Yinchenhao decoction attenuates obstructive jaundice-induced liver injury and hepatocyte apoptosis by suppressing protein kinase RNA-like endoplasmic reticulum kinase-induced pathway

BACKGROUND Chronic biliary obstruction results in ischemia and hypoxia of hepatocytes,and leads to apoptosis.Apoptosis is very important in regulating the homeostasis of the hepatobiliary system.Endoplasmic reticulum(ER)stress is one of the signaling pathways that induce apoptosis.Moreover,the protein kinase RNA-like endoplasmic reticulum kinase(PERK)-induced apoptotic pathway is the main way;but its role in liver injury remains unclear.Yinchenhao decoction(YCHD)is a traditional Chinese medicine formula that alleviates liver injury and apoptosis,yet its mechanism is unknown.We undertook this study to investigate the effects of YCHD on the expression of ER stress proteins and hepatocyte apoptosis in rats with obstructive jaundice(OJ).AIM To investigate whether YCHD can attenuate OJ-induced liver injury and hepatocyte apoptosis by inhibiting the PERK-CCAAT/enhancer-binding protein homologous protein(CHOP)-growth arrest and DNA damage-inducible protein 34(GADD34)pathway and B cell lymphoma/leukemia-2 related X protein(Bax)/B cell lymphoma/leukemia-2(Bcl-2)ratio.METHODS For in vivo experiments,30 rats were divided into three groups:control group,OJ model group,and YCHD-treated group.Blood was collected to detect the indicators of liver function,and liver tissues were used for histological analysis.For in vitro experiments,30 rats were divided into three groups:G1,G2,and G3.The rats in group G1 had their bile duct exposed without ligation,the rats in group G2 underwent total bile duct ligation,and the rats in group G3 were given a gavage of YCHD.According to the serum pharmacology,serum was extracted and centrifuged from the rat blood to cultivate the BRL-3A cells.Terminal deoxynucleotidyl transferase mediated dUTP nick end-labelling(TUNEL)assay was used to detect BRL-3A hepatocyte apoptosis.Alanine aminotransferase(ALT)and aspartate transaminase(AST)levels in the medium were detected.Western blot and quantitative real-time polymerase chain reaction(qRT-PCR)analyses were used to detect protein and gene expression levels of PERK,CHOP,GADD34,Bax,and Bcl-2 in the liver tissues and BRL-3A cells.RESULTS Biochemical assays and haematoxylin and eosin staining suggested severe liver function injury and liver tissue structure damage in the OJ model group.The TUNEL assay showed that massive BRL-3A rat hepatocyte apoptosis was induced by OJ.Elevated ALT and AST levels in the medium also demonstrated that hepatocytes could be destroyed by OJ.Western blot or qRT-PCR analyses showed that the protein and mRNA expression levels of PERK,CHOP,and GADD34 were significantly increased both in the rat liver tissue and BRL-3A rat hepatocytes by OJ.The Bax and Bcl-2 levels were increased,and the Bax/Bcl-2 ratio was also increased.When YCHD was used,the PERK,CHOP,GADD34,and Bax levels quickly decreased,while the Bcl-2 levels increased,and the Bax/Bcl-2 ratio decreased.CONCLUSION OJ-induced liver injury and hepatocyte apoptosis are associated with the activation of the PERK-CHOP-GADD34 pathway and increased Bax/Bcl-2 ratio.YCHD can attenuate these changes.

Prostaglandin E1 protects hepatocytes against endoplasmic reticulum stress-induced apoptosis via protein kinase A-dependent induction of glucose-regulated protein 78 expression

AIM To investigate the protective effect of prostaglandin E1(PGE1) against endoplasmic reticulum(ER) stressinduced hepatocyte apoptosis, and to explore its underlying mechanisms.METHODS Thapsigargin(TG) was used to induce ER stress in the human hepatic cell line L02 and hepatocarcinomaderived cell line Hep G2. To evaluate the effects of PGE1 on TG-induced apoptosis, PGE1 was used an hour prior to TG treatment. Activation of unfolded protein response signaling pathways were detected by western blotting and quantitative real-time RTPCR. Apoptotic index and cell viability of L02 cells and Hep G2 cells were determined with flow cytometry and MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2 H-tetrazolium] assay. RESULTS Pretreatment with 1 μmol/L PGE1 protected against TG-induced apoptosis in both L02 cells and Hep G2 cells. PGE1 enhanced the TG-induced expression of C/EBP homologous protein(CHOP), glucose-regulated protein(GRP) 78 and spliced X box-binding protein 1 at 6 h. However, it attenuated their expressions after 24 h. PGE1 alone induced protein and m RNA expressions of GRP78; PGE1 also induced protein expression of DNA damage-inducible gene 34 and inhibited the expressions of phospho-PKR-like ER kinase, phosphoeukaryotic initiation factor 2α and CHOP. Treatment with protein kinase A(PKA)-inhibitor H89 or KT5720 blocked PGE1-induced up-regulation of GRP78. Further, the cytoprotective effect of PGE1 on hepatocytes was not observed after blockade of GRP78 expression by H89 or small interfering RNA specifically targeted against human GRP78.CONCLUSION Our study demonstrates that PGE1 protects against ER stress-induced hepatocyte apoptosis via PKA pathwaydependent induction of GRP78 expression.

