内质网应激反应在严重烧伤大鼠心肌细胞凋亡中的作用

目的内质网应激反应(endoplasmic reticulum stress,ERS)介导的凋亡是真核细胞重要凋亡途径之一,通过观察严重烧伤大鼠心肌ERS不同通路蛋白表达变化,探讨其在心肌细胞凋亡中的可能作用。方法雄性7周龄Wistar大鼠64只,体重200～220 g;随机分为两组,每组32只。实验组大鼠背部制备30%体表面积Ⅲ度烫伤;对照组制备假伤模型。伤后1、4、7、14 d两组各处死8只大鼠取心肌组织,透射电镜观察心肌超微结构变化,TUNEL法检测心肌细胞凋亡,Western blot检测ERS相关蛋白,如葡萄糖调节蛋白78(glucose regulated protein 78,GRP 78)、C/EBP同源蛋白(C/EBP-homologous protein,CHOP)、半胱氨酸天冬氨酸蛋白酶12(Caspase 12)剪切体表达变化。结果大鼠均存活至实验结束。透射电镜观察示实验组大鼠心肌细胞呈凋亡改变。伤后各时间点实验组心肌细胞凋亡指数均明显高于对照组(P<0.05),伤后1、4、7 d凋亡指数逐渐升高,14 d时下降,各时间点间比较差异均有统计学意义(P<0.05)。实验组心肌细胞GRP78、CHOP及Caspase 12剪切体蛋白表达持续升高,其中各时间点GRP 78及Caspase 12剪切体表达均较对照组显著升高,差异有统计学意义(P<0.05);除伤后1 d外,其余各时间点实验组CHOP蛋白表达均较对照组升高(P<0.05)。结论严重烧伤后大鼠心肌发生ERS,其中CHOP、Caspase 12介导的凋亡通路活化,ERS可能是心肌细胞凋亡的途径之一。     

Albumin induces endoplasmic reticulum stress and apoptosis in renal proximal tubular cells

Chronic proteinuria appears to be a key factor in tubulointerstitial damage. Recent studies have emphasized a pathogenic role of endoplasmic reticulum (ER) stress which is induced by the accumulation of misfolded proteins in ER, extracellular stress, etc. In the present study, we investigated ER stress and ER stress-induced apoptosis in proximal tubular cells (PTCs). Immortalized rat PTCs (IRPTCs) were cultured with bovine serum albumin (BSA). The viability of IRPTCs decreased proportionately with BSA overload in a time-dependent manner. Quantitative real-time polymerase chain reaction analysis revealed that 40 mg/ml BSA increases mRNA of ER stress markers by 7.7- and 4.6-fold (glucose-regulated protein 78 (GRP78) and oxygen-regulated protein 150 (ORP150), respectively) as compared to control. The increased expression of ORP150 and GRP78 in IRPTCs with albumin overload was detected by Western blot and immunofluorescence study. These in vitro observations were supported by in vivo studies, which demonstrated that ER stress proteins were upregulated at PTCs in experimental proteinuric rats. Furthermore, increased ER stress-induced apoptosis and activation of caspase-12 were observed in IRPTCs with albumin overload and kidneys of experimental proteinuric rats. We confirmed that apoptotic cell death was attenuated by co-incubation with caspase-3 inhibitor or calpain inhibitors. These results indicate that the ER stress-induced apoptosis pathway contributed to the insult of tubular cells by proteinuria. In conclusion, renal tubular cells exposed to high protein load suffer from ER stress. ER stress may subsequently lead to tubular damage by activation of caspase-12.     

