PSMA mimotope isolated from phage displayed peptidelibrary can induce PSMA specific immune response

Prostate-specific membrane antigen (PSMA) is a cellsurface glycoprotein expressed predominantly in prostatesecretory acinar epithelium and prostate cancer cells aswell as in several extraprostatic tissues. Mouse monoclonal antibody 4G5 specific to the extracellular domainof PSMA was used to screen two phage displayed peptide libraries (9aa linear and 9aa cys library). Three 4G5reactive phagotopes were identified. Sequence analysis ofisolated clones demonstrated that the interaction motif'VDPA/SK' has high homology to 719-725aa on PSMA.Immunohistochemical staming of the prostate cancer sam ple with the PSMA-mimic phagotope (mimotope) immunized serum antibodies demonstrate that the mimotopeisolated from the phage displayed peptide libraries can induce PSMA specific immune response in vivo.

Screening and Identification of a Novel Hepatocellular Carcinoma Cell Binding Peptide by Using a Phage Display Library

The purpose of this study was to screen peptides that can specifically bind to human hepatocellular carcinoma （hHCC） cells using phage display of random peptide library in order to develope a peptide-based carrier for the diagnosis or therapy of hHCC. A peptide 12-mer phage display library was employed and 4 rounds of subtractive panning were performed using the hHCC cell line HepG2 as the target. After panning, the phages that specifically bound to and internalized in hHCC cells were selected. The selected phages demonstrated highly specific affinity to HepG2 cells analyzed by ELISA and immunofluorescence analysis. 57.3% of the selected phage clones displayed repeated sequence FLLEPHLMDTSM, and 4 amino acid residues, FLEP were extremely conservative. Based on the sequencing results, a 16-mer peptide （WH-16） was synthesized. The competitive EL1SA showed that the binding of the phage clones displayed sequence FLLEPHLMDTSM to HepG2 cells was efficiently inhibited by WH-16. Our findings indicate that cellular binding of phage is mediated via its displayed peptide and the synthesized 16-mer peptide may have the potential to be a delivery carrier in target diagnosis or therapy for hHCC.

SELECTION OF NEW EPITOPES FROM MONOVALENT DISPLAYED PHAGE OCTAPEPTIDE LIBRARY

A library of 2 ×107 random octapeptides was constructed by use of phagemid-based monovalent phage display system. The randomly synthesized degenerated oligodeoxyribonucleotides (oligos ) were fused to the truncated g Ⅲ (p230-p403). Sequence analysis of 11 randomly chosen clones suggested that the degenerated inserts and its deduced amino acid (aa) sequences are randomly distributed. The library was used to select binding peptides to the monoclonal antibody (mAb) 9E10, which recognizes a continuous decapeptide epi- tope of denatured human c-myc protein. After four to five rounds of panning, most of the eluted clones could bind to 9E10. Sequence analysis of the selected positive clones indicated that the binding sequences could fall into two classes, one class (clone 1) shares a consensus motif, ISE x x L, with c-myc decapeptide; and the sequences of the other class are entirely different. The binding of both classes to 9E10 could be specifically inhibited by free c-myc decapeptide. The immunogenicity of the phage peptide was further investigated by construction of multivalent displayed phage peptides and immunization of animals with or without adjuvant. ELISA and competitive ELISA showed that anti-serum from both mice and rabbit immunized with either clone could bind to the original antigen, c-myc decapeptide. These results denote that in spite of the dissimilarity of the selected peptides with c-myc decapeptide, they are capable of inducing similar immune respones in vivo, thus actually mimicking the antigen epitope.

Screening and Identification of a Targeting Peptide to nGLP-1R from Phage Display Peptide Library

In order to provide the structure information for designing new exendin-4 analogues, a phage display peptide library was screened by targeting the N-terminal extracellular domain of GLP-1R（nGLP-1R）. After four rounds of selection, nine sequences were obtained, four of them have higher affinity for nGLP-1R than the others. We chose two of them named X and Y peptides. Islet β-cell proliferation assay suggested that X and Y peptides didn＇t have any activity to increase islet β-cell proliferation. In other words, X and Y peptides were not agonists to GLP-1R. However, the conservative motifs of X and Y peptides provided us useful information to design new exendin-4 analogues.