Role of endoplasmic reticulum stress in the loss of retinal ganglion cells in diabetic retinopathy

Endoplasmic reticulum stress is closely involved in the early stage of diabetic retinopathy. In the present study, a streptozotocin-induced diabetic animal model was given an intraperitoneal injection of tauroursodeoxycholic acid. Results from immunofluorescent co-localization experiments showed that both caspase-12 protein and c-Jun N-terminal kinase 1 phosphorylation levels significantly in- creased, which was associated with retinal ganglion cell death in diabetic retinas. The C/ERB ho- mologous protein pathway directly contributed to glial reactivity, and was subsequently responsible for neuronal loss and vascular abnormalities in diabetic retinopathy. Our experimental findings in- dicate that endoplasmic reticulum stress plays an important role in diabetes-induced retinal neu- ronal loss and vascular abnormalities, and that inhibiting the activation of the endoplasmic reticulum stress pathway provides effective protection against diabetic retinopathy.

Neuroprotective role of edaravone and the effects of endoplasmic reticulum stress in an adult rat model of focal cerebral ischemia/reperfusion

BACKGROUND： Endoplasmic reticulum （ER） stress impairs ER functions and leads to the accumulation of unfolded or misfolded proteins in the ER lumen. ER stress-induced cell death plays an important role in cerebral ischemia. Edaravon （3-methyl-1-phenyl-2-pyrazolin-5-one） is a potent and novel scavenger of free radicals that inhibit delayed neuronal death, as demonstrated by in vitro and animal studies. However, its effect on ER stress and induced neuronal apoptosis in a rat model of brief middle cerebral artery occlusion remains unclear. OBJECTIVE： To explore the effects of edaravone on the expression of ER stress-related factors and neuronal apoptosis, based on the hypothesis that edaravone influences ER stress in a rat model of cerebral ischemia/reperfusion. DESIGN, TIME AND SETTING： A randomized, controlled, animal study was performed at the Laboratory of Department of Neurology, Xiangya Hospital and the Department of Laboratory Animals, Xiangya Medical College, Central South University in China from June 2005 to May 2006. MATERIALS： Edaravone was purchased from Simcere Pharmaceutical Group, China. METHODS： A total of 216 adult, male, Sprague Dawley rats were randomly assigned to sham-surgery, model and edaravone groups, with 72 rats in each group, Brief middle cerebral artery occlusion was established in the model and edaravone groups. In addition, the edaravone group rats were injected with 3 mg/kg edaravone through the tail vein. MAIN OUTCOME MEASURES： RNA-dependent protein kinase-like endoplasmic reticulum eukaryotic translation initiation factor 2a kinase （PERK） and C/EBP homology protein （CHOP） mRNA expression in the ischemic parietal cortex was determined by reverse transcriptionpolymerase chain reaction; phosphorylated PERK and CHOP protein expression was detected by immunohistochemistry; neuronal apoptosis was detected by TdT-mediated-dUTP nick end labeling. RESULTS： Neurological deficit scores were significantly reduced in the edaravone group compared to the model group at 12, 24, and 72 hours following reperfusion （P〈 0.05）. In addition, PERK and CHOP mRNA as well as phosphorylated PERK and CHOP protein expression were significantly reduced in the edaravone group compared to the model group at 1,3, and 6 hours following reperfusion （P 〈 0.05, P 〈 0.01）. CHOP mRNA expression was decreased in the edaravone group compared to the model group at 3, 6, 12, and 24 hours following reperfusion （P〈 0.01）, while CHOP protein expression was less than the model group at 6, 12, and 24 hours following reperfusion （P 〈 0.05）. CONCLUSION： Edaravone treatment resulted in decreased PERK and CHOP expression following ischemia/reperfusion, as well as reduced neuronal apoptosis. Edaravone exhibited a neuroprotective role by inhibiting endoplasmic reticulum stress.

