蛋白质组研究的现状与展望

蛋白质组是后基因组时代出现的一个新兴研究领域。蛋白质组的研究主要是先通过双向凝胶电泳等方法分离蛋白质,然后用质谱等技术进行鉴定。它是后基因组重要的研究方向之一,具有巨大的商业应用前景,将会推动整个生命科学的发展。蛋白质组研究取得了很大进展,已经成为生物技术中的一个重要领域。     

Comparative proteome analysis of breast cancer and normal breast

Breast cancer is a leading cause of death for women. The underlying molecular mechanism is still not well understood. In this study, two-dimensional gel electrophoresis combined with mass spectrometry was used to analyze changes in the proteome of infiltrating ductal carcinoma compared to normal breast tissue. Ten sets of two-dimensional gels per experimental condition were analyzed and more than 500 spots each were detected. This revealed 39 spots for which expression in breast cancer cells were reproducibly altered more than twofold compared to normal controls (p<0.01). These spots represented 25 different proteins after identification using the database search after mass spectrometry, comprising cell defense proteins, enzymes involved in glycolytic energy metabolism and homeostasis, protein folding and structural proteins, proteins involved in cytoskeleton and cell motility, and proteins involved in other functions. In addition, 28 nondifferentially expressed proteins with different functions were also mapped and identified, which might help to establish a two-dimensional gel electrophoresis reference map of human breast cancer. Our study shows that proteomics offers a powerful methodology to detect the proteins that show different expression patterns in breast cancer tissue and may provide an accurate molecular classification. The differentially expressed proteins may be used as potential candidate markers for diagnostic purposes or for determination of tumor sensitivity to therapy. The functional implications of the identified proteins are discussed.     

Advances in plant proteomics-key techniques of proteome

Following the completion of genome sequen-cing of model plants,such as rice (Oryza sativa L.) and Arabidopsis thaliana,the era of functional plant genomics has arrived which provides a solid basis for the develop-ment of plant proteomics.We review the background and concepts of proteomics,as well as the key techniques which include:(1) separation techniques such as 2-DE (two-dimensional electrophoresis),RP-HPLC (reverse phase high performance liquid chromatography) and SELDI (surface enhanced laser desorption/ionization) protein chip; (2) mass spectrometry such as MALDI-TOF-MS (matrix assisted laser desorption/ionization-time of flight- mass spectrometry) and ESI-MS/MS (elec-trospray ionization mass spectrometry/mass spectro-metry); (3) Peptide sequence tags; (4) databases related to proteomics; (5) quantitative proteome; (6) TAP (tandem affinity purification) and (7) yeast two-hybrid system.In addition,the challenges and prospects of pro-teomics are also discussed.     

The holm oak leaf proteome: analytical and biological variability in the protein expression level assessed by 2-DE and protein identification tandem mass spectrometry de novo sequencing and sequence similarity searching

As a first approach in establishing the holm oak leaf proteome, we have optimised a protocol for this plant and tissue which includes the following steps: trichloroacetic acid-acetone extraction, two-dimensional gel electrophoresis (2-DE) on pH 5 to 8 linear gradient immobilised pH gradient strips as the first dimension, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis on 13% polyacrylamide gels as the second one. Proteins were detected by Coomassie staining. Gel images were recorded and digitalized, and the protein spots quantified by using a linear regression equation of protein quantity on spot volume obtained against standard proteins. Analytical variance was calculated for one-hundred protein spots from three replicate 2-DE gels of the same protein extract. Biological variance was determined for the same protein spots from independent tissue extracts corresponding to leaves from different trees, or the same tree at different orientations or sampling times during a day. Values of 26% for the analytical variance and 58.6% for the biological variance among independent trees were obtained. These values provide a quantified and statistical basis for the evaluation of protein expression changes in comparative proteomic investigations with this species. A representative set of the major proteins, covering the isoelectric point range of 5 to 8 and the relative molecular mass(r) range of 14 to 78 kDa, were subjected to liquid chromatography-tandem mass spectrometry analysis. Due to the absence of Quercus DNA or protein sequence databases, a method based on the procedure reported by Liska and Shevchenko including de novo sequencing and BLAST similarity searching against other plant species databases was used for protein identification. Out of 43 analysed spots, 35 were positively identified. The identified proteins mainly corresponded to enzymes involved in photosynthesis and energetic metabolism, with a significant number corresponding to RubisCO.     

