Activation of caspase-12 by endoplasmic reticulum stress induced by transient middle cerebral artery occlusion in mice

We sought to clarify the involvement of caspase-12, a representative molecule related to endoplasmic reticulum (ER) stress-induced cell-death signaling pathways, in neuronal death resulting from ischemia/reperfusion in mice. Transient focal cerebral ischemia (1 h) was produced by intraluminal occlusion of the middle cerebral artery (MCA). We assessed the expression patterns of caspase-12, Bip/GRP78, an ER-resident molecular chaperone whose expression serves as a good marker of ER stress, and caspase-7 by Western blotting and/or immunohistochemistry. Double-fluorescent staining of caspase-12 immunohistochemistry and the terminal deoxynucleotidyl transferase-mediated DNA nick-end labeling (TUNEL) method was performed to clarify the involvement of caspase-12 in cell death. We confirmed that ER stress was induced during reperfusion in our model, as witnessed by up-regulated Bip/GRP78 expression in the MCA territory. Western blot analysis revealed that caspase-12 activation occurred at 5-23 h of reperfusion, and immunoreactivity for caspase-12 was enhanced mainly in striatal neurons on the ischemic side at the same time points. We found the co-localization of caspase-12 immunoreactivity and DNA fragmentation detectable by the TUNEL method. We did not detect the presence of caspase-7 in the ER fraction at the period of caspase-12 cleavage. Our results imply that cerebral ischemia/reperfusion induces ER stress and that caspase-12 activation concurred with ER stress. Caspase-12 seems to be involved in neuronal death induced by ischemia/reperfusion. Caspase-7 is not likely to contribute to the cleavage of caspase-12 in our experimental model.     

The protection of Bcl-2 overexpression on rat cortical neuronal injury caused by analogous ischemia/reperfusion in vitro

Recent studies have suggested that neuronal apoptosis in cerebral ischemia could arise from dysfunction of endoplasmic reticulum (ER) and mitochondria. B-cell lymphoma/leukemia-2 gene (Bcl-2) has been described as an inhibitor both in programmed cell death (PCD) and ER dysfunction during apoptosis, and the Bcl-2 family play a key role in regulating the PCD, both locally at the ER and from a distance at the mitochondrial membrane. However, its signal pathways and concrete mechanisms in endoplasmic reticulum-initiated apoptosis remain incompletely understood. We therefore investigate whether ischemia/reperfusion (I/R) causes neuronal apoptosis in part via cross-talk between ER and mitochondria or not, and how the overexpression of Bcl-2 prevents this form of cell death. Here we show that analogous I/R-induced cell death occurs consequent to interactions of ER stress and mitochondrial death pathways. The participation of the mitochondrial pathway was demonstrated by the release of cytochrome C (cyt C) from mitochondrial into cytoplasmic fractions and caspase-9 cleavage. The involvement of ER stress was further supported by the observable increase of glucose-regulated protein 78(GRP78)/BiP expression and caspase-12 activity. Furthermore, prior to these changes, swelling of the ER lumen and dissociation of ribosomes from rough ER were detected by electron microscopy. Bcl-2 overexpression inhibits the release of cyt C and the activation of caspase-9/-8/-3 but not caspase-12 based on the results of Western blot. These suggest that cross-talk between ER and mitochondria participate in neuronal damage after ischemia/reperfusion. Bcl-2 overexpression could suppress I/R-induced neuronal apoptosis via influencing mitochondrial integrity.     

