线粒体电压依赖阴离子通道对携带线粒体DNAA4263G突变的细胞株线粒体钙循环的影响

目的 研究线粒体外膜电压依赖阴离子通道(voltage-dependent anion channel,VDAC)在携带线粒体DNA (mitochondrial DNA, mtDNA) A4263G突变的细胞株线粒体钙循环中的作用. 方法 对该家系的4个母系成员(3个血压异常和1个血压正常者)和3名遗传背景相同的对照者建立了传代淋巴细胞系,利用共聚焦显微镜评价VDAC在携带mtDNA A4263G突变的高血压患者细胞线粒体钙循环中的作用. 结果 与正常对照者淋巴细胞比较,突变细胞株线粒体内钙荧光强度及线粒体膜电势(Δψm)降低,加入苍术苷(线粒体通道蛋白开放剂)后正常者线粒体内钙荧光强度增加,而突变携带者没有明显改变,但两者Δψm均降低,加入环孢素A(CsA)后可以抑制苍术苷作用. 结论 线粒体VDAC功能异常导致mtDNA A4263G突变携带者细胞线粒体对钙通透性增加,Δψm降低,加入苍术苷进一步导致Δψm降低,加入CsA后可以抑制苍术苷作用.     

H.pylori对胃癌细胞线粒体外膜蛋白VDAC1表达的影响

目的观察幽门螺杆菌(H.pylori)作用于胃癌细胞后线粒体外膜蛋白VDAC1 mRNA及蛋白的表达变化,探讨H.pylori通过线粒体途径致凋亡的分子机制。方法H.pylori分别作用于胃癌细胞0、12、24、48 h后,收集细胞,应用RT-PCR和Western blot法检测各时相点VDAC1 mRNA和蛋白表达变化。结果H.pylori与胃癌细胞共培养12 h后,VDAC1 mRNA及蛋白的表达增加,24 h增加更明显,48 h达到高峰。VDAC1 mRNA及蛋白各时相点的表达量明显高于对照组(P<0.05)。结论H.pylori可能通过上调胃癌细胞线粒体外膜蛋白VDAC1 mRNA及蛋白的表达,引起线粒体外膜通透性改变,导致凋亡发生。     

线粒体DNA3537A→G、4824A→G、5351A→G突变与2型糖尿病的相关性研究

目的研究T2DM患者线粒体ND1基因3537A→G和ND2基因4824A→G、5351A→G突变与T2DM的相关性。方法应用PCR-RFLP技术检测145例T2DM和334例正常对照者（NC）线粒体DNA（mtDNA）3537A→G、4824A→G、5351A→G突变情况。结果NC组mtDNA4824A→G突变率高于T2DM组（P＜0．05）。3537A→G及5351A→G突变率在两组中无统计学差异（P〉0．05）。结论mtDNA4824A→G突变可能为T2DM患病的保护因素。3537A→G及5351A→G突变可能与T2DM不相关。     

S1通过线粒体途径诱导人卵巢癌细胞凋亡

目的探讨小分子化合物S1对人卵巢癌(SKOV3)细胞线粒体凋亡的影响。方法通过倒置显微镜观察S1作用卵巢癌细胞的形态学改变;不同剂量S1作用8 h,JC-1染色检测线粒体膜电势变化;Western印迹检测线粒体凋亡相关蛋白细胞色素(Cyto)c、Bcl-2和Bax蛋白表达的变化。结果与对照组相比S1作用24 h能明显诱导SKOV3凋亡;流式细胞术结果显示,S1引起SKOV3细胞线粒体膜电势降低(P<0.05,n=3);蛋白水平检测S1作用8 h能明显抑制SKOV3细胞Bcl-2蛋白表达,胞浆Cyto c和Bax蛋白表达增高(P<0.05,n=3)。结论 S1可能通过抑制Bcl-2蛋白诱导人卵巢癌细胞线粒体凋亡。     