Towards the proteome of Burkholderia cenocepacia H111: setting up a 2-DE reference map

Polyphasic-taxonomic studies of the past decade have shown that the Burkholderia cepacia complex (Bcc) comprises at least nine species, which share a high degree of 16S rDNA (98-100%) sequence similarity but only moderate levels of DNA-DNA hybridization. Members of the Bcc are well known as opportunistic pathogens of plants, animals and humans but also as biocontrol and bioremediation agents. In this study intra-, surface-associated and extracellular proteins of B. cenocepacia H111, which was isolated from a cystic fibrosis patient, were examined by 2-DE coupled to MALDI-TOF MS. MS and MS/MS data were searched against a database comprising all currently available annotated proteins of genetically closely related strains. In total 642 proteins spots were successfully identified corresponding to 390 different protein species, which were classified into functional categories. The majority of these proteins could be linked to housekeeping functions in energy production, amino acid metabolism, protein folding, post-translational modification and turnover, and translation. Noteworthy is the fact that a significant number of truly secreted and membrane proteins were identified in the extracellular and surface-associated sub-proteomes. This indicates that the pre-fractionation protocol used in this study is a highly valuable strategy for unravelling the cellular location of the identified proteins.     

Current knowledge of the human sperm proteome

The knowledge of the mature sperm proteome is undoubtedly the basis for understanding sperm function, the mechanisms responsible for fertilization, the reasons for infertility and possible treatments. The methods of sperm protein extraction depend mainly on the proteins of interest and the protein separation techniques that will be employed. The isolation of the membrane proteins appears to be most problematic step. Nevertheless, two-dimensional electrophoresis and mass spectrometry have become the main techniques used in human sperm protein analysis. We outline the present techniques used to examine the sperm proteome and data generated from studies on the human sperm and different types of male infertility. We present the most characteristic proteins that are involved in sperm function. Their value as biomarkers for diagnosis and treatment of infertility would require further validation. We focus on selected and critical studies of the human sperm proteome to present our subjective view of this fast-moving field.     

蛋白质组研究的技术体系及其进展

随着后基因组时代的到来,蛋白质组研究越来越受到国内外科学工作者的密切关注, 我国国家自然科学基金委员会已把蛋白质组研究列为重大科研项目.概述了蛋白质组研究中的基本技术,包括双向凝胶电泳的样品制备和分离、蛋白质的检测、凝胶图像分析、蛋白质的鉴定以及蛋白质数据库构建等,并就蛋白质鉴定的常用方法如氨基酸组成分析方法、蛋白质末端序列分析、肽质量指纹谱作了详细阐述.直观地列出了蛋白质组研究的技术体系流程图,着重介绍了蛋白质组研究的最新技术及其进展.     

Analysis of the human saliva proteome

Interest in the characterization of the salivary proteome has increased in the last few years. This review discusses the different techniques and methodologies applied to the separation and identification of salivary proteins. Nowadays, proteomic techniques are the state of the art for the analysis of biologic materials and saliva is no exception. 2D electrophoresis and tryptic digest analysis by mass spectrometry are the typical methodology, but new approaches using 2D liquid chromatography/mass spectrometry methods have already been introduced for saliva analysis. Due to their important physiologic role in the oral cavity, low-molecular-weight proteins and peptides are also included in this article and the methodologies discussed.     

Proteomic analysis of individual variation in normal livers of human beings using difference gel electrophoresis

Normal Chinese Liver Proteome Expression Profile is one of the major parts of Human Liver Proteome Project. Before starting the studies, it is necessary to examine the interindividual variation of normal liver proteome and evaluate the minimal size of samples for proteomic analysis. In this study, normal liver samples from ten individual volunteers were collected and the proteome profiles of these samples were analyzed using 2-D difference gel electrophoresis (DIGE) combined with MALDI-TOF/TOF MS. The individual liver tissue lysates were labeled with Cy3 and Cy5 while the pooled sample was labeled with Cy2 as an internal standard, which minimized gel-to-gel variation. After analysis by the DeCyder software, up to 2056 protein spots were detected on the master gel. The CV of standardized abundance was calculated for the protein spots that were matched across all ten gels. The CV values of these protein spots ranged from 6.4 to 108.5% and the median CV was approximately 19%, which demonstrated that the protein expression of normal liver among different individuals was relatively stable. The eight proteins with CV values over 50% were identified which would be a caveat when considering these proteins as potential disease-related markers. Moreover, the one-way ANOVA feature showed a correlation between sample size and individual variations. The results showed that when the sample size exceeded 7, the individual variations were not significant to the whole pool. Our results are an important basis for liver protein expression profiles and comparative proteomics of liver disease.     

