蛋白泛素途径及其非降解功能研究新进展

泛素化是单个或多个泛素在泛素激活酶、泛素结合酶及泛素蛋白连接酶的作用下共价修饰底物蛋白质的过程。在蛋白质降解的过程中，泛素化标记被蛋白水解酶体特异性识别，发挥着枢纽的作用。而近年来的研究发现。泛素化不仅仅是蛋白质降解的标志，它有更为广泛的用途，参与了大量的生命活动。这些研究极大地丰富了对泛素化蛋白水解系统的认识，也使得在分子水平上对蛋白质降解异常导致的顽疾进行治疗不再是梦想。     

泛素特异性蛋白酶USP18在肺腺癌中的表达及其影响研究

目的 拟探讨泛素特异性蛋白酶USP18在肺腺癌中的表达及其对人肺腺癌细胞A549增殖、迁移能力的影响.方法 基于癌症数据库TCGA-LUAD中的转录组数据,分析USP18在肺腺癌中的表达量;通过基因富集分析,探索USP18在肺腺癌发生发展中的功能.利用人肺腺癌A549细胞过表达USP18蛋白,生长曲线、克隆形成以及划痕实验探究USP18对A549细胞增殖、迁移能力的影响.结果 在TCGA-LUAD数据库中,相比于癌旁组织,肺腺癌组织的USP18 mRNA水平明显升高;细胞生长曲线和克隆形成实验结果显示,转染Flag-USP18的人肺腺癌A549细胞较转染空载体细胞增殖能力增强;划痕实验显示,转染Flag-USP18的人肺腺癌A549细胞较转染空载体细胞迁移能力增强.结论 肺腺癌细胞中USP18表达增强,且高表达的USP18可增强肺腺癌细胞增殖、迁移能力.     

泛素连接酶CUL4A-DDB1复合体参与DNA损伤修复的研究进展

泛素化修饰在DNA损伤信号中发挥重要功能,包括细胞周期监控、DNA修复、细胞衰老和程序性死亡的调控。CUL4A-DDB1泛素连接酶通过DCAFs靶向调控特异性的底物,启动DNA切除修复机制对受损DNA进行修复。近期的研究表明CUL4A-DDB1泛素连接酶协助DNA修复因子与受损DNA的识别,来维持基因组的稳定性和正确性。     

ABRO1研究进展

ABRO1（Abraxas Brother 1）,也称为KIAA0157或FAM175B,是BRISC去泛素化酶复合体的一个重要组分,该复合体的主要功能是特异性剪切K－63链接的多聚泛素链。该文系统综述了ABRO1的结构特点,参与BRISC复合体组成及调节去泛素化酶活性、调控干扰素应答、参与氧化应激反应和抗心肌缺血等多方面的研究进展,为进一步研究ABRO1的生理功能及与免疫、心血管疾病的关联提供新思路。     

ABRO1研究进展

ABRO1(Abraxas Brother 1),也称为KIAA0157或FAM175B,是BRISC去泛素化酶复合体的一个重要组分,该复合体的主要功能是特异性剪切K-63链接的多聚泛素链。该文系统综述了ABRO1的结构特点,参与BRISC复合体组成及调节去泛素化酶活性、调控干扰素应答、参与氧化应激反应和抗心肌缺血等多方面的研究进展,为进一步研究ABRO1的生理功能及与免疫、心血管疾病的关联提供新思路。     

HECT类泛素连接酶Smurf1自身调控机制的研究

目的泛素连接酶Smurf1在胚胎发育、骨形成调控和细胞极性控制中具有重要的生理功能,但是其自身的泛素化降解机制尚不清楚。本论文拟研究Smurf1分子间自我调控的机制,以期揭示一种新的泛素连接酶调控方式。方法通过免疫共沉淀实验确证了Smurf1分子间存在相互作用,体内泛素化、半衰期及降解实验研究了Smurf1的自身泛素化降解。结果 Smurf1存在分子间相互作用和泛素化降解,这种分子间的相互调控是由C2和WW结构域介导。结论 Smurf1分子间存在自我泛素化修饰及蛋白酶体依赖的降解,是一种新的HECT类泛素连接酶的调控机制。     