突变的大肠癌线粒体DNA转染NIH3T3及LST细胞的研究

目的了解大肠癌细胞株（SW480，LOVO，HT29）线粒体DNA的突变，克隆突变的大肠癌线粒体DNA（mtDNA）基因，构建peDNA3．1（＋）-mtDNA真核表达重组体，并导入NIH3T3及LST细胞，以探讨线粒体基因突变与肿瘤发生的关系。方法提取大肠癌细胞株（SW480，LOVO，HT29）mtDNA，扩增D—LOOP区，产物用DNA自动测序法进行序列分析。利用DNA重组技术将其定向插入真核表达质粒peDNA3．1（＋），并用脂质体法导人NIH3T3及LST细胞。用MitoCa．ptureMitochondrialApoptosisDetectionKit试剂盒染色后用流式细胞仪及荧光显微镜检测转染细胞的凋亡情况。扩增并测序分析转染细胞的D—LOOP区突变特点。结果检测出大肠癌细胞株SW480，LOVO，HT29细胞mtDNAD—LOOP分别有10，9，8个突变位点。转染前后，各组间细胞凋亡无明显变化。转染细胞的核基因组可扩增出目的基因及Neo基因。4株NIH3T3转染细胞mtDNAD-环区分别检测到9，11，8，4个突变点，并相应有3，4，3，2个多态性变化。结论（1）转染突变的大肠癌细胞mtDNA后转染细胞的mtDNA均可发生多处的突变位点。（2）通过转染后突变的外源性的mtDNA可以整合到核基因组内。（3）突变的mtDNA转染LST细胞及NIH3T3细胞后，不影响转染细胞的凋亡改变。（4）mtDNA的突变可能通过影响体细胞mtDNA的突变和通过外源性mtDNA在核内的整合从而影响癌基因或抑癌基因的表达异常，从而参与肿瘤的发生发展。     

蛋白酶体抑制剂乳胞素对胶质母细胞瘤U87MG的抑制作用

目的目的探讨蛋白酶体抑制剂乳胞素对人胶质母细胞瘤U87MG的抑制作用。方法培养人胶质母细胞瘤U87MGM,分别以5、10、15μmol/L作用于细胞株。MTT法检测细胞存活率;bcl-2、Bax及caspase-3 mRNA水平用RT-PCR法检测;Rh123法检测线粒体膜电势;Hoechst33342检测细胞凋亡情况;U87MG细胞Bax及bcl-2的蛋白表达用Western印迹法检测。结果与未处理组相比对,U87MG细胞在实验组的存活率下降,bcl-2、Bax mRNA及蛋白表达和线粒体膜电势均下降,caspase-3 mRNA表达水平上升。结论在体外条件下,乳胞素对胶质母细胞瘤U87MG细胞具有较强的抑制效应。     

丹参酮ⅡA诱导人肝癌HepG2细胞凋亡的机制

目的探讨中药活性单体丹参酮ⅡA对人肝癌Hep G2细胞株增殖抑制和诱导凋亡的可能机制。方法用5、10、20、30、40、50μmol/L丹参酮ⅡA处理Hep G2细胞,应用MTT法分析细胞活力,MUSE细胞分析仪、PI染色等检测细胞增殖抑制、细胞周期以及凋亡情况。免疫蛋白印迹技术检测p53、Bax及Bcl-2等凋亡相关蛋白的表达。结果 5~50μmol/L丹参酮ⅡA显著降低细胞存活率(P0.01),形态学观察可见细胞凋亡改变,细胞发生G2/M期周期阻滞。免疫印迹结果显示丹参酮ⅡA上调p53、Bax蛋白的表达,下调Bcl-2蛋白的表达。结论丹参酮ⅡA对Hep G2细胞的增殖抑制作用可能部分通过诱导细胞G2/M周期阻滞和线粒体途径凋亡实现。     

线粒体通透性转换与非酒精性脂肪性肝病

线粒体通透性转换孔（MPTP）是由位于线粒体内、外膜,多蛋白成分组成的小分子通道,由其介导线粒体与胞浆间蛋白及离子转运。线粒体通透性转换（MPT）引起的质子转运导致线粒体膜电势崩塌,是引起ATP合成减少、能量失衡的重要原因;MPT的开放引起线粒体水肿及膜间隙促凋亡蛋白细胞色素c（cytochromec）等释放,一方面使线粒体呼吸链的完整性受损,加重细胞氧化应激损伤;另一方面则激活了细胞死亡机制。     

