三磷酸腺苷后处理对兔心肌缺血再灌注损伤保护作用的研究

目的观察ATP后处理对再灌注损伤挽救激酶信号通路中的蛋白激酶B(Akt)及细胞外信号调节激酶(ERK1/2)表达的影响,探讨ATP后处理的心血管保护效应及可能机制。方法选择48只健康新西兰白兔,随机分为缺血再灌注组(再灌注组)、ATP后处理组(后处理组)、磷脂酰肌醇3激酶(PI3K)抑制剂Wortmannin+ATP后处理组(Wortmannin+ATP组)、ERK1/2抑制剂PD98059+ATP后处理组(PD98059+ATP组),每组12只。建立兔急性心肌缺血再灌注模型。实验终点检测各组心肌梗死面积、细胞凋亡指数,Western blot法检测心肌p Akt,p ERK1/2蛋白表达。结果后处理组心肌梗死面积、细胞凋亡指数明显低于再灌注组(P<0.01)。Western blot检测显示,后处理组p-Akt、p-ERK1/2表达水平明显高于再灌注组(P<0.05)。结论 ATP后处理可以减轻兔缺血再灌注心肌的梗死面积,降低细胞凋亡指数,同时上调p Akt和p-ERK1/2的表达,提示PI3K/Akt及ERK1/2信号通路参与了ATP后处理对兔缺血再灌注心肌的保护作用。     

非小细胞肺癌中PI3K/Akt信号通路通过Cdh1调控Skp2表达的机制研究

目的探讨非小细胞肺癌（NSCLC）中Cdc20同源蛋白1（Cdh1）参与磷脂酰肌醇三羟基激酶（PI3K）/Akt信号通路对S期激酶相关蛋白2（Skp2）表达调控的机制。方法体外培养NSCLC细胞系A549、LK2和H460,LY294002特异性阻断PI3K/Akt信号通路后,Western blot检测Skp2、Cdh1及p-Akt蛋白表达的变化,免疫荧光（IF）检测Cdh1在NSCLC中的定位变化。结果 LY294002处理后,与对照组相比3种细胞中Skp2蛋白表达和Akt磷酸化水平均降低（P〈0.01）,Cdh1在3种细胞的核内表达均增多。结论 NSCLC中PI3K/Akt信号通路抑制剂LY294002使Skp2蛋白表达下调与Cdh1由细胞质向细胞核转位有关。     

Akt和胞外信号调节激酶通路间的信号交流对内质网应激条件下肝癌细胞周期的调控

目的 研究内质网应激介导的磷脂酰肌醇3激酶(PI3K)/Akt和丝裂原活化蛋白激酶(MEK)/胞外信号调节激酶(ERK)途径间的信号交流及其对内质网应激条件下肝癌细胞周期的调控作用.方法 采用PI3K抑制剂LY294002、Akt激活型突变载体myr-Akt和MEK抑制剂U0126分别阻断或激活内质网应激介导的Akt和ERK活化,并利用Western blot和流式细胞技术分析内质网应激条件下PI3K/Akt和MEK/ERK途径间的信号交流及其对肝癌细胞株SMMC-7721、Hep3B和HepG2细胞周期的调控作用.数据处理采用Sperman等级相关分析,P＜0.05为差异有统计学意义.结果 阻断PI3K/Akt明显促进内质网应激介导的MEK/ERK活化,而过度激活PI3K/Akt则抑制内质网应激介导的MEK/ERK活化.阻断MEK/ERK对内质网应激介导的PI3K/Akt活化无影响.持续活化的Akt突变载体myr-Akt和MEK抑制剂U0126均明显抑制了内质网应激诱导的压力细胞G0/G1期阻滞.结论 PI3K/Akt和MEK/ERK信号途径在内质网应激肝癌细胞中存在信号交流,该信号交流对细胞周期起重要调控作用.     