Identification and Characterization of Peptides Binding AgEG1 from a Phage Display Library

Endoglucanases are the main cellulolytic enzymes digestion as well as its good kinetic properties make it an attractive of Anoplophora glabripennis. Their high activities in cellulose target for development of cellulase inhibitors. In this study, random pepfide phage display technology was employed to identify peptides that bound the AgEG1, a member of endoglucanase isozymes. Phage clones with peptide LPPNPTK and XPP （X is residue T, L, A or H） motif frequently occurred in the selected phage population and showed a higher phage recovery than other clones. Peptide LPPNPTK was chemically synthesized and characterized tor its binding activities to AgEG1. The synthetic peptide exhibited high specificity for AgEG1. The peptide LPPNPTK has the potential to be developed into inhibitors of the endoglucanase of A. glabripennis.

Selection of the specific coalescent peptide of human CD59 by phage display techniques

To screen and identify the short peptides with specific binding activity to human CD59 and to design the short-peptide clamp against tumor escape, the phage display peptide library containing 12 peptides was used to select the highly expressed specific coalescent peptide of human CD59 in CHO cells. Positive phage clones obtained after 5 rounds of biopanning and detected with ELISA were obtained, in which 8 of them with high binding activity to human CD59 were sequenced. The 3 sequences thus obtained showed high homology with each and certain homology with sequence with human CD2 （PubMed 339HGAAENSLSPSS）, and all contained primary structure , of which this sequence may be the mimic confonnational epitope binding to human CD59. These results in the present study may be helpful to design the short-peptide clamp against the active sites of CD59 on tumor escape.

Transforming growth factor-β1 phage model peptides isolated from a phage display 7-mer peptide library can inhibit the activity of keloid fibroblasts

Background Transforming growth factor-β1 （TGF-β1） is known to have a role in keloid formation through the activation of fibroblasts and the acceleration of collagen deposition. The objective of this current study was to isolate TGF-β1 phage model peptides from a phage display 7-mer peptide library to evaluate their therapeutic effect on inhibiting the activity of keloid fibroblasts.Methods A phage display 7-mer peptide library was screened using monoclonal anti-human TGF-β1 as the target to obtain specific phages containing ectogenous model peptides similar to TGF-β1. Enzyme-linked immunosorbent assay （ELISA） was performed to select monoclonal phages with good binding activity, which underwent DNA sequencing. MTT assay and apoptosis assessment were used to evaluate the biological effects of the phage model peptides on keloid fibroblasts. Immunofluorescence assay was employed to show the binding affinity of the model peptides on phages causing keloid fibroblasts. Quantitative real-time PCR analysis was carried out to detect the expressions of nuclear factor κB （NF-κB） mRNA, connective tissue growth factor （CTGF） mRNA and TGF-β receptor Ⅱ （TβRII） mRNA in keloid fibroblasts.Results Specific phages with good results of ELISA were beneficiated. Four phage model peptides were obtained. The data of MTT showed that TGF-β1 and one phage model peptide （No. 4） could promote keloid fibroblasts proliferation,however, three phage model peptides （No. 1-3） could inhibit keloid fibroblasts proliferation. The results of apoptosis assessment showed that the three phage model peptides could slightly induce the apoptosis in keloid fibroblasts. The data of immunofluorescence assay revealed that the model peptides on phages rather than phages could bind to keloid fibroblasts. The findings of quantitative real-time PCR analysis suggested that the expressions of NF-κB mRNA and CTGF mRNA in the three phage model peptide groups decreased, while the expression of TβRII mRNA slightly increased.Conclusions Three phage model peptides isolated from a phage display 7-mer peptide library can inhibit keloid fibroblasts proliferation and induce the apoptosis in keloid fibroblasts. They can inhibit the activity of keloid fibroblasts by blocking TGF-β1 binding to its receptor and then regulating the expressions of NF-κB, CTGF and TβRII.

An overview on application of phage display technique in immunological studies

Phage display is very strong technique in drug discovery and development. Phage display has many applications in improving the immunological studies. Development of monoclonal antibody, peptides, peptidomimetics and epitope mapping are main application of phage display. Selection of monoclonal antibody or peptides that are displayed on the surface of the phages can be occurred through biopanning process. In biopanning process phage library is incubated with antigen and particular phages can be identified and isolated. Increasing the stringency in the biopanning rounds can be help to select phages with high affinity and specificity. Here, we describe an overview of phage display application with focusing on monoclonal antibody production and epitope mapping.

Phage display: development of nanocarriers for targeted drug delivery to the brain

The blood brain barrier represents a formidable obstacle for the transport of most systemati- cally administered neurodiagnostics and neurotherapeutics to the brain. Phage display is a high throughput screening strategy that can be used for the construction of nanomaterial peptide libraries. These libraries can be screened for finding brain targeting peptide ligands. Surface functionalization of a variety of nanocarriers with these brain homing peptides is a sophisticated way to develop nanobiotechnology-based drug delivery platforms that are able to cross the blood brain barrier. These efficient drug delivery systems raise our hopes for the diagnosis and treatment of various brain disorders in the future.