SCF泛素化途径对c-Myc蛋白降解的调节作用

泛素-蛋白酶体途径（ubiquitin-proteasome pathway，UPP）是细胞内降解蛋白质的重要途径，与细胞多种生理功能调节密切相关。本文主要论述了SCF（Skp-cullin-F-boxprotein）泛素化途径及对原癌基因c-myc产物的降解调控作用。     

肠致病性大肠杆菌效应因子E2348C-1040泛素连接酶活性及泛素链连接方式的鉴定

目的 鉴定肠致病性大肠杆菌（EPEC）效应因子E2348C-1040泛素连接酶活性,检测其催化形成的泛素链的连接方式。方法 构建原核表达质粒,转化感受态细胞,表达纯化E2348C-1040蛋白质。通过体外泛素化实验鉴定其泛素连接酶活性,利用泛素赖氨酸位点突变蛋白结合Western印迹实验检测该分子催化形成的泛素链的连接位点。结果 成功构建原核表达质粒,获得纯度大于85%、浓度约为0.5 mg/ml的E2348C-1040蛋白质。分子水平的酶活实验结果表明E2348C-1040分子具有泛素连接酶活性,能催化形成不依赖于赖氨酸的泛素链。通过构建真核表达质粒转染HEK-293T细胞,发现E2348C-1040分子可在宿主细胞中催化形成甲硫氨酸（methionine 1,M1）连接的线性泛素链。结论 EPEC效应因子E2348C-1040具有泛素连接酶活性,能催化泛素形成M1连接的线性泛素链。这一发现将为揭示效应因子E2348C-1040在宿主细胞内的作用机制提供研究线索。     

慢性肾衰竭血清对兔主动脉内皮细胞泛素-蛋白酶体途径的影响

目的 研究慢性肾衰竭(CRF)血清对兔主动脉内皮细胞泛素-蛋白酶体途径的影响,初步探讨CRF血清对主动脉内皮细胞作用的可能机制.方法 建立CRF兔模型,建模后12周,取CRF模型兔及正常兔下腔静脉血血清备用.原代培养健康兔主动脉内皮细胞,用正常兔血清或CRF兔血清刺激后,分别采用RT-PCR、Western blotting及特异底物反应法检测不同血清对主动脉内皮细胞泛素化蛋白、泛素激活酶(简称E1)mRNA表达,泛素化蛋白、E1、κB抑制因子(IκB)蛋白表达及蛋白酶体活性的影响.结果 CRF血清使主动脉内皮细胞泛素、E1 mRNA表达增加,明显高于正常血清(P<0.01).CRF血清对主动脉内皮细胞泛素化蛋白的表达无明显影响,但使E1蛋白表达增加,使蛋白酶体20S亚基活性增强,明显高于正常血清(P<0.01).CRF血清使主动脉内皮细胞IκB蛋白表达降低,与正常血清相比,差异有统计学意义(P<0.01).结论 CRF血清可致兔主动脉内皮细胞泛素-蛋白酶体途径活化,进而影响NF-κB信号通路.     

MARCH1:一种新的树突细胞功能调控者

近期研究发现树突细胞(DCs)表面MHC-Ⅱ类分子的含量是通过MHC-Ⅱ类分子β链的泛素化水平来调控的[1],而MARCH1,一种E3泛素连接酶,在这一过程中起关键性的作用.但目前MARCH1在体内如何调控MHC-Ⅱ类分子的表达尚不清楚.研究表明,许多生理学上重要的受体都是细胞表面跨膜蛋白,与相应的配体发生作用后表达下调以避免对细胞的过度刺激.在很多情况下,表达的下调是通过受体的降解来完成的.表皮生长因子(EGF)受体即为其中的一种,研究发现泛素化是该受体降解过程中一种重要的蛋白修饰方式,E3泛素连接酶c-Cbl被认为是EGF受体泛素化的关键酶[2 3].近年来有学者证实泛素化对于免疫应答相关膜蛋白的稳态具有重要作用,许多生物学作用过程中涉及的膜蛋白均受泛素化调控[4 7].     