Neuroprotective effects of atorvastatin against cerebral ischemia/reperfusion injury through the inhibition of endoplasmic reticulum stress

Cerebral ischemia triggers secondary ischemia/reperfusion injury and endoplasmic reticulum stress initiates cell apoptosis. However, the regulatory mechanism of the signaling pathway remains unclear. We hypothesize that the regulatory mechanisms are mediated by the protein kinase-like endoplasmic reticulum kinase/eukaryotic initiation factor 2α in the endoplasmic reticulum stress signaling pathway. To verify this hypothesis, we occluded the middle cerebral artery in rats to establish focal cerebral ischemia/reperfusion model. Results showed that the expression levels of protein kinase-like endoplasmic reticulum kinase and caspase-3, as well as the phosphorylation of eukaryotic initiation factor 2α, were increased after ischemia/reperfusion. Administration of atorvastatin decreased the expression of protein kinase-like endoplasmic reticulum kinase, caspase-3 and phosphorylated eukaryotic initiation factor 2α, reduced the infarct volume and improved ultrastructure in the rat brain. After salubrinal, the specific inhibitor of phosphorylated eukaryotic initiation factor 2α was given into the rats intragastrically, the expression levels of caspase-3 and phosphorylated eukaryotic initiation factor 2α in the were decreased, a reduction of the infarct volume and less ultrastructural damage were observed than the untreated, ischemic brain. However, salubrinal had no impact on the expression of protein kinase-like endoplasmic reticulum kinase. Experimental findings indicate that atorvastatin inhibits endoplasmic reticulum stress and exerts neuroprotective effects. The underlying mechanisms of attenuating ischemia/reperfusion injury are associated with the protein kinase-like endoplasmic reticulum kinase/eukaryotic initiation factor 2α/caspase-3 pathway.

A novel mechanism of PHB2-mediated mitophagy participating in the development of Parkinson's disease

Endoplasmic reticulum stress and mitochondrial dysfunction play important roles in Parkinson s disease,but the regulato ry mechanism remains elusive.Prohibitin-2(PHB2)is a newly discove red autophagy receptor in the mitochondrial inner membrane,and its role in Parkinson’s disease remains unclear.Protein kinase R(PKR)-like endoplasmic reticulum kinase(PERK)is a factor that regulates cell fate during endoplasmic reticulum stress.Parkin is regulated by PERK and is a target of the unfolded protein response.It is unclear whether PERK regulates PHB2-mediated mitophagy thro ugh Parkin.In this study,we established a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP)-induced mouse model of Parkinson’s disease.We used adeno-associated virus to knockdown PHB2 expression.Our res ults showed that loss of dopaminergic neurons and motor deficits were aggravated in the MPTP-induced mouse model of Parkinson’s disease.Ove rexpression of PHB2 inhibited these abnormalities.We also established a 1-methyl-4-phenylpyridine(MPP+)-induced SH-SY5Y cell model of Parkinson’s disease.We found that ove rexpression of Parkin increased co-localization of PHB2 and microtubule-associated protein 1 light chain 3,and promoted mitophagy.In addition,MPP+regulated Parkin involvement in PHB2-mediated mitophagy through phosphorylation of PERK.These findings suggest that PHB2 participates in the development of Parkinson’s disease by intera cting with endoplasmic reticulum stress and Parkin.