Application of phage display technology in targeted therapy of breast cancer

Phage display is a technology of gene expression and screening, it is widely used in the fields of defining antigen epitopes, signal transduction, genetic treatment, parasites research and tumor targeted therapy. Breast cancer is the most common cancer in women, we can obtain peptides specially associated with breast cancer by using phage display technology, and this method has great potential in early diagnosis of breast cancer and development new targeted drugs.

Construction of a Multipurpose M13KE Phage Display System

In this study, a multipurpose M13KE phage display vector was constructed from wild-type M13KE phage for long peptide or protein display libraries without helper phage to expand the scope of targeted high-throughput screening. Based on the relationship between the structure and function of minor coat protein of wild-type MI3KE （wt-plII）, a truncated gene III （tglll） encoding minor coat protein from M13KE phage was cloned. A fusion gene fragment harboring a hw/tac promoter, signal peptide and C-terminal region sequence of gill was assembled with SOEing-PCR （splice-overlapping-extension polymerase chain reaction） method and inserted into M13KE vector. SDS-PAGE and Western blot analysis with anti-M13 pIII moneclonal antibody were employed to detect the expression of re- combinant protein, c-Myc and HA tag sequences were fused into the recombinant protein. The results showed that tglll was inserted into an unessential region of M13KE. According to the results of SDS-PAGE and Western blot with anti-M13 pIII antibody, pIII was expressed by wt-gIII and tgIII, glII harboring two tags ex- pressed both c-Myc and HA peptides using SDS-PAGE and Western blot with the corresponding monoclonal antibodies. In this study, a multipurpose M13KE phage display system was successfully constructed, which could express both short and long peptide libraries without helper phage. In future, the obtained M13KE phage display system may be used for targeted high-throughput screening of long peptide libraries without helper phage.

Selection of trkB-binding peptides from a phage-displayed random peptide library

Brain-derived neurotrophic factor (BDNF) shows potential in the treatment of neurode-generative diseases, but the therapeutic application of BDNF has been greatly limited because it is too large in molecular size to permeate blood-brain barrier. To develop low-molecular-weight BDNF-like peptides, we selected a phage-displayed random peptide library using trkB expressed on NIH 3T3 cells as target in the study. With the strategy of peptide library incubation with NIH 3T3 cells and competitive elution with 1 mg/mL of BDNF in the last round of selection, the specific phages able to bind to the natural conformation of trkB and antagonize BDNF binding to trkB were enriched effectively. Five trkB-binding peptides were obtained, in which a core sequence of CRA/TXfXXfXXC (X represents the random amino acids, f represents T, L or I) was identified. The BDNF-like activity of these five peptides displayed on phages was not observed, though all of them antagonized the activity of BDNF in a dose-dependent manner. Similar results were obtained with the synthetic peptide of C1 clone, indicating that the 5 phage-derived peptides were trkB antagonists. These low-molecular-weight antagonists of trkB may be of potential application in the treatment of neuroblastoma and chronic pain. Meanwhile, the obtained core sequence also could be used as the base to construct the secondary phage-displayed peptide library for further devel-opment of small peptides mimicking BDNF activity.

Screening of Peptide Inhibitors of TACE from a Phage Display Random 15-Peptide Library by Recombinant TACE Ectodomain

Tumor necrosis factor(TNF)-α-converting enzyme(TACE)is the major protease responsible for processing pro-TNF-αfrom membrane-anchored precursors to secreted TNF-α.In the present study,a 15-peptide library was used to identify potential TACE antagonists.To obtain the recombinant TACE ectodomain and to use it as a selective molecule for the screening of peptide inhibitors of TACE,cDNA coding for the catalytic domain(T800)and full-length ectodomain(T1300)of TACE were amplified by reverse transcription–polymerase chain reaction.The expression plasmid were constructed by inserting T800/T1300 into plasmid pET-28a/c respectively and were transformed into Escherichia coli BL21(DE3).Sodium dodecyl sulfate–polyacrylamide gel electrophoresis(SDSPAGE)andWestern blot analysis revealed that T800/T1300 were highly expressed in the form of an inclusion body induced by isopropylthiogalactoside.After Ni2+–NTA resin affinity chromatography,the purity of the recombinant T800/T1300 protein was more than 90%.T800 and T1300 proteins were used in the screening of T800/T1300-binding peptides from a phage display random 15-peptide library.After four rounds of biopanning,the positive phage clones were analyzed by enzyme-linked immunosorbent assay,competitive inhibition assay(ELESA),and DNA sequencing.A common amino acid sequence(TRWLVYFS RPYLVAT)was confirmed and synthesized.A synthetic peptide was shown to bind to TACE and to inhibit TNF-αrelease from lipopolysaccharide(LPS)-stimulated human peripheral blood mononuclear cells(PBMC)by up to 60.3%.Fluorescence-activated cell sorter(FACS)analysis revealed that the peptide mediated the accumulation of TNF-αon an LPS-stimulated PBMC surface.These results demonstrate that the TACE-binding peptide is an effective antagonist of TACE and that the deduced motif might be applied to the molecular design of anti-inflammatory drugs.

