葡萄糖调节蛋白78促进肝硬化大鼠心肌细胞凋亡及其机制

 目的： 探讨葡萄糖调节蛋白78/免疫球蛋白重链结合蛋白(GRP78/BiP)是否促进肝硬化大鼠心肌细胞凋亡及其发生机制。方法： 采用复合致病因素法建立肝硬化大鼠模型,在4周、6周和8周分别取材。实验1：取心脏称重并测量左室壁厚度,计算左室壁厚度与心脏重量比值及心脏指数。实验2： TUNEL法观察心肌细胞凋亡情况;免疫组化方法检测心肌组织中GRP78/BiP蛋白以及凋亡相关蛋白CCAAT增强子结合蛋白同源蛋白/生长停滞及DNA诱导蛋白153（CHOP/GADD153）、半胱氨酸天冬氨酸蛋白酶12（caspase-12）、核转录因子κB p65（NF-κB p65）、B细胞淋巴瘤/白血病蛋白2（Bcl-2）的表达。结果： 随肝硬化病程进展,左室壁厚度与心脏重量比值以及心脏指数逐渐增加,8周组增加显著(P<0.05);心肌细胞凋亡指数、CHOP/GADD153和caspase-12阳性蛋白表达指数逐渐升高,8周组差异显著(P<0.05);NF-κB p65和Bcl-2阳性蛋白表达指数呈一致性变化,在4周组较其它组明显增高(P<0.05); GRP78/BiP蛋白阳性表达指数与心肌细胞凋亡指数、CHOP/GADD153、caspase-12蛋白阳性表达指数呈显著正相关,CHOP/GADD153与NF-κB p65、Bcl-2蛋白阳性表达指数呈显著负相关。结论： GRP78高表达在内质网应激介导的肝硬化心肌病发病中可能发挥重要作用。     

葡萄糖调节蛋白78在复合致病因素诱导的大鼠肝肺综合征中的作用

目的: 探讨葡萄糖调节蛋白78(GRP78)在大鼠肝肺综合征发病中的作用及其与肠源性内毒素血症的关系。方法: Wistar大鼠被随机分为4周组、6周组和8周组3个时点,采用复合致病因素法制备大鼠肝硬化合并肝肺综合征(HPS)模型,并设标准饮食的正常大鼠作为对照组。采用HE染色观察肺组织病理变化;测定血浆中丙氨酸氨基转移酶(ALT)、内毒素、TNF-α和肺组织匀浆中的TNF-α、丙二醛(MDA)的含量。Western blotting和RT-PCR法检测肺组织标本中GRP78蛋白和mRNA表达水平。结果: 模型组动物血浆内毒素含量随病程进展逐渐增高;肺组织中GRP78蛋白和mRNA的表达随HPS进展逐步增高,且各时点间的表达有显著差异(P<0.05);血浆内毒素与升高的GRP78蛋白水平间呈高度正相关(P<0.01)。血浆ALT和TNF-α含量以及肺组织匀浆中TNF-α和MDA含量随病程进展逐渐增高;血浆内毒素含量以及肺组织中GRP78蛋白分别与血浆TNF-α和肺组织中TNF-α、MDA的含量呈高度正相关(P<0.01)。在各时点,模型组动物血浆TNF-α含量、肺组织匀浆TNF-α、GRP78蛋白及mRNA均显著高于正常对照组(P<0.05)。在第6周和第8周,模型组动物血浆内毒素和ALT的含量以及肺组织匀浆中MDA的含量均显著高于正常对照组(P<0.05)。结论: 肝硬化时形成的肠源性内毒素血症作为内质网应激的重要应激原,通过氧化应激激活肺组织的内质网应激反应导致GRP78表达增高,很可能是HPS发病的重要机制。     

