The effects of fluorescent protein recombinant plasmid with XIAP and OMI/HTRA2 on HeLa cells

目的 探讨XIAP、Omi/HtrA2、米非司酮对HeLa细胞凋亡的影响以及XIAP、Omi/HtrA2的相互作用.方法 细胞转染、米非司酮诱导HeLa细胞凋亡,利用共聚焦显微镜及流式细胞术观察XIAP、Omi/HtrA2在细胞内的表达和定位,并检测其对HeLa细胞凋亡影响的情况,使用共聚焦显微镜检测XIAP、Omi/HtrA2的相互作用.结果 (1)在转染了重组质粒pDsRed2-XIAP、pDsRed2-Omi/HtrA2的HeLa细胞中,加入米非司酮后其凋亡率分别是:只加米非司酮组为46.16%;米非司酮+转染质粒pDsRed2-XIAP为26.41%;米非司酮+转染质粒pDsRed2-Omi/HtrA2为78.85%.(2)利用共聚焦显微镜检测XIAP、Omi/HtrA2在HeLa细胞中存在能量共振转移现象.结论 米非司酮能促进HeLa细胞凋亡;DsRed2-XIAP融合蛋白能够抑制由米非司酮诱导的HeLa细胞凋亡;DsRed2-Omi/HtrA2融合蛋白能够促进HeLa细胞凋亡,米非司酮能增加Omi/HtrA2促凋亡作用.在活HeLa细胞中,利用荧光共振能量转移技术直接证实XIAP与Omi/HtrA2在部分细胞中存在相互作用.     

XIAP、OMI/HTRA2蛋白对HeLa细胞的影响及两种蛋白间相互作用

目的探讨XIAP、Omi/HtrA2、米非司酮对HeLa细胞凋亡的影响以及XIAP、Omi/HtrA2的相互作用。方法细胞转染、米非司酮诱导HeLa细胞凋亡,利用共聚焦显微镜及流式细胞术观察XIAP、Omi/HtrA2在细胞内的表达和定位,并检测其对HeLa细胞凋亡影响的情况,使用共聚焦显微镜检测XIAP、Omi/HtrA2的相互作用。结果 (1)在转染了重组质粒pDsRed2-XIAP、pDsRed2-Omi/HtrA2的HeLa细胞中,加入米非司酮后其凋亡率分别是:只加米非司酮组为46.16%;米非司酮+转染质粒pDsRed2-XIAP为26.41%;米非司酮+转染质粒pDsRed2-Omi/HtrA2为78.85%。(2)利用共聚焦显微镜检测XIAP、Omi/HtrA2在HeLa细胞中存在能量共振转移现象。结论米非司酮能促进HeLa细胞凋亡;DsRed2-XIAP融合蛋白能够抑制由米非司酮诱导的HeLa细胞凋亡;DsRed2-Omi/HtrA2融合蛋白能够促进HeLa细胞凋亡,米非司酮能增加Omi/HtrA2促凋亡作用。在活HeLa细胞中,利用荧光共振能量转移技术直接证实XIAP与Omi/HtrA2在部分细胞中存在相互作用。     

线粒体在细胞凋亡中的作用及分子机制

本文综述了线粒体在细胞凋亡的启动和调控方面的最新进展。细胞受凋亡刺激,Bcl-2家族BH3蛋白(Bim,Bad,Bid等)和其他可能的途径将凋亡信号转入线粒体中,与Bcl-2家族凋亡诱导蛋白共同调节,诱导释放线粒体凋亡蛋白细胞色素c、caspase的二级线粒体激活蛋白Smac、凋亡诱导蛋白、内核酸酶G和Omi/HtrA2等,进而通过caspase依赖途径和非依赖途径诱导细胞凋亡。     

线粒体在细胞凋亡中的作用及分子机制

本文综述了线粒体在细胞凋亡的启动和调控方面的最新进展。细胞受凋亡刺激，Bcl-2家族BH3蛋白(Bim，Bad，Bid等)和其他可能的途径将凋亡信号转入线粒体中，与Bcl-2家族凋亡诱导蛋白共同调节，诱导释放线粒体凋亡蛋白细胞色素c、caspase的二级线粒体激活蛋白Smac、凋亡诱导蛋白、内核酸酶G和Omi/HtrA2等，进而通过caspase依赖途径和非依赖途径诱导细胞凋亡。     

