细胞培养中的程序性细胞死亡

许多在商业上广泛应用的细胞株,包括杂交瘤和骨髓瘤细胞,在细胞培养中都会发生程序性死亡,这使培养效率降低。本文简要介绍程序性细胞死亡的特征、与这一过程有关的基因、细胞培养中如何抑制程序性死亡以及常用的检测方法。     

植物细胞程序性死亡中的类caspases蛋白酶

细胞程序性死亡对于植物的正常生长发育及病理过程具有十分重要的生物学意义。现有的实验证据表明,细胞程序性死亡在动物和植物中有许多相似之处,但也各有特点。在植物中,VPEs、metacaspases和saspases等酶类在细胞程序性死亡过程中发挥了关键性作用。该文详细比较了动、植物细胞程序性死亡的差异,并阐述TVPEs、metacaspases和saspases三种类caspases蛋白酶在植物程序性细胞死亡中所起的作用。     

多胺参与细胞程序性死亡调控的研究进展

多胺被认为是影响细胞存活的一个关键分子。有证据显示,多胺可直接或间接参与细胞程序性死亡的调控。多胺与细胞程序性死亡直接相关,是指其参与特定的生物学过程及与导致细胞程序性死亡的分子/结构发生相互作用;间接相关,是指多胺通过调控细胞程序性死亡的代谢衍生物,如异化和互变产物来调控这一过程。此外,多胺代谢过程中的细胞毒性产物也参与到细胞程序性死亡的级联反应中。因此,对动植物中依赖于多胺的细胞程序性死亡的最新研究进展进行综述,可为进一步研究提供一些参考。     

植物细胞程序性死亡中的类caspases 蛋白酶

细胞程序性死亡对于植物的正常生长发育及病理过程具有十分重要的生物学意义。现有的实验证据表明, 细胞程序性死亡在动物和植物中有许多相似之处, 但也各有特点。在植物中, VPEs、metacaspases和saspases 等酶类在细胞程序 性死亡过程中发挥了关键性作用。该文详细比较了动、植物细胞程序性死亡的差异, 并阐述了VPEs 、metacas pases 和saspases三种类caspases蛋白酶在植物程序性细胞死亡中所起的作用。     

细胞程序性死亡的非Caspase依赖型途径

程序性细胞死亡是一种程序化的主动性细胞死亡,半胱胺酸天冬氨酸特异性蛋白酶家族(在该过程中起着不可忽视的作用.基于Caspase在程序性细胞死亡过程中所起的作用,将程序性细胞死亡分为两大类:Caspase依赖型和Caspase非依赖型.前者即典型的凋亡,后者包括自体吞噬、副凋亡、有丝分裂灾变、凋亡样程序性死亡、坏死样程序性死亡等.这些Caspase非依赖型的细胞程序性死亡途径与生理及病理现象密切相关.     

细胞程序性死亡通路的研究进展

细胞程序性死亡(programmed cell death,PCD)一直被看做是细胞凋亡(apoptosis).随着细胞生物学研究的深入,新的细胞死亡途径逐渐被揭示出来,如胀亡、自噬、副凋亡等.这些通路有些是caspase依赖的,有些不依赖于caspase途径.在细胞程序性死亡过程中,各种通路不是单独起作用的,而是相互交联的,有彼此重叠的机制出现.目前,Clarke形态学分类法是得到大多数学者认可的细胞程序性死亡的分类方式.按照该分类法,可将PCD分为3大类,即:Ⅰ型细胞程序性死亡、Ⅱ型细胞程序性死亡和Ⅲ型细胞程序性死亡.     

上海四膜虫大核类似程序性死亡的诱导

足叶乙甙可以诱导上海四膜虫大核在形态和生化方面出现类似程序性死亡的典型特征,如染色质凝集成颗粒状;分散的核仁连接成串;ＤＮＡ凝胶电泳出现阶梯状条带;彗星电泳出现慧尾。这就提示,利用足叶乙甙诱导四膜虫大核发生类似程序性死亡是一个有用的实验模式,它可能对阐明在自然状态下大核类似程序性死亡的机理有启发和借鉴意义。同时也提出了染色体形态特征变化和彗星电泳有可能作为鉴定四膜虫大核发生类似程序性死亡的指标。     

细胞程序性死亡在植物适应逆境中的意义

细胞程序性死亡是近年来生命科学的研究热点之一,它不仅在植物生长发育中起重要作用,而且与植物适应逆境也密切相关。本文就细胞程序性死亡在植物适应逆境中的重要作用进行了综述,以期对细胞程序性死亡的研究进一步深入和对植物适应逆境的潜力有新的认识。     

胱冬肽酶非依赖性的细胞程序性死亡

在多细胞有机体的组织内稳态维持和正常发育过程中,细胞程序性死亡发挥着重要的作用。细胞程序性死亡有多种形式(如细胞凋亡、类细胞凋亡和类坏死等),其中了解较清楚的是细胞凋亡。一直以来,胱冬肽酶(caspase)被认为是细胞凋亡发生中关键的一种蛋白酶。但是最近的研究表明,包括细胞凋亡在内的一些细胞程序性死亡可以以一种不依赖胱冬肽酶的方式发生。细胞程序性死亡与胱冬肽酶之间存在非依赖性关系。     