PI3K/Akt信号通路及内质网应激在肝纤维化大鼠肝细胞凋亡中的作用

目的观察磷脂酰肌醇-3激酶/蛋白激酶(PI3K/Akt)信号通路及葡萄糖调节蛋白78(GRP78)、生长停滞及DNA损伤基因(CHOP/GADD153)在四氯化碳(CCl4)诱导的肝纤维化中的表达并探讨其可能的作用。方法将30只SD大鼠随机分为正常组、肝纤维化模型(皮下注射40%CCl4橄榄油溶液)4及8周组。HE染色法观察肝组织病理形态学;用real-time PCR技术检测肝脏内GRP78及CHOP mRNA的表达;用Western blot检测肝脏内PI3K/Akt信号通路中Akt1、磷酸化Akt1及内质网应激相关蛋白GRP78及CHOP的表达;用原位末端转移酶标记(TUNEL)检测细胞凋亡。结果与正常组大鼠比较,肝纤维化模型4及8周组大鼠肝脏内GRP78及CHOP mRNA和蛋白表达均明显升高(P0.05),而肝脏内Akt1和磷酸化Akt1蛋白的表达则较正常大鼠显著降低(P0.05);与正常组大鼠比较,肝纤维化模型4及8周组大鼠肝细胞凋亡显著升高(P0.05)。结论 PI3K/Akt信号通路及内质网应激可能在肝纤维化大鼠肝细胞凋亡中发挥了重要作用。     

H2S调节miR-21表达抑制内质网应激介导肺成纤维化细胞凋亡

目的：探讨H2S是否可调节miR-21表达抑制内质网应激介导肺成纤维细胞凋亡。方法：体外培养小鼠成纤维细胞(NIH3T3),随机分为对照组、TGF-β1组和NaHS干预组。采用CCK-8分别检测细胞增殖,流式细胞仪检测NIH3T3凋亡率;qRT-PCR法和Western blot分别分析葡萄糖调节蛋白78(GRP78)、增强子结合蛋白同源蛋白(CHOP)和caspase-12的表达;检测miR-21是否参与H2S抑制ERS介导的肺成纤维化细胞凋亡,将其随机分为3组：对照组、miR-21激动剂(miR-21 agomir)组和miR-21拮抗剂(miR-21 antagomir)组。miR-21激动剂组和miR-21拮抗剂组分别给予40 μmol/L的NaHS 预处理,再进行TGF-β1处理,检测GRP78、CHOP 及caspase-12的表达。结果：与对照组比较,NaHS干预组小鼠肺成纤维化细胞的增殖率、细胞凋亡率、miR-21蛋白及mRNA的表达均明显降低;与TGF-β1组比较,NaHS可明显降低内质网应激相关因子GRP78、CHOP及 caspase-12蛋白和mRNA表达;与阴性对照组比较,miR-21 agomir组GRP78、CHOP 及caspase-12的蛋白及mRNA表达均显著升高。而与miR-21 agomir组比较,miR-21 antagomir组结果则与之相反。结论：H2S可通过调节miR-21的表达,调控TGF-β1诱导小鼠肺成纤维化细胞的ERS稳态减少细胞凋亡,发挥其内源性的保护作用。     

前列腺素E1通过抑制内质网应激保护心肌梗死后大鼠的心脏

目的:探讨前列腺素E1(PGE1)对心肌梗死(MI)后大鼠心脏的影响及相关分子机制。方法:将SPF级雄性SD大鼠分为假手术组、模型组和模型+PGE1组。通过结扎冠状动脉左前降支建立MI大鼠模型。通过超声心动图分析大鼠心功能变化;通过HE和Masson染色分析心肌组织形态学变化;通过TTC染色评估心肌梗死情况;通过TUNEL法检测心肌细胞死亡情况;通过免疫组化和Western blot检测内质网应激(ERS)相关因子葡萄糖调节蛋白78(GRP78)、C/EBP同源蛋白(CHOP)和caspase-12,以及凋亡相关因子Bcl-2、Bax和cleaved caspase-3的表达情况。结果:与假手术组比较,模型组大鼠心功能降低,心肌组织出现病理形态学改变,心肌梗死面积扩大,心肌细胞死亡增多,心肌组织中GRP78、CHOP、caspase-12、Bax和cleaved caspase-3的蛋白水平升高,Bcl-2表达降低(P0. 01)。与模型组比较,模型+PGE1组大鼠心功能明显提高,心肌组织病理损伤明显减轻,心肌梗死的面积显著减小,心肌细胞死亡显著减少,心肌组织中GRP78、CHOP、caspase-12、Bax和cleaved caspase-3的蛋白水平降低,Bcl-2表达升高(P0. 01)。结论:PGE1能通过降低ERS水平而减少胶原沉积、减轻炎症并提高心功能,从而保护心肌细胞免受MI的损伤。     