HBSP抑制缺氧复氧心肌H9C2细胞Omi/HtrA2胞内转位及细胞凋亡

目的探讨促红细胞生成素衍生肽(HBSP)对缺氧复氧心肌细胞Omi/Htr A2胞内转位及细胞凋亡的影响。方法将乳鼠心肌细胞(H9C2细胞)分为对照(Ctrl)组、缺氧复氧(H/R)组、HBSP组和EPO组。培养结束后MTS法检测细胞存活率,酶标仪检测细胞上清液中LDH释放率,Western blot检测细胞内cleaved caspase-3表达,TUNEL法检测心肌细胞凋亡;分离H9C2细胞胞质及线粒体,Western blot分别检测线粒体及细胞质Omi/Htr A2表达。结果与Ctrl组相比,H/R组细胞存活率下降(P0.05),LDH释放、cleaved caspase-3表达、心肌细胞凋亡及Omi/Htr A2胞内转位均明显上升(P0.05);与H/R组相比,EPO组的细胞存活率升高(P0.05),LDH释放降低、cleaved caspase-3表达减弱、心肌细胞凋亡减少、Omi/Htr A2线粒体转位明显减少(P0.05);随着HBSP浓度的增加,各组细胞存活率逐渐上升,LDH释放、cleaved caspase-3表达、心肌细胞凋亡及Omi/Htr A2胞内转位率逐渐下降(P0.05)。结论 HBSP具有与EPO类似的保护作用,可抑制经H/R诱导的心肌细胞凋亡,其机制可能是通过减少Omi/Htr A2蛋白的胞内转位,抑制caspases通路激活,进而发挥细胞保护作用。     

Fas／FasL在超抗原SEA诱导T细胞凋亡中的作用

目的超抗原能诱导 T细胞凋亡 ,但其作用机制尚未阐明 ,Fas系统与 Ca2 在其中的作用尚待进一步研究。方法超抗原金黄色葡萄球菌肠毒素 A(SEA)诱导人外周血建立的短期 SEA反应 T细胞系凋亡 ,1.8%琼脂糖凝胶 DNA电泳于不同时间观察凋亡的特征条带 ;FCM检测 Fas、Fas L 的表达量变化 ,Fura- 2 / AM荧光指示剂检测胞浆游离 [Ca2 ]i的变化。结果使用 FCM特异性检测凋亡亚 G0 / G1峰大小及 1.8%琼脂糖凝胶电泳检测凋亡 DNA梯状图谱证明 ,SEA能诱导短期 SEA反应 T细胞凋亡 ,其凋亡的时间与程度与 SEA的剂量有关。SEA1μg/ ml建立的短期 SEA反应 T细胞对 SEA1μg/ml的再次刺激 ,凋亡量随作用时间的延长而增多 ,在作用的第 16 h最高 ,达 5 8%。 FCM间接荧光染色法检测发现 ,Fas及Fas L 亦随 SEA作用时间的延长而表达增多 ,16 h时表达最多 ,分别为 92 %和 6 0 %。用 Fura- 2 / AM荧光指示剂检测 ,此时细胞胞浆 [Ca2 ]i已从刺激前的 (2 90± 33) nm ol/ L 上升到 (6 80± 16 ) nmol/ L。结论 Fas系统与 SEA诱导的 T细胞凋亡密切相关。换言之 ,Fas系统在超抗原诱导 T细胞凋亡中起作用 ,而胞浆 [Ca2 ]i升高与 SEA诱导的凋亡 T细胞 DNA断裂及其它凋亡形态变化有关。     

p38 MAPK基因敲除对亚砷酸盐诱导细胞凋亡的影响

目的： 研究p38丝裂原活化蛋白激酶（MAPK）在应激刺激诱导的细胞凋亡中的作用。方法: p38+/+和p38-/-细胞用NaAsO₂刺激后，用多聚甲醛固定及DAPI染核，利用荧光显微镜观察细胞核的形态改变。NaAsO₂刺激的p38+/+和p38-/-细胞用Annexin V-FITC与PI双标后，用流式细胞分析仪分析细胞凋亡百分率。结果: NaAsO₂刺激后，大部分p38-/-细胞产生典型的凋亡细胞形态学变化，p38+/+细胞仅少数细胞出现核固缩。而且，p38-/-细胞中凋亡细胞百分率较刺激前和p38+/+细胞都显著增加，而p38+/+细胞的凋亡率没有明显变化。结论: p38基因敲除使细胞对亚砷酸盐应激刺激的耐受性下降，容易发生凋亡；p38丝裂原活化蛋白激酶可能在提高细胞的应激适应能力上发挥着重要的作用。     

