Chaperone therapy for molecular pathology in lysosomal diseases

In lysosomal diseases, enzyme deficiency is caused by misfolding of mutant enzyme protein with abnormal steric structure that is expressed by gene mutation. Chaperone therapy is a new molecular therapeutic approach primarily for lysosomal diseases. The misfolded mutant enzyme is digested rapidly or aggregated to induce endoplasmic reticulum stress. As a result, the catalytic activity is lost. The following sequence of events results in chaperone therapy to achieve correction of molecular pathology. An orally administered low molecular competitive inhibitor (chaperone) is absorbed into the bloodstream and reaches the target cells and tissues. The mutant enzyme is stabilized by the chaperone and subjected to normal enzyme protein folding (proteostasis). The first chaperone drug was developed for Fabry disease and is currently available in medical practice. At present three types of chaperones are available: competitive chaperone with enzyme inhibitory bioactivity (exogenous), non-competitive (or allosteric) chaperone without inhibitory bioactivity (exogenous), and molecular chaperone (heat shock protein; endogenous). The third endogenous chaperone would be directed to overexpression or activated by an exogenous low-molecular inducer. This new molecular therapeutic approach, utilizing the three types of chaperone, is expected to apply to a variety of diseases, genetic or non-genetic, and neurological or non-neurological, in addition to lysosomal diseases.     

内质网应激在Bim介导缺氧致心肌细胞凋亡中的作用

 目的：探讨内质网应激在Bim介导缺氧致心肌细胞凋亡中的作用。方法：在体外原代培养出生1~3 d大鼠心肌细胞,并用抗α-横纹肌肌动蛋白免疫组化法进行鉴定。设计并化学合成3对靶向bim的siRNA,用脂质体法将siRNA转染心肌细胞,筛选沉默效率最高的siRNA。实验分组：（1）空白对照组;（2）缺氧组;（3）缺氧+脂质体组;(4)缺氧+阴性对照siRNA组;(5)缺氧+Bim-siRNA组。MTT法观察细胞活性;流式细胞术检测细胞凋亡率及细胞内钙离子浓度变化情况;Western blotting检测内质网应激标志分子caspase-12和三磷酸肌醇（IP3）的表达情况。结果：免疫组化鉴定证实大鼠心肌细胞原代培养成功。在荧光显微镜下,转染了阴性对照siRNA组的细胞中观察到绿色荧光,即转染成功;Western blotting 结果显示,Bim-siRNA转染均能有效降低Bim蛋白的表达,其中第2对沉默效率最高,达到86.73%。缺氧损伤导致心肌细胞活性明显下降（P<005）,转染Bim-siRNA后细胞活性较阴性对照组升高。缺氧细胞凋亡率较对照组明显增加（P<0.01）,细胞内钙离子浓度明显增高,而沉默bim的表达能降低细胞凋亡率和细胞内钙离子浓度。缺氧导致内质网应激标志分子caspase-12和IP3表达较空白对照组明显上调（均P<005）,而抑制Bim表达后caspase-12和IP3表达明显降低。结论：沉默bim的表达能有效抑制缺氧导致心肌细胞凋亡的作用,内质网应激标志分子caspase-12和IP3可能参与了Bim介导缺氧致心肌细胞凋亡的过程。这有望为临床心肌缺血缺氧损伤的治疗提供新思路。     

miRNA-125b Signaling Ameliorates Liver Injury Against Obstructive Jaundice-Induced Excessive Fibrosis in Experimental Rats

PurposeMultiple pathways are involved in inducing liver fibrosis, which can damage the integrity of liver. Among them, miR-125b has been found to exert an activating action on hepatic stellate cells. Endoplasmic reticulum stress and autophagy lead to liver disorders. Here, we evaluated the therapeutic influence of miR-125b on the endoplasmic reticulum function in injured livers submitted to bile duct ligation.Materials and MethodsFor inducing injury, bile duct ligation was done on miR-125b transgenic rats (miR-125b-Tg) in wild type rats. The rat T-6 cells received transfection of miR-125b mimic and Tunicamycin. Protein expressions were observed by western blot analysis.ResultsCompared to wild type rats, liver-injured rats showed significant impairment of liver function as assessed by the total bilirubin levels. The miR-125b-Tg rats showed decrease in activity of aspartate transaminase and alanine transaminase. Liver tissues of miR-125b-Tg rats showed weaker fibrotic matrix formation. Upregulation of miR-125b decreased the bile duct ligation-mediated hepatic disturbances for the expressions of endoplasmic reticulum kinase, inositol-requiring kinase 1alpha, sXBP1, CHOP, LC3, p62, ULK, and caspase-3/-8/-9. T-6 cells transfected with miR-125b mimic and treated with Tunicamycin caused decrease in levels of cleaved caspase-3, sXBP1, CHOP, and LC3. The miR-125b signaling showed protective effect on the liver tissues subjected to injury and fibrosis histopathology.ConclusionThis study demonstrates a novel insight into the miR125b-mediated stabilization of endoplasmic reticulum integrity, which slows the progression of injury-induced hepatic deterioration.     

