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.     

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.     

Emodin induces apoptosis of human osteosarcoma cells via mitochondria- and endoplasmic reticulum stress-related pathways

Aim: Emodin showed anti-cancer activity against multiple human malignant tumors by inducing apoptosis. However, the apoptotic inducing effect against human osteosarcoma and related mechanism are still not studied. This study was aimed to investigate them. Methods: Emodin was used to incubate human OS cell U2OS cells at serially diluted concentrations. Hoechst staining was used to evaluate apoptosis; flow cytometry was applied to assess the collapse of mitochondrial membrane potential (MMP); intracellular ROS generation was detected by DCFH-DA staining; endoplasmic reticulum stress activation was examined by western blotting. Results: Cell apoptosis of U2OS cells was induced by emodin incubation in a concentration-dependent manner; MMP collapse and ROS generation were identified at starting concentration of 80 μmol/L of emodin in a concentration-dependent manner. ER stress activation was found at beginning concentration of 40 μmol/L of emodin. The MMP collapse was inhibited while the ER stress was not inhibited by NAC administration. Conclusions: Emodin induces death of human osteosarcoma cells by initiating ROS-dependent mitochondria-induced and ROS-independent ER stress-induced apoptosis.     

内质网相关性降解与呼吸系统疾病

内质网相关性降解（ERAD）通过清除内质网腔内的错误折叠蛋白质,从而预防和缓解内质网应激,是真核生物蛋白质质量控制和维持细胞正常功能状态的重要机制。ERAD包含底物（即错误折叠蛋白）识别、底物泛素化与逆转运、底物降解三个基本环节,其中任何一个环节失调都会导致细胞功能障碍,并可能进一步导致疾病的发生与发展。近几年研究发现,ERAD参与了COPD、肺癌、肺囊性纤维化等疾病发生过程。本文就参与ERAD的相关因子的研究进展进行综述。     

软骨细胞中内质网应激信号通路的研究进展

内外环境多种刺激均可导致内质网中未折叠蛋白的积聚,引起细胞内的应激反应,改变细胞的功能和存活状态,这个过程称为内质网应激（ERS）。软骨细胞是关节软骨内唯一的细胞成分,低糖性损伤、白细胞介素-1β和一氧化氮以及一些药物均能使其发生ERS。ERS可引发蛋白激酶R样内质网调节激酶（PERK）、肌醇需酶（IRE）1和活化转录因子（ATF）6三条主要的信号通路构成未折叠的蛋白反应（UPR）。UPR中多种信号分子对软骨细胞的生长、程序性死亡以及软骨的炎症都有重要的影响,本文就ERS信号通路机制、PERK信号通路、IRE1信号通路和ATF6信号通路等研究进展作一综述。     

Effect of endoplasmic reticulum stress on the activation of high glucose-induced monocytes

Objective To observe the effects of endoplasmic reticulum stress (ERS) on the activation of monocytes induced by high glucose and explore the underlying mechanism. Methods The monocyte cell line THP-1 was stimulated with high glucose, and then treated with molecular chaperone betaine. The levels of glucose regulation protein 78 (GRP78) and p-JNK, which were associated with ERS were detected by real-time PCR and Western blotting. The proliferation of the cell line was detected by MTT method. Transwell and immunofluorescence were applied to observe the chemotaxis and phenotype of cells respectively. Results The levels of GRP78 and p-JNK of THP-1 cells stimulated by high glucose were significantly increased compared with the normal control group (all P＜0.05). The proliferation and chemotactic were also enhanced (all P＜0.05). The number of cells in M1 phenotype was increased remarkably (P＜0.05). All the indexes above could be rescued by betaine. Conclusion The activation of THP-1 cells can be induced by high glucose through ERS, while molecular chaperone betaine can reverse the activation.     

光动力疗法治疗恶性肿瘤作用机制的研究进展

【摘要】 光动力疗法(PDT)是继手术、放化疗等传统治疗肿瘤手段外的一种新的抗肿瘤模式。PDT机制目前尚不完全清楚, 已知其利用肿瘤细胞高摄取光敏剂的特性, 使用相应波长的激光照射, 使光敏剂产生单线态氧或其他活性氧, 通过非细胞凋亡途径或直接高效诱导凋亡或导致肿瘤组织坏死杀死癌细胞。PDT也可损伤肿瘤组织的血管内皮细胞及介导自身免疫系统的激活。