脑源性神经营养因子对人冠状动脉内皮细胞增殖和克隆的影响

目的探讨脑源性神经营养因子(BDNF)对人冠状动脉内皮细胞(human coronary artery ebditgekuak cells,HCAEC)功能的影响及其作用机制。方法将HCAEC分为2组,其中一组添加BDNF(50 ng/μL)作为实验组,另一组不做其他处理作为对照组。采用CCK8法和平板克隆形成实验分别检测2组细胞的增殖能力和克隆能力,采用Western blot检测2组细胞中PI3K/Akt/mTOR信号通路、ERK信号通路及Wnt/β-catenin信号通路相关蛋白水平。结果与对照组相比,实验组细胞的增殖能力和克隆能力均显著提高(P 0. 05)。Western blot结果表明,实验组细胞中的磷酸化Akt(p-Akt)和磷酸化哺乳动物雷帕霉素靶蛋白(p-mTOR)水平显著升高(P 0. 05),并且Wnt蛋白家族1(Wnt1)、跨膜受体卷曲蛋白1(Frizzled1)和胞浆调节散乱蛋白1(Dsh)的表达水平也明显增加(P 0. 05),磷酸化细胞外调节蛋白激酶(p-ERK1/2)水平升高(P 0. 05)。结论BDNF促进了HCAEC的细胞增殖和克隆形成能力,PI3K/Akt/mTOR信号通路、ERK信号通路和Wnt/β-catenin信号通路可能参与其中。     

普伐他汀对骨髓间充质干细胞迁移和黏附能力的影响

目的观察普伐他汀干预对人骨髓间充质干细胞(bone marrow mesenchymal stem cells,BMMSCs)迁移和黏附能力的影响及其相关细胞信号传导通路。方法使用普伐他汀干预体外培养的第6代人BMMSCs,Western blotting检测作用前后ERK1/2、p38MAPK及PI3K/Akt通路蛋白的表达情况。将10μmol/L普伐他汀预处理人BMMSCs1h后,通过Transwell小室进行细胞迁移实验,并进行细胞黏附性测定,进一步用特异的细胞信号通路抑制剂或激动剂阻断或激活ERK1/2、p38MAPK及PI3K/AKT途径,观察其对普伐他汀作用的影响。结果普伐他汀可使人BMMSCs的PI3K/Akt通路磷酸化水平升高,抑制p38MAPK通路磷酸化水平,而其对人BMMSCs的ERK通路和总Akt、总p38MAPK水平无显著影响。经普伐他汀作用后迁移细胞显著增多(P<0.05),Ly294002预处理后这种作用消失,anisomycin预处理对这种作用影响不明显。普伐他汀作用后贴壁细胞显著增多(P<0.05),但Ly294002或anisomycin预处理对这种作用影响均不明显。结论普伐他汀具有增强人BMMSCs迁移和黏附能力的作用。其增强迁移能力的作用与激活人BMMSCs的PI3K/Akt通路有关。但是它对黏附能力的作用与PI3K/Akt和p38MAPK通路均无关。     

5-氮杂胞苷通过PI3K/Akt/mTOR通路介导人脂肪间充质干细胞向心肌细胞定向分化的研究

目的:研究磷脂酰肌醇3激酶(PI3K)及其下游分子丝氨酸/苏氨酸激酶(Akt)和雷帕霉素靶蛋白(mTOR)所组成的信号通路在5-氮杂胞苷(5-aza)诱导人脂肪间充质干细胞(ADMSCs)向心肌细胞定向分化中的作用,探讨其信号转导机制。方法:利用胶原酶法分离、培养ADMSCs,并用10μmol/L的5-aza诱导其向心肌细胞定向分化,采用Western blot的方法分析5-aza诱导前后Akt通路相关蛋白的表达情况。结果:5-aza诱导前ADMSCs内Akt通路相关蛋白的表达水平较低,诱导后增强。PI3K抑制剂Ly294002处理后,Western blot结果显示,细胞内PI3K的磷酸化受到抑制和TnT的表达水平显著降低,具有统计学意义。结论:5-aza能诱导ADMSCs向心肌细胞分化,PI3K/Akt/mTOR信号通路在5-aza诱导ADMSCs向心肌细胞分化中发挥重要的调控作用。     

细胞外信号调节激酶1/2在抗纤维化短肽AcSDKP调节大鼠心脏成纤维细胞增殖和胶原表达中的作用

目的 探讨AcSDKP是否通过阻断细胞外信号调节激酶1/2(ERK1/2)途径调节血小板源性生长因子(PDGF)诱导的大鼠心脏成纤维细胞增殖和胶原蛋白表达. 方法 CCK-8法检测心脏成纤维细胞代谢活性.流式细胞仪法检测细胞周期.免疫细胞化学法、Western blot法检测Ⅰ、Ⅲ型胶原蛋白表达.Western blot法检测ERK1/2及磷酸化-ERK1/2蛋白表达. 结果 10-9mol/L AcSDKP能够抑制PDGF诱导的大鼠心脏成纤维细胞代谢活性,减少了细胞由G1期向S期的转化,细胞增殖指数下降.抑制了Ⅰ、Ⅲ型胶原及磷酸化-ERK1/2蛋白的表达,而ERK1/2蛋白表达无明显改变. 结论 AcSDKP能够通过阻断PDGF介导的ERK1/2通路的激活进而抑制大鼠心脏成纤维细胞增殖和胶原蛋白表达.     

