沙眼衣原体通过激活MAPK/ERK信号通路抑制宿主细胞凋亡

目的:研究沙眼衣原体抑制宿主细胞凋亡活性与MAPK/ERK信号通路的关系。方法:利用化学抑制剂U0126阻断MAPK/ERK信号通路,然后分别采用流式细胞术、Caspase-3活性检测试剂盒和Western Blot实验检测沙眼衣原体感染细胞在凋亡诱导剂Etoposide作用下细胞凋亡率和Caspase-3活性变化,以及PARP是否发生裂解。结果:当MAPK/ERK信号通路被阻断时,在Etoposide的作用下,沙眼衣原体感染细胞凋亡率明显上升,同时Caspase-3被活化和PARP发生裂解。结论:沙眼衣原体抑制宿主细胞凋亡活性与MAPK/ERK信号通路激活有关。     

衣原体抗宿主细胞凋亡调控机制研究进展

衣原体为完成发育周期以及逃避宿主免疫,进化形成一整套机制以实现持续性感染并对宿主细胞进行调控,抑制宿主细胞凋亡。细胞感染衣原体后,早期可以抑制Caspase酶系,抑制相关信号转导途径,且胞内线粒体发生一系列结构和功能的变化,抑制凋亡因子释放,一系列因子协同作用,抑制宿主细胞凋亡。本文从凋亡途径、凋亡蛋白、凋亡信号通路三个主要方面作了衣原体抑制宿主细胞凋亡机制概述,对进一步了解衣原体发育及其致病机制提供了新的研究思路。     

衣原体调控宿主细胞凋亡的机制研究进展

衣原体是一类专性细胞内寄生的原核微生物,常引起性传播疾病、失明和肺炎等疾病。衣原体可能已经进化出调控宿主细胞的若干机制,通过改变宿主细胞蛋白位置,干扰宿主细胞凋亡信号通路等来抑制细胞凋亡,维持其自身的存活,核转录因子NF-κB也涉及到衣原体感染细胞凋亡抑制;衣原体可以经半胱氨酸蛋白酶依赖途径等机制诱导细胞凋亡,进而感染邻近细胞。     

沙眼衣原体感染HeLa229细胞Bim表达及抑制凋亡研究

研究沙眼衣原体(D血清型)感染的HeLa229细胞中Bim蛋白质的表达及凋亡诱导剂作用后的凋亡情况。Western-blot检测沙眼衣原体感染和未感染的HeLa229细胞Bim蛋白质的表达水平。凋亡诱导剂etopo- side作用HeLa229细胞后,经Hoechst33258染色用荧光显微镜观察核浓缩和凋亡小体;流式细胞仪检测凋亡率。HeLa229细胞在未感染及感染沙眼衣原体6 h后可检测到Bim的表达;在感染24、48 h后均未检测到Bim的表达。经etoposide作用后,未感染的HeLa229细胞观察到明显的核浓缩和凋亡小体;流式细胞仪检测的凋亡率为90.64%。感染24 h的HeLa229细胞,未观察到核浓缩和凋亡小体;流式细胞仪检测的凋亡率为11.50%,与未感染的HeLa229细胞诱导后的凋亡率比较有统计学意义(P<0.05)。沙眼衣原体感染HeLa229细胞后可降低Bim蛋白质的表达;并能抑制etoposide诱导的细胞凋亡。     

细胞凋亡的分子机制

多细胞生物在发生,发展过程中,为了保持正常的生理机能,一部分的细胞发生自发性细胞死亡,这种细胞死亡是被细胞内一系列相关性的分子所调控,并伴随有典型的形态学改变,这种现象被称为细胞凋亡（ａｐｏｐｔｏｓｉｓ）作为一种积极排队生物体内的过剩细胞和有害细胞的机制在个体形态形成,形态改变等发生过程中,成体的恒常性的维持以及生物体的防御等方面发挥作用,此外在许多病理状态下也存在着细胞凋亡,近年的研究已经明确了     

沙眼衣原体感染细胞中IFN—γ信号通路的初步研究

研究IFN γ诱导激活沙眼衣原体感染细胞中信号转导。采用Westernblotting检测IFN γ作用于沙眼衣原体K型株感染的McCoy细胞引起蛋白激酶磷酸化及其对Jak1,Stat1p91诱导活化的浓度效应和时相特点。IFN γ可以在短时间内引起沙眼衣原体感染细胞蛋白激酶的瞬时磷酸化 ;并在短时间内激活Jak1,Stat1p91,不同浓度作用下 ,5 μg/L时达最大活化 ;10min时活化程度最高。IFN γ可诱导沙眼衣原体感染细胞蛋白激酶磷酸化 ;并激活Jak1,Stat1p91。     