Di-lysine motif-like sequences formed by deleting the C-terminal domain of aquaporin-4 prevent its trafficking to the plasma membrane

Aquaporin-4 is a transmembrane water channel protein, the C-terminal domain of which is facing the cytosol. In the process of investigating the role of the C-terminal domain of aquaporin-4 with regard to intracellular trafficking, we observed that a derivative of aquaporin-4, in which the C-terminal 53 amino acids had been removed (Δ271-323), was localized to intracellular compartments, including the endoplasmic reticulum, but was not expressed on the plasma membranes. This was determined by immunofluorescence staining and labeling of the cells with monoclonal antibody specifically recognizing the extracellular domain of aquaporin-4, followed by confocal microscopy and flow cytometry. Deletion of additional amino acids in the C-terminal domain of aquaporin-4 led to its redistribution to the plasma membrane. This suggests that the effect of the 53-amino acid deletion on the subcellular localization of aquaporin-4 could be attributed to the formation of a signal at the C terminus that retained aquaporin-4 in intracellular compartments, rather than the loss of a signal required for plasma membrane targeting. Substitution of the lysine at position 268 with alanine could rescue the Δ271-323-associated retention in the cytosol, suggesting that the C-terminal sequence of the mutant served as a signal similar to a di-lysine motif.     

发热伴血小板减少综合征病毒在巨噬细胞中的亚细胞定位

目的 发热伴血小板减少综合征病毒(SFTSV)是新发传染病发热伴血小板减少综合征的致病病原,为布尼亚病毒科白蛉病毒属一种新型病毒.通过研究发热伴血小板减少综合征病毒在巨噬细胞中的亚细胞定位,了解SFTSV在细胞内的复制组装机制.方法 应用两种人源巨噬细胞系THP-1细胞和U937细胞,通过免疫荧光共聚焦方法分析SFTSV感染巨噬细胞后与高尔基体和内质网的共定位.结果 SFTSV可特异性感染巨噬细胞,在SFTSV感染的巨噬细胞中SFTSV核蛋白与高尔基体共定位于核周,与内质网紧密相邻,但没有共定位.结论 在SFTSV感染的巨噬细胞中,内质网和高尔基体可能是病毒进行加工修饰及包装成熟的重要场所.     