内质网应激在白蛋白诱导肾小管上皮细胞凋亡中的作用

目的 探讨内质网应激在白蛋白超负荷诱导肾小管上皮细胞凋亡中的作用和分子机制。 方法 Western印迹法检测肾小管上皮细胞（HKC）内质网伴侣蛋白糖调节蛋白78（GRP78）和内质网应激蛋白CHOP（CCAAT增强子结合蛋白同源蛋白,也称为GADD153）表达与人血清白蛋白（HSA）作用时间和浓度的关系。实时荧光定量PCR法检测CHOP siRNA对CHOP基因转录的抑制情况。Western印迹法检测CHOP siRNA转染后CHOP蛋白水平的变化。膜联蛋白V和碘化丙锭（Annexin V-FITC和PI）双染的流式细胞术检测白蛋白诱导HKC凋亡的变化以及CHOP siRNA对HKC凋亡的影响。 结果 （1）分别以0、5、10、20 g/L白蛋白作用于HKC 24 h,GRP78、CHOP蛋白表达及细胞凋亡均随白蛋白浓度的增加而上调,各组间差异有统计学意义（P ＜ 0.01）;以20 g/L白蛋白分别作用于HKC 0、6、12、24、36 h,GRP78蛋白表达在6 h即显著增加,CHOP蛋白表达及HKC凋亡则在12 h显著增加,各组间差异有统计学意义（P ＜ 0.01）。（2）CHOP siRNA显著抑制白蛋白诱导的CHOP 基因转录及蛋白表达（P ＜ 0.01）,对白蛋白诱导的HKC凋亡有显著抑制作用（P ＜ 0.01）。 结论 白蛋白超负荷可诱导肾小管上皮细胞发生内质网应激,并通过上调促凋亡因子CHOP表达引起肾小管上皮细胞内质网相关的细胞凋亡,这可能是蛋白尿引起肾小管间质病变的重要机制。     

N-acetylcysteine protects against cadmium-induced germ cell apoptosis by inhibiting endoplasmic reticulum stress in testes

Cadmium (Cd) is a reproductive toxicant that induces germ cell apoptosis in the testes. Previous studies have demonstrated that endoplasmic reticulum (ER) stress is involved in Cd-induced germ cell apoptosis. The aim of the present study was to investigate the effects of N-acetylcysteine (NAC), an antioxidant, on Cd-induced ER stress and germ cell apoptosis in the testes. Male CD-1 mice were intraperitoneally injected with CdCl₂ (2.0 mg kg⁻¹). As expected, acute Cd exposure induced germ cell apoptosis in the testes, as determined by terminal dUTP nick-end labelling (TUNEL). However, the administration of NAC alleviated Cd-induced germ cell apoptosis in the testes. Further analysis showed that NAC attenuated the Cd-induced upregulation of testicular glucose-regulated protein 78 (GRP78), an important ER molecular chaperone. Moreover, NAC inhibited the Cd-induced phosphorylation of testicular eukaryotic translation initiation factor 2α (eIF2α), a downstream target of the double-stranded RNA-activated kinase-like ER kinase (PERK) pathway. In addition, NAC blocked the Cd-induced activation of testicular X binding protein (XBP)-1, indicating that NAC attenuates the Cd-induced ER stress and the unfolded protein response (UPR). Interestingly, NAC almost completely prevented the Cd-induced elevation of C/EBP homologous protein (CHOP) and phosphorylation of c-Jun N-terminal kinase (JNK), two components of the ER stress-mediated apoptotic pathway. In conclusion, NAC protects against Cd-induced germ cell apoptosis by inhibiting endoplasmic reticulum stress in the testes.     

Intracellular death platform steps-in: targeting prostate tumors via endoplasmic reticulum (ER) apoptosis

Molecular targeting of apoptotic signaling pathways has been extensively studied in recent years and directed towards the development of effective therapeutic modalities for treating advanced androgen-independent prostate tumors. The majority of therapeutic agents act through intrinsic or mitochondrial pathways to induce programmed cell death. The induction of apoptosis through endoplasmic reticulum (ER) stress pathways may provide an alternative to treat patients. The functional interaction between the BCL-2 family members and regulation of calcium homeostasis in the ER provides a critical link to the life or death outcome of the cell. Apoptosis induction mediated by ER stress-inducing agents is just beginning to be exploited for therapeutic targeting of prostate tumors. Insightful dissection of recently discovered apoptotic signaling pathways that function through the endoplasmic reticulum may identify novel molecules that could effectively target both androgen-dependent and androgen-independent prostate tumors. In this review, we focus on linking ER stress-induced apoptosis to therapeutic targeting of prostate tumors and dissect its cross-talk with the intrinsic and extrinsic apoptotic pathways.     

