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《生命科学》2016,(3)
植物病毒编码一些含有核定位信号(nuclear localization signal,NLS)或者核输出信号(nuclear export signal,NES)的核质转运蛋白,这些已被验证的转运蛋白有三种类型:核输入蛋白、核输出蛋白和核质穿梭蛋白。它们通过识别寄主核质转运受体Importinα和Importinβ,介导含有经典核定位信号的蛋白质入核过程,以及寄主蛋白Ran参与,由XPO1介导的富含亮氨酸核输出信号的蛋白质出核过程。植物病毒核质转运蛋白利用寄主的转运机制,进出细胞核发挥相应功能,如介导病毒基因组的核输入和核输出、介导病毒长距离运输及系统侵染、抵抗寄主细胞启动的RNA沉默、调节寄主细胞转录活性、调控病毒的复制及表达和参与病毒症状的形成等。对植物病毒蛋白核质转运的相关研究进展进行综述,着重介绍植物病毒蛋白核质转运类型、核输入和输出信号、转运机制和生物学意义,以及寄主蛋白介导的互作等研究的最新成果。 相似文献
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旺盛的细胞核、质间的物质运输(nuclear-cytoplasmic transport)是真核细胞代谢的基础.核质运输不仅将蛋白质运到目的地,还能通过在特定时间、地点结合靶分子,改变其在胞内的局部浓度,调控诸如有丝分裂等重要细胞活动.tRNA是细胞中最重要的大分子之一,合成于细胞核,在细胞质中参加蛋白质翻译.一直以来,学术界认为tRNA只是蛋白质合成的参与者,tRNA核质运输是tRNA跨越核膜进入细胞质是单向主动运输过程.然而,最近的研究成果在颠覆传统观念,tRNA不但能被转运出核,还能被逆向转运入核.2008年,新概念“tRNA核质动态分布”(tRNA nuclear-cytoplasmic dynamics)被提出,取代tRNA核质运输,描述tRNA在细胞核、质间的流动.在酿酒酵母中tRNA核质动态分布可以调控蛋白质翻译,锁定细胞周期.此领域内的最新研究正在改变着教科书中有关tRNA的传统论断. 相似文献
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核转运与P53功能调控 总被引:1,自引:0,他引:1
细胞核是真核细胞内最重要的细胞器。真核细胞胞内部分被核膜分为核区与质区两个区域 ,因此 ,不可避免地存在核区与质区之间连续而有选择性的双向物质交换 (核转运 )。这一生理过程不是一个简单的机制 ,而是受到精密的调控 ,同时 ,核转运也调控着细胞其他生理过程 ,如基因表达。P5 3是一个转录调控因子 ,它的抑癌作用就是依靠其转录调控活性来实现的。对P5 3的抑癌作用及其转录调控机制的研究已经比较深入 ,但近年的研究发现 ,P5 3抑癌功能的发挥与其自身及相关蛋白质的核转运有很大的联系。在对肿瘤细胞的研究中发现有三类突变会影响P5… 相似文献
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细胞凋亡是细胞生命活动中一种预定的、并受到严格控制的程序性死亡,它是细胞内一系列促凋亡因子和抗凋亡因子相互作用后获得平衡的结果。细胞凋亡的调控可以发生在表观遗传、转录、翻译、修饰、转运等不同水平,也可以发生在细胞不同的区域,如细胞核、胞质、线粒体、质膜等处。作者近年来发现的新的促/抗凋亡因子从多种不同的角度去诠释细胞凋亡网络的调控。例如,Caspase新的激活机制;凋亡蛋白磷酸化和泛素化修饰以及蛋白通过对中间纤维的影响来诱导线粒体介导的凋亡等等。另外,对凋亡信号如何从胞核流向胞质进而促发线粒体引起的凋亡途径也进行了描述。这些新的凋亡调控机理进一步证明了,细胞凋亡可以发生在细胞生长发育不同的时相和空间,并存在着一个极其复杂的信号传递网络,这一调控网络一旦失去平衡,细胞会引发肿瘤。 相似文献
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Caspase激活与调控的分子机制 总被引:10,自引:0,他引:10
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. 相似文献
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Nucleocytoplasmic transport in apoptosis 总被引:5,自引:0,他引:5
Ferrando-May E 《Cell death and differentiation》2005,12(10):1263-1276
The apoptotic demolition of the nucleus is accomplished by diverse proapoptotic factors, most of which are activated in the cytoplasm and gain access to the nucleoplasm during the cell death process. The nucleus is also the main target for genotoxic insult, a potent apoptotic trigger. Signals generated in the nucleus by DNA damage have to propagate to all cellular compartments to ensure the coordinated execution of cell demise. The nucleocytoplasmic shuttling of signalling and execution factors is thus an integral part of the apoptotic programme. Several proteins implicated in apoptotic cell death have been shown to migrate in and out of the nucleus following apoptosis induction. This review summarises the current knowledge on nucleocytoplasmic trafficking of apoptosis-relevant proteins. The effects of apoptosis induction on the nucleocytoplasmic transport machinery are also discussed. Finally, a potential role of nuclear transport as a critical control point of the apoptotic signal cascade is proposed. 相似文献
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In response to severe stress, apoptotic cell death is engaged. Apoptosis is a well orchestrated process that involves the activation and implication of many factors. In this study, we identified a role for the nuclear trafficking factor TRN2 (transportin 2) in cell death. TRN2 is normally responsible for the nuclear import of the RNA-binding protein HuR. During apoptosis, however, HuR accumulates in the cytoplasm. This is due to the caspase-mediated cleavage of the cytoplasmic fraction of HuR. One of the cleavage fragments generated by this processing of HuR interacts with TRN2 and thus blocks the re-import of HuR into the nucleus. This concentrates HuR in the cytoplasm, advancing apoptosis. Therefore, increasing or decreasing the levels of TRN2 has an inverse consequential effect on cell death, demonstrating for the first time the role of a nucleocytoplasmic transport factor in apoptosis. 相似文献
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Gelina S. Kopeina Evgeniia A. Prokhorova Inna N. Lavrik Boris Zhivotovsky 《Cell proliferation》2018,51(5)