细胞凋亡抑制因子

细胞凋亡 (ａｐｏｐｔｏｓｉｓ)是一种细胞的生理性自杀行为 ,对保持周围组织的健康和正常生长具有十分重要的意义。细胞凋亡的紊乱与许多致病性疾病的发生有关 ,涉及细胞凋亡过度的疾病如ＡＩＤＳ、神经变性紊乱、局部缺血等 ;涉及到细胞凋亡程度过低而导致的疾病如癌症的发生等。因此对细胞凋亡途径具有调节作用的蛋白质引起人们的广泛关注。ＩＡＰ(ｉｎｈｉｂｉｔｏｒｏｆａｐｏｐｔｏｓｉｓ)家族蛋白最早发现于杆状病毒 ,它能抑制由病毒感染而诱导的细胞凋亡。杆状病毒在长期进化过程中 ,为适应自身的生活环境及繁殖的需要 ,获得了一些…     

大鼠输卵管沙眼衣原体感染后体内树突状细胞的变化

目的观察大鼠输卵管沙眼衣原体(CT)感染后体内树突状细胞(DC)的变化.方法选择成年雌性Wistar大鼠,从卵巢囊接种沙眼衣原体E型株.于感染后第1/2d、7d、14d、21d、28d和第35d处死动物取材,显示输卵管和脾内DC的变化.结果 1. 实验1/2d组输卵管未出现S-100 DC,在实验第7d、14d、21d、28d和第35d组输卵管均有S-100 DC出现;2.感染后脾淋巴小结数量增多,体积较大,淋巴小结内S-100 DC密集,动脉周围淋巴鞘内S-100 DC增多.结论输卵管CT感染后,输卵管和脾内S-100 DC增加,提示在体内DC对CT具有抗原提呈和启动机体免疫应答的作用,DC具有作为CT治疗性疫苗基础构建的潜力.     

促凋亡基因p53AIP1的研究进展

p53AIPl基因是近年发现的促凋亡基因,在p53依赖性的凋亡通路中起重要作用。p53AIPl介导线粒体凋亡途径,其表达依赖于p53蛋白的Ser^46的磷酸化。p53AIPl可直接促进凋亡,其促凋亡作用可能强于p53本身,并对p53抗性的肿瘤细胞也有作用。因此,对p53AIPl的深入研究可能会为对p53基因治疗有抗性的肿瘤患者带来新的希望。     

NF-kappa B activation is not required for Chlamydia trachomatis inhibition of host epithelial cell apoptosis

Chlamydia trachomatis, an obligate intracellular bacterial species, is known to inhibit host cell apoptosis. However, the chlamydial antiapoptotic mechanism is still not clear. Because NF-kappaB activation is antiapoptotic, we tested the potential role of NF-kappaB activation in chlamydial antiapoptotic activity in the current study. First, no obvious NF-kappaB activation was detected in the chlamydia-infected cells when these cells were resistant to apoptosis induced via either the intrinsic or extrinsic apoptosis pathways. Second, inhibition of NF-kappaB activation with pharmacologic reagents failed to block the chlamydial antiapoptotic activity. Finally, NF-kappaB p65 gene deletion did not prevent chlamydia from inhibiting host cell apoptosis. These observations together have demonstrated that NF-kappaB activation is not required for the chlamydial antiapoptotic activity.     

EB病毒免疫逃逸的分子机制

EB病毒(Epstein-Barr vius,EBV)是一种最广泛的对人类感染的γ疱疹病毒,与人类多种疾病尤其是恶性肿瘤有关。其致病的一个重要条件是能够在人体B细胞中长期潜伏,并且在人体免疫力低下时被激活并增殖,这表明EB病毒存在逃逸宿主细胞免疫的机制。从潜伏期EB病毒基因表达的下调、干扰抗原加工和提呈、调节细胞毒性T细胞(Cytotoxic lymphocyte,CTL)免疫应答、干扰细胞因子的作用、干扰CTL的活动及抑制宿主细胞凋亡、抑制辅助性T细胞1(Helper T cell 1,Th1)免疫应答等方面,对EB病毒免疫逃逸的分子机制作一简要综述。     

Apaf1 inhibition promotes cell recovery from apoptosis

The protein apoptotic protease activating factor 1 (Apaf1) is the central component of the apoptosome, a multiprotein complex that activates procaspase-9 after cytochrome c release from the mitochondria in the intrinsic pathway of apoptosis. We have developed a vital method that allows fluorescence-activated cell sorting of cells at different stages of the apoptotic pathway and demonstrated that upon pharmacological inhibition of Apaf1, cells recover from doxorubicin- or hypoxia-induced early apoptosis to normal healthy cell. Inhibiting Apaf1 not only prevents procaspase-9 activation but delays massive mitochondrial damage allowing cell recovery.     