氢气对PC12细胞缺氧复氧时内质网应激的影响

目的 探讨氧气对PC1 2细胞缺氧复氧时内质网应激的影响.方法 PC12细胞采用随机数字表法,将其随机分为4组,正常对照组:细胞常规培养25 h;阳性对照组:细胞正常培养1h后,用氧气饱和的RPM1-1640培养基继续培养24 h;缺氧复氧组:细胞缺氧1h后复氧24 h;氢气组:细胞缺氧1 h后,州氧气饱和的RPM1,1640培氧基复氧24 h.PC12细胞加入含Na2S2O4终浓度为5.0mmol/L的RPMI-1640培养液,5％ CO2培养箱37 ℃孵育1h;更换正常RPMI-1640培养液,继续培养24h,制备PC12细胞缺氧复氧模型.采用WST-1法测定细胞相对增殖率,采用硫代巴比妥酸法测定MDA浓度,采用免疫组化法检测caspase-3表达,采用RT-PCR法检测活化转录因子4(ATF4)mRNA和C/EBP同源蛋白(CHOP)mRNA的表达.结果 与正常对照组和阳性对照组比较,缺氧复氧组细胞相对增殖率降低,MDA浓度升高,caspase-3、ATF4 mRNA和CHOP mRNA的表达七调,氧气组ATF4 mRNA和CHOP mRNA的表达上调(P＜0.05);正常对照组和阳性对照组间细胞相对增殖率、MDA浓度、caspase-3 、ATF4nRNA和CHOP mRNA的表达比较差异无统计学意义(P＞0.05);与缺氧复氧组比较,氢气组细胞相对增殖率升高,MDA浓度降低,caspase-3、ATF4 mRNA和CHOP mRNA的表达下调(P＜0.05).结论 氧气可能通过抑制内质网应激,降低细胞凋亡,减轻PC12细胞缺氧复氧损伤.     

山莨菪碱对大鼠急性肾损伤时内质网应激的影响

目的 评价山莨菪碱对大鼠急性肾损伤时内质网应激(ERS)的影响.方法 雄性SD大鼠42只,体重200 ～ 220 g,采用随机数字表法将其分为3组:对照组(C组,n=6),双侧后肢肌肉注射生理盐水10 ml/kg;急性肾损伤组(AKI组,n=18),双侧后肢肌肉注射50％ (v/v)甘油10 ml/kg;山莨菪碱组(AD组,n=18),腹腔注射山莨菪碱10 mg/kg,20 min后处理同AKI组.C组于肌肉注射生理盐水后即刻(T0),AKI组和AD组于甘油给药后1 h(T1)、6 h(T2)、24 h(T3)分别随机取6只大鼠,采集肾组织标本,HE染色后行肾小管损伤评分,采用免疫组化和Western blot法测定肾组织葡萄糖调节蛋白78(GRP78)和氧调节蛋白150(ORP150)表达.结果 与C组比较,AKI组和AD组各时点肾小管损伤评分升高,肾组织GRP78和ORP150表达上调(P＜0.01);与AKI组比较,AD组各时点肾小管损伤评分降低,肾组织GRP78和ORP150表达下调(P＜0.05或0.01).结论 山莨菪碱可抑制肾小管上皮细胞ERS,可能减轻了ERS途径诱导的细胞凋亡,从而减轻了大鼠急性肾损伤.     