吗啡成瘾及戒断大鼠前额叶皮质蛋白质组变化的初步研究

目的：探讨与大鼠吗啡成瘾和戒断相关的前额叶皮质（PFC）蛋白。方法：以固相pH梯度等电聚焦为第一向和垂直SDS-PAGE为第二向,分别对吗啡成瘾和自然戒断大鼠及正常大鼠的PFC蛋白质样品进行二维分离,2-DE图谱经ImageMaster 2D Plat-inum v5.0软件分析,选取4个差异蛋白点用基质辅助激光解吸附离子化飞行时间质谱（MALDI-TOF-MS）进行鉴定。结果：通过对2-DE图谱蛋白斑点的匹配及对比分析,与吗啡成瘾和自然戒断相关的差异表达蛋白斑点为79个;经质谱鉴定出2个有意义的差异表达的蛋白斑点：Snap25亚型-βSnap25突触相关蛋白25,β-肌动蛋白。结论：PFC的某些蛋白可能与吗啡成瘾和戒断相关,其中尤其是神经毒性相关的蛋白可能与吗啡成瘾机制相关。     

Characterization of the human urine proteome by preparative electrophoresis in combination with 2-DE

The protein components of urine are useful indicators of renal function and human health in general. Urine samples are easily attainable making them ideal substrates for biomarker research. Analysis of the urine proteome however, has been hindered by the great variability of the urine specimens, and the presence of various proteins in low abundance or modified forms. To alleviate some of these problems urine samples from five different individuals were pooled, concentrated and the proteome characterized by a combination of preparative electrophoresis and 2-DE, followed by PMF. A total of 778 protein spots corresponding to 141 different gene products were identified. In comparison, 171 spots corresponding to 44 unique proteins were identified in the unfractionated starting material. Among the proteins identified from the preparative electrophoresis were many of low abundance such as proteins involved in signal transduction. Furthermore, the median molecular mass of the identified proteins from the preparative electrophoresis was significantly lower in comparison to the proteins identified from the unfractionated starting material (39 886 Da versus 71 317 Da, respectively). Concluding, application of this methodology provides a coherent analysis of the urine proteome and contributes to the generation of the urine protein map in health and disease.     

Extensive analysis of the human platelet proteome by two-dimensional gel electrophoresis and mass spectrometry

Platelets play a key role in the control of bleeding and wound healing, contributing to the formation of vascular plugs. Under pathologic circumstances, they are involved in thrombotic disorders, including heart disease. Since platelets do not have a nucleus, proteomics offers a powerful alternative approach to provide data on protein expression in these cells, helping to address their biology. In this publication we extend the previously reported analysis of the pI 4-5 region of the human platelet proteome to the pI 5-11 region. By using narrow pI range two-dimensional electrophoresis (2-DE) for protein separation followed by high-throughput tandem mass spectrometry (MS/MS) for protein identification, we were able to identify 760 protein features, corresponding to 311 different genes, resulting in the annotation of 54% of the pI 5-11 range 2-DE proteome map. We evaluated the physicochemical properties and functions of the identified platelet proteome. Importantly, the main group of proteins identified is involved in intracellular signalling and regulation of the cytoskeleton. In addition, 11 hypothetical proteins are reported. In conclusion, this study provides a unique inventory of the platelet proteome, contributing to our understanding of platelet function and building the basis for the identification of new drug targets.     

Proteomic tools for cell biology

Acquisition of large bodies of genomic sequence is facilitating the use of global techniques to assay cellular function. DNA microarrays have enabled the measurement of global mRNA levels and are able to detect changes in gene expression between different cellular states. Since much of the regulation of physiolgical processes happens post-translationally, measuring only the mRNA levels gives an incomplete picture. Strategies to assay global expression, localization, or interaction of proteins fall into the emerging field of proteomics, with various combinations of techniques being utilized to separate and identify proteins. In this review, we will present a general overview of the currently available proteomic tools and then give examples of how these tools are being utilized to answer questions in cell biology.     