脉冲电场对肝癌细胞的凋亡诱导效应及线粒体跨膜电位的影响研究

为研究脉冲电场对肿瘤细胞的杀伤作用,采用Annexin V-FITC凋亡试剂盒和流式细胞技术检测电脉冲(1kV/cm、100μs和1 Hz)作用后人肝癌细胞HepG2和人肝细胞L02在不同作用时间点(8、15、30和60 s)下的凋亡效应。实验结果表明:与对照组相比,8 s刺激时间不足以诱导HepG2细胞凋亡,而15、30和60 s的刺激时间与可以明显的诱导HepG2凋亡,并且凋亡率随刺激时间增加而增大,说明延长刺激时间可以增大肿瘤细胞的凋亡程度;另外,在刺激60 s时,肿瘤细胞凋亡率是正常细胞的2倍,这表明肿瘤细胞比正常细胞对电脉冲的刺激更敏感。采用罗丹明123探针染色,用激光共聚焦显微镜实时观测细胞的线粒体膜电位荧光强度变化,观察到电刺激30 s前细胞线粒体膜电位无明显变化,而30 s后开始出现膜电位陡升后急剧降低的变化现象,揭示线粒体途径可能是脉冲诱导肿瘤细胞凋亡的机理之一。     

沙眼衣原体pORF5 蛋白通过激活PI3K / Akt 信号通路抑制细胞凋亡

目的:探讨沙眼衣原体(Chlamydia trachomatis,Ct)pORF5 蛋白对细胞凋亡的影响,并进一步分析其分子机制,为阐明Ct 致病机制提供实验依据。方法:pGEX-6p/ pORF5 重组质粒转化XL1-blue 大肠杆菌,IPTG 诱导表达GST-pORF5融合蛋白,融合蛋白经谷胱甘肽琼脂糖凝胶4B 纯化及蛋白酶切除GST 标签后得到pORF5 蛋白。用不同浓度的pORF5 蛋白刺激HeLa 细胞,Western blot 检测不同时间Bax 和Bcl-2 的表达水平以及PI3K/ Akt 磷酸化水平,Hoechst 33342 及流式细胞技术分析细胞凋亡情况;HeLa 细胞经PI3K/ Akt 特异性抑制剂LY294002 预处理1 h 后,再用pORF5 蛋白刺激24 h,测定细胞凋亡率,并进一步分析凋亡相关蛋白Bax 和Bcl-2 的表达水平及PI3K/ Akt 磷酸化水平。结果:凋亡相关蛋白Bax 和Bcl-2 的表达变化与pORF5 蛋白浓度呈现一定的浓度和时间依赖性,当pORF5 蛋白浓度达10 μg/ ml 时,Bax 表达下调,Bcl-2 的表达上调,当升高至15 μg/ ml 时,Bax 和Bcl-2 的表达量变化最明显;15 μg/ ml 的pORF5 蛋白刺激HeLa 细胞24 h,Bax 和Bcl-2 表达变化最明显;流式细胞检测结果显示:pORF5 蛋白刺激组较TNF鄄琢处理组和未处理组细胞凋亡率分别降低了27.3% (P<0.01)和8.4% (P<0.05);Akt 在pORF5 蛋白刺激15 min 后发生磷酸化,30 min 后磷酸化水平达到峰值,用PI3K 抑制剂LY294002 预处理Hela 细胞后,发现Akt 的磷酸化显著减少,Bax 蛋白表达明显上调,Bcl-2 表达明显下调;LY294002 处理组细胞凋亡率相比于对照组增加了13.0% (P<0.01)。结论:pORF5 蛋白通过激活PI3K/ Akt 信号通路调节Bcl-2 和Bax 蛋白的表达抑制细胞凋亡。     

