ADP-核糖基化调控泛素化修饰的研究进展

正在生物体内,蛋白质翻译后修饰具有十分重要的作用,ADP-核糖基化和泛素化修饰作为2个重要的蛋白翻译后修饰类型,参与重要的生命活动。ADP-核糖基化在维持基因组的稳定性,转录调节、细胞分化与信号转导、肿瘤的发生发展等重要的生命活动相关。泛素化在蛋白质定位、代谢、功能、调节和降解中发挥重要作用,几乎参与一切生命活动的调控。蛋白翻译后修饰过程不是孤立存在的,同一生理或病理过程的发     

阿片成瘾的相关磷酸化蛋白研究

蛋白质磷酸化是最常见、最重要的一种蛋白翻译后修饰方式，已有越来越多的证据表明，蛋白磷酸化在阿片耐受和成瘾机制中的重要作用，近年来有许多这方面的研究工作，涉及蛋白激酶C，cAMP依赖蛋白激酶A，依赖与钙．钙调蛋白的蛋白激酶，cGMP依赖蛋白激酶G，G蛋白受体激酶等，这些蛋白作为分子开关调控着阿片的耐受和成瘾。     

蛋白质糖基化的研究进展

作为一种普遍存在的翻译后修饰,糖基化对蛋白质的结构和功能有着重要影响,弄清糖基化发生发展的规律是理解蛋白质复杂多样的生物功能的一个重要前提。文章就糖基化对蛋白质结构的影响、对治疗性蛋白的药理学意义、糖基化位点分析及糖链分析方法作了简要介绍。     

Hsp90抑制剂的研究进展

热休克蛋白90（heat shock protein 90,Hsp90）是热休克蛋白家族中重要的蛋白之一,参与调控,维持细胞内多种蛋白的构象和功能,在调节细胞的生长、分化和凋亡等方面发挥重要的作用。热休克蛋白90抑制剂是一类能与Hsp90调节位点结合,引起Hsp90构象改变干扰其执行分子伴侣的功能,阻碍蛋白质翻译后的加工修饰,使功能蛋白丧失相应的功能甚至诱导底物蛋白降解而发挥药理作用以Hsp90为作用靶点的化合物。近年来的研究表明,很多癌基因蛋白均为Hsp90的客户蛋白,在肿瘤的发生进展方面发挥至关重要的作用,因此,通过抑制Hsp90的功能,间接干扰Hsp90客户蛋白的功能甚至促进癌基因蛋白的降解可以有效的抑制肿瘤的进展。该文主要对Hsp90抑制剂的研究进展做一综述。     

蛋白质组学在药物研究中的应用

蛋白质组是指基因组表达的所有相应的蛋白质，是指细胞或组织或机体全部蛋白质的存在及其活动方式。蛋白质组具有多样性和可变性，同一机体的不同细胞中，蛋白质的种类和数量是各不相同的，即使是同一种细胞。在不同时期、不同生理条件下，其蛋白质组都是在不断变化之中，在病理过程或药物作用下，细胞蛋白质的组成及其变化，与正常生理过程也是不同的。蛋白质组学是从整体的蛋白质水平上，从生命本质的层次上，研究和发现生命活动的规律和重要生理、病理现象的本质。蛋白质的研究技术主要应用于两个方面，一个是特殊细胞、组织或有机体的系统鉴定和所有蛋白的定量，这是系统生物学的核心，可以提供一个完全量化的含翻译后修饰变体的蛋白质组，更重要的是可以在相关样品中寻找差异，即在生理状态发生变化而产生的蛋白质图谱中的差异。另一个方面主要是蛋白质功能和蛋白质相互作用的研究，包括如蛋白质序列、结构、相互作用和生化活性的分析等多种试验方法。药物蛋白质组学的重要研究内容在临床前包括新药和靶的发现、药物作用模式、毒理学研究，在临床研究方面包括疾病特异性蛋白作为有效患者选择的依据和临床试验的标志。应用类似于药物遗传学的方法，按照蛋白质谱来分类患者，并预测药物作用疗效。     

