡在12 h和24 h 时Sf caspase-1分别出现两个活性高峰, 表明其作为效应因子在细胞凋亡级联反应过程中具有影响作用。喜树碱显著抑制Sf9细胞拓扑异构酶Ⅰ活性, 阻断解旋负超螺旋pBR322 DNA, 导致DNA损伤进而启动细胞凋亡级联反应使Sf caspase-1活性增加, 提示其信号转导过程是细胞凋亡诱导机制之一。本研究通过分析喜树碱的诱导昆虫Sf9细胞凋亡, 对揭示喜树碱诱导昆虫细胞凋亡的作用机制具有重要启示和帮助。     

Caspases: evolutionary aspects of their functions in vertebrates

Caspases (cysteine-dependent aspartyl-specific protease) belong to a family of cysteine proteases that mediate proteolytic events indispensable for biological phenomena such as cell death and inflammation. The first caspase was identified as an executioner of apoptotic cell death in the worm Caenorhabditis elegans . Additionally, a large number of caspases have been identified in various animals from sponges to vertebrates. Caspases are thought to play a pivotal role in apoptosis as an evolutionarily conserved function; however, the number of caspases that can be identified is distinct for each species. This indicates that species-specific functions or diversification of physiological roles has been cultivated through caspase evolution. Furthermore, recent studies suggest that caspases are also involved in inflammation and cellular differentiation in mammals. This review highlights vertebrate caspases in their universal and divergent functions and provides insight into the physiological roles of these molecules in animals.     

The multifaceted activity of insect caspases

Caspases are frequently considered synonymous with apoptotic cell death. Increasing evidence demonstrates that these proteases may exert their activities in non-apoptotic functions. The non-apoptotic roles of caspases may include developmentally regulated autophagy during insect metamorphosis, as well as neuroblast self-renewal and the immune response. Here, we summarize the established knowledge and the recent advances in the multiple roles of insect caspases to highlight their relevance for physiological processes and survival.     

Caspase activation, inhibition, and reactivation: a mechanistic view

Caspases, a unique family of cysteine proteases, execute programmed cell death (apoptosis). Caspases exist as inactive zymogens in cells and undergo a cascade of catalytic activation at the onset of apoptosis. The activated caspases are subject to inhibition by the inhibitor-of-apoptosis (IAP) family of proteins. This inhibition can be effectively removed by diverse proteins that share an IAP-binding tetrapeptide motif. Recent structural and biochemical studies have revealed the underlying molecular mechanisms for these processes in mammals and in Drosophila. This paper reviews these latest advances.     

Recruitment of apoptotic cysteine proteases (caspases) in influenza virus-induced cell death.

Influenza virus infection induces apoptosis in cultured cells with an augmented expression of Fas (APO-1/CD95). Caspases, a family of cysteine proteases structurally related to interleukin-1-beta-converting enzyme (ICE), play crucial roles in apoptosis induced by various stimuli, including Fas. However, activation of the caspase-cascade seems to be different in various pathways of apoptotic stimuli. We therefore examined the involvement of caspases in influenza virus-induced apoptosis using caspase inhibitors. We found that z-VAD-fmk and z-IETD-fmk effectively inhibited virus-induced apoptosis, whereas Ac-DEVD-CHO and Ac-YVAD-CHO showed partial and little effect on virus-induced cell death, respectively. Consistently, caspase-3-like activity, but not caspase-1-like activity, was increased in the virus-infected cells. The transfection of plasmids encoding viral inhibitors of caspase (v-FLIP or crmA) into HeLa cells inhibited apoptosis by virus infection. The peptide inhibitors of caspases used in this study did not inhibit viral replication. We conclude that influenza virus infection activates some caspases, and that this activation may be downstream of viral replication.     

Caspase的活化及其在细胞凋亡中的作用

Caspase是执行细胞凋亡的主要酶类,目前已鉴定的哺乳动物Caspase有14种。Caspase以酶原的形式合成,催化活性很低,必须激活以后才能发挥作用。活化的Caspase通过特异性的裂解一套底物而导致细胞凋亡。与Caspase有关的细胞凋亡通路至少有三种：线粒体／细胞色素c通路、死亡受体通路和内质网通路。Caspase总是与其抑制剂共存,以防止Caspase酶原意外激活而对正常细胞造成损伤。     