肽聚糖通过TLR2诱导人绒毛外滋养细胞的凋亡及意义

目的初步研究肽聚糖通过Toll样受体2(TLR2)诱导人早孕绒毛外滋养细胞株TEV-1细胞的凋亡及其意义。方法免疫细胞化学检测TLR2蛋白在TEV-1细胞的定位表达,不同浓度肽聚糖刺激TEV-1细胞后AnnexinV/PI流式细胞术检测细胞的凋亡率。结果①TEV-1细胞表达TLR2,且定位于细胞膜和细胞浆。②30μg/ml肽聚糖刺激TEV-1细胞24小时后与对照组比较,细胞凋亡率无明显增加(8.17±0.1%,P>0.05),而刺激时间延长至48h可诱导出明显增加的细胞凋亡(16.03±1.51%,P<0.01);大剂量组80μg/ml肽聚糖刺激TEV-1细胞24h、48h均可诱导明显增加的细胞凋亡(14.13±1.06%和51.67±1.56%,P<0.01)。结论人绒毛外滋养细胞株TEV-1表达TLR2,肽聚糖可通过TLR2诱导TEV-1细胞凋亡,且存在时间和剂量依赖性,提示宫内感染时G+菌可能通过TLR2介导胎盘滋养细胞凋亡来影响妊娠的结局。     

Immunohistochemical analysis of Omi/HtrA2 expression in stomach cancer

The serine protease Omi/HtrA2 is released from mitochondria into the cytosol after apoptosis stimuli, inducing apoptosis in a caspase-independent manner through its protease activity and in a caspase-dependent manner by neutralizing the inhibition of inhibitor of apoptosis proteins (IAPs) on caspases. Alteration of apoptosis is essential for cancer development, and cancer cell death by radiation and chemotherapy is largely dependent upon apoptosis. Thus, analysis of the expression status of Omi/HtrA2, a regulator of apoptosis, in cancer tissues is needed for an understanding of cancer development. In the current study, we analyzed the expression of Omi/HtrA2 in 60 advanced gastric adenocarcinomas by immunohistochemistry using a tissue microarray approach. Immunopositivity (defined as >/=30%) was observed for Omi/HtrA2 in 43 (72%) of the 60 cancers. By contrast, the surface mucous cells and mucous neck cells in the normal gastric mucosa showed no or weak expression of Omi/HtrA2. Taken together, these results suggest that stomach cancer cells in vivo may need Omi/HtrA2 expression for apoptosis, and that Omi/HtrA2 expression might be involved in stomach cancer development.     

Loss of function mutations in the gene encoding Omi/HtrA2 in Parkinson's disease

Recently targeted disruption of Omi/HtrA2 has been found to cause neurodegeneration and a parkinsonian phenotype in mice. Using a candidate gene approach, we performed a mutation screening of the Omi/HtrA2 gene in German Parkinson's disease (PD) patients. In four patients, we identified a novel heterozygous G399S mutation, which was absent in healthy controls. Moreover, we identified a novel A141S polymorphism that was associated with PD (P<0.05). Both mutations resulted in defective activation of the protease activity of Omi/HtrA2. Immunohistochemistry and functional analysis in stably transfected cells revealed that S399 mutant Omi/HtrA2 and to a lesser extent, the risk allele of the A141S polymorphism induced mitochondrial dysfunction associated with altered mitochondrial morphology. Cells overexpressing S399 mutant Omi/HtrA2 were more susceptible to stress-induced cell death than wild-type. On the basis of functional genomics, our results provide a novel link between mitochondrial dysfunction and neurodegeneration in PD.     

Omi/HtrA2 catalytic cleavage of inhibitor of apoptosis (IAP) irreversibly inactivates IAPs and facilitates caspase activity in apoptosis

Omi/HtrA2 is a mitochondrial serine protease that is released into the cytosol during apoptosis to antagonize inhibitors of apoptosis (IAPs) and contribute to caspase-independent cell death. Here, we demonstrate that Omi/HtrA2 directly cleaves various IAPs in vitro, and the cleavage efficiency is determined by its IAP-binding motif, AVPS. Cleavage of IAPs such as c-IAP1 substantially reduces its ability to inhibit and ubiquitylate caspases. In contrast to the stoichiometric anti-IAP activity by Smac/DIABLO, Omi/HtrA2 cleavage of c-IAP1 is catalytic and irreversible, thereby more efficiently inactivating IAPs and promoting caspase activity. Elimination of endogenous Omi by RNA interference abolishes c-IAP1 cleavage and desensitizes cells to apoptosis induced by TRAIL. In addition, overexpression of cleavage-site mutant c-IAP1 makes cells more resistant to TRAIL-induced caspase activation. This IAP cleavage by Omi is independent of caspase. Taken together, these results indicate that unlike Smac/DIABLO, Omi/HtrA2's catalytic cleavage of IAPs is a key mechanism for it to irreversibly inactivate IAPs and promote apoptosis.     