白藜芦醇通过IRE1α-XBP1通路抑制衣霉素诱导的神经元凋亡和GSK-3β/Tau蛋白磷酸化

研究白藜芦醇(resveratrol,Res)对内质网应激途径细胞凋亡和糖原合成酶激酶-3β(glycogen synthase kinase-3β,GSK-3β)/Tau蛋白磷酸化作用的影响。体外原代培养神经元细胞,采用衣霉素(tunicamycin,TM)建立内质网应激模型,Western blot法检测内质网分子伴侣蛋白葡萄糖调节蛋白78(glucose-regulated protein 78,GRP78)、未折叠蛋白反应相关的肌醇需要酶1α(inositol-requiring enzyme 1α,IRE1α)的Ser724磷酸化、剪接的X盒结合蛋白1(spliced form of X-box binding protein 1s,XBP1s)表达、GSK-3β的Ser9和Tau蛋白的Ser396磷酸化水平。生物化学方法分析细胞质中半胱天冬酶-12(Caspase-12)和半胱天冬酶-3(Caspase-3)活性、细胞凋亡水平。结果显示,TM能够诱导内质网应激作用,导致神经元细胞GSK-3β的活化和Tau蛋白磷酸化水平升高(P<0.01)、神经元细胞经内质网途径凋亡(P<0.05)。与内质网应激抑制剂4-苯基丁酸结果相似,Res组显著降低了GRP78的表达(P<0.01)、降低了IRE1α-XBP1通路的活性(P<0.01)。Res可以减缓TM诱导的内质网途径细胞凋亡级联反应中Caspase-12和Caspase-3的活性(P<0.01)。Res抑制了TM诱导的GSK-3β的Ser9位点磷酸化水平和Tau蛋白Ser396位点的磷酸化水平(P<0.01)。结果表明,Res能够降低TM诱导的IRE1α-XBP1途径内质网应激作用、GSK-3β的活性及Tau蛋白发生磷酸化水平,减弱神经元细胞经内质网途径凋亡的级联反应作用。

Unravelling the story of protein misfolding in diabetes mellitus

Both environmental and genetic factors contribute to the development of diabetes mellitus and although monogenic disorders are rare,they offer unique insights into the fundamental biology underlying the disease.Mutations of the insulin gene or genes involved in the response to protein misfolding cause early onset diabetes.These have revealed an important role for endoplasmic reticulum stress in β-cell survival.This form of cellular stress occurs when secretory proteins fail to fold efficiently.Of all the professional secretory cells we possess,β-cells are the most sensitive to endoplasmic reticulum stress because of the large fluctuations in protein synthesis they face daily.Studies of endoplasmic reticulum stress signaling therefore offer the potential to identify new drug targets to treat diabetes.

The Role and Mechanism of Unfolded Protein Response Pathway in Tumor Drug Resistance

In the process of tumor proliferation and metastasis,tumor cells encounter hypoxia,low glucose,acidosis,and other stressful environments.These conditions prompt tumor cells to generate endoplasmic reticulum stress(ERS).As a signal mechanism that mitigates ERS in eukaryotic cells,the unfolded protein response(UPR)pathway can activate cells and tissues,regulating pathological activities in various cells,and maintaining ER homeostasis.It forms the most crucial adaptive and defensive mechanism for cells.However,under the continuous influence of chemotherapy drugs,the quantity of unfolded proteins and erroneous proteins produced by tumor cells significantly increases,surpassing the normal regulatory range of UPR.Consequently,ERS fails to function properly,fostering tumor cell proliferation and the development of drug resistance.This review delves into the study of three UPR pathways(PERK,IRE1,and ATF6),elucidating the mechanisms of drug resistance and research progress in the signal transduction pathway of UPR related to cancers.It provides a profound understanding of the role and relationship between UPR and anti-tumor drugs,offering a new direction for effective clinical treatment.

黄芪皂苷通过调控蛋白激酶R样内质网激酶途径抑制高糖诱导的人视网膜色素上皮细胞自噬的研究

目的:探讨黄芪皂苷通过调控蛋白激酶R样内质网激酶(PERK)途径影响高糖诱导的人视网膜色素上皮细胞(ARPE-19细胞)自噬水平。方法:体外培养人视网膜色素上皮细胞,实验分为正常对照组(5.5 mmol/L葡萄糖),高糖组(30 mmol/L葡萄糖),黄芪皂苷组(30 mmol/L葡萄糖+2.5、5、10μg/mL黄芪皂苷)。噻唑蓝比色(MTT)法检测ARPE-19细胞活性,流式细胞仪检测细胞凋亡率,蛋白免疫印迹(Western blot)法检测自噬相关蛋白及PERK途径关键因子表达水平。添加PERK特异性抑制剂GSK2606414,Western blot检测对细胞自噬水平的影响。结果:与正常对照组比较,高糖组ARPE-19细胞活性降低,凋亡率升高,自噬相关蛋白LC3表达水平明显升高,另一自噬相关蛋白p62蛋白表达水平明显降低。PERK途径关键因子葡萄糖调节蛋白78(GRP78)、Perk和增强子结合蛋白的同源蛋白(CHOP)表达水平明显上调,差异具有统计学意义(P<0.05)。与高糖组比较,黄芪皂苷组ARPE-19细胞活性升高,凋亡率降低,LC3蛋白表达水平明显下调,p62蛋白表达水平明显上调,GRP78、Perk和CHOP蛋白水平明显降低,差异具有统计学意义(P<0.05)。PERK特异性抑制剂GSK2606414能够进一步抑制黄芪皂苷组ARPE-19细胞LC3蛋白表达水平,上调p62蛋白表达水平,差异具有统计学意义(P<0.05)。结论:黄芪皂苷能够抑制高糖诱导的人视网膜色素上皮细胞自噬水平,其作用机制可能与抑制蛋白激酶R样内质网激酶途径有关。