Apoptosis is a mode of regulated cell death that is indispensable for the morphogenesis, development and homeostasis of multicellular organisms. Caspases are cysteine‐dependent aspartate‐specific proteases, which function as initiators and executors of apoptosis. Caspases are cytosolic proteins that can cleave substrates located in different intracellular compartments during apoptosis. Many years ago, the involvement of caspases in the regulation of nuclear changes, a hallmark of apoptosis, was documented. Accumulated data suggest that apoptosis‐associated alterations in nucleocytoplasmic transport are also linked to caspase activity. Here, we aim to discuss the current state of knowledge regarding this process. Particular attention will be focused on caspase nuclear entry and their functions in the demolition of the nucleus upon apoptotic stimuli. 相似文献
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Fahrenkrog B 《Canadian journal of physiology and pharmacology》2006,84(3-4):279-286
The nuclear pore complex (NPC) is the sole gateway between the nucleus and the cytoplasm of interphase eukaryotic cells, and it mediates all trafficking between these 2 cellular compartments. As such, the NPC and nuclear transport play central roles in translocating death signals from the cell membrane to the nucleus where they initiate biochemical and morphological changes occurring during apoptosis. Recent findings suggest that the correlation between the NPC, nuclear transport, and apoptosis goes beyond the simple fact that NPCs mediate nuclear transport of key players involved in the cell death program. In this context, the accessibility of key regulators of apoptosis appears to be highly modulated by nuclear transport (e.g., impaired nuclear import might be an apoptotic trigger). In this review, recent findings concerning the unexpected tight link between NPCs, nuclear transport, and apoptosis will be presented and critically discussed. 相似文献
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《Biochimica et Biophysica Acta (BBA)/General Subjects》2014,1840(9):2953-2960
BackgroundIn eukaryotic cells, molecular trafficking between the nucleus and cytoplasm is a highly regulated process related to cellular homeostasis and cellular signaling. However, various cellular stresses induce the perturbation of conventional nucleocytoplasmic transport pathways, resulting in the nucleocytoplasmic redistribution of many functional proteins.Scope of reviewWe describe the recent insights into the mechanism and functions of nuclear import of cytosolic chaperone HSP70 under stress conditions and the cellular distribution and functions of its co-chaperones.Major conclusionsHikeshi mediates the nuclear import of the molecular chaperone HSP70. A few of the regulators of the HSP70 chaperone system also accumulate in the nucleus under heat stress conditions. These proteins function collaboratively to protect cells from stress-induced damage and aid in the recovery of cells from stress.General significanceStudies on the regulation of nucleocytoplasmic transport under several cellular stresses should provide new insights into the fundamental principles of protein homeostasis (proteostasis) in both compartments, the nucleus and cytoplasm. 相似文献
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In the eukaryotic cell, exchange of biomolecules between nucleus and cytoplasm is a highly regulated process which responds sensitively to changes of the environment. One well-known cellular response to environmental challenges is cell death by apoptosis. In fact, apoptosis has been shown to affect the nucleocytoplasmic transport machinery, in particular the nuclear pore, by modulating its size exclusion limit for passive diffusion. The underlying molecular factors are still unknown, mainly because of the lack of a suitable system to detect and quantitate the apoptotic effects on the nuclear pore. Here we present an assay that was designed to measure alterations of the permeability of the nuclear envelope under apoptotic conditions. The assay is based on the well-established technique of selective permeabilization of the plasma membrane with digitonin and allows assessment of permeability changes in nonfixed samples. It comprises a computer program, called Nuclear Permeability Assay, for the quantitation of the nuclear fluorescence signal, which may be generally employed for the evaluation of in vitro transport systems using semipermeabilized cells, such as assays for nuclear import and export. 相似文献