mtDNA突变与大肠癌发病关系的基础研究

目的观察大肠癌突变型mtDNA转导NIH3T3细胞后转染细胞的生物学特性。方法通过脂质体法（lipofection2000^TM）将大肠癌细胞突变的mtDNA真核表达载体转染NIH3T3细胞，利用G418抗性筛选克隆细胞：用荧光标记的染色体原位杂交（HSH）观察mtDNA在核内的整合情况；观察转染前后细胞异型性及进行染色体核型分析；PCR法检测转染细胞线粒体突变情况；流式细胞仪（FCM）检测转染细胞的凋亡情况；用四唑盐比色法（MTT）测定不同组间细胞增殖的吸光度值。结果突变的大肠癌mtDNA可通过影响NIH3T3细胞的mtDNA的突变、多态性和通过外源性mtDNA在核内的整合从而影响NIH3T3细胞的染色体核型及细胞增殖、凋亡等生物学行为。结论突变型mtDNA可能参与大肠癌的发生与发展。     

线粒体电压依赖性阴离子通道与心血管疾病

电压依赖性阴离子通道(VDAC)是位于线粒体外膜的通道蛋白,是线粒体与细胞质之间转运ATP以及其他代谢产物的主要通道,在线粒体代谢和细胞生长中发挥重要调控作用.近期研究发现,在心肌缺血再灌、糖尿病、心衰、高血压和动脉粥样硬化时,VDAC表达明显增加,引起细胞内钙离子循环紊乱、氧化应激,进而导致细胞凋亡,已成为心血管疾病研究的新热点.本文就VDAC的分子功能,调控及其在心血管疾病中的作用和相关机制进行综述.     

Diabetes-associated mitochondrial DNA mutation A3243G impairs cellular metabolic pathways necessary for beta cell function

Aims/hypothesis Mitochondrial DNA (mtDNA) mutations cause several diseases, including mitochondrial inherited diabetes and deafness (MIDD), typically associated with the mtDNA A3243G point mutation on tRNALeu gene. The common hypothesis to explain the link between the genotype and the phenotype is that the mutation might impair mitochondrial metabolism expressly required for beta cell functions. However, this assumption has not yet been tested.Methods We used clonal osteosarcoma cytosolic hybrid cells (namely cybrids) harbouring mitochondria derived from MIDD patients and containing either exclusively wild-type or mutated (A3243G) mtDNA. According to the importance of mitochondrial metabolism in beta cells, we studied the impact of the mutation on key parameters by comparing stimulation of these cybrids by the main insulin secretagogue glucose and the mitochondrial substrate pyruvate.Results Compared with control mtDNA from the same patient, the A3243G mutation markedly modified metabolic pathways leading to a high glycolytic rate (2.8-fold increase), increased lactate production (2.5-fold), and reduced glucose oxidation (−83%). We also observed impaired NADH responses (−56%), negligible mitochondrial membrane potential, and reduced, only transient ATP generation. Moreover, cybrid cells carrying patient-derived mutant mtDNA exhibited deranged cell calcium handling with increased cytosolic loads (1.4-fold higher), and elevated reactive oxygen species (2.6-fold increase) under glucose deprivation.Conclusions/interpretation The present study demonstrates that the mtDNA A3243G mutation impairs crucial metabolic events required for proper cell functions, such as coupling of glucose recognition to insulin secretion.     