内质网应激PERK凋亡通路研究进展

蛋白激酶R样内质网激酶(protein kinase R—like ER kinase,PERK)是位于内质网膜上的一种I型跨膜蛋白,属于elF2a上游激酶家族中的一种。PERK信号通路的激活发生在内质网应激早期,通过抑制蛋白质的合成对细胞起保护作用、促进细胞的生存。随着内质网应激时间的延长,PERK通过诱导CHOP的表达而促进细胞凋亡。PERK特异性的磷酸酶去磷酸化抑制PERK,调控的信号途径在中枢神经系统、缺血一再灌注损伤及代谢异常等病理过程中发挥着重要的作用。

PERK介导的内质网应激参与血管紧张素Ⅱ诱导心肌肥大的机制

目的:研究蛋白激酶R样内质网激酶(PERK)介导的内质网应激(ERS)反应在血管紧张素Ⅱ(AngⅡ)诱导心肌细胞肥大中的作用。方法:在AngⅡ诱导原代培养的乳大鼠心肌细胞肥大模型上,采用[3H]-亮氨酸掺入、心肌细胞表面积测定等评估心肌细胞肥大程度;以实时定量PCR、RT-PCR和Western blotting检测ERS标志性分子葡萄糖调节蛋白78(GRP78)、钙网蛋白(CRT)、蛋白激酶R样内质网激酶(PERK)、真核细胞翻译起始因子2α(eIF2α)和C/EBP同源蛋白(CHOP)mRNA和蛋白表达变化。结果:与正常对照组比较,AngⅡ组CRTmRNA和蛋白表达分别高146.4%和125.3%(P<0.05),GRP78 mRNA和蛋白的表达分别高84.0%和77.6%(P<0.05),PERK mRNA和蛋白表达分别高165.4%和132.1%(P<0.05),eIF2αmRNA和蛋白表达分别高110.9%和46.5%(P<0.05),CHOP mRNA和蛋白表达分别高117.7%和63.3%(P<0.05)。结论:PERK介导的内质网应激反应参与了AngⅡ诱导的心肌细胞肥大。

低剂量电离辐射诱导小鼠睾丸细胞内质网应激及PERK-CHOP信号通路的激活

目的:探讨低剂量电离辐射与小鼠睾丸细胞内质网应激的发生以及PERK-CHOP通路激活的相关性。方法:健康雄性昆明小鼠随机分成时程-效应(75 mGy照射后0、3、6、12和24 h)和剂量-效应(0、50、75、100和200 mGy照射后12 h)组,每组动物10只。采用H2O2和MDA试剂盒比色法检测其含量;利用实时定量逆转录PCR(quantitative RT-PCR)检测GRP78、PERK和CHOP mRNA;Western印迹和图像分析技术检测GRP78、PERK、磷酸化PERK(phosphorylated PERK,pho-PERK)和CHOP蛋白表达。结果:小鼠经75 mGy全身照射后,睾丸组织中H2O2含量随时间延长而增加,MDA含量在3和6 h稍有降低,而后随时间延长而增加,二者在12和24 h较0 h时显著增加(P<0.05,P<0.01);除了GRP78 mRNA(3和24 h)和蛋白表达(6 h)分别在照射后有降低趋势外,GRP78(12 h)、PERK(3、6、12和24 h)和CHOP(12和24 h)的mRNA表达较0 h显著增加(P<0.05,P<0.01),GRP78(12和24 h)、pho-PERK(3、12和24 h)和CHOP(3、6、12和24 h)的蛋白表达也都较0 h显著增加(P<0.05,P<0.01),PERK蛋白表达则无明显变化规律。小鼠经50～200 mGy全身照射后12 h,睾丸组织中H2O2含量在50～100 mGy照射后随剂量增加而增加,200 mGy照射后则稍有降低,MDA含量随剂量增加而增加,而且H2O2含量(75和100 mGy)和MDA含量(75、100和200 mGy)显著高于0 mGy组(P<0.05,P<0.01);除了GRP78mRNA表达在50和200 mGy照射后有降低趋势外,GRP78(75和100 mGy)、PERK(75、100和200 mGy)和CHOP(50、75、100和200 mGy)的mRNA表达都显著高于0 mGy组(P<0.05,P<0.01),GRP78(100和200 mGy)、pho-PERK(50、100和200 mGy)和CHOP(50、75、100和200 mGy)的蛋白表达也都显著高于0 mGy组(P<0.05,P<0.01),而PERK蛋白表达则无明显变化规律。结论:低剂量电离辐射能够诱导小鼠睾丸细胞发生内质网应激,并且激活PERK-CHOP信号通路。