Amyloid β-induced ER stress is enhanced under mitochondrial dysfunction conditions

Previously we reported that endoplasmic reticulum (ER)-mitochondria crosstalk is involved in amyloid-β (Aβ)-induced apoptosis. Now we show that mitochondrial dysfunction affects the ER stress response triggered by Aβ using cybrids that recreate the defect in mitochondrial cytochrome c oxidase (COX) activity detected in platelets from Alzheimer's disease (AD) patients. AD and control cybrids were treated with Aβ or classical ER stressors and the ER stress-mediated apoptotic cell death pathway was accessed. Upon treatment, we found increased glucose-regulated protein 78 (GRP78) levels and caspase-4 activation (ER stress markers) which were more pronounced in AD cybrids. Treated AD cybrids also exhibited decreased cell survival as well as increased caspase-3-like activity, poli-ADP-ribose-polymerase (PARP) levels and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive apoptotic cells. Finally, we showed that Aβ-induced caspase-3 activation in both cybrid cell lines was prevented by dantrolene, thus implicating ER Ca(2+) release in ER stress-mediated apoptosis. Our results demonstrate that mitochondrial dysfunction occurring in AD patients due to COX inhibition potentiates cell susceptibility to Aβ-induced ER stress. This study further supports the close communication between ER and mitochondria during apoptosis in AD.     

β_1-肾上腺素受体自身抗体通过激活内质网应激诱导心肌细胞凋亡

目的:探讨内质网应激在β_1-肾上腺素受体自身抗体(β_1-AA)引起心肌细胞凋亡中的作用。方法:采用β_1-肾上腺素受体细胞外第二环抗原肽段主动免疫大鼠,应用SA-ELISA法检测大鼠血清中β_1-AA的水平,TUNEL染色检测心肌组织的凋亡水平,Western blot法和免疫组化法检测心肌组织中葡萄糖调节蛋白78(GRP78)、C/EBP同源蛋白(CHOP)及caspase-12的蛋白表达。利用亲和层析法纯化的β_1-AA处理H9c2心肌细胞,CCK-8法检测细胞活力,Annexin V-FITC/PI双染流式细胞术检测心肌细胞凋亡;采用内质网应激抑制剂4-苯基丁酸(4-PBA)预处理H9c2心肌细胞,再给予β_1-AA干预,CCK-8法和流式细胞术分别检测细胞活力及凋亡的变化情况。结果:与对照组相比,主动免疫大鼠血清中β_1-AA水平在免疫2周时显著增加,进一步增加至8周,并且主动免疫2周大鼠心肌组织凋亡率明显升高,持续升高至8周。与对照组相比,主动免疫大鼠心肌组织中GRP78、CHOP及caspase-12的蛋白表达在免疫4周和8周时均明显增加。β_1-AA引起H9c2心肌细胞活力持续降低,凋亡明显增加。与β_1-AA单独处理组相比,内质网应激抑制剂4-PBA预处理H9c2心肌细胞可以有效逆转β_1-AA诱导的细胞凋亡增加和活力下降。结论:β_1-AA可以通过激活内质网应激诱导心肌细胞凋亡。     

Overexpression of GRP78 protects glial cells from endoplasmic reticulum stress

Endoplasmic reticulum (ER) stress induces apoptotic cell death by causing the accumulation of structurally abnormal proteins. The 78-kDa glucose-regulated protein (GRP78) is an ER chaperone that regulates protein folding in the ER and has been suggested to contribute to cell survival. Using the rat C6 glioma cell line and flow cytometry, we assessed GRP78 expression following tunicamycin- and glutamate-induced ER stress. The results showed that GRP78 expression is upregulated following ER stress and has protective effects on injured glial cells. Annexin V and propidium iodide labeling revealed cells transiently expressing GRP78 prior to injury were protected against high-concentrations of tunicamycin and glutamate within 72 h. Our findings support the hypothesis that GRP78 inhibits cell death associated with ER stress.     

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.     