多巴胺及其受体激动剂对PC12细胞增殖和Akt、ERK信号转导的影响

目的观察多巴胺（DA）及其受体激动剂对PC12细胞增殖和胞内Akt、ERK信号转导的影响。方法应用不同浓度的DA、D1多巴胺受体激动剂（SKF38393）和D2多巴胺受体激动剂（Quinpirole）处理PC12细胞,MTT法检测其对PC12细胞增殖的影响,Western blot法检测其对PC12细胞胞内Akt、ERK信号转导的影响。结果 1～100μM的DA对PC12细胞的增殖无明显影响;SKF38393可促进PC12细胞的增殖,且呈剂量依赖性;Quinpirole可抑制PC12细胞的增殖,亦呈剂量依赖性。0～300μM DA可明显降低Akt的磷酸化,SKF38393可剂量依赖性的增加Akt、ERK的磷酸化,而Quinpirole则可剂量依赖性的降低Akt、ERK磷酸化。结论 DA、SKF38393和Quinpirole对PC12细胞增殖影响的差异,可能与其对Akt、ERK信号转导影响的不同有关。     

1-磷酸鞘氨醇受体1参与晚期糖基化终产物引起的血管平滑肌细胞增殖和迁移

目的观察1-磷酸鞘氨醇受体1(S1PR1)在晚期糖基化终产物(AGE)引起的血管平滑肌细胞增殖和迁移中的作用。方法培养人脐动脉平滑肌细胞(HUASMC),葡萄糖与牛血清白蛋白(BSA)孵育法获得AGE-BSA,分为对照组、BSA组和AGE-BSA组,采用CCK-8实验检测平滑肌细胞增殖能力,采用细胞划痕和Transwell实验检测平滑肌细胞迁移能力,并进一步观察BSA和AGE-BSA在有或无S1PR1拮抗剂VPC23019/激动剂SEW2871预处理后的细胞增殖和迁移。结果与对照组比较,BSA和AGE-BSA均能诱导HUASMC增殖和迁移,AGE-BSA的作用比BSA更加显著(P0.05);S1PR1拮抗剂VPC23019可以明显抑制BSA和AGE-BSA诱导的HUASMC增殖和迁移;S1PR1激动剂SEW2871本身就可以促进HUASMC增殖和迁移,并且进一步促进BSA诱导的HUASMC增殖和迁移,而对AGE-BSA诱导的HUASMC增殖和迁移没有进一步的促进作用。结论血浆白蛋白本身对平滑肌细胞的增殖具有促进作用,糖基化修饰的白蛋白这一作用更加明显;S1PR1的激活参与了BSA和AGE-BSA促进平滑肌细胞增殖和迁移,AGE-BSA对S1PR1的激活作用更加显著。     

洛伐他汀经PI3K/Akt和ERK1/2信号通路抑制大鼠骨髓间充质干细胞凋亡

目的 体外以缺氧无血清条件模拟心肌梗死后的心脏缺血微环境,研究洛伐他汀能否抑制缺氧无血清引起的骨髓间充质干细胞(MSC)凋亡并探讨其机制.方法 以Hocchst33342染色荧光显微镜观察法及Annexin V/PI流式细胞术检测洛伐他汀的抗凋亡作用,并进一步采用Westernblot方法 检测洛伐他汀对线粒体凋亡途径的抑制作用以及对磷脂酰肌醇3激酶(PI3K)/丝氨酸苏氨酸激酶(Akt)途径和丝裂原活化的蛋白激酶(MAPK)的激酶(MEK)/细胞内信号调节蛋白激酶(ERK1/2)途径的激活作用.结果 0.01～1 μmol/L浓度范围的洛伐他汀能够有效地抑制缺氧无血清引起的MSC凋亡.洛伐他汀抑制线粒体凋亡途径,洛伐他汀抑制细胞色素C释放,降低天冬氨酸特异性半胱氨酸蛋白酶-3(caspase-3)活化,从而保护线粒体功能.洛伐他汀的抗凋亡效应以及其抑制细胞色素C释放的作用均可被PI3K抑制剂LY294002和MEK抑制剂U0126阻断.洛伐他汀能够激活PI3K/Akt和MEK/ERK1/2两条细胞存活信号通路,分别导致Akt和GSK-3β及ERK1/2磷酸化.结论 洛伐他汀能够抑制线粒体凋亡途径,并激活PI3K/Akt和MEK/ERK1/2细胞存活通路,最终发挥抗缺氧无血清引起的MSC凋亡.该研究为提高移植干细胞的存活率提供了一种可能有效的干预措施.     