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E Ferrando-May V Cordes I Biller-Ckovric J Mirkovic D G?rlich P Nicotera 《Cell death and differentiation》2001,8(5):495-505
In eukaryotic cells, both soluble transport factors and components of the nuclear pore complex mediate protein and RNA trafficking between the nucleus and the cytoplasm. Here, we investigated whether caspases, the major execution system in apoptosis, target the nuclear pore or components of the nuclear transport machinery. Four nucleoporins, Nup153, RanBP2, Nup214 and Tpr are cleaved by caspases during apoptosis. In contrast, the nuclear transport factors, Ran, importin alpha and importin beta are not proteolytically processed, but redistribute across the nuclear envelope independently and prior to caspase activation. Also, mRNA accumulates into the nucleus before caspases become active. Microinjection experiments further revealed that early in apoptosis, the nucleus becomes permeable to dextran molecules of 70 kD molecular weight. Redistribution of import factors and mRNA, as well as nuclear permeabilisation, occur prior to caspase-mediated nucleoporin cleavage. Our findings suggest that the apoptotic programme includes modifications in the machinery responsible for nucleocytoplasmic transport, which are independent from caspase-mediated degradation of nuclear proteins. 相似文献
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Tanno M Sakamoto J Miura T Shimamoto K Horio Y 《The Journal of biological chemistry》2007,282(9):6823-6832
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Ursula Stochaj Katherine L. Rother 《BioEssays : news and reviews in molecular, cellular and developmental biology》1999,21(7):579-589
Proteins and RNAs move between the nucleus and cytoplasm by translocation through nuclear pore complexes in the nuclear envelope. To do this, they require specific targeting signals, energy, and a cellular apparatus that catalyzes their transport. Several of the factors involved in nucleocytoplasmic trafficking of proteins have been identified and characterized in some detail. The emerging picture for nuclear transport proposes a central role for the small GTPase Ran and proteins with which it interacts. In particular, asymmetric distribution of these proteins between nucleus and cytoplasm appears to be responsible for the vectorial nature of nucleocytoplasmic transport. Here, we summarize the role of Ran and Ran-binding proteins in nuclear trafficking of proteins with classical nuclear localisation signals. We also discuss examples of the growing number of alternative pathways that are involved in transport of proteins across the nuclear envelope. BioEssays 21:579–589, 1999. © 1999 John Wiley & Sons, Inc. 相似文献
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Cathepsin-regulated apoptosis 总被引:6,自引:0,他引:6
Chwieralski CE Welte T Bühling F 《Apoptosis : an international journal on programmed cell death》2006,11(2):143-149
Apoptosis can be mediated by different mechanisms. There is growing evidence that different proteolytic enzymes are involved
in the regulation of apoptosis. Cathepsins are proteases which, under physiologic conditions, are localized intralysosomally.
In response to certain signals they are released from the lysosomes into the cytoplasm where they trigger apoptotic cell death
via various pathways, including the activation of caspases or the release of proapoptotic factors from the mitochondria. Here,
we review different mechanisms that induce the release of lysosomal enzymes, and the functional relevance of defined cathepsins
in defined models of apoptosis. 相似文献