Peptide-binding heat shock protein GRP78 protects cardiomyocytes from hypoxia-induced apoptosis

Myocardial ischemia is a severe stress condition that causes extensive biochemical changes triggering cardiac cell death. The 78-kDa glucose-regulated protein (GRP78), a heat shock protein present in all cells and a widely used marker of endoplasmic reticulum stress, functions in controlling the structural maturation of nascent glycoproteins. However, GRP78 was also found to be expressed on the cell surface of several cells such as endothelial cells, macrophages, and tumor cells where it functions as a receptor for a variety of ligands in signaling pathways. Recently, we have identified peptides from two different sources that specifically bind GRP78 protein. We have shown that binding of these peptides to endothelial cell surface GRP78 resulted in angiogenesis. In this study, we first established the presence of cell surface GRP78 on cardiac myocytes. Analysis of cardiomyocytes under hypoxia determined the significant increase in cell surface GRP78 in addition to gene expression and total protein. Apoptosis that was significantly increased in cardiomyocytes under hypoxic conditions was inhibited by the presence of the peptide-binding GRP78 during hypoxia. Inhibition of apoptosis was mediated by the binding of the peptide to cardiomyocytes cell surface GRP78 resulting in blocking caspase-3/7 activation. Silencing GRP78 RNA that reduced GRP78 receptor abrogated the peptide activity. Apoptosis of cardiac cells induced by myocardial infarction in a mouse model was also significantly inhibited by the administration of the peptide to mouse hearts. Our findings may make ADoPep1 a useful therapeutic tool for relieving of ischemia.     

Thapsigargin-induced apoptosis was prevented by glycogen synthase kinase-3 inhibitors in PC12 cells

Uncontrolled calcium stress has been linked causally to a variety of neurodegenerative diseases, including ischemia, excitotoxicity and Alzheimer's disease. Thapsigargin, which increases [Ca²⁺]_i, induces apoptotic cell death (chromatin condensation and DNA fragmentation) accompanied by caspase-3 activation in PC12 cells. We examined whether GSK-3 is involved in thapsigargin-induced cell death by using GSK-3 inhibitors in PC12 cells. Cells treated with 0.1 μM thapsigargin for 24 h shrank. The injured cells underwent chromatin condensation and nuclear fragmentation, indicating apoptotic cell death. We assayed the effects of selective GSK-3 inhibitors, SB216763, azakenpaullone and alsteropaullone on thapsigargin-induced apoptosis. These inhibitors completely protected cells from thapsigargin-induced apoptosis. Alsterpaullone did not reduce the GRP78 protein expression induced by thapsigargin, suggesting that GSK-3 activation is not involved in induction of GRP78. In addition, GSK-3 inhibitors inhibited caspase-3 activation accompanied by thapsigargin-induced apoptosis. We showed in this report that thapsigargin-induced apoptosis is prevented by GSK-3 inhibitors, suggesting that thapsigargin induces caspase-dependent apoptosis mediated through GSK-3 activation in PC12 cells.     

Pathways of macrophage apoptosis within the interface membrane in aseptic loosening of prostheses

Aseptic loosening is a major cause of failure of total hip arthroplasty (THA). Macrophage apoptosis in interface membrane has been proved to play an important role in the pathogenesis of aseptic loosening. The purpose of current study was to identify the apoptotic mechanism of macrophages in the interface membrane of aseptic loosening. We collected periprosthetic interface membrane from 23 patients undergoing the revision operations for aseptic loosening of hip joint prostheses. To serve as the control group, samples of capsule were collected from 18 patients undergoing the primary hip arthroplasties for osteoarthritis (OA). The ultrastructure of interface membrane was examined by transmission electron microscopy (TEM), and in situ apoptotic macrophage identification was performed by TUNEL staining. Furthermore, using immunohistochemical methods we investigated the expression of some apoptosis-related markers such as inducible nitric oxide synthase (iNOS), peroxynitrite (ONOO(-)), cleaved caspase-3/4/8/9, cytochrome c, glucose regulated protein 78 (GRP78), and growth arrest and DNA damage-inducible gene 153 (GADD153) in macrophages. These markers were regarded as apoptotic inducers or specific indicators of different apoptotic pathways such as death receptor pathway, mitochondrial pathway and endoplasmic reticulum (ER) stress pathway. TEM showed that a great deal of wear debris was phagocytosed by macrophages, which displayed morphological changes characteristic of apoptosis. The results of TUNEL staining demonstrated that there were more apoptotic macrophages in interface membrane. The expression levels of iNOS, ONOO(-), cleaved caspase-3/4/8/9, cytochrome c, GRP78 and GADD153 in macrophages in interface membrane were significantly higher than those in the control samples (p?相似文献   

miR-9-5p attenuates ischemic stroke through targeting ERMP1-mediated endoplasmic reticulum stress