线粒体转运RNA基因突变与原发性高血压的相关研究

目的探究线粒体转运RNA(tRNA)基因突变与母系遗传原发性高血压(EH)的关联性。方法依据EH诊断和母系遗传判别标准,筛选2015年1月至2018年12月解放军总医院心血管内科收治的母系遗传EH患者17例(A组)、非母系遗传EH患者65例(B组)。选取同期来院进行健康体检的正常对照人群33名(C组)。对全线粒体DNA(mtDNA)进行测序并与线粒体基因文库MitoMap的修正剑桥序列进行比对,分析3组受试者线粒体tRNA基因突变率差异及其与母系遗传EH发生的关系。应用SPSS 19.0软件对数据进行分析。结果纳入人群中母系遗传EH占总EH 20.7%(17/82)。mtDNA序列对比分析发现,与C组(0.04%)比较,A组(0.28%,P=0.024)及B组(0.12%,P=0.046)患者线粒体tRNA基因总变异率明显升高,但A与B组间比较差异无统计学意义(P=0.076)。对A组患者进一步分析显示,仅有1个线粒体tRNA基因位点突变的先证者A06、A11和A13所在3个家系分别发生mtDNA A5823G、mtDNA T4386C与mtDNA C15910T突变,三个家系母系成员EH发病率分别为53.8%(7/13)、87.5%(7/8)和75.0%(9/12),发病率均较高,提示这3个位点突变可能与母系遗传EH发生密切关联。另外,mtDNA 5597缺失在A组(4例,23.5%)、B组(14例,21.5%)和C组(1例,3.0%)均出现。与C组比较,A组(P=0.002)与B组(P=0.002)患者mtDNA 5597缺失率均显著升高,但A组与B组间比较差异无统计学意义(P=0.127)。结论 mtDNA A5823G、mtDNA T4386C与mtDNA C15910T突变与母系遗传EH有较好的关联性,但mtDNA 5597缺失与母系遗传EH关系不大。     

Comparison of the level of mitochondrial DNA A3243G mutation in esophageal epithelium and myocardium from individuals of very advanced age

The A3243G mutation, one of the changes of human mitochondrial DNA (mtDNA) that accumulates in cells during aging, is a useful marker for investigating the aging of cells. We measured the mutation level of the mtDNA A3243G mutation using DNAs from two different tissues (esophageal epithelium and myocardium) from advanced elderly individuals. The mean level of the A3243G mutation for the esophageal epithelium was 0.0063+/-0.0019, and that for the myocardium was 0.0098+/-0.0031. The mutation level in the myocardium was significantly higher than that in the esophageal epithelium, indicating that more mtDNA A3243G mutations accumulated in the myocardium than in the esophageal epithelium. Since the myocardium is static with respect to cell turnover, but in the esophageal epithelium renewal is very rapid, it is possible that the mtDNA A3243G mutation in the myocardium accumulates more rapidly than in the esophageal epithelium. This phenomenon may reflect the difference in the longevity of cells in each of these tissues and their different levels of oxidative stress.     

Involvement of VDAC1 and Bcl-2 family of proteins in VacA-induced cytochrome c release and apoptosis of gastric epithelial carcinoma cells

OBJECTIVE: It is known that the vacuolating cytotoxin (VacA) could induce apoptosis. However, the mechanism remained to be elucidated. The aim of this study is to investigate the role of Bcl family of proteins (Bcl-2 and Bax) and the mitochondrial voltage-dependent anion channel (VDAC) in VacA-induced apoptosis of AGS cells. METHODS: Plasmid pGBKT7-VacA p58 was constructed and transfected into the AGS cells. RT-PCR and Western blotting were used to determine the expressions of cytochrome c, caspase-3, Bax, Bcl-2 and VDAC1 mRNA and proteins. RESULTS: VacA p58 can induce cytochrome c release and activate caspase-3 in AGS cells. It up-regulated the expressions of Bax and VDAC1 mRNA and proteins, and decreased the expression of Bcl-2 in AGS cells. CONCLUSION: VacA p58 induces apoptosis in AGS cells. This apoptotic process is associated with the up-regulation of Bax/VDAC1 and downregulation of Bcl-2. These findings suggest that the release of cytochrome c by VacA p58 is mainly through VDAC-dependent and Bcl-2 family-dependent pathways.     

Mechanism of apoptotic effects induced selectively by ursodeoxycholic acid on human hepatoma cell lines