番茄红素对缺氧/复氧诱导小鼠心肌细胞内质网应激和凋亡的影响

目的 评价番茄红素对缺氧/复氧(hypoxia/reoxygenation,H/R)引起的小鼠心肌细胞内质网应激(endoplasmic reticulum stress,ERS)和凋亡的影响. 方法 建立C57BU6乳鼠心肌细胞H/R模型,采用随机数字表法将C57BL/6小鼠心肌细胞分为正常对照组(C组)、番茄红素组(Lyc组,含5μmol/L番茄红素的培养基预处理4h)、H/R组(H/R组,缺氧4h复氧6h)和番茄红素+H/R组(Lyc+H/R组,给予5μmol/L番茄红素预处理4h后行H/R处理).采用水溶性四氮唑-8(cell counting Kit-8,CCK-8)法检测心肌细胞存活率,倒置显微镜下观察细胞搏动频率,TUNEL法检测细胞凋亡率,二氯荧光素法(dichlomnuorescein diacetate,DCFH-DA)检测细胞内活性氧(reactive oxygen species,ROS)含量,实时荧光定量PCR (real-time PCR)检测葡萄糖调节蛋白78(glucose-regulated protein 78,GRP78)、C/EBP同源蛋白(C/EBP homologous protein,CHOP)及半胱天冬氨酸蛋白酶-12 (cysteme aspartate specific protease-12,caspase-12)mRNA的表达,Western blot法分析剪切的半胱天冬氨酸蛋白酶-12(cleaved cysteme aspartate specific protease-12,Cleaved-caspase-12)和剪切的半胱天冬氨酸蛋白酶-3(cleaved cysteme aspartate specific protease-3,Cleaved-caspase-3)的表达. 结果 与C组比较,H/R组心肌细胞存活率显著降低[(100±5)％,(69±6)％](P＜0.01),搏动频率显著降低[(94±6),(28±5)次/min](P＜0.01),心肌细胞凋亡率[(4.9±1.5)％,(25.6±2.6)％]和ROS含量[(100±11)％,(226±10)％]显著升高(P＜0.01);CHOP mRNA[(1.00±0.10)、(2.60±0.19)]和GRP78 mRNA[(1.00±).18)、(4.12±0.23)]表达水平显著升高(P＜0.05);caspase-12 mRNA[(1.00±0.09)、(1.79±0.14)]、Cleaved-caspase-12[(1.00±0.08)、(1.85±0.10)]和Cleaved-caspase-3[(1.00±0.07)、(1.89±0.14)]表达水平显著升高(P＜0.05).与H/R组比较,Lyc+H/R组心肌细胞存活率明显升高[(69±6)％、(84±7)％](P＜0.05),搏动频率增加[(28±5)、(73±6)次/min] (P＜0.05),凋亡率显著降低[(25.6±2.6)％,(18.2±2.2)％](P＜0.05),细胞内ROS含量[(226±10)％、(140±16)％]明显降低,CHOP mRNA [(2.60±0.19)、(1.71±0.14)]和GRP78 mRNA[(4.12±0.23),(1.98±0.19)]表达水平显著降低(P＜O.05);caspase-12 mRNA[(1.79±0.14)、(1.38±0.11)]、Cleaved-caspase-12[(1.85±0.10)、(1.26±0.12)]和Cleaved-caspase-3[(1.89±0.14)、(1.36±0.12)]表达水平显著降低(P＜0.05). 结论 番茄红素可抑制H/R过程中的ERS及其凋亡信号途径而减轻心肌细胞损伤.     

乳化异氟醚对大鼠肺缺血-再灌注内质网应激的影响

目的探索乳化异氟醚预处理对大鼠肺缺血-再灌注损伤诱导内质网应激的影响。方法雄性SD大鼠32只随机分成四组:假手术组(S组)、缺血-再灌注组(IR组)、乳化异氟醚预处理(EI组)、脂肪乳组(IL组)。S组腹腔注射生理盐水10.5ml/kg,24h后仅开胸游离左肺门,不进行阻断左肺门;IR组、EI组和IL组分别腹腔注射生理盐水、8%乳化异氟醚10.5 ml/kg、30%脂肪乳10.5ml/kg,24h后通过阻断左肺门1h后再灌注2h建立大鼠原位肺缺血-再灌注损伤模型。于再灌注2h即刻经左心室采集血样检测PaO2、PaCO2值;取左肺组织测湿重/干重比(W/D),通过HE染色评估肺组织病理损伤程度;通过RT-PCR和Western blot检测肺组织中GRP78和CHOP的表达水平。结果与S组比较,IR组、EI组和IL组PaCO2、肺组织GRP78、CHOP mRNA和CHOP蛋白表达明显升高,PaO2明显降低(P0.05),GRP78蛋白表达水平差异无统计学意义;与IR组比较,EI组、IL组PaCO2、肺组织GRP78mRNA、CHOP mRNA和CHOP蛋白表达明显降低、PaO2明显升高(P0.05),GRP78蛋白表达水平差异无统计学意义。与IL组比较,EI组PaCO2、肺组织W/D、GRP78、CHOP mRNA和CHOP蛋白表达明显降低、PaO2明显升高(P0.05),GRP78蛋白表达水平差异无统计学意义。病理显示EI组和IL组肺损伤轻于IR组,EI组肺损伤轻于IL组。结论乳化异氟醚和脂肪乳预处理均可减轻大鼠术后肺缺血-再灌注损伤引起的过度内质网应激,并且乳化异氟醚的保护效果更显著。     