应用噬菌体随机12肽库筛选TβR Ⅱ特异性序列

目的从噬菌体随机12肽库中筛选TGF-β1Ⅱ型受体(TGF-beta receptorⅡ,TβRⅡ)的特异性序列,评估其对瘢痕疙瘩成纤维细胞的作用。方法以人TGF-β1单克隆抗体为靶,在噬菌体随机12肽库中进行4轮生物筛选;应用ELISA法挑选结合活性较好的单克隆噬菌体,进行DNA序列分析;MTT法评估TGF-β1单克隆噬菌体对瘢痕疙瘩成纤维细胞的生物学效应。结果测序共获得5种类似于TβRⅡ的特异性序列。MTT结果显示其中有3种噬菌体模拟肽能够抑制瘢痕疙瘩成纤维细胞增殖。结论具有TβRⅡ特异性序列的噬菌体模拟肽能够抑制瘢痕疙瘩成纤维细胞增殖。

A resistin binding peptide selected by phage display inhibits 3T3-L1 preadipocyte differentiation

Background Resistin, a newly discovered cysteine-rich hormone secreted mainly by adipose tissues, has been proposed to form a biochemical link between obesity and type 2 diabetes. However, the resistin receptor has not yet been identified. This study aimed to identify resistin binding proteins/receptor. Methods Three cDNA fragments with the same 11 bp 5＇ sequence were found by screening a cDNA phage display library of rat multiple tissues. As the reading frames of the same 11 bp 5＇ sequence were interrupted by a TGA stop codon, plaque lift assay was consequently used to prove the readthrough phenomenon. The stop codon in the same 11 bp 5＇ sequence was replaced by tryptophan, and the binding activity of the coded peptide [AWIL, which was designated as resistin binding peptide （RBP）] with resistin was identified by the confocal microscopy technique and the affinity chromatography experiment, pDual GC-resistin and pDual GC-resistin binding peptide were co-transfected into 3T3-L1 cells to confirm the function of resistin binding peptide. Results Three cDNA fragments with the same 11 bp 5＇ sequence were found. The TGA stop codon in reading frames of the same 11 bp 5＇ sequence was proved to be readthroughed. The binding activity of RBP with resistin was consequently identified. The expression of the resistin binding peptide in 3T3-L1 preadipocytes expressing pDual G-C-resistin significantly inhibited the adipogenic differentiation. Conclusion RBP could effectively rescue the promoted differentiation of resistin overxepressed 3T3-L1 preadipocyte.

Keratinocyte growth factor phage model peptides can promote epidermal cell proliferation without tumorigenic effect

Background Keratinocyte growth factor （KGF） significantly influences epithelial wound healing. The aim of this study was to isolate KGF phage model peptides from a phage display 7-mer peptide library to evaluate their effect on promoting epidermal cell proliferation. Methods A phage display 7-mer peptide library was screened using monoclonal anti-human KGF antibody as the target. Enzyme linked immunosorbent assay （ELISA） was performed to select monoclonal phages with good binding activity. DNA sequencing was done to find the similarities of model peptides. Three-（4,5-dimethylthiazol-2-yl） -2,5-diphenyl tetrazolium bromide （MTT） assay, immunofluorescence assay and quantitative real-time PCR analysis were employed to evaluate the effect of the phage model peptides on epidermal cells. Results Thirty-three out of fifty-eight （56.9%） of the isolated monoclonal phages exhibited high binding activity by ELISA. Ten of fifteen obtained phage model peptides were similar to KGF or epidermal growth factor （EGF）. MTT assay data showed that four （No. 1-4） of the ten phage model peptides could promote epidermal cell proliferation. The expression of keratinocyte growth factor receptor （KGFR） mRNA in the KGF control group and the two phage model peptide groups （No. 1 and No. 2） increased. Expression of c-Fos mRNA and c-Jun mRNA in the KGF control group increased, but did not increase in the four phage model peptide groups （No.1-4）. Conclusion Four phage model peptides isolated from the phage display 7-mer peptide library can safely promote epidermal cell proliferation without tumorigenic effect.