MR-1通过抑制PERK/Nrf2途径减轻缺氧/复氧诱导的心肌细胞凋亡

目的:研究肌原纤维形成调节因子1(MR-1)是否通过抑制蛋白激酶R样内质网激酶(PERK)/核因子E2相关因子2(Nrf2)途径减轻缺氧/复氧(H/R)诱导的心肌细胞凋亡。方法:在原代培养的乳大鼠心肌细胞H/R模型上,采用Annexin V/PI双标法检测心肌细胞的凋亡率;以Western blotting检测葡萄糖调节蛋白78(GRP78)、磷酸化PERK、Nrf2、活化转录因子4(ATF4)、C/EBP同源蛋白(CHOP)、Bcl-2和Bax的蛋白水平,研究过表达或敲低对于H/R致心肌细胞凋亡的影响及其与PERK/Nrf2途径活化的关系。结果:H/R引起心肌细胞凋亡;过表达MR-1减轻H/R引起的细胞凋亡(P<0.01),下调CHOP表达(P<0.05),引起Bcl-2/Bax值升高(P<0.01),并抑制H/R诱导的PERK磷酸化、Nrf2核转位和ATF4表达(P<0.01)。敲低MR-1加重H/R引起的细胞凋亡(P<0.01)、CHOP表达上调(P<0.05)和Bcl-2/Bax值下降(P<0.01),并加重H/R诱导的PERK磷酸化(P<0.05)、Nrf2核转位和ATF4表达(P<0.01)。结论:MR-1通过抑制PERK/Nrf2途径而减轻缺氧/复氧诱导的心肌细胞凋亡。

高血压大鼠全脑缺血再灌注后海马区c-Jun氨基末端激酶激活与GRP78表达的关系

目的全脑缺血再灌注(cerebral ischemia/reperfusion,CI/R)后c-Jun氨基末端激酶(c-JunN-terminal kinase,JNK)活化与内质网应激的内在关系尚不明确。文中探讨高血压大鼠CI/R后海马区JNK激活与糖调节蛋白78(glucose-regulated proteins 78,GRP78)表达的关系。方法 90只雄性自发性高血压大鼠(spontaneously hypertensive rats,SHR)分为假手术组、CI/R组、JNK特异性抑制剂SP600125干预组(以下简称SP600125干预组)。改良的Pulsineli 4血管阻断(4-VO)法制作CI/R。分别在术后6、24、48 h取脑组织,应用甲苯胺蓝染色观察海马区神经细胞形态变化;免疫组化法和免疫印迹法检测海马区GRP78和磷酸化JNK表达。结果与假手术组比较,CI/R组各时间点存活神经元密度降低,GRP78表达和磷酸化JNK表达增高。与CI/R组比较,SP600125干预组中各时间点存活神经元密度增加,GRP78表达增高,磷酸化JNK表达减少,相关性分析显示CI/R组中GRP78和磷酸化JNK蛋白表达相关(r=-0.862,P<0.01);SP600125干预组中GRP78和磷酸化JNK蛋白表达相关(r=-0.898,P<0.01)。结论高血压大鼠CI/R后海马区JNK激活与GRP78表达有关;抑制JNK信号通路可上调高血压全脑缺血大鼠海马区GRP78表达,对神经有保护作用。

内质网应激相关因子PERK和ATF6在结肠癌中的表达及意义

目的探讨内质网应激相关因子蛋白激酶R样内质网调节激酶(PERK)和活化转录因子6(ATF6)在结直肠癌组织中的表达情况,分析PERK和ATF6在结肠癌发生发展中的作用。方法选择手术切除结肠癌组织及距离病变组织5 cm以上正常组织,采用实时荧光定量PCR技术(RTPCR)检测PERK和ATF6的mRNA表达情况,免疫组织化学法(IHC)、Western blot法检测PERK和ATF6蛋白的表达情况,并结合临床病理特征,分析其与结肠癌发生、发展之间的关系。结果肿瘤组织ATF6和PERK mRNA表达均较正常组织下调(P<0.05)。IHC和Western blot结果显示PERK和ATF6在结肠癌中的表达均显著低于正常组织(P<0.05)。PERK和ATF6主要定位于上皮细胞中。结论PERK和ATF6在结肠癌中的表达水平下降说明缺乏适当的内质网应激反应可能在肿瘤的发生机制中起作用。