AIM: To investigate the effects of ursodeoxycholic acid (UDCA) on apoptosis and proliferation of hepatoma cell lines. METHODS: Human hepatoma cell lines HepG2 and BEL 7402 were cultured in medium supplemented with different concentrations of UDCA, normal human hepatic line L-02 was used as control. Cell proliferation, apoptosis and gene expression were detected using methyl thiazolyl tetrazolium (MTT) assay, flow cytometry, Western blot, DNA ladder assay, electron microscopy, and immunocytochemistry. RESULTS: Ursodeoxycholic acid inhibited the proli- feration of HepG2 and BEL7402 cell lines in a dose- dependent manner. Ursodeoxycholic acid can change cell cycle distribution of HepG2 and BEL7402, the proportion of cells in G0-G1 phase increased whereas the proportion of S phase cells and G2-M phase cells decreased. Ursodeoxycholic acid arrested the cell cycle in G0-G1 phase by down-regulating the cell cycle related proteins cyclin D1, D3 and retinoblastoma protein (pRb). The apoptotic rates of HepG2 and BEL7402 treated with UDCA (1.0 mmol/L) were significantly higher than those of control. In the HepG2 and BEL7402 treated with UDCA, expression of bcl-2 decreased whereas expression of Bax increased, the nuclear fragmentation and chromosomal condensed, cells shrank and lost attachment, apoptotic bodies and DNA ladders appeared. UDCA had no effect in inducing apoptosis on L-02 cell lines. CONCLUSION: UDCA can selectively inhibit proliferation and induce apoptosis of HepG2 and BEL7402 cell lines by blocking cell cycle and regulating the expression of Bax/bcl-2 genes.     

Mutation in D-loop region of mitochondrial DNA in gastric cancer and its significance

AIM:To investigate the mutation in D-loop region of mitochondrial DNA in gastric cancer and its influence on the changes of reactive oxygen species (ROS) and cell cycle. METHODS: The D-loop region was amplified by PCR and sequenced.Reactive oxygen species and cell cycle were detected by flow cytometry in 20 specimens from gastric cancer and adjacent normal tissues.According to the sequence results,gastric cancer tissue was divided into mutation group and control group.Reactive oxygen species,apoptosis and proliferation in the two groups were compared. RESULTS:Among the 20 gastric cancer specimens, 18 mutations were identified in 7 patients,the mutation rate being 35%.There were four microsatellite instabilities in the mutations. No mutation was found in the adjacent tissues. Reactive oxygen species,apoptosis,and proliferation in the mutation group were all significantly higher than those in control group. CONCLUSION: Mutation in D-loop region plays a role in the genesis and development of gastric cancer.     

人剪切修复基因D介导ox-LDL促进HUVEC凋亡作用

目的探讨人剪切修复基因D(XPD)是否介导氧化型低密度脂蛋白(ox-LDL)促进人脐静脉内皮细胞(HUVEC)凋亡。方法以ox-LDL建立HUVEC凋亡模型。用脂质体将XPD-siRNA转染HUVEC,给予ox-LDL处理。实验分6组:空白对照组;阴性对照siRNA组;XPD-siRNA组;ox-LDL组;ox-LDL+阴性对照siRNA组;ox-LDL+XPDsiRNA组。MTT测定细胞活力;流式细胞仪检测细胞凋亡率和细胞周期;用RT-PCR和Western blot检测XPD、Bax和Bcl-2的表达。结果建立HUVEC凋亡模型ox-LDL的最佳浓度为100 mg/L。与阴性对照siRNA组相比,XPDsiRNA组的细胞凋亡率明显下降(P0.05),存活率明显增加(P0.01),G0/G1期细胞减少(P0.05)、S期细胞增加(P0.05),XPD、Bax表达降低(P均0.05),Bcl-2表达增高(P0.05);与空白对照组相比,ox-LDL组细胞凋亡率明显增加(P0.01),细胞存活率下降(P0.05),G0/G1期细胞增加(P0.05)、S期细胞明显减少(P0.01),XPD、Bax表达升高(P均0.05),Bcl-2表达降低(P0.05);与ox-LDL+阴性对照siRNA组相比,ox-LDL+XPD-siRNA组细胞凋亡率下降(P0.05),细胞存活率明显增加(P0.01),G0/G1期细胞减少(P0.05)、S期细胞增加(P0.05),XPD、Bax表达降低(P均0.05),Bcl-2表达增高(P0.05)。结论 XPD能介导ox-LDL促进HUVEC凋亡作用。     

BH4 domain of antiapoptotic Bcl-2 family members closes voltage-dependent anion channel and inhibits apoptotic mitochondrial changes and cell death