N-乙酰葡萄糖胺糖基化修饰与糖尿病、阿尔茨海默病及心脏病的关系

蛋白质的O位N-乙酰葡萄糖胺(O-GlcNAc)糖基化作为一种区别于一般糖基化的翻译后修饰,会使蛋白质的功能发生多种改变。近年的研究发现,蛋白质O-GlcNAc糖基化修饰参与糖尿病、阿尔茨海默病与心脏病等多种疾病病理生理过程,因此对其研究具有积极意义。本文对蛋白质O-GlcNAc糖基化修饰与糖尿病、阿尔茨海默病和心脏病发生的关系作一综述。     

基于iTRAQ技术分析联合用药作用大鼠肝星状细胞后差异表达的蛋白

目的 筛选联合用药作用大鼠肝星状细胞(HSC-T6)后差异表达的蛋白质,以探讨联合用药抑制肝星状细胞增殖的机制。方法 以牛磺酸、表没食子儿茶素没食子酸酯(EGCG)和三羟基异黄酮三者组成的联合用药作用HSC-T6后,提取细胞总蛋白,运用同位素标记的iTRAQ技术结合高效液相色谱-电喷雾串联质谱(LC-ESI-MS/MS)的定量蛋白质组学方法,分析和鉴定差异表达的蛋白质,运用生物信息学分析差异表达的蛋白质功能。结果 质谱共分析鉴定到727种蛋白质。3次实验分别鉴定到的差异表达蛋白质数量分别为85,102,94个,在3次重复均鉴定到的差异表达蛋白为52个,其中上调蛋白24个,下调蛋白28个。生物信息学分析表明,差异表达的蛋白参与翻译后修饰、转录、重组和信号传导等过程,在这些蛋白质中既有与肝纤维化发生、发展直接相关的蛋白质如基质金属蛋白酶抑制剂1、层黏连蛋白、前纤维蛋白2等,也有在蛋白质的相互作用中处于功能网络交叉点的蛋白质如细胞周期素依赖性激酶4、肝癌衍生生长因子、谷氨酸脱氢酶 1和丝氨酸/精氨酸剪接因子9等。结论 联合用药抑制肝星状细胞增殖的作用,可能是通过调控多种蛋白质的表达来实现,所获得的差异表达蛋白可能在肝纤维化发生发展和药物抗肝纤维化作用过程中扮演重要角色。     

蛋白质的化学合成

蛋白质是生物体中功能最重要的一类生物大分子,目前蛋白质的制备方法主要有3种:生化提取法、基因工程法和化学合成法[1].各种方法利弊并存[2～3],没有一种方法能够完全适用于所有蛋白质的制备.生化提取法来源少,基因工程法翻译后难以修饰,易形成包合体等不恰当的折叠构型;相比之下,化学合成法提供了一条快速、高效的蛋白质制备途径,同时它能方便地引入非天然氨基酸,改变碳链骨架以及其他化学修饰来提高蛋白质活性,构建新蛋白.     

内质网应激与胰岛素抵抗

内质网(endoplasmic reticulum,ER)是哺乳动物细胞中重要的Ca2+贮存器,同时也是蛋白质合成与翻译后修饰、多肽链正确折叠与装配的重要场所。低氧、高糖、化学毒物或突变等多种因素通过耗竭ER腔内Ca2+、抑制蛋白糖基化、引起二硫键错配、减少蛋白质从ER向高尔基体转运,导致未折叠或错误折叠蛋白质在ER腔内蓄积等,均可使ER功能发生改变,即为未折叠蛋白反应(UPR),又称为内质网应激(ERS)。肥胖的动物     

赖氨酸乙酰化作用：更为广泛的蛋白调控方式

蛋白质赖氨酸残基上的乙酰化修饰,包括非组蛋白赖氨酸的乙酰化修饰,是一种普遍存在的可逆性翻译后修饰作用,然而检测技术上的限制一直阻碍着赖氨酸乙酰化修饰在细胞中的功能解析和研究。随着赖氨酸乙酰化检测技术的不断成熟,现已发现大量的非组蛋白存在赖氨酸乙酰化修饰的现象。目前,调控细胞内赖氨酸乙酰化的分子机制还不十分清楚,对于活体内高度动态的赖氨酸乙酰化修饰的捕捉尚存困难,但已有越来越多的证据表明,赖氨酸乙酰化修饰广泛地参与细胞的生长、凋亡、动力学、能量代谢等生理活动过程。本文以不断发展的赖氨酸检测技术为出发点,介绍非组蛋白赖氨酸乙酰化修饰的特点和研究进展,并着重讨论赖氨酸乙酰化修饰在肿瘤细胞的转录调控、能量代谢和肿瘤治疗中的作用及应用前景。     