内质网应激和NOD样受体蛋白3在重症中暑小鼠肠黏膜损伤中的作用

目的:研究内质网应激和NOD样受体蛋白3（NOD-like receptor protein 3,NLRP3）在重症中暑肠黏膜损伤中的作用及内质网应激抑制剂4-苯基丁酸（4-phenylbutyric acid,4-PBA）的保护效应。方法:30只雄性BALB /c小鼠随机（随机数字法）分成对照组（control）、重症中暑组（heat stroke,HS）和4-PBA预处理组（4-PBA+HS,4-PBA 120 mg/kg,腹腔注射）。Control组置于室温,HS组和4-PBA+HS组置于高温气候动物培养箱[温度（35.5±0.5） ℃,湿度（60.0±5.0）%],小鼠直肠温度达到42 ℃为重症中暑造模成功标准。中暑6 h后,采用比色法检测小肠匀浆丙二醛（MDA）及超氧化物歧化酶（SOD）,ELISA法检测血清白介素-1β（IL-1β）及白介素-18 （IL-18）,HE染色观察肠道组织病理,电镜下观察肠道超微结构,Western blot检测葡萄糖调节蛋白78（glucose regulated protein 78,GRP78）、CCAAT/增强子结合蛋白同源蛋白（CCAAT/enhancer-binding protein homologous protein,CHOP）、NLRP3和活化含半胱氨酸的天冬氨酸蛋白水解酶-1（cleaved caspase-1）蛋白表达。计量资料多组间比较如满足方差齐性采用单因素方差分析,组间两两比较采用LSD- t检验;如不满足方差齐性采用Welch分析,组间两两比较采用Dunnett's T3检验,以 P<0.05为差异有统计学意义。 结果:与control组相比,HS组小肠匀浆MDA升高（ t=14.243, P<0.01）而SOD下降（ t=7.781, P<0.01）,血清IL-1β和IL-18显著升高（ t=12.664, P<0.01; t=16.240, P<0.01）,小肠绒毛广泛破坏伴有炎症细胞浸润,内质网扩张及线粒体肿胀空泡化,小肠组织GRP78、CHOP、NLRP3和cleaved caspase-1蛋白表达增加（ t=14.824, P<0.01; t=12.667, P<0.01; t=9.298, P<0.01, t=6.588, P=0.001）。与HS组相比,4-PBA预处理降低MDA（ t=9.167, P<0.01）并升高SOD（ t=6.077, P<0.01）,降低血清IL-1β和IL-18（ t=4.889, P=0.001; t=5.693, P<0.01）,减轻小肠黏膜的病理改变及超微结构的损伤,降低了GRP78、CHOP、NLRP3和cleaved caspase-1蛋白表达（ t=9.080, P<0.01; t=7.152, P<0.01; t=4.249, P=0.005; t=3.650, P=0.011）。 结论:内质网应激和NLRP3参与重症中暑肠黏膜损伤,4-BPA通过抑制内质网应激及NLRP3炎症小体活化减轻重症中暑肠黏膜损伤。     

Exploring the impact of a naturally occurring sapogenin diosgenin on underlying mechanisms of Ca2+ movement and cytotoxicity in human prostate cancer cells

Literature has shown that diosgenin, a naturally occurring sapogenin, inducedcytotoxic effects in many cancer models. This study investigated the effect of diosgenin on intracellular Ca²⁺ concentration ([Ca²⁺]i) and cytotoxicity in PC3 human prostate cancer cells. Diosgenin (250‐1000 μM) caused [Ca²⁺]i rises which was reduced by Ca²⁺ removal. Treatment with thapsigargin eliminated diosgenin‐induced [Ca²⁺]i increases. In contrast, incubation with diosgeninabolished thapsigargin‐caused [Ca²⁺]i increases. Suppression of phospholipase C with U73122 eliminated diosgenin‐caused [Ca²⁺]i increases. Diosgenin evoked Mn²⁺ influx suggesting that diosgenin induced Ca²⁺ entry. Diosgenin‐induced Ca²⁺influx was suppressed by PMA, GF109203X, and nifedipine, econazole, or SKF96365. Diosgenin (250‐600 μM) concentration‐dependently decreased cell viability. However, diosgenin‐induced cytotoxicity was not reversed by chelation of cytosolic Ca²⁺ with BAPTA/AM. Together, diosgenin evoked [Ca²⁺]i increases via Ca²⁺ release and Ca²⁺ influx, and caused Ca²⁺‐non‐associated deathin PC3 cells. These findings reveal a newtherapeutic potential of diosgenin for human prostate cancer.     

Effect of high volume hemofiltration on CHOP protein from a canine model of multiple organ dysfunction syndrome