金属硫蛋白降低GRP78和CHOP蛋白表达减轻大鼠砷中毒肝细胞凋亡

目的 研究葡萄糖调节蛋白78(GRP78)、C/EBP环磷酸腺苷反应元件结合转录因子同源蛋白(CHOP)在金属硫蛋白(MT)减轻大鼠砷中毒肝细胞凋亡中的作用.方法 建立MT治疗亚砷酸钠(NaAsO2)诱导的大鼠砷中毒肝损伤模型,用MT治疗2周,以TUNEL法检测肝细胞凋亡,免疫组化法、Western blot检测大鼠肝脏GRP78、CHOP蛋白表达.结果 砷中毒模型组大鼠肝细胞凋亡、肝组织GRP78和CHOP蛋白表达较对照组显著升高(P＜0.05),MT治疗组肝细胞凋亡、肝组织GRP78和CHOP蛋白表达明显回降(P＜0.05),但仍然高于对照组(P＜0.05).结论 MT可通过降低GRP78和CHOP蛋白表达减轻大鼠砷中毒所致的肝细胞凋亡.     

单侧输尿管梗阻的大鼠内质网应激相关蛋白表达上调

目的探究内质网应激(ERS)相关凋亡通路在单侧输尿管梗阻(UUO)大鼠肾间质纤维化中的作用机制。方法将大鼠随机分为假手术组及UUO模型组,UUO组行左侧输尿管结扎术,于术后3、7和14 d HE和Masson染色观察肾脏病理变化;眼底静脉丛取血,分离血清测定血尿素氮及肌酐;Western blot检测葡萄糖调节蛋白78(GRP78)、内质网源性转录因子(CHOP)、凋亡相关蛋白半胱氨酸天门冬氨酸蛋白酶3(caspase-3)及caspase-12蛋白表达。结果与假手术组相比,UUO模型组可见:1)肾小管扩张和肾间质纤维化程度随输尿管梗阻时间延长而渐进性加重;2)GRP78、CHOP、caspase-3及caspase-12蛋白表达在术后3 d均有上调,随着梗阻时间延长,上述蛋白表达更显著(P0.01)。结论内质网应激相关标志性蛋白在UUO大鼠肾间质纤维化的早期即存在表达上调,可能促进了肾间质纤维化不断进展。     

二甲双胍对大鼠脊髓损伤后内质网应激和细胞凋亡的影响

目的:研究二甲双胍(MET)对大鼠脊髓损伤(SCI)后内质网应激(ERS)和细胞凋亡的影响,探讨二甲双胍对SCI的保护作用及机制。方法:成年雌性SD大鼠随机分为3组,分别是假手术组(Sham组)、单纯脊髓损伤组(SCI组)和二甲双胍干预组(MET组)。采用Allen方法制备大鼠SCI模型,MET组和SCI组大鼠建模后,立即腹腔注射MET(50 mg·kg~(-1)·d~(-1))或等量生理盐水,连续处理7天后,取脊髓组织,用实时定量PCR检测各组脊髓组织中葡萄糖调节蛋白78 (GRP78),CCAAT/增强子结合蛋白同源蛋白(CHOP)和半胱氨酸的天冬氨酸蛋白水解酶-12(caspase-12)的mRNA水平,免疫印迹检测各组脊髓组织中GRP78、CHOP、caspase-12和active caspase-3的蛋白水平,免疫荧光染色检测各组脊髓组织中GRP78、CHOP和caspase-12的蛋白水平,TUNEL染色法检测各组脊髓组织中细胞凋亡水平,BBB评分检测大鼠SCI后运动功能情况。结果:与Sham组相比,SCI组中GRP78、CHOP和caspase-12的mRNA和蛋白水平明显升高,activecaspase-3蛋白表达和细胞凋亡数目明显增加,BBB评分明显降低;与SCI组相比,MET组中GRP78、CHOP和caspase-12的mRNA和蛋白水平明显降低,active caspase-3蛋白表达和细胞凋亡数目明显减少,BBB运动评分明显升高。结论:二甲双胍可以抑制大鼠SCI后细胞凋亡,促进后肢运动功能恢复,其机制可能与抑制ERS有关。     