白芨多糖对心肌梗死大鼠PI3K/AKT/GRP78信号通路及心肌细胞内质网应激凋亡的影响

目的探究白芨多糖对心肌梗死(MI)大鼠磷脂酰肌醇-3-激酶(PI3K)/蛋白激酶B(AKT)及葡萄糖调节蛋白(GRP)78信号通路蛋白表达及对心肌细胞内质网(ERS)凋亡的影响。方法SD大鼠随机分为假手术组、模型组、白芨多糖低(100 mg/kg)、中(200 mg/kg)、高(400 mg/kg)剂量组、阳性对照组(卡托普利,2.25 mg/kg),每组10只。采用冠状动脉结扎法建立大鼠MI模型,连续给药4 w,1次/d后,取心肌组织和颈动脉血,用三苯基氯化四氮唑(TTC)染色检测MI面积;苏木素-伊红(HE)染色法检测心肌病理形态;Tunel法检测心肌细胞凋亡率;酶联免疫吸附试验(ELISA)检测血清中磷酸肌酸同工酶(CK-MB)、肌钙蛋白(cTn)I水平;Western印迹检测PI3K/AKT/GRP78通路蛋白及下游蛋白激酶R样内质网激酶(PERK)/真核细胞翻译起始因子(eIF)2α、促凋亡蛋白半胱氨酸天冬氨酸蛋白酶(caspase)-12相对表达水平。结果与假手术组相比,其余各组心肌组织纤维变性、间质水肿、炎性细胞浸润等病理损伤严重,MI面积、心肌细胞凋亡率显著升高,PI3K/AKT通路蛋白表达显著降低,其介导的内质网应激凋亡GRP78/PERK/eIF2α/caspase-12通路蛋白表达显著升高(均P<0.05)。与模型组相比,白芨多糖各剂量组及阳性对照组心肌组织病理损伤减轻,MI面积、心肌细胞凋亡率显著降低,PI3K/AKT通路蛋白表达显著升高,其介导的内质网应激凋亡GRP78/PERK/eIF2α/caspase-12通路蛋白表达显著降低(P<0.05),且白芨多糖剂量越高上述指标改善效果越明显(P<0.05)。结论白芨多糖可激活PI3K/AKT通路,抑制GRP78/PERK/eIF2α信号通路蛋白表达,降低心肌细胞ERS凋亡,改善MI大鼠心肌坏死。

冬凌草甲素对脑小血管病大鼠认知功能及PERK/CHOP信号通路的影响

目的:探究冬凌草甲素对脑小血管病(CSVD)大鼠认知功能及蛋白激酶R样内质网激酶(PERK)/C/EBP同源蛋白(CHOP)信号通路的影响。方法:通过体外注入同种系微栓子建立CSVD模型,将72只SD大鼠随机分为6组:假手术组、模型组、尼莫地平组(10 mg·kg^(-1))、冬凌草甲素低(5 mg·kg^(-1))、中(10 mg·kg^(-1))、高(15 mg·kg^(-1))剂量组,每组12只,除假手术组外,其余组大鼠均建模。按分组治疗28 d后,采用Morris水迷宫实验测定大鼠认知功能,试剂盒测定海马组织中超氧化物歧化酶(SOD)和丙二醛(MDA)的含量,苏木精-伊红染色法(HE)观察大鼠大脑海马组织的病理学特征,逆转录-合酶链反应法(RT-PCR)测定海马组织中PERK、转录因子4(ATF4)、CHOP mRNA的表达,蛋白免疫印迹(Western blot)检测海马组织中p-PERK、PERK、ATF4、CHOP蛋白的表达。结果:与假手术组相比,模型组大鼠逃避潜伏期时间延长、跨越原平台次数减少、在目标象限停留时间缩短、海马组织SOD含量显著降低、MDA含量增加(P<0.05),海马组织产生损伤,海马组织中PERK、ATF4、CHOP mRNA及p-PERK/PERK、ATF4、CHOP蛋白表达水平显著上调(P<0.05);与模型组相比,冬凌草甲素各剂量组大鼠逃避潜伏期时间缩短、跨越原平台次数增加、在目标象限停留时间延长、海马组织SOD含量显著增加、MDA含量降低(P<0.05),海马组织病变减轻,海马组织中PERK、ATF4、CHOP mRNA及p-PERK/PERK、ATF4、CHOP蛋白表达水平下调(P<0.05),且呈剂量依赖性(P<0.05);冬凌草甲素高剂量组与尼莫地平组各项指标比较差异无统计学意义(P>0.05)。结论:冬凌草甲素可提高CSVD大鼠的认知功能,缓解大鼠CSVD症状,可能与其调控PERK/CHOP通路有关。