Ischemic stroke (IS) is a cerebrovascular disease with serious neurological function impairment, which may activate endoplasmic reticulum (ER) stress. However, the underlying regulatory mechanism of ER stress under IS remains unclear. miR-9-5p is enriched in the brain tissues and plays a role in the pathological process of IS. Therefore, the purpose of this study is to explore the effect of miR-9 on ER stress and underlying mechanism in IS. Here, a middle cerebral artery occlusion (MCAO) rat model was utilized to examine the alteration of brain pathology, and the expressions of miR-9 and ER stress-related proteins. Then SH-SY5Y cells with oxygen-glucose deprivation (OGD) were performed to further evaluate the functional role of miR-9 and preliminary mechanism. The results showed that miR-9 levels were decreased in the ischemic region of rats after MCAO. MCAO significantly increased the brain infract volume, reduced Nissl bodies and cell apoptosis, and increased ER stress-related proteins (ERMP1, GRP78, p-PERK, p-eIF2α and CHOP). Furthermore, overexpression of miR-9 by miR-9 mimics increased cell viability, inhibited LDH activity and cell apoptosis, and inactivated ER stress in OGD-neurons. Luciferase activity results showed that miR-9 negatively regulated ERMP1 expression by directly targeting ERMP1 3′ UTR. Subsequently, we found that ERMP1 overexpression reversed the inhibition of miR-9 on GRP78-PERK−CHOP pathway in OGD neurons. In summary, our results suggest that the attenuation of miR-9 on ischemic injury may be involved in targeting ERMP1-mediated ER stress, which provides an available target for IS treatment.     

柚皮素对心肌缺血/再灌注损伤大鼠PI3K/AKT信号通路和内质网应激及其相关凋亡通路的影响

目的:观察柚皮素对缺血/再灌注(I/R)大鼠心脏损伤的影响,并探讨柚皮素的作用是否涉及PI3K/AKT信号通路和内质网应激及其相关凋亡通路.方法:48只SD大鼠按随机数字表法分成假手术组(sham组)、模型组(I/R组)、柚皮素处理组(NAR组)和柚皮素处理+LY294002组(NL组).结扎大鼠冠状动脉左前降支30 ...     

MnTBAP对大鼠局灶性脑缺血损伤的保护作用

目的探讨锰卟啉(MnTBAP)对大鼠局灶性脑缺血损伤的保护作用及其可能机制。方法采用线拴法建立大鼠大脑中动脉栓塞(MCAO)模型,分为假手术组、缺血组、MnTBAP治疗组。缺血组和治疗组术后立即腹腔注射生理盐水和MnTBAP(10mg/kg体重),缺血24h后处死,用原位末端标记技术(TUNEL)和免疫组织化学方法对缺血侧脑组织神经细胞凋亡和凋亡调控蛋白Caspase-3表达进行检测。结果与假手术组相比,缺血组脑组织神经细胞凋亡及Caspase-3蛋白表达水平明显增加(P<0.01);与缺血组相比,MnTBAP治疗组神经细胞凋亡及Caspase-3蛋白表达水平显著减少。结论 MnTBAP能下调Caspase-3蛋白表达,抑制脑组织神经细胞凋亡,对缺血性脑损伤具有保护作用。     