噬菌体随机十二肽库淘选三水白虎汤作用于类风湿关节炎滑膜细胞的靶点研究

目的:利用噬菌体随机十二肽库淘选出与三水白虎汤(SSBH)作用的类风湿关节炎滑膜成纤维细胞(RASFs)特异性结合的多肽,寻找SSBH治疗类风湿关节炎的蛋白靶点。方法:以SSBH处理过的RASFs为靶细胞,生理盐水(NS)处理的RASFs为吸附细胞,全细胞差减筛选法对噬菌体十二肽库进行3轮淘选,挑取单克隆、扩增纯化噬菌体,并初步鉴定噬菌体克隆的亲和力,阳性克隆测序后进行生物学分析。结果:3轮淘选后,随机挑选32个噬菌体克隆进行DNA序列分析,展示SGVYKVAYDWQH十二肽的噬菌体被富集约为56%(18/32)。结论:从噬菌体肽库筛选到SSBH作用RASFs的特异性结合短肽,并分析出相关作用蛋白。

幽门螺杆菌基因克隆表达及其抗原表位分析

目的克隆表达幽门螺杆菌基因hp0410,构建12肽噬菌体展示库,对hp0410的抗原表位进行筛选和分析,为构建多表位嵌合疫苗提供理论依据。方法从幽门螺杆菌NCTC11639基因组DNA中扩增出hp0410,并克隆入pGEX-4T-1中表达。利用纯化重组蛋白筛选出特异性单抗E018,利用该单抗和M13噬菌体12肽随机肽库,构建HP0410抗原表位的抗原展示库。竞争-抑制实验验证获得的阳性噬菌体并测序,生物信息学分析HP0410的抗原表位。结果成功构建可高水平分泌型表达HP0410的原核表达系统。对13株阳性噬菌体测序后获得8个表位,其中候选表位1个。HP0410可有效抑制展示该表位的噬菌体与单抗E018结合。分析表明,获得的8个表位与HP0410同源性不高,但处于生物信息学预测的区域。结论获得8个HP0410高抗原性区域的模拟表位,其中1个为模拟单抗E018特异性结合的抗原决定基的候选表位。

噬菌体肽库筛选转化生长因子βⅡ型受体亲和肽

目的:从噬菌体随机肽库中筛选转化生长因子β(TGF-β)Ⅱ型受体的亲和短肽。方法:以重组可溶性人TGF-βⅡ型受体作为靶标,应用噬菌体随机十二肽库进行筛选,经过3轮淘选,提取阳性噬菌体克隆ssDNA,测序并进行序列分析。结果:通过筛选噬菌体获得富集,挑选10个能与人TGF-βⅡ型受体特异性结合的噬菌体克隆,测序得到4个核酸序列,未发现共有保守序列。结论:通过噬菌体肽库技术能筛选出与TGF-βⅡ型受体结合的噬菌体展示肽,为进一步研究TGF-βⅡ型受体亲和短肽及在抗肝纤维化中的作用提供依据。

基于抗原表位预测的MUC1模拟肽表位筛选

目的:预测粘蛋白1(Mucin1,MUC1)抗原的B细胞表位,从噬菌体随机多肽文库筛选及鉴定MUC1抗原的模拟表位。方法:对MUC1的二级结构及免疫原性进行分析,预测MUC1的抗原表位。利用纯化获得的Ma695抗体筛选噬菌体随机12肽库,夹心ELISA分析噬菌体克隆,测定阳性克隆DNA序列,竞争性抑制实验鉴定阳性噬菌体克隆。结果:MUC1存在有17个潜在的抗原表位区域。经3轮筛选,获得了14个阳性克隆,DNA序列分析并推导出其氨基酸序列:KHYDPFHHRMPQ,QADTARSVALAG,VPSKPDLHVRSI及MTPIHYWNHNRV;4个噬菌体展示肽克隆抑制率均在50%以上。结论:预测MUC1抗原B细胞表位,为进一步研究MUC1结构和功能奠定了基础。所得序列KHYDPFHHRMPQ,QADTARSVALAG,VPSKPDLHVRSI及MTPIHYWNHNRV能模拟MUC1抗原表位。