Nuclear proteins: promising targets for cancer drugs

Recent progress in cancer drug therapy has recognized that the nucleus of the eukaryotic cell is an active site for many cellular processes important to the development of cancer. Many of these processes take place in specialized compartments of the nucleus. One of such sub-nuclear compartments is the promyelocytic leukemia nuclear body (PML NB). In acute promyelocytic leukemia (APL), PML forms a fusion protein with the retinoic acid receptor (RAR) alpha as a result of chromosomal translocation. This PML-RAR alpha fusion protein is responsible for the proliferative and de-differentiated phenotype of the leukemic cells and is the target of all-trans retinoic acid (ATRA). Another example of the specialized sub-nuclear compartments important in the targeting of cancer is the nucleolus. Recently, it has been proposed that the nucleolus serves as a stress sensor for the cell, and the molecular mechanism underlying this proposal has been discovered. Moreover, many anti-cancer drugs target specific protein-protein interactions within the nucleus. We will discuss current development surrounding two such target proteins: the hypoxia-inducible factor 1 alpha (HIF-1alpha) and FKBP25. Furthermore, chromatin structure, which is affected by modifications of core histones, has become a target of anti-cancer drugs. In this review, we will emphasize the significance of nuclear proteins as promising targets for cancer drug therapy by discussing a few key ideas, in three broad categories of specialized sub-nuclear compartments, protein-protein interactions, and the modifications of the chromatin structure.     

The challenge of drying method selection for protein pharmaceuticals: product quality implications

Numerous drying methods are used to dry solutions of proteins in the laboratory and/or in pharmaceutical manufacturing. In this review article, we will discuss many of these drying methods. We will briefly introduce and compare the unit operations involved in the drying methods to give an insight on thermal history, and the different stresses that a drying method can present to an active ingredient, particularly for protein molecules. We will review and compare some important physico-chemical properties of the dried powder that result from using different drying methods such as specific surface area, molecular dynamics, secondary structure (for protein molecules), and composition heterogeneity. We will discuss some factors that might lead to differences in the physico-chemical properties of different powders of the same formulation prepared by different techniques. We will examine through a literature review how differences in some of these properties can affect storage stability. Also, we will review process modifications of the basic drying methods and how these modifications might impact physico-chemical properties, in-process stability and/or storage stability of the dried powders.     

Inhibitors of the subtilase-like pro-protein convertases (SPCs)

Following protein biosynthesis, some of the most important cellular mechanisms that generate biological diversity are the enzymatically driven post-translational modifications that ultimately lead to the formation of bioactive molecules. Within the secretory pathway, a multitude of precursor proteins are thus modified resulting in hormones, neuropeptides, growth factors, receptors and even enzymes. These modifications include cleavage at specific sites through endo- or exo-peptidase action, amidation, glycosylation and sulfation. In recent years, an important family of these processing enzymes was discovered and characterized. The so-called proprotein convertases are the products of seven distinct genes and function as endopeptidases that cleave protein precursors C-terminal to basic residue sites. They are structurally related to the bacterial subtilisin family of enzymes and are thus referred to as the subtilisin-like proprotein convertases (SPCs). Many studies have examined the inhibition of this family of enzymes, through the search of endogenous inhibitors or through the development of peptidyl, non-peptidyl or protein inhibitors. Some potent inhibitors have been discovered or engineered. While it is certain that potent inhibitors could serve as important tools to further elucidate the specific functions of each SPC, it has also been suggested that such inhibitors may be developed into lead compounds that could have important therapeutic applications. This review examines the progress made in regards to endogenous and engineered inhibitors and evidence for possible uses as molecular tools or in therapeutic applications. It is noted that although important inhibitory potencies have often been reported, there is generally insufficient evidence to demonstrate high levels of specificity. It is thus suggested that an important short-term challenge before the field will be a better understanding of the catalytic specificity of each SPC.     