乐尔脉对脑缺血再灌注损伤后期大鼠海马神经细胞凋亡的作用

 目的： 探讨乐尔脉胶囊（LEM）对脑缺血再灌注损伤后期大鼠海马神经细胞凋亡的作用与机制。方法: 采用大鼠左侧大脑中动脉内栓线阻断法(MCAO)造成局灶性脑缺血再灌注模型。缺血2 h再灌注30 d后,应用原位末端标记法（TUNEL）检测海马神经细胞凋亡,免疫组化、RT-PCR 法检测海马神经细胞Fas、Bax、caspase-3、caspase-9蛋白及 mRNA的表达,并进行阳性细胞计数及Mias图像程序分析结果。结果: 大鼠缺血再灌注30 d后,模型组缺血侧海马CA1、CA2区凋亡细胞显著高于假手术组(P<0.05), Fas、Bax、 caspase-3、caspase-9蛋白表达明显增加,fas、bax、caspase-3、caspase-9 mRNA的表达上调(P<0.05)。LEM2.00 g/kg、0.87 g/kg和氟桂利嗪可显著减少海马神经细胞凋亡数,降低Fas、Bax、caspase-3、caspase-9蛋白表达,fas、bax、caspase-3、caspase-9 mRNA的表达下调,LEM 0.87 g/kg作用次于2.00 g/kg。LEM对bax mRNA有显著抑制作用。结论: LEM抑制海马神经细胞的凋亡,明显地减轻缺血再灌注后期大鼠海马神经细胞的损伤,其作用机制与调节细胞凋亡信号转导通路及相关蛋白有关。     

Abnormal innervation patterns in the anorectum of ETU-induced fetal rats with anorectal malformations

Valproate (VPA) is commonly used in the treatment of bipolar disorder and epilepsy. The mechanism underlying its clinical efficacy is complicated, including its ability to inhibit histone deacetylase (HDAC). Here, we show that VPA promoted endoplasmic reticulum (ER) chaperone expression and attenuated ER-induced apoptosis after ischemia/reperfusion (I/R) injury in retina. Male Wistar rats were randomly divided into four groups: sham (group A), sham + VPA (group B), I/R + vehicle (group C), and I/R + VPA (group D). VPA was administered subcutaneously at 300 mg/kg twice daily before insult. Morphological changes were analyzed on stained histological sections and flat-mounted retinas labeled by Fluoro-gold. Western blot analysis was used to determine protein levels of GRP78, CHOP, caspase-12 and acetylation of histone H3 in each group. In group C, the severe retinal damage was shown in histological sections, however, the damage was reduced by VPA in group D. Significant loss of retinal ganglion cells (RGCs) was observed in group C, whereas, the density of RGCs was significantly higher in group D at 7 days post-insult. VPA increased GRP78 expression and acetylation of histone H3, attenuated upregulation of CHOP and activation of caspase-12 in group D. Our results suggest that VPA can protect ischemic retinas from ER stress-induced apoptosis by mechanisms that may involve HDAC inhibition.     

Berberine ameliorates pro-inflammatory cytokine-induced endoplasmic reticulum stress in human intestinal epithelial cells in vitro

Endoplasmic reticulum stress (ER stress) in intestinal epithelial cells (IECs) plays an important role in the pathogenesis and perpetuation of inflammatory bowel disease (IBD). The aim of this study is to explore the potential of berberine (BBR) in regulating pro-inflammatory cytokine-induced ER stress and apoptosis in IECs. ER stress in cultured Caco-2 cells was induced by IFN-γ/TNF-α and tunicamycin, respectively. The experimental groups were pretreated with BBR. Cell viability was determined by MTT assay. In vitro apoptosis was examined by flow cytometry using annexin V-FITC labeling. The molecular markers of ER stress, including GRP-78, p-JNK, caspase-12, and cleaved caspase-3 were analyzed by Western blot. Xbp-1 mRNA splicing was detected by RT-PCR. Pretreatment of BBR helped to survive in cytokine-induced Caco-2 cells. BBR significantly attenuated cytokine-induced Caco-2 apoptosis. GRP78 expression and xbp-1 mRNA splicing were enhanced significantly in the presence of IFN-γ/TNF-α and tunicamycin, and they could be dampened by BBR. Further study revealed BBR could downregulate JNK phosphorylation, and the level of caspase-12 and cleaved caspase-3. Berberine can ameliorate pro-inflammatory cytokines induced ER stress in vitro, and it might be one of the targeted therapeutic agents for IBD.     