沙眼衣原体疫苗候选抗原研究进展

沙眼衣原体(CT)是引起感染性致盲的首要病因,也是引起性传播疾病的主要病原体。CT感染缺乏明显的临床症状,临床上容易被忽视而引起严重的疾病,故疫苗是预防CT生殖道感染经济有效的措施之一。综述了CT疫苗候选抗原的结构特点,免疫保护作用及其在预防CT感染性疾病的应用前景。     

Epstein-Barr virus: inhibition of apoptosis as a mechanism of cell transformation

Epstein-Barr virus is a potent mitogen for human B lymphocytes and is associated with a large number of human malignancies. This large virus expresses several genes that may contribute to the transformed phenotype of infected cells and it possesses multiple strategies for the inhibition of apoptosis. The interferon-inducible protein kinase PKR is an important target for the anti-apoptotic actions of the virus and its activity is regulated by the small untranslated RNA, EBER-1. This review summarizes the mechanisms of action of EBER-1 and other Epstein-Barr virus gene products in the regulation of apoptosis, and presents a model of how EBER-1 exerts its effects on PKR activity.     

Accumulation of diacylglycerol in the Chlamydia inclusion vacuole: possible role in the inhibition of host cell apoptosis

Intracellular pathogens have developed strategies to survive for extended periods inside their host cells. These include avoidance of host microbicidal effectors, often by sequestration in a protected subcompartment of the host cell. In some cases, the parasites exert also an antiapoptotic effect that prolongs the life of the infected host cell. Chlamydia utilizes both strategies, but the underlying molecular mechanisms are incompletely understood. Comparatively, little is known regarding the effects that Chlamydia exerts on the metabolism and distribution of the host cell lipids. The expression of fluorescently tagged C1 domains revealed that diacylglycerol is greatly accumulated in the immediate vicinity of Chlamydia inclusion vacuoles. The concentrated diacylglycerol recruits protein kinase Cdelta (PKCdelta), a proapoptotic effector, to the immediate vicinity of the vacuole. PKCdelta normally exerts its pro-apoptotic effects at the mitochondria and in the nucleus. We speculate that Chlamydia antagonizes the pro-apoptotic effect of PKCdelta by sequestering the enzyme on the inclusion vacuole away from its conventional target sites. Accordingly, we found that the ectopic expression of a catalytic fragment of PKCdelta that cannot be recruited by the vacuole, because it lacks a functional C1 domain, overcame the anti-apoptotic effect of the bacteria. The scavenging of pro-apoptotic factors may provide a novel mechanism whereby pathogens promote their own survival by extending the life of the host cells they infect.     

A competition model for viral inhibition of host cell proliferation

Some viruses encode proteins that promote cell proliferation while others, such as the human immunodeficiency virus (HIV), encode proteins that prevent cell division. It has been hypothesized that the selective advantage determining which strategy evolves depends on the ability of the virus to induce a cellular environment which maximizes both virus production and cell life span. In HIV, the protein that causes cell cycle arrest is Vpr. In this paper, we develop a mathematical model, based on difference equations, to study the competition between two genotypes of HIV - one that encodes this protein (Vpr+) and one that does not (Vpr-). In particular, we are interested in parameters that could be different between the in vitro condition, where the Vpr- genotype dominates, and the in vivo condition, where the Vpr+ genotype dominates. Our model indicates that the infected cell death-rate, the viral half-life, and the dynamics of the target cell population all effect the competition dynamics between the Vpr+ and Vpr- viral genotypes. Perturbing any of these parameters from the in vitro estimates while holding the others fixed has no affect on the competition outcome, i. e., the Vpr- genotype dominates. Perturbing the infected cell death-rate and the target cell source causes a switch in competitive outcome, although not necessarily at values, which represent the in vivo condition. Adding a perturbation in the viral half-life from in vitro to in vivo condition results in a switch of the competitive advantage from the Vpr- genotype to the Vpr+ genotype with parameters for all three mechanisms set to estimated in vivo values.