白芍总苷预处理对乳鼠心肌缺血再灌注心肌细胞糖调节蛋白78、增强子结合蛋白同源蛋白、caspase-12表达及凋亡的影响

目的:观察白芍总苷(TGP)预处理对大鼠心肌缺血再灌注心肌细胞糖调节蛋白78(GRP78)、增强子结合蛋白同源蛋白(CHOP)、caspase-12表达及凋亡的影响。方法:差速贴壁法培养的乳鼠心肌细胞,随机分为正常对照组、白芍总苷组、缺血再灌注组(缺氧3 h,复氧1 h)、心肌缺血再灌注+低、中、高剂量白芍总苷组终浓度为25、50、100mg/L预处理24 h后,再置于上述缺氧复氧环境中培养,MTT法检测各组活细胞数、流式细胞仪检测各组心肌细胞凋亡率,免疫印迹检测细胞GRP78、CHOP、caspase-12蛋白表达。结果:与缺血再灌注组相比,白芍总苷对降低GRP78、CHOP、caspase-12蛋白表达、提升心肌细胞存活率并降低细胞凋亡率呈浓度依赖性。结论:白芍总苷对乳鼠心肌细胞缺血再灌注具有提高心肌细胞存活率和降低细胞凋亡率作用,其机制可能与抑制心肌细胞内质网应激相关蛋白GRP78表达,下凋CHOP、caspase-12水平等有关。     

内质网应激在创伤致大鼠心肌细胞凋亡中的作用

目的:探讨内质网应激(ERS)在创伤致大鼠心肌细胞凋亡中的作用。方法:应用Noble-Collip创伤仪构建机械创伤SD大鼠模型,并将大鼠随机分为伪创伤组(n=6),创伤组(创伤后0 h、3 h、6 h、12 h和24 h各时点n=6)和创伤+ERS抑制剂4-苯基丁酸(4-PBA)组(n=6)。用试剂盒检测大鼠心肌组织凋亡蛋白caspase-3活性;用Western blot检测大鼠心肌组织caspase-3的活化水平,ERS标志分子葡萄糖调节蛋白78(GRP78)、转录激活因子6(ATF6)、蛋白激酶R样内质网激酶(PERK)和需肌醇酶1α(IRE1α)的表达或磷酸化水平,以及ERS相关凋亡分子C/EBP同源蛋白(CHOP)和caspase-12的表达或活化水平。结果:与伪创伤组相比,创伤组大鼠心肌组织caspase-3活性增强,cleaved caspase-3、GRP78、ATF6、磷酸化PERK、磷酸化IRE1α、CHOP和cleaved caspase-12蛋白水平均显著升高(P0. 05或P0. 01);而给予创伤大鼠4-PBA处理后,caspase-3活性及CHOP、cleaved caspase-12和cleaved caspase-3蛋白水平均显著降低(P0. 05)。结论:创伤所致大鼠心肌细胞凋亡可能是由于激活ERS凋亡途径引起的。     

内质网应激参与低浓度DNA加成性损伤剂诱发的细胞应答反应

目的：研究内质网应激在DNA损伤剂/致癌物诱发的细胞应答反应中的作用。 方法: 选择3种引起不同DNA损伤类型的DNA损伤剂/致癌物，烷化性DNA损伤剂N-甲基-N’-硝基-N-亚硝基胍（MNNG），大块加成性DNA损伤剂苯并［a］芘-7,8-9-二氢二醇-9,10-环氧化物（BPDE，环境致癌物苯并［a］芘在体内代谢形成的终致癌物）以及交联性DNA损伤剂丝裂霉素C（MMC）对人羊膜细胞FL系内质网应激反应的影响。采用SDS－PAGE 和免疫印迹法检测内质网应激蛋白GRP78/BiP, GADD153/CHOP的表达改变和定位于内质网的半胱天冬酶-12(caspase-12)的激活。 结果： 低浓度MNNG（0.25 μmol/L和1 μmol/L）和BPDE（5 nmol/L和50 nmol/L）均能引起FL细胞中GRP78/BiP和GADD153/CHOP的上调和caspase-12的激活；3种浓度的MMC（5 μmol/L、50 μmol/L和500 μmol/L）均引起GRP78/BiP的下调，不伴有GADD153/CHOP水平的改变和caspase-12的激活，更低浓度的MMC（5 nmol/L 和50 nmol/L）对此并无影响。 结论： 低浓度MNNG和BPDE可诱发暴露细胞的内质网应激，而MMC则导致在内质网应激反应诱发过程中起介导作用的GRP78/BiP蛋白的下调，从而可能改变细胞对内质网应激原的反应性。内质网应激在DNA损伤剂/致癌剂诱发的细胞应答反应中有一定作用。     

