Stearylated antimicrobial peptide [D]-K6L9 with cell penetrating property for efficient gene transfer