大鼠2/3肝切除72 h后再生肝脏质膜比较蛋白质组学研究

大鼠2/3肝切除模型为研究肝细胞增殖和生理性血管生成提供了一个很好的活体内模型.为了揭示肝再生过程中与肝细胞增殖终止相关及与血管生成启动相关的质膜蛋白质,本研究对大鼠肝2/3部分切除72 h后的肝脏质膜进行了研究：利用两步蔗糖密度梯度离心法对切除组和假手术组的肝脏质膜进行纯化;然后通过双向电泳和质谱技术对肝切除样品进行了比较分析并对几个关键蛋白程序性凋亡相关蛋白-6和丝蛋白-A进行了免疫印迹验证.相对于假手术对照组(Sham组),21种蛋白质在切除后72 h的肝脏中上调,15种蛋白质下调.所鉴定的差异表达蛋白参与了血管生成、细胞分裂增殖和凋亡、细胞分化调控、肝脏组织重新构建、代谢及应急反应.本研究为肝脏再生及其血管生成的研究提供了理论依据.     

The effect of environmental salinity on the proteome of the sea bass (Dicentrarchus labrax L.)

The European sea bass, Dicentrarchus labrax L., tolerates a range of salinities from freshwater to hyper-saline. To study differences in protein expression, fish were reared in both freshwater and seawater. After 3-month acclimation, gill and intestine epithelia were collected and the soluble protein extracted. In all, 362 spots were differentially expressed in the gills and intestines of fishes reared in seawater compared to those from freshwater. Fifty differential protein spots were excised from a colloidal Coomassie-stained gel. Nine separate protein spots were identified unambiguously by mass spectrometry and database searching. Among the six proteins over-expressed in gill cells in seawater, five were cytoskeleton proteins and one was the aromatase cytochrome P450. In gill cells under freshwater conditions, the two over-expressed proteins identified were the prolactin receptor and the major histocompatibility complex class II β -antigen. In intestinal cells under freshwater conditions, the Iroquois homeobox protein Ziro5 was upregulated over ninefold. The expression of these proteins, their possible direct or indirect roles in the adaptation of D. labrax to salinity, and their correspondences with a previous study are discussed.     

Effect of 5-azacytidine on the protein expression of porcine bone marrow mesenchymal stem cells in vitro

Bone marrow-derived mesenchymal stem cells （MSCs） are pluripotent stem cells that show a vital potential in the clinical application for cell transplantation. In the present paper, proteomic techniques were used to approach the protein profiles associated with porcine bone marrow MSCs and investigate the regulation of MSC proteins on the effect of 5-azacytidine （5-aza）. Over 1,700 protein species were separated from MSCs according to gel analysis. Compared with the expression profiling of control MSCs, there were 11 protein spots up-regulated and 26 downregulated in the protein pattern of 5-aza-treated cells. A total of 21 proteins were successfully identified by MALDI-TOF-MS analysis, among which some interesting proteins, such as alpha B-crystallin, annexin A2, and stathmin 1, had been reported to involve in cell proliferation and differentiation through different signaling pathways. Our data should be useful for the future study of MSC differentiation and apoptosis.     

蛋白质组双向电泳实验中一些常见失误的分析

从以固相pH梯度等电聚焦为第一向,SDS-PAGE电泳为第二向进行的蛋白质组双向电泳实验中挑选了一些常见的硝酸银染色2-DE失误图谱,将它们进行分类,初步分析造成各类失误的可能原因,探讨相应的解决方法和总结实验操作中应该注意的事项．     

Large-scale identification of proteins in human salivary proteome by liquid chromatography/mass spectrometry and two-dimensional gel electrophoresis-mass spectrometry

Human saliva contains a large number of proteins and peptides (salivary proteome) that help maintain homeostasis in the oral cavity. Global analysis of human salivary proteome is important for understanding oral health and disease pathogenesis. In this study, large-scale identification of salivary proteins was demonstrated by using shotgun proteomics and two-dimensinal gel electrophoresis-mass spectrometry (2-DE-MS). For the shotgun approach, whole saliva proteins were prefractionated according to molecular weight. The smallest fraction, presumably containing salivary peptides, was directly separated by capillary liquid chromatography (LC). However, the large protein fractions were digested into peptides for subsequent LC separation. Separated peptides were analyzed by on-line electrospray tandem mass spectrometry (MS/MS) using a quadrupole-time of flight mass spectrometer, and the obtained spectra were automatically processed to search human protein sequence database for protein identification. Additionally, 2-DE was used to map out the proteins in whole saliva. Protein spots 105 in number were excised and in-gel digested; and the resulting peptide fragments were measured by matrix-assisted laser desorption/ionization-mass spectrometry and sequenced by LC-MS/MS for protein identification. In total, we cataloged 309 proteins from human whole saliva by using these two proteomic approaches.