植物Metacaspase研究进展

过敏性坏死反应是植物的一种重要的抗病机制, 类似于动物细胞凋亡, 它是一种程序性细胞死亡(programmed cell death, PCD)过程。目前, 已经确定半胱天冬蛋白酶(caspase)在动物PCD过程中起核心作用。在植物中, 尚未发现其直系同源蛋白, 但是有一类与其结构相似的蛋白酶, 称为metacaspase。在植物不同的PCD过程中, 有的依赖于metacaspase, 而有的则不依赖于该类蛋白酶。目前对metacaspase的结构和功能已有了初步的研究, 对其深入的研究则进展缓慢, 其具体的生物学功能和在PCD信号路径中的定位有待进一步探索。     

Caspase Work Model During Pathogen Infection

Caspases are an evolutionarily conserved family of aspartate-specific cystein-dependent proteases with essential functions in apoptosis and normally exist in cells as inactive proenzymes. In addition to the inflammatory caspases, the initiator and effector caspases have been shown to have an important role in regulating the immune response, but are involved in different ways. We give a brief introduction on the benefit of apoptosis on the clearance of invasive pathogens, and the caspase functions involved i...     

Nonapoptotic functions of caspases: caspases as regulatory molecules for immunity and cell-fate determination

Caspases are a family of cysteine proteases that are highly conserved in multicellular organisms and function as central regulators of apoptosis. Recent investigations in Caenorhabditis elegans, Drosophila and mice suggest that caspases also function as regulatory molecules for immunity and cell-fate determination. Here, we review genetic studies of nonapoptotic functions of caspases and discuss the regulatory mechanisms of caspases for executing nonapoptotic functions.     

Fas Antigen Modulates Ultraviolet B-Induced Apoptosis of SVHK Cells: Sequential Activation of Caspases 8, 3, and 1 in the Apoptotic Process

Interferon-gamma (IFN-gamma) induces various apoptosis-related proteins, including Fas antigen (Fas) in keratinocytes. Ultraviolet B (UVB) irradiation produces "sunburn cells," a specific type of apoptosis. Previously, we reported that IFN-gamma augments Fas-dependent apoptosis of SV40-transformed human keratinocytes (SVHK cells). Caspases are a new class of cysteine proteinases that play an important role in apoptosis. We investigated the mechanism of UVB-induced apoptosis by examining activation of the caspase cascade. UVB irradiation of SVHK cells increased the activities of caspases 1, 3, and 8, which were detected at 3 h, and peak activities occurred at 6 h. Pretreatment of SVHK cells with IFN-gamma significantly increased the activity of caspases 1, 3, and 8. UVB-induced caspase 8 stimulation was significantly suppressed only by caspase 8 inhibitor, while inhibitors of caspases 1, 3, and 8 significantly suppressed UVB-induced caspase 1 stimulation. Caspase 3 and 8 inhibitors, but not caspase 1 inhibitor, significantly suppressed UVB-induced caspase 3 activity, suggesting sequential activation of caspases 8, 3, and 1 in UVB-irradiated SVHK cells. Cross-linking and immunoprecipitation analyses showed multimerization of Fas antigen following UVB irradiation of SVHK cells. Pretreatment of SVHK cells with IFN-gamma significantly augmented UVB-induced apoptosis that was accompanied by increased Fas expression. The susceptibility to UVB-induced apoptosis was also increased in Fas-transfected SVHK cells (F2 cells). Neutralizing anti-Fas antibody significantly suppressed caspase activation and Fas-dependent apoptosis of SVHK cells and F2 cells. In contrast, UVB-induced caspase activation and apoptosis were not inhibited by neutralizing anti-Fas antibody in both cell lines. Our results suggest that UVB directly activates Fas and subsequent caspase cascade resulting in apoptosis of SVHK cells. Furthermore, the expression level of Fas antigen in keratinocytes influenced their susceptibility to UVB-induced apoptosis.     

The kinder side of killer proteases: Caspase activation contributes to neuroprotection and CNS remodeling

Caspases are a family of cysteine proteases that are expressed as inactive zymogens and undergo proteolytic maturation in a sequential manner in which initiator caspases cleave and activate the effector caspases 3, 6 and 7. Effector caspases cleave structural proteins, signaling molecules, DNA repair enzymes and proteins which inhibit apoptosis. Activation of effector, or executioner, caspases has historically been viewed as a terminal event in the process of programmed cell death. Emerging evidence now suggests a broader role for activated caspases in cellular maturation, differentiation and other non-lethal events. The importance of activated caspases in normal cell development and signaling has recently been extended to the CNS where these proteases have been shown to contribute to axon guidance, synaptic plasticity and neuroprotection. This review will focus on the adaptive roles activated caspases in maintaining viability, the mechanisms by which caspases are held in check so as not produce apoptotic cell death and the ramifications of these observations in the treatment of neurological disorders.