缺血性脑损伤与程序性死亡

脑缺血后细胞会产生程序性死亡（ｐｒｏｇｒａｍｍｅｄ ｃｅｌｌ ｄｅａｔｈ,ＰＣＤ）,并参与脑损伤;神经元的迟发性死亡属于ＰＣＤ。脑缺血后细胞内钙增加,一氧化氮的生产、脂质过氧化反应、Ｐ５３基因的表达等,在程序性死亡的形成中具有重要作用。     

巨噬细胞凋亡及其调控

巨噬细胞通过介导和调控自身及其他细胞凋亡而实现其免疫调节和效应细胞功能.引起巨噬细胞凋亡的原因有生物、化学、病理、自身等因素.不仅巨噬细胞自身凋亡和凋亡调控有其特点,更为有趣的是,巨噬细胞可根据需要：介导或抑制自身凋亡;介导或抑制其他细胞凋亡;抑制自身凋亡,介导其他细胞凋亡.这可能是巨噬细胞在免疫调节,特别是肿瘤免疫中发挥重要作用的基础.     

雷帕霉素对二种鳞翅目昆虫细胞自噬和凋亡的影响

以2种鳞翅目昆虫细胞为材料,采用雷帕霉素进行处理,初步研究自噬作用与昆虫细胞凋亡的关系。结果表明:雷帕霉素能够提高家蚕细胞系BMN-e细胞的自噬水平,并能诱导BMN-e细胞发生凋亡;自噬抑制剂3-甲基腺嘌呤能抑制雷帕霉素诱导的BMN-e细胞凋亡。相反,雷帕霉素虽能诱导斜纹夜蛾细胞系SL-HP细胞的自噬水平提高,但不能诱导斜纹夜蛾Spodoptera litura(Fabricius)细胞发生凋亡;雷帕霉素的预处理能抑制放线菌素D诱导的斜纹夜蛾细胞系SL-HP细胞发生凋亡;自噬抑制剂3-甲基腺嘌呤对放线菌素D诱导的细胞凋亡没有影响。因此家蚕Bombyx mori细胞自噬水平的提高与细胞凋亡具有正相关性,而斜纹夜蛾细胞自噬水平的提高与细胞凋亡不相关,相反还对细胞凋亡的诱导具有一定的抑制作用。     

Glycochenodeoxycholic acid (GCDC) induced hepatocyte apoptosis is associated with early modulation of intracellular PKC activity

The effect of GCDC-induced apoptosis on PKC activity and PKC's role in GCDC-induced hepatocyte apoptosis is unclear. The specific aims of this study were to determine if GCDC-induced apoptosis changed intracellular PKC activity and if modulation of PKC activity affected GCDC-induced hepatocyte apoptosis.Apoptosis was induced in isolated hepatocytes using GCDC. PKC activity was measured and specific PKC and calpain inhibitors were used to study the effects of PKC and calpain modulation on GCDC-induced apoptosis.After 4 h exposure, 50 M GCDC induced apoptosis in 42% of hepatocytes. Intracellular PKC activity decreased to 44% of controls 2 h after exposure of hepatocytes to GCDC (p < 0.001). Pre-incubation of hepatocytes with the calpain protease inhibitor restored PKC activity in GCDC exposed hepatocytes to 91± 5% of control cells. Pre-incubation of hepatocytes with a calpain inhibitor decreased GCDC-induced apoptosis as did pre-incubation with the PKC activating phorbol ester, PMA. The combination of calpain inhibition and PMA further reduced GCDC-induced apoptosis but caused low level hepatic apoptosis. Inhibition of PKC with chelerythrine also substantially reduced GCDC-induced hepatocyte apoptosis.GCDC-induced apoptosis is associated with decreases in total cellular PKC activity, which appear to be dependent on intracellular calpain-like protease activity. The combination of protease inhibition and phorbol ester pretreatment preserved total cellular PKC activity and decreased GCDC-induced apoptosis but induced low level apoptosis in the absence of GCDC exposure. PKC inhibition also decreased GCDC-induced hepatocyte apoptosis highlighting the complex interactions of PKC and proteases during GCDC-induced apoptosis.     