大鼠脑缺血再灌流后神经细胞凋亡与caspase-3和caspase-9基因表达

目的：探讨大鼠局灶性脑缺血再灌流后神经细胞凋亡及其与caspase-3和caspase-9基因表达的关系。方法：应用原位末端标记和原位杂交技术分别观察细胞凋亡与caspase-3mRNA和caspase-9mRNA表达。结果：脑缺血再灌流后，凋亡神经细胞主要分布于缺血半影区，随着时间的延长凋亡细胞数逐渐增加，至24h达高峰。在缺血半影区，再灌流后神经细胞caspase-3mRNA和caspase-9mRNA表达逐渐增强，到24h阳性细胞数目最多，COD值最高，而缺血中心区两基因均弱表达。结论：脑缺血再灌流后神经细胞凋亡是一个动态的渐进过程。caspase-3和caspase-9基因表达在介导细胞凋亡过程中起重要作用。     

Nitric oxide-mediated neuronal apoptosis in rats with recurrent febrile seizures through endoplasmic reticulum stress pathway

Nitric oxide (NO), as a neurotransmitter, exerts various physiological and pathological effects on the brain. Excess NO is toxic to neurons and may cause neuronal apoptosis. However, the cascade of NO-mediated apoptosis is not fully understood. We utilized a recurrent febrile seizures (FS) rat model and found that plasma NO was increased, neuronal apoptosis was evident, the expression of glucose-regulated protein78 (GRP78, a well-established marker of ER stress) was elevated, and caspase-12 (an ER stress-specific proapoptosis molecule) was activated in the hippocampus in a time-dependent manner after recurrent FS. Administration of sodium nitroprusside (SNP, an NO donor) enhanced neuronal apoptosis, down-regulated the expression of GRP78, and increased that of caspase-12 in FS+SNP groups compared with FS groups. In contrast, treatment with N(G)-nitrol-l-arginine methyl ester (l-NAME, a competitive NO synthase inhibitor) inhibited neuronal apoptosis, up-regulated the expression of GRP78, and decreased that of caspase-12 in FS+l-NAME groups compared with FS groups. These results suggest that NO mediates neuronal apoptosis caused by recurrent FS, and that the ER stress pathway is involved in NO-mediated neuronal apoptosis.     

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。     

Metformin regulates palmitate-induced apoptosis and ER stress response in HepG2 liver cells

The excessive supply of fatty acids to the liver contributes to hepatic insulin resistance and endoplasmic reticulum (ER) stress associated with obesity or type 2 diabetes mellitus. Furthermore, excess and/or prolonged ER stress contributes to hepatic cell death deteriorating nonalcoholic fatty liver disease to steatohepatitis. The aim of this study was to investigate the effects of metformin on palmitate-induced ER stress and hepatic insulin resistance in HepG2 cells. Metformin significantly inhibited palmitate-induced cell death and apoptosis via caspase-3 activation. Metformin also blocked the induction of ER stress proteins (GRP78, Chop, Cleaved ATF-6, p-eIF2 alpha and XBP-1) and regulated serine phosphorylation of IRS-1. Metformin may therefore protect hepatocytes from death induced by saturated fatty acids. These data may also provide a further rationale for exploring the use of metformin in the treatment of non-alcoholic fatty liver disease, revealing its blocking effect for hepatic insulin resistance evoked by saturated fatty acids.