Post-translational modification of heat-shock protein 90: impact on chaperone function

Heat-shock protein 90 (Hsp90) is a molecular chaperone required for the stability and function of many signaling proteins that are often activated, mutated or overexpressed in cancer cells and that underly cancer cell proliferation and survival. Hsp90 is a conformationally flexible protein that associates with a distinct set of cochaperones depending on ATP or ADP occupancy of an N-terminal binding pocket. Nucleotide exchange and ATP hydrolysis by Hsp90 itself, with the assistance of cochaperones, drive the Hsp90 chaperone machine to bind, chaperone and release client proteins. Cycling of the Hsp90 chaperone machine is critical to its function. Although ATP binding and hydrolysis have been convincingly implicated in regulating the Hsp90 cycle, growing evidence suggests that various post-translational modifications of Hsp90, including phosphorylation, acetylation and other modifications, provide an additional overlapping or parallel level of regulation. A more complete understanding of how these various protein modifications are regulated and interact with each other at the cellular level to modulate Hsp90 chaperone activity is critical to the design of novel approaches to inhibit this medically important molecular target.     

An integrated approach to identifying chemically induced posttranslational modifications using comparative MALDI-MS and targeted HPLC-ESI-MS/MS

Identification of multiple and novel posttranslational modifications remains a major challenge in proteomics. The present approach uses comparative analysis by matrix-assisted laser/desorption ionization (MALDI) MS of proteolytic digests from control and treated proteins to target differences due to modifications, without initial assumption as to type or residue localization. Differences between modified and unmodified digest MS spectra highlight peptides of interest for subsequent tandem mass spectrometry (MS/MS) analysis. Targeted HPLC-electrospray ionization (ESI)-MS/MS is then used to fragment peptides, and manual de novo sequencing is used to determine the amino acid sequence and type of modification. This strategy for identifying posttranslational modifications in an unbiased manner is particularly useful for finding modifications produced by exogenous chemicals. Successful characterization of chemically induced posttranslational modifications and novel chemical adducts is given as an example of the use of this strategy. Histone H4 from butyrate-treated LLC-PK1 cells is separated on a gel into bands representing different overall charge state. Bands are analyzed by comparative MALDI-MS and LC-MS/MS to identify the sites of methylation and acetylation. Previous attempts to identify chemically adducted proteins in vivo have been unsuccessful in part due to a lack of understanding of the final adduct form. Cytochrome c is adducted in vitro with benzoquinone, an electrophilic metabolite of benzene capable of interacting with nucleophilic sites within proteins. De novo sequencing identifies a novel cyclized diquinone adduct species as the major reaction product, targeting Lys and His residues at two specific locations on the protein surface. This unpredicted reaction product is characterized using our unbiased methods for detection and demonstrates the important influence of protein structure on chemical adduction.     

肠易激综合征的主要致病因素及中医药治疗

肠易激综合征 (Irritable bowel syndrome,IBS) 是一种慢性复发性功能性胃肠道疾病。IBS 的病理生理学尚未完全了解,并且它的致病是多因素的。IBS有许多致病因素,这些因素不一定全部存在于每个患者中,但都对IBS的发病发挥着重要作用。IBS 的典型临床表现是因排便形式的改变而产生的不适或腹痛。IBS 的及时诊断很重要,因此可以引入可缓解症状（腹泻、便秘、疼痛）的治疗方法。本文整理了 IBS 在现有研究中可能致病的发病因素,为研究者在研究治疗 IBS 药物的新靶标上提供更多的思路,同时总结了 IBS 在中医诊断下的证候,对中医药治疗 IBS 进行综述。     

Rationale for using serotonergic agents to treat irritable bowel syndrome.