Distinct mechanism of cell death is responsible for tunicamycin-induced ER stress in SK-N-SH and SH-SY5Y cells

In order to elucidate underlying mechanism of cell death pathways in neuronal cells in humans, we studied responsible pathways involved in the endoplasmic reticulum (ER) stress-induced cell death in neuroblastoma cells, SK-N-SH and its neuroblast-type subclone SH-SY5Y cells. A time-dependent induction of ER chaperons, glucose regulated protein (GRP)78 and GRP94, was observed after treatment with tunicamycin (TM), and cell death was also induced concomitantly in both cells. Although the pro-caspase-12-like protein was defined in both cells, a decrease in the protein was observed in only SH-SY5Y cells after exposure to TM. In contrast, pro-caspase-4 was detected in only SK-N-SH cells, and the cleaved-form was induced by the treatment with TM. A caspase-4 inhibitor, Z-LEVD-FMK attenuated TM-induced cell death in SK-N-SH cells. Calpain- and caspase-3-mediated proteolysis of alpha II-spectrin was also increased after the treatment with TM in both cells. A calpain inhibitor, calpeptin, repressed TM-induced cell death in only SK-N-SH cells. GADD153/C/EBP homologous protein (CHOP) was significantly induced after exposure to TM in only SH-SY5Y cells and RNA interference to GADD153/CHOP repressed TM-induced cell death. These results demonstrate that induction of GADD153/CHOP plays a pivotal role in mechanism of ER stress-induced cell death in SH-SY5Y cells, on the other hand, cleavage of pro-caspase-4 by activation of calpain play a crucial role in SK-N-SH cells. It is also suggested that the relevance of caspase-4 to ER stress is cell-specific even between human-origin cell lines.     

益气温阳活血化痰方通过抑制内质网应激对HHPH大鼠脑的保护作用

目的:评价益气温阳活血化痰方通过抑制内质网过度应激反应减轻大鼠低氧高二氧化碳性肺动脉高压(HHPH)所致脑损伤的作用。方法:雄性SD大鼠50只,采用随机数字表法分为5组:对照组,低氧高CO_2组,益气温阳活血化痰方低、中、高剂量给药组。对照组置于常氧环境中饲养,其余4组置于低氧高CO_2氧仓中饲养,共饲养4周。益气温阳活血化痰方低、中、高剂量组大鼠每天分别按0.15 g/kg、0.3 g/kg和0.6 g/kg灌服益气温阳活血化痰方浸膏,低氧高CO_2组大鼠给予等体积生理盐水灌胃。连续给药4周后对大鼠进行手术,记录肺动脉平均压后进行心脏灌流,结束后开颅快速取脑组织检测脑组织含水量并开胸取肺组织。光镜下观察脑组织及肺动脉形态学变化,TUNEL法检测脑细胞凋亡指数,分光光度计法检测脑组织caspase-3酶活性,Western blot和RTPCR法检测c-Jun氨基末端激酶(JNK)、caspase-12、C/EBP同源蛋白(CHOP)和葡萄糖调节蛋白78(GRP78)的蛋白及mRNA水平。结果:与对照组相比,其余组肺动脉平均压、脑含水量、细胞凋亡指数、caspase-3酶活性以及JNK、caspase-12、CHOP和GRP78的蛋白及mRNA均有升高,组织形态学结构亦有损伤性变化;与低氧高CO_2组比较,益气温阳活血化痰方低、中、高剂量组的肺动脉平均压、脑含水量、细胞凋亡指数、caspase-3酶活性以及JNK、caspase-12、CHOP和GRP78蛋白及mRNA均有降低,脑组织及肺组织结构损伤性的变化亦有明显减轻,并以中剂量组最为显著。结论:益气温阳活血化痰方可能通过抑制内质网过度应激反应减轻HHPH所致的脑损伤。     