1-Naphthyl isocyanate and 1-naphthylamine as metabolites of 1-naphthylisothiocyanate

Abstract: The importance of the bioactivation of 1-naphthylisothiocyanate was studied. Forty minutes after 1-naphthylisothiocyanate administration to rats, bile was collected over a 2.5-h period; the liver was then excised and homogenized. 1-naphthylisothiocyanate and its metabolites in bile and liver of rats were identified and quantified using coupled gas chromatography-mass spectrometry. Three main compounds were found in all 1-naphthylisothiocyanate-treated animals. They were identified as 1-naphthyl isocyanate, 1-naphthylamine and the parent compound, 1-naphthylisothiocyanate. When rats were given cycloheximide, which attenuates 1-naphthylisothiocyanate toxicity, 30 min before 1-naphthylisothiocyanate (300 mg/kg), 1-naphthyl isocyanate concentration was significantly lower than in rats receiving only 1-naphthylisothiocyanate. The appearance of 1-naphthylamine was also inhibited by cycloheximide, although not to the same extent as 1-naphthyl isocyanate. On the other hand, phenobarbital, which potentiates 1-naphthylisothiocyanate hepatotoxicity, enhanced 1-naphthyl isocyanate and 1-naphthylamine formation. It is suggested that 1-naphthyl isocyanate, 1-naphthylamine and the highly reactive sulfur released from 1-naphthylisothiocyanate might be involved in the hepatotoxic effect of 1-naphthylisothiocyanate.     

The target of ezetimibe is Niemann-Pick C1-Like 1 (NPC1L1)

Ezetimibe is a potent inhibitor of cholesterol absorption that has been approved for the treatment of hypercholesterolemia, but its molecular target has been elusive. Using a genetic approach, we recently identified Niemann-Pick C1-Like 1 (NPC1L1) as a critical mediator of cholesterol absorption and an essential component of the ezetimibe-sensitive pathway. To determine whether NPC1L1 is the direct molecular target of ezetimibe, we have developed a binding assay and shown that labeled ezetimibe glucuronide binds specifically to a single site in brush border membranes and to human embryonic kidney 293 cells expressing NPC1L1. Moreover, the binding affinities of ezetimibe and several key analogs to recombinant NPC1L1 are virtually identical to those observed for native enterocyte membranes. KD values of ezetimibe glucuronide for mouse, rat, rhesus monkey, and human NPC1L1 are 12,000, 540, 40, and 220 nM, respectively. Last, ezetimibe no longer binds to membranes from NPC1L1 knockout mice. These results unequivocally establish NPC1L1 as the direct target of ezetimibe and should facilitate efforts to identify the molecular mechanism of cholesterol transport.     

Inhibition of procarcinogen-bioactivating human CYP1A1, CYP1A2 and CYP1B1 enzymes by melatonin

Abstract:  Administration of melatonin to rodents decreases the incidence of tumorigenesis initiated by benzo[ a ]pyrene or 7,12-dimethylbenz[ a ]anthracene, which requires bioactivation by cytochrome P450 enzymes, such as CYP1A1, CYP1A2 and CYP1B1, to produce carcinogenic metabolites. The present study tested the hypothesis that melatonin is a modulator of human CYP1 catalytic activity and gene expression. As a comparison, we also investigated the effect of melatonin on the catalytic activity of CYP2A6, which is also a procarcinogen-bioactivating enzyme. Melatonin (3–300 μ m ) decreased 7-ethoxyresorufin O -dealkylation catalyzed by human hepatic microsomes and recombinant CYP1A1, CYP1A2 and CYP1B1, whereas it did not affect coumarin 7-hydroxylation catalyzed by hepatic microsomes or recombinant CYP2A6. Melatonin inhibited CYP1 enzymes by mixed inhibition, with apparent K _i values (mean ± S.E.M.) of 59 ± 1 (CYP1A1), 12 ± 1 (CYP1A2), 14 ± 2 (CYP1B1) and 46 ± 8 μ m (hepatic microsomes). Additional experiments indicated that melatonin decreased benzo[ a ]pyrene hydroxylation catalyzed by hepatic microsomes and CYP1A2 but not by CYP1A1 or CYP1B1. Treatment of MCF-10A human mammary epithelial cells with melatonin (up to 300 μ m ) did not affect basal or benzo[ a ]pyrene-inducible CYP1A1 or CYP1B1 gene expression. Consistent with this finding, melatonin did not influence reporter activity in aryl hydrocarbon receptor-dependent pGudluc6.1-transfected MCF-10A cells treated with or without benzo[ a ]pyrene, as assessed in an in vitro cell-based luciferase reporter gene assay. Overall, melatonin is an in vitro inhibitor of human CYP1 catalytic activity, and it may be useful to develop potent analogues of melatonin as potential cancer chemopreventive agents that block CYP1-mediated chemical carcinogenesis.     