Involvement of endoplasmic reticulum (ER) stress in podocyte injury induced by excessive protein accumulation

BACKGROUND: An imbalance between protein load and folding capacity is referred to as endoplasmic reticulum (ER) stress. As a defense mechanism, cells express ER stress inducible chaperons, such as oxygen-regulated proteins 150 (ORP150) and glucose-regulated proteins (GRPs). While ER stress is important in various diseases, a pathophysiologic role for ER stress in kidney disease remains elusive. Here we investigate expression of ER stress proteins in cultured rat podocytes as well as in our recently developed animal model of abnormal protein retention within the ER of podocytes (i.e., megsin transgenic rat). METHODS: The expression of ER stress inducible proteins (ORP150, GRP78, or GRP94) in cultured podocytes treated with tunicamycin, A23187, SNAP, hypoxia, or hyperglycemia, and the renal tissues or isolated glomeruli from megsin transgenic rats was analyzed by Western blotting analysis, immunohistochemistry, or confocal microscopy. RESULTS: Cultured podocytes demonstrated that treatment with tunicamycin, A23187, and SNAP, but not hypoxia or hyperglycemia, up-regulate expression of ER stress proteins. Extracts of isolated glomeruli from megsin transgenic rats reveal marked up-regulation of ER stress chaperones in podocytes, which was supported by immunohistochemical analysis. Confocal microscopy revealed that ER stress in podocytes was associated with cellular injury. Podocytes of transgenic rats overexpressing a mutant megsin, without the capacity for polymerization within the ER, do not exhibit ER stress or podocyte damage, suggesting a pathogenic role of ER retention of polymerized megsin. CONCLUSION: This paper implicates a crucial role for the accumulation of excessive proteins in the podocyte ER in the induction of ER stress and associated podocyte injury.     

异丙酚预先给药对大鼠脑缺血再灌注时内质网应激性细胞凋亡的影响

目的 评价异丙酚预先给药对大鼠局灶性脑缺血再灌注损伤时内质网应激性细胞凋亡的影响.方法 健康成年雄性SD大鼠80只,体重240～280 g,采用随机数字表法,将大鼠随机分为4组(n=20):假手术组(S组);局灶性脑缺血再灌注组(FCIR组)采用阻塞大脑中动脉4h恢复灌注的方法制备大鼠局灶性脑缺血再灌注模型;异丙酚预先给药组(P组)于缺血前30 min股静脉泵注异丙酚12mg·kg-1·h-1至缺血15min;脂肪乳预先给药组(Ⅰ组)给予脂肪乳1.2 ml·kg-1·h-1.于再灌注6h时各组随机取10只大鼠采用Longa评分法行神经功能缺陷评分(NDS),处死取左侧大脑,用干湿重法测定脑含水量,余10只大鼠处死后取左侧海马,采用Western blot法检测C/EBP环磷酸腺苷反应元件结合转录因子同源蛋白(CHOP)、Bcl-2和活化型caspase-3蛋白的表达水平.结果 与S组比较,FCIR组再灌注6h时NDS评分和脑含水量升高,CHOP和活化型caspase-3蛋白表达上调,Bcl-2蛋白表达下调,P组NDS评分升高(P＜0.05);与FCIR组比较,P组再灌注6h时NDS评分和脑含水量降低,CHOP和活化型caspase-3蛋白表达下调,Bcl-2蛋白表达上调(P＜0.05),Ⅰ组各指标差异无统计学意义(P＞0.05).结论 异丙酚可通过抑制内质网应激介导的细胞凋亡减轻大鼠局灶性脑缺血再灌注损伤.     