Atorvastatin inhibits myocardial cell apoptosis in a rat model with post-myocardial infarction heart failure by downregulating ER stress response

Objective: To determine the effect of atorvastatin on rat heart failure after myocardial infarction and to investigate the underlying mechanism of atorvastatin-mediated myocardium protection.Methods: Thirty-eight rats were randomly divided into three groups: a heart failure model group (model group), a heart failure plus atorvastatin treatment group (atorvastatin group) and a sham-surgery group (control group). The rat heart failure model was established by ligation of the left anterior descending of coronary arteries (LADs). Changes in hemodynamics parameters were recorded after the final drug administration. Plasma brain natriuretic peptide (BNP) concentration was determined by enzyme-linked immunosorbent assay (ELISA). Histological diagnosis was achieved by hematoxylin and eosin (H&E) and Masson''s trichrome staining. The expressions of 78kDa glucose-regulated protein 78 (GRP78), caspase-12 and C/EBP homologous protein (CHOP, also known as GADD153) in myocardial cells and cultured cardiac myocytes were examined by Western blot. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) was used to evaluate myocardial cell apoptosis, and flow cytometry was performed to examine the cell apoptosis of cultured cardiac myocytes.Results: In the atorvastatin group, myocardial cells were lined up more orderly and myocardial fibrosis level was decreased compared to the model group. The expressions of GRP78, caspase-12 and CHOP in myocardial cells were decreased in atorvastatin group. Moreover, in the atorvastatin-treated group the cell apoptosis rate was reduced and the endoplasmic reticulum (ER) stress was activated in response to heart failure and angiotensin II(Ang II) stimulation.Conclusions: By down-regulating GRP78, caspase-12 and CHOP expressions in myocardial cells in rat heart failure after myocardial infarction, atorvastatin treatment decreased the apoptosis of myocardial cells, suggesting the possible mechanism by which atorvastatin functions in protecting against heart failure.     

Increased expression of 78 kD glucose-regulated protein promotes cardiomyocyte apoptosis in a rat model of liver cirrhosis

Aims: This study was to investigate the role and underlying mechanism of 78 kD glucose-regulated protein (GRP78) in cardiomyocyte apoptosis in a rat model of liver cirrhosis. Methods: A rat model of liver cirrhosis was established with multiple pathogenic factors. A total of 42 male SD rats were randomly divided into the liver cirrhosis group and control group. Cardiac structure analysis was performed to assess alterations in cardiac structure. Cardiomyocytes apoptosis was detected by TdT-mediated dUTP nick end labeling method. Expression of GRP78, CCAAT/enhancer-binding protein homologous protein (CHOP), caspase-12, nuclear factor kappa-light-chain-enhancer of activated B cells p65 subunit (NF-κB p65) and B cell lymphoma-2 (Bcl-2) was detected by immunohistochemical staining. Results: The ratios of left ventricular wall thickness to heart weight and heart weight to body weight were significantly increased with the progression of liver cirrhosis (P < 0.05). Apoptosis index of cardiomyocytes was significantly increased with the progression of liver cirrhosis (P < 0.05). The expression levels of GRP78, CHOP and caspase-12 were significantly increased in the progression of liver cirrhosis (P < 0.05). The expression levels of NF-κB p65 and Bcl-2 were highest in the 4-wk liver cirrhosis, and they were decreased in the 6-wk and 8-wk in the progression of liver cirrhosis. GRP78 expression levels were positively correlated with apoptosis index, CHOP and caspase-12 expression levels (P < 0.05). CHOP expression levels were negatively correlated with NF-κB p65 and Bcl-2 expression levels (P < 0.05). Conclusion: Increased expression of GRP78 promotes cardiomyocyte apoptosis in rats with cirrhotic cardiomyopathy.     