PURPOSE: The role of serotonin in gastrointestinal (GI)-tract functioning, the pharmacologic rationale for using serotonergic agents in the treatment of irritable bowel syndrome (IBS), and clinical experience with novel serotonergic agents are described. SUMMARY: IBS is a common multisymptom disorder that is associated with a high socioeconomic burden. The goal of treatment is to provide rapid and sustained global relief of the multiple symptoms of IBS with a single, effective, well-tolerated agent. Traditional treatment options target single symptoms, and many patients are dissatisfied with the level of relief achieved and adverse effects. Research has revealed that serotonin is involved in three major actions in the gut: (1) mediating intestinal motility, (2) mediating intestinal secretion in the GI tract, and (3) modulating perception in the bowels. Serotonin is also a vital link in the brain-gut axis. Alterations in key elements of serotonin signaling have been demonstrated in patients with IBS. Tegaserod, a selective serotonin type 4 (5-HT(4))-receptor partial agonist, is indicated for use in women with IBS whose primary bowel symptom is constipation. Alosetron, a 5-HT(3)-receptor antagonist, is indicated for use in women with severe diarrhea-predominant IBS in whom traditional therapies have failed. The clinical usefulness of several other serotonergic agents for IBS is being investigated. CONCLUSION: The use of serotonergic agents in patients with IBS is based on the critical role that serotonin plays in the maintenance of normal gut function and brain-gut communication. Pharmacologic therapies targeting specific serotonin receptors represent an important step in the management of IBS.     

Rational design and engineering of therapeutic proteins

An increasing number of engineered protein therapeutics are currently being developed, tested in clinical trials and marketed for use. Many of these proteins arose out of hit-and-miss efforts to discover specific mutations, fusion partners or chemical modifications that confer desired properties. Through these efforts, several useful strategies have emerged for rational optimization of therapeutic candidates. The controlled manipulation of the physical, chemical and biological properties of proteins enabled by structure-based simulation is now being used to refine established rational engineering approaches and to advance new strategies. These methods provide clear, hypothesis-driven routes to solve problems that plague many proteins and to create novel mechanisms of action. We anticipate that rational protein engineering will shape the field of protein therapeutics dramatically by improving existing products and enabling the development of novel therapeutic agents.     

Increased oxidative stress status in rat serum after five minutes treadmill exercise

Although it is accepted that an important correlation exists between the physical exercise and the oxidative stress status, the data regarding the levels of the main oxidative stress markers after physical training have been difficult to interpret and a subject of many controversies. There are also very few studies regarding the effects of short-time exercise on the oxidative stress status modifications. Thus, in the present report we were interested in studying the modifications of some oxidative stress markers (two antioxidant enzymes-superoxide dismutase and glutathione peroxidase, a lipid peroxidation parameter — malondyaldehide, the total antioxidant status and protein carbonyl levels), from the serum of rats that were subject to one bout of five minutes exercise on a treadmill, when compared to a control sedentary group. In this way, we observed a decrease of superoxide dismutase specific activity in the rats which performed the exercises. Still, no modifications of glutathione peroxidase specific activity were found between groups. In addition, increased levels of malondyaldehide and protein carbonyls were observed in the rats subjected to exercises. In conclusion, our data provides new evidence regarding the increase of the oxidative stress status, as a result of a 5-minutes bout of treadmill exercising in rats, expressed through a decrease in the SOD specific activity and the total antioxidant status and also an increase of the lipid peroxidation and protein oxidation processes.     

Quality of life in irritable bowel syndrome.

Quality-of-life (QOL) assessment is becoming increasingly important in the evaluation of the impact of disease and the effect of therapy. This is particularly so forirritable bowel syndrome (IBS) where there is often a tendency for a chronic clinical course, but with no associated mortality. Instruments used to study quality of life may be generic or disease specific, and care needs to be taken to ensure that the instrument used has been adequately validated for the purpose intended. Several disease-specific instruments [Irritable Bowel Syndrome Quality of Life (IBS-QOL, IBSQOL) and Functional Digestive Disorders Quality of Life (FDDQL)], in addition to generic measures, are now available for use in IBS. Quality of life in patients with IBS is surprisingly poor, particularly in the population seeking healthcare, where it can be compared with conditions which carry a high mortality, such as ischaemic heart disease, heart failure and diabetes mellitus. Pain severity appears to be an important factor in determining quality of life in IBS, although bowel disturbance and psychological difficulties are also likely to be important. There is limited data on the effect of treatment of IBS on quality of life. Improvement has been reported with dietry modification, drug treatments and hypnotherapy. It is likely that, in the future, QOL measures will become increasingly used as secondary end-points in therapeutic trials in IBS.