Objective To observe the effect of high volume hemofiltration (HVHF) on the expression of CCAAT enhancer binding protein(CHOP) during the treatment of multiple organ dysfunction syndrome (MODS). To investigate the role of CHOP protein act in apoptosis pathway mediated by the endoplasmic reticulum stress. Methods Twelve Beagle dogs were subjected to hemorrhagic shock plus resuscltation and endotixemia to establish MODS model, then they were randomly divided into two groups: HVHF group (n=6) and MODS group (n=6). After endotoxin injection completed, the HVHF group received HVHF treatment for 24 hours; MODS group did not receive. Vivo experiments: Blood samples were obtained at different time points(before operation, 0 h, 6 h, 12 h, 24 h after the injection of endotoxin). The dogs were killed and the tissue samples from lung, liver and kidney were took, then the expression of CHOP mRNA was determined. Vitro experiments: human umbilical vein endothelial cells (HUVECs) were induced by two groups’ blood samples to establish the apoptosis model. Gene expression, protein quantification and cell apoptosis rate were determined before and after the interference. Results Vivo experiments: The levels of CHOP mRNA from lung, liver and kidney had no significant difference between the two groups (P＞0.05). Vitro experiments: (1)The expression of CHOP mRNA: Compared with MODS group, the expression levels of CHOP mRNA were significantly decreased in HVHF group at 6 h, 24 h after the injection of endotoxin (P＜0.05). Compared with before, the expression levels of CHOP mRNA in the two groups were both significantly decreased after CHOP siRNA interference (P＜0.05). (2)The expression of CHOP protein: Compared with MODS group, the expression levels of CHOP protein were significantly decreased in HVHF group at each time points (P＜0.05). Compared with before, the expression levels of CHOP protein in the two groups were both significantly decreased after CHOP siRNA interference(P＜0.05). (3)Endothelial cell apoptosis rate: Compared with the preoperative rate, the two group’s endothelial cell apoptosis rate was decreased significantly at each time points(P＜0.05). Compared with MODS group, the endothelial cell apoptosis rate was significantly decreased in HVHF group at each time points(P＜0.05). Compared with before, the endothelial cell apoptosis rate in the two groups was both significantly decreased after CHOP siRNA interference(P＜0.05). Conclusion In the treatment of MODS process, HVHF can reduce endothelial cell apoptosis which may be related to the inhibition of CHOP mRNA expression and protein synthesis.     

内质网应激相关蛋白CHOP/GADD153在结肠癌组织中的表达及意义

目的：探讨结肠癌组织内质网应激相关蛋白CHOP/GADD153的表达,并分析其与临床病理特征的关系。方法： 选择82例结肠癌患者的结肠癌组织与相应的癌旁正常结肠组织（距癌组织>5 cm）制作蜡块后构建组织芯片,分别用免疫组化法及Western blot法检测CHOP/GADD153蛋白的表达,并分析其表达与患者临床病理特征分关系。结果：免疫组化与Western blot结果均显示,结肠癌组织CHOP/GADD153蛋白的表达水平明显癌旁正常结肠组织（P<0.05）;与临床病理特征的关系分析显示,结肠癌组织中CHOP/GADD153蛋白的表达水平随结肠癌组织分化程度的降低而增强（P<0.05）,而与患者的年龄、性别、肿瘤的大小、肿瘤的浸润深度和淋巴结转移等因素无关（均P>0.05）。结论：结肠癌组织中CHOP/GADD153蛋白的表达增高,并与结肠癌织的分化程度密切相关,提示内质网应激可能参与了肿瘤分化的调控。

     

The role of Ca2+ release from sarcoplasmic reticulum in the regulation of sinoatrial node automaticity

Summary The role of Ca²⁺ release channels in the sarcoplasmic reticulum in modulating physiological automaticity of the sinoatrial (SA) node was studied by recording transmembrane action potentials and membrane ionic currents in small preparations of the rabbit SA node. Ryanodine, which modifies the conductance and gating behavior of the Ca²⁺ release channels, was used to block Ca²⁺ release from the sarcoplasmic reticulum. Superfusion of 1-mM ryanodine decreased the spontaneous firing frequency as well as the maximal rate of depolarization of the SA, and these reductions reached a steady state within approximately 5min. The action potential recordings revealed that the latter part of diastolic depolarization was depressed and that the take-off potential became less negative. This suggested that the negative chronotropic effect of ryanodine resulted from the blockade of physiological Ca²⁺ release from the sarcoplasmic reticulum. In voltage clamp experiments, using double-microelectrode techniques, ryanodine did not markedly reduce the Ca²⁺ current (I_Ca) but decreased the delayed rectifying K+ current (I_K), the steady-state inward current (I_ss), and the hyperpolarization-activated inward current (I_h). These observations suggest that, even when the function of Ca²⁺ channels in the cell membrane is normally maintained, depression of Ca²⁺ release channels in the sarcoplasmic reticulum would prevent sufficient elevation of the Ca²⁺ concentration in SA node cells for the activation of various ionic currents, and, thus adversely affect the physiological automaticity of this primary cardiac pacemaker.