冬凌草甲素对HepG2细胞内质网应激蛋白IRE-1、PERK和CHOP的作用研究

目的研究内质网应激对冬凌草甲素处理的肝癌细胞HepG2的作用。方法采用特异性小干扰RNA(siRNA)转染HepG2细胞72 h抑制内质网应激蛋白RNA激活蛋白激酶样内质网激酶(PERK)、抑制物阻抗性酯酶1(IRE-1)和CCAAT增强子结合蛋白同源蛋白(CHOP)表达后,MTT法观察40μmol·L-1冬凌草甲素处理12h的转染细胞的细胞存活率。结果 PERK和IRE-1 siRNA转染抑制相应蛋白表达后增加冬凌草甲素诱导的HepG2细胞死亡(P<0.05);而抑制CHOP表达对冬凌草甲素处理的HepG2细胞存活率没有影响(P>0.05)。结论冬凌草甲素诱导的内质网应激对HepG2细胞具有保护作用。

内质网应激PERK-eIF2α-ATF4信号通路在延缓APP/PS1小鼠移植瘤生长中的作用

目的:探讨内质网应激(ERS)及内质网自噬对移植黑色素瘤模型淀粉样蛋白前体蛋白(APP)/早老素1(PS1)小鼠移植瘤生长的抑制作用,并阐明蛋白激酶R样内质网激酶(PERK)-真核翻译起始因子2α(eIF2α)-活化转录因子4(ATF4)通路在其抑制作用中的可能机制。方法:体外培养B16细胞,通过皮下注射分别植入C57和APP/PS1小鼠背部皮下,建立C57BL/6J和APP/PS1雄性小鼠移植黑色素瘤模型,作为C57移植瘤组(n=7)和APP/PS1移植瘤组(n=7)。观察2组小鼠出瘤时间并计算肿瘤体积,实时荧光定量PCR(RT-qPCR)法检测2组小鼠移植瘤组织中葡萄糖调节蛋白78(GRP78)、PERK和溶酶体组织蛋白酶L(cathepsin L)mRNA表达水平,Western blotting法检测2组小鼠移植瘤组织中GRP78、PERK、磷酸化PERK(p-PERK)、真核翻译起始因子2α(eIF2α)、磷酸化eIF2α(p-eIF2α)、活化转录因子4(ATF4)和内质网自噬标志蛋白FAM134B蛋白表达水平,免疫组织化学法检测移植瘤组织中蛋白质二硫异构酶(PDI)蛋白表达情况,免疫荧光法测定2组小鼠移植瘤组织中腺嘌呤核苷三磷酸(ATP)水平。结果:与C57移植瘤组比较,APP/PS1移植瘤组小鼠出瘤时间晚,肿瘤体积小(P<0.05),移植瘤组织中ERS相关基因GRP78和PERK mRNA表达水平升高(P<0.05),移植瘤组织中GRP78、p-eIF2α/eIF2α和ATF4蛋白表达水平及p-PERK/PERK比值均升高(P<0.05)。C57移植瘤组肿瘤细胞胞质内多见黑色素颗粒,为移植瘤组织的形态特征,可见少量棕黄色颗粒,为PDI阳性颗粒;APP/PS1移植瘤组肿瘤细胞胞质内可见少量黑色素颗粒和广泛表达的棕黄色颗粒。与C57移植瘤组比较,APP/PS1移植瘤组小鼠移植瘤组织中内质网自噬标志蛋白FAM 134B蛋白表达水平升高(P<0.05),cathepsin L mRNA表达水平升高(P<0.05),ATP水平降低(P<0.05)。结论:APP/PS1移植瘤模型小鼠肿瘤生长缓慢,其机制可能与ERS的PERK-eIF2α-ATF4信号通路被激活有关。