A change of mitochondrial membrane permeability is essential for apoptosis, leading to translocation of apoptogenic cytochrome c and apoptosis-inducing factor into the cytoplasm. We recently showed that the Bcl-2 family of proteins regulate cytochrome c release and the mitochondrial membrane potential (Deltapsi) by directly modulating the activity of the voltage-dependent anion channel (VDAC) through binding. Here we investigated the biochemical role of the conserved N-terminal homology domain (BH4) of Bcl-x(L), which has been shown to be essential for inhibition of apoptosis, with respect to the regulation of mitochondrial membrane permeability and found that BH4 was required for Bcl-x(L) to prevent cytochrome c release and Deltapsi loss. A study using VDAC liposomes revealed that Bcl-x(L), but not Bcl-x(L) lacking the BH4 domain, inhibited VDAC activity. Furthermore, BH4 oligopeptides of Bcl-2 and Bcl-x(L), but not mutant peptides, were able to inhibit both VDAC activity on liposomes even in the presence of Bax and apoptotic Deltapsi loss in isolated mitochondria. It was also shown that the BH4 domain, fused to the protein transduction domain of HIV TAT protein (TAT-BH4), efficiently prevented apoptotic cell death. These results indicate that the BH4 of Bcl-2/Bcl-x(L) is essential and sufficient for inhibiting VDAC activity, which in turn prevents apoptotic mitochondrial changes, and for preventing apoptotic cell death. Finally, the data suggest that the TAT-BH4 peptide is potentially useful as a therapeutic agent for diseases caused by accelerated apoptosis.     

Prevalence and progression of diabetes in mitochondrial disease

Aims/Hypothesis The aims of this study were (1) to determine the prevalence and rate of progression in diabetes secondary to mitochondrial DNA (mtDNA) mutations; and (2) to determine whether percentage heteroplasmy predicts clinical outcome in patients carrying the m.3243A>G mutation. Methods We prospectively assessed 242 patients attending a specialist neuromuscular clinic using a validated mitochondrial disease rating scale. Retrospective clinical data on these patients from up to 25 years of follow-up were also included. Percentage heteroplasmy in blood, urine and muscle was determined for the m.3243A>G group and correlated against clinical features. Results Patients carrying the m.3243A>G mutation formed the largest group of patients with diabetes (31/81 patients). The highest prevalence of diabetes was in the m.12258C>A group (2/2 patients), the lowest in the multiple mtDNA deletions group (3/43 patients). The earliest age of onset was in the m.3243A>G group (37.9 years) with the highest age of presentation in the multiple deletion group (56.3 years). Of patients presenting with m.3243A>G, 12.9% required insulin; an additional 32.3% progressed to insulin requirement over a mean of 4.2 years after presentation. Percentage heteroplasmy in blood, urine or muscle did not predict progression of diabetes or risk of developing complications. Early age of presentation with diabetes did predict poor clinical outcome. Conclusions/Interpretation Although patients carrying the m.3243A>G mutation account for the majority of cases of diabetes secondary to mtDNA mutations, several other genotypes are also associated with the development of diabetes, some with high penetrance. All show a gradual progression to insulin requirement. Percentage heteroplasmy is a poor predictor of severity of diabetes in the m.3243A>G group.     

Exogenous phosphatidylethanolamine induces apoptosis of human hepatoma HepG2 cells via the bcl-2/bax pathway

AIM： To investigate the signaling pathways implicated in phosphatidylethanolamine （PE）-induced apoptosis of human hepatoma HepG2 cells. METHODS： Inhibitory effects of PE on human hepatoma HepG2 cells were detected by 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide （MTT） assay. Cell cycle, apoptosis and mitochondrial transmembrane potential （△ψm） were analyzed by flow cytometry. Immunocytochemical assay and Western blotting were used to examine Bcl-2, Bax and caspase-3 protein levels in HepG2 cells treated with PE. RESULTS： PE inhibited the growth of HepG2 cells in a dose- and time- dependent manner. It did not affect the cell cycle, but induced apoptosis. PE significantly decreased △ψm at 0.25, 0.5 and 1 mmol/L, respectively, suggesting that PE induces cell apoptosis by decreasing the mitochondrial transmembrane potential. The Bcl-2 expression level induced by different concentrations of PE was lower than that in control groups. However, the Bax expression level induced by PE was higher than that in the control group. Meanwhile, PE increased the caspase-3 expression in a dose- and time-dependent manner. CONCLUSION： Exogenous PE induces apoptosis of human hepatoma HepG2 cells via the bcl-2/bax pathway.