抗衰老Klotho蛋白减轻大鼠乳鼠心肌细胞缺氧/复氧损伤

目的:观察抗衰老Klotho蛋白对大鼠乳鼠原代心肌细胞缺氧/复氧(H/R)损伤的作用并探讨其作用机制。方法:建立大鼠乳鼠心肌细胞H/R模型,并将心肌细胞分为正常对照组、H/R模型组和不同浓度(0.1μmol/L、1μmol/L和10μmol/L)Klotho作用H/R组。观察各组心肌细胞H/R前后搏动频率变化,利用MTT方法检测细胞存活率;测定各组心肌细胞H/R后LDH、CK、AST的漏出量及MDA含量、SOD活性;流式细胞术检测各组心肌细胞的凋亡率;real-time PCR检测各组心肌细胞中内质网应激标记及凋亡相关分子GRP78、CRT和CHOP和caspase-12 mRNA的表达情况;Western blot法检测心肌细胞内内质网应激凋亡蛋白CHOP和caspase-12蛋白表达及Akt磷酸化水平。结果:与正常对照组相比,H/R模型组中心肌细胞搏动频率和细胞存活率显著下降,细胞凋亡率显著升高(P0.05);LDH、CK、AST和MDA含量升高而SOD活性显著降低(P0.05);GRP78、CRT、CHOP和caspase-12 mRNA表达显著增高(P0.05);CHOP和caspase-12蛋白表达随之增高而Akt的磷酸化水平显著降低(P0.05)。与H/R模型组相比,抗衰老Klotho蛋白作用H/R心肌细胞后,心肌细胞搏动频率和细胞存活率显著升高,细胞凋亡率逐渐降低(P0.05),LDH、CK、AST和MDA含量下降而SOD活性显著增高(P0.05),GRP78、CRT、CHOP和caspase-12 mRNA的表达逐渐降低(P0.05),CHOP和caspase-12蛋白表达也随之降低,而Akt磷酸化水平显著增加(P0.05)。结论:抗衰老Klotho蛋白能够提升H/R损伤后心肌细胞的存活率,抑制细胞凋亡,通过抵抗氧化应激和过度内质网应激反应发挥作用,并与激活Akt磷酸化有关。     

Shiga toxin 2 causes apoptosis in human brain microvascular endothelial cells via C/EBP homologous protein

Shiga toxin 1 (Stx1) and Stx2 produced by Escherichia coli O157 are known to be cytotoxic to Vero and HeLa cells by inhibiting protein synthesis and by inducing apoptosis. In the present study, we have demonstrated that 10 ng/ml Stx2 induced DNA fragmentation in human brain microvascular endothelial cells (HBMEC), with cleavage activation of caspase-3, -6, -8, and -9. A microarray approach used to search for apoptotic potential signals in response to Stx2 revealed that Stx2 treatment induced a marked upregulation of C/EBP homologous protein (CHOP)/growth arrest and DNA damage-inducible protein 153 (GADD153). Increased CHOP expression was dependent on enzymatically active Stx1. Knockdown of CHOP mRNA reduced the activation of caspase-3 and prevented apoptotic cell death. These results suggest that Stx2-induced apoptosis is mediated by CHOP in HBMEC and involves activation of both the intrinsic and extrinsic pathways of apoptosis.     

过度内质网应激在慢性环孢素A肾毒性细胞凋亡中的作用机制*

 目的：探讨过度内质网应激在慢性环孢素A(CsA)肾毒性细胞凋亡中的作用机制。方法：将Sprague-Dawley大鼠分为正常对照组和慢性CsA肾毒性组,分别给予皮下注射橄榄油(1 mg·kg-1·d-1)和CsA (15 mg·kg-1·d-1)1周或4周后处死大鼠。三色染色和TUNEL染色观察肾小管间质纤维化和细胞凋亡;免疫组织化学染色和免疫印迹检测免疫球蛋白结合蛋白(BiP)、 磷酸化的真核细胞翻译起始因子2α(eIF2α)、 生长阻滞及DNA损伤诱导蛋白153(GADD153)、caspase-12和caspase-3蛋白表达。结果：CsA注射1周观察不到肾小管间质纤维化和TUNEL阳性细胞,而给予CsA注射4周大鼠表现为明显的肾小管间质纤维化［(38.9±3.3)% vs (0.0±0.0)%, P<0.01］和大量TUNEL阳性细胞 ［(89±9)% vs (7±2)%, P<0.01］。与对照组比较,CsA组BiP和caspase-12蛋白的表达于1周达到高峰,4周后降至正常水平;反之,eIF2α和caspase-3蛋白表达呈时间依赖性增加。结论：在慢性CsA肾毒性中,过度的内质网应激耗尽分子伴侣,激活凋亡途径,从而导致肾小管上皮细胞凋亡和肾小管间质损伤。