Radiation-induced apoptosis and its relationship to loss of clonogenic survival

Ionizing radiation can be an effective inducer of apoptosis and studies of many aspects of the pathways and mechanisms involved in this apoptosis induction have been published. This review stresses two aspects: the relationship between apoptosis and loss of clonogenic ability in irradiated cells and the time course for the appearance of apoptosis after radiation exposure. Although it was initially assumed that apoptosis occurred relatively quickly (within hours) after irradiation, evidence is presented and discussed here showing that apoptosis can occur at long times after irradiation (out to 20 days) in some cell types. This late, or delayed, apoptosis occurs after the cells have divided once or several times. The impact of delayed apoptosis on loss of clonogenicity after irradiation remains unclear. It seems likely that in some cell types, e.g., fibroblasts, the occurrence of late apoptosis is minimal and may have little impact on long term cell survival of the population, but in at least one instance, with a cell line of hematopoietic origin, it appears that late apoptosis can account for all the loss of clonogenicity in irradiated cells. The role of p53 in radiation-induced apoptosis is also discussed, with data presented showing that both p53-dependent and independent pathways for radiation-induced apoptosis exist, depending on the cell type.     

Usefulness of R72H PCR assay for differentiation between Vibrio parahaemolyticus and Vibrio alginolyticus species: validation by DNA-DNA hybridization

Cell death by apoptosis is a common response to environmental stimuli and a frequent event in a multicellular organism. Not surprisingly, apoptosis is also found in microbial infections where it may contribute to progression and outcome. Perhaps less predictably, a number of bacteria have also been found to alleviate or even to inhibit apoptosis. Today we are at a point where our in some parts detailed knowledge of the molecular pathway to apoptosis allows us to probe situations in biology for the occurrence of apoptosis and to inquire into mechanisms of apoptosis induction and inhibition. In this brief article we will focus on anti-apoptotic activities exhibited by various bacteria. We will attempt to present the current knowledge on how the contact between mammalian and bacterial cell decrees resistance to apoptosis, what the respective contributions of the two partners are and how this interaction relates to the molecular path to apoptosis.     

Phenoptosis in yeasts

The current view on phenoptosis and apoptosis as genetic programs aimed at eliminating potentially dangerous organisms and cells, respectively, is given. Special emphasis is placed on apoptosis (phenoptosis) in yeasts: intracellular defects and a plethora of external stimuli inducing apoptosis in yeasts; distinctive morphological and biochemical hallmarks accompanying apoptosis in yeasts; pro- and antiapoptotic factors involved in yeast apoptosis signaling; consecutive stages of apoptosis from external stimulus to the cell death; a prominent role of mitochondria and other organelles in yeast apoptosis; possible pathways for release of apoptotic factors from the intermembrane mitochondrial space into the cytosol are described. Using some concrete examples, the obvious physiological importance and expediency of altruistic death of yeast cells is shown. Poorly known aspects of yeast apoptosis and prospects for yeast apoptosis study are defined.     

A New Fungal Diterpene Induces VDAC1-dependent Apoptosis in Bax/Bak-deficient Cells

The pro-apoptotic Bax and Bak proteins are considered central to apoptosis, yet apoptosis occurs in their absence. Here, we asked whether the mitochondrial protein VDAC1 mediates apoptosis independently of Bax/Bak. Upon screening a fungal secondary metabolite library for compounds inducing apoptosis in Bax/Bak-deficient mouse embryonic fibroblasts, we identified cyathin-R, a new cyathane diterpenoid compound able to activate apoptosis in the absence of Bax/Bak via promotion of the VDAC1 oligomerization that mediates cytochrome c release. Diphenylamine-2-carboxilic acid, an inhibitor of VDAC1 conductance and oligomerization, inhibited cyathin-R-induced VDAC1 oligomerization and apoptosis. Similarly, Bcl-2 overexpression conferred resistance to cyathin-R-induced apoptosis and VDAC1 oligomerization. Silencing of VDAC1 expression prevented cyathin-R-induced apoptosis. Finally, cyathin-R effectively attenuated tumor growth and induced apoptosis in Bax/Bak-deficient cells implanted into a xenograft mouse model. Hence, this study identified a new compound promoting VDAC1-dependent apoptosis as a potential therapeutic option for cancerous cells lacking or presenting inactivated Bax/Bak.     

Apoptosis and anticancer drug resistance.

Anticancer agents induce cancer cell death through apoptosis or necrosis. As anticancer agents at low and high concentrations cause apoptosis and necrosis, respectively, cancer cells may be merely injured by an anticancer agent in apoptosis, and cell death may result from an activation of the internal constituents to induce apoptosis. Therefore, an alternation of apoptotic pathway must change the efficacy of anticancer agents. As an escape of cancer cells from apoptosis seems to be closely associated with the development of anticancer resistance, this report focuses on mechanisms of apoptosis and its association with anticancer resistance. A Bax induces apoptosis mitochondria-dependently, whereas Fas can induce apoptosis mitochondria-independently. An interaction of Bax and Bcl-2 is very important to decide cell life or death, and Bcl-2 phosphorylation may control this interaction: Paclitaxel treatment induced Bcl-2 phosphorylation and typical apoptosis, whereas hyperthermia induced not Bcl-2 phosphorylation but nuclear translocation and failed to induce apoptosis. Moreover, Fas was localized in the cytoplasm of exponentially growing cells and on the cell membrane of confluent cells. We would like to emphasize that it is very important to check the localization of constituents of apoptosis in order to evaluate the susceptibility of cancer cells to apoptosis.