Lisinopril suppresses the endoplasmic reticulum stress associated tubular cell apoptosis induced by proteinuria in adriamycin nephropathy

Objective To investigate the role of endoplasmic reticulum stress in tubular epithelial cell apoptosis in chronic proteinuria rat model and the effect of lisinopril intervention. Methods Adriamycin nephropathy was induced in male Wistar rats (n=12) by a single injection of adriamycin at 2 mg/kg body weight. Rats were then randomly assigned to model group or treatment group, to which distilled water or lisinopril were administered respectively for 12 weeks. Six normal rats serving as controls were administered distilled water. 24 h urine samples were collected at week 4, 8, 12 and the urine protein was measured. At the end of study, serum was obtained and physiological parameters (serum creatinine, urea, total protein and albumin) were measured. Renal tubular epithelial cell apoptosis was assessed by TUNEL. GRP78, CHOP protein expression in kidney was quantified by immunohistochemistry and Western blotting. Results Compared to control group rats, increased proteinuria was observed in model group rats at week 4, 8, 12 (P＜0.05). Lisinopril treatment attenuated urine protein excretion significantly (P＜0.05). At week 12, hypoalbuminemia was detected in model group rats (P＜0.05), whereas the condition was alleviated by lisinopril (P＜0.05). There were no significant differences of serum creatinine, urea and total protein in each group (P＞0.05). Compared to control group rats, increased TUNEL positive tubular epithelial cells and tubular GRP78 and CHOP expression were also observed in model group rats (P＜0.05); however, these conditions in the kidney were significantly decreased in treatment group (P＜0.05). Conclusions Endoplasmic reticulum stress may be involved in the process of tubular epithelial cell apoptosis induced by proteinuria. Lisinopril may attenuate tubular epithelial cell apoptosis through regulating this signal pathway.     

异硫氰酸苯乙酯通过内质网应激途径促进乳腺癌细胞凋亡及增殖的研究

目的探索异硫氰酸苯乙酯(PEITC)对乳腺癌SK-BR-3细胞凋亡及增殖的影响。方法分别采用不同浓度(0、10、30、50μmol/L)的PEITC处理SK-BR-3细胞,然后采用MTT法和BrdU染色法检测各组细胞的增殖能力,TUNEL法和流式细胞技术检测细胞凋亡,Western blot法和实时荧光定量PCR(qRT-PCR)法检测凋亡相关指标如Bcl-2、Bax、髓细胞白血病基因1(MCL-1)和内质网应激(ERS)相关指标如蛋白激酶R样内质网激酶(PERK)、CCAAT/增强子结合蛋白同源蛋白(CHOP)、肌醇依赖内质网调节细胞核信号激酶1α(IRE1α)、活化转录因子6α(ATF6α)、真核生物翻译起始因子2α亚基(eIF2α)的表达情况。结果与对照组(0μmol/L PEITC处理组)细胞比较,MTT法和BrdU染色法检测结果均显示10、30、50μmol/L PEITC处理组SK-BR-3细胞增殖能力降低且随浓度升高呈依次降低的趋势;TUNEL法和流式细胞技术检测结果均显示10、30、50μmol/L PEITC处理组SK-BR-3细胞的凋亡率升高且随浓度升高呈依次升高的趋势;Western blot和qRT-PCR法检测结果显示抗凋亡指标(Bcl-2、MCL-1)的蛋白和mRNA表达水平均降低且随浓度升高呈依次降低的趋势,而促凋亡指标Bax和ERS相关指标(PERK、CHOP、IRE1α、ATF6α、eIF2α)的蛋白和mRNA表达水平均升高且随浓度升高呈依次升高的趋势。结论从本研究初步研究结果看,PEITC能促进乳腺癌SK-BR-3细胞凋亡、抑制细胞增殖,其可能通过调控凋亡相关指标和ERS相关指标表达来实现。     

内质网应激在糖尿病肾病中的作用和机制

在欧美国家,糖尿病肾病(DN)是导致终末期肾病最常见的病因[1].在我国,随着糖尿病发病率的升高,DN也上升至终末期肾脏疾病(ESRD)病因的第2位[2],发展至肾衰竭的比例为20%～40%[3].因此,研究DN的发病机制和相应的干预措施将为人类带来巨大的健康收益.目前有多种学说试图对DN的发病机制做出解释.