Glutamine supplementation in vitro and in vivo,in exercise and in immunodepression

In situations of stress, such as clinical trauma, starvation or prolonged, strenuous exercise, the concentration of glutamine in the blood is decreased, often substantially. In endurance athletes this decrease occurs concomitantly with relatively transient immunodepression. Glutamine is used as a fuel by some cells of the immune system. Provision of glutamine or a glutamine precursor, such as branched chain amino acids, has been seen to have a beneficial effect on gut function, on morbidity and mortality, and on some aspects of immune cell function in clinical studies. It has also been seen to decrease the self-reported incidence of illness in endurance athletes. So far, there is no firm evidence as to precisely which aspect of the immune system is affected by glutamine feeding during the transient immunodepression that occurs after prolonged, strenuous exercise. However, there is increasing evidence that neutrophils may be implicated. Other aspects of glutamine and glutamine supplementation are also addressed.     

Temporal changes in the oxidation state in in vitro blood

The rates at which the paramagnetic compounds deoxyhemoglobin (Hb) and methemoglobin (MHb) form in vivo within an area of hemorrhage are unknown. The present experiment establishes the baseline concentrations and rates of change in paramagnetic hemoglobin concentrations, as well as the pH in normal heparinized and clotted human blood maintained in vitro at 37 degrees C under anaerobic conditions over 30 hours. There was a moderate increase in Hb concentration in normal heparinized blood (average increase was 15.5%, rate = 0.50%/hour) and a slight increase in MHb concentration in the heparinized blood and clots (average increase was 1.4%, rate = 0.044%/hour). A second experiment was done to verify the activity of the RBC systems responsible for maintaining the hemoglobin molecule in the reduced state. Conversion of MHb to Hb in these samples proceeded at a rate of 5.6%/hour. In a third experiment, blood from 11 normal subjects maintained at 4 degrees C 25 degrees C was analyzed for MHb concentration over the course of 28 days. The level of MHb formation remained in the range of normal for at least 11 days in all subjects. The authors conclude that at basal conditions created in vitro, the blood levels of both Hb and MHb remain at relatively low levels. Therefore, if the accumulation of Hb and/or MHb occurs in acute in vivo hematomas it must be driven by intrinsic tissue factors.     

Carcinoma in situ in cryptorchid testes in post-pubertal patients]

The pathohistologic analysis of testis sections of 37 postpuberty patients with different types of cryptorchism is performed. The tissue samples were taken during orchiopehy, fixed in Bouin's solution and treated by the standard histologic techniques. The morphologic criteria are presented for identification of the presence of the so called carcinoma in situ cells found in two cases. Besides, in 13 patients rare, mainly single, atypical germinative cells were found in a smaller number of the seminiferous tubules. It has been concluded that the presence of carcinoma in situ cells in undescended testes of some patients and considering the simple way of sampling, lack of complications and high reliability of the diagnostic procedure, it is absolutely justified to take routine biopsy of testes during orchiopexy in each postpuberty and perhaps prepuberty patient.     

我国医用辐射防护研究概况

医学放射学技术的迅速发展及介入放射学在临床广泛应用，使更多的人受到电离辐射的照射，同时也促进了医疗照射防护工作的发展。文中重点综述了我国医用辐射防护工作者近年来在Ｘ射线ＣＴ的医疗照射防护、对介入放射学工作者的剂量监测以及应用医疗照射防护体系，降低医疗照射剂量等方面所作出的成绩和研究进展     

Hepatic steatosis in obesity in children

The fatty liver infiltrations of the children are not uncommon and are often seen in particular diseases, mainly related to intoxication or metabolic diseases. The authors reported a case of heterogeneous fatty liver infiltration due to obesity with a good evolution after a hypocaloric diet.