甲型H1N1与季节性H1N1流感病毒血凝素基因比较分析

目的分析泰安市2008～2009年度季节性流感与2009年度甲型H1N1流感病原学检测结果 ,比较季节性H1N1与甲型H1N1血凝素基因变异情况。方法选择国家级流感监测哨点医院以及暴发疫情的疫点,采集流感样病例的鼻咽拭子标本,通过RealtimePCR进行病毒检测,用MDCK细胞进行病毒分离,通过RT-PCR扩增血凝素HA1片段的基因并测序,利用生物信息学进行序列分析。结果 2008～2009年共检测鼻咽拭子标本283份,分离出流感病毒33株,分离阳性率为11.67%,其中季节性H1N1亚型31株。2009年5月1日～12月31日,检测鼻咽拭子标本996份,流感核酸检测阳性417份,阳性率为41.86%,其中甲型H1N1337份,季节性H1N1亚型1份。6株季节性H1N1病毒均在多个氨基酸位点上发生变异,与疫苗株A/Brisbane/59/2007(H1N1)比较,有11个位点发生了突变,其中5个位点位于抗原决定簇上;测序成功的6株甲型H1N1病毒在多个氨基酸位点发生变异,与疫苗株A/California/07/2009(H1N1)比较,有6个位点发生突变,其中1个位点位于抗原决定簇的B区。结论 2008～2009年度季节性H1N1为优势株,甲流暴发后,甲型H1N1成为绝对优势毒株。季节性H1N1分离株有多处氨基酸替换,抗原决定簇B区变异频繁;甲型H1N1病毒分离株的基因有变异,但关键位点第222位仍为D(天冬氨酸),与疫苗株相比抗原决定簇的关键位点变化不大。     

Characterization of MTHFR,GSTM1, GSTT1, GSTP1, and CYP1A1 genotypes in childhood acute leukemia

The role of methylenetetrahydrofolate reductase (MTHFR C677T), glutathione S-transferases (GSTM1 and GSTT1 null, GSTP1 Ile105Val), and cytochromes p450 (CYP1A1*2A) genotypes in the etiology of childhood leukemia was simultaneously investigated. 144 Turkish children with acute lymphoblastic leukemia (ALL) and 33 with acute nonlymphoblastic leukemia (ANLL) were studied and compared with 185 healthy pediatric controls. The frequency of MTHFR genotype was insignificantly higher in ALL (7.7%) and ANLL (6.3%) than in controls (4.4%). Equal distribution of the GSTM1 null genotype was detected between ALL patients and controls (55%), while its incidence was slightly higher in ANLL patients (61.3%). Although GSTT1 null genotype was insignificantly lower in ALL patients (20.9%) than controls (22.7%), it was significantly underrepresented in ANLL patients (6.5%) (P = 0.05, OR 0.24, 95% CI 0.05-1.03). The homozygous frequency of GSTP1 genotype did not differ significantly between groups of ALL (3.7%), ANLL patients (9.1%) and controls (4.9%). Homozygous CYP1A1*2A genotype was underrepresented in ALL patients (1%) as compared to control (4.8%) but the differences did not reach to statistical significance (OR 0.21; 95% CI 0.03-1.72). Homozygosity for this genotype was not detected in ANLL patients. No particular association was noted between different combinations of combined genotypes and risk of development of childhood ALL and ANLL. These results suggested that there are no significant associations between the studied genotypes and the risk of developing either form of acute leukemia except GSTT1 null and homozygosity for CYP1A1 genotypes that may play protective roles in the development of ANLL in Turkish children.