A large-scale genetic association study to evaluate the contribution of Omi/HtrA2 (PARK13) to Parkinson's disease

High-profile studies have provided conflicting results regarding the involvement of the Omi/HtrA2 gene in Parkinson's disease (PD) susceptibility. Therefore, we performed a large-scale analysis of the association of common Omi/HtrA2 variants in the Genetic Epidemiology of Parkinson's disease (GEO-PD) consortium.GEO-PD sites provided clinical and genetic data including affection status, gender, ethnicity, age at study, age at examination (all subjects); age at onset and family history of PD (patients). Genotyping was performed for the five most informative SNPs spanning the Omi/HtrA2 gene in approximately 2-3 kb intervals (rs10779958, rs2231250, rs72470544, rs1183739, rs2241028). Fixed as well as random effect models were used to provide summary risk estimates of Omi/HtrA2 variants.The 20 GEO-PD sites provided data for 6378 cases and 8880 controls. No overall significant associations for the five Omi/HtrA2 SNPs and PD were observed using either fixed effect or random effect models. The summary odds ratios ranged between 0.98 and 1.08 and the estimates of between-study heterogeneity were not large (non-significant Q statistics for all 5 SNPs; I² estimates 0-28%). Trends for association were seen for participants of Scandinavian descent for rs2241028 (OR 1.41, p = 0.04) and for rs1183739 for age at examination (cut-off 65 years; OR 1.17, p = 0.02), but these would not be significant after adjusting for multiple comparisons and their Bayes factors were only modest.This largest association study performed to define the role of any gene in the pathogenesis of Parkinson's disease revealed no overall strong association of Omi/HtrA2 variants with PD in populations worldwide.     

Caspase activation by granzyme B is indirect,and caspase autoprocessing requires the release of proapoptotic mitochondrial factors

Apoptosis in response to granzyme B involves activation of caspase-dependent target cell death pathways. Herein, we show that granzyme B initiates caspase processing but cannot fully process procaspase-3 in intact Jurkat T leukemia or NT2 neuronal cells. Rather, the release from mitochondria of proapoptotic mediators cytochrome c, Smac/Diablo, and HtrA2/Omi facilitates full activation of caspases that results from autoprocessing. Bcl-2 overexpression in mitochondria suppresses the release of these proapoptotic molecules, resulting in cell survival despite partial procaspase processing by granzyme B. We propose that binding of inhibitor of apoptosis (IAP) proteins to partially processed procaspases inhibits cell death unless mitochondrial disruption also occurs in response to granzyme B or activated BH3-domain proteins such as truncated Bid.     

HtrA1 is a novel mast cell serine protease of mice and men

Mast cells are rich sources of proteases, such as tryptases and chymases that control many physiological and pathological processes, for example vascular permeability, smooth muscle cell proliferation or extracellular matrix remodeling. Murine mucosal mast cells mature under the influence of TGF-beta and play a role in asthmatic and anti-helminthic immune responses. In an attempt to identify novel genes that are highly upregulated during mucosal mast cell differentiation, we detected HtrA1 protease as a novel protein in mast cells by microarray experiments. HtrA1 level was much higher in murine mucosal than in connective tissue-type mast cells. Furthermore, HtrA1 is not localized in the secretory granules and is constitutively secreted by human mast cells. Although HtrA1 has been attributed a TGF-beta-inhibitory activity, it did not show any influence on TGF-beta-induced mucosal mast cell differentiation. As many extracellular target proteins have been suggested for HtrA1, this protease may participate in the mast cell-induced extracellular remodeling.     

The expression levels and prognostic value of high temperature required A2 (HtrA2) in NSCLC

High temperature required A2 (HtrA2) is a serine kinase that is released from mitochondria into the cytosol upon apoptotic stimuli, inducing apoptosis in various cancers. Thus, analysis of the expression of HtrA2 in non-small-cell lung cancer (NSCLC) tissues is needed for the understanding of this malignancy. In this study we firstly analyzed the apoptosis effect of HtrA2 in A549 cells by RNA interference and cisplatin with Western blot and flow cytometry. Then HtrA2 expression was evaluated by Western blot and immunohistochemistry in NSCLC tissues. Western blot and flow cytometry analyses indicated that deletion of HtrA2 was negatively correlated with apoptosis-induced protein in A549 cells. HtrA2 was lowly expressed in NSCLC and significantly associated with histological differentiation and clinical stage. Besides, low expression of HtrA2 was a prognostic factor for NSCLC patients’ inferior survival. In conclusion, HtrA2 might promote the apoptosis of NSCLC cells, and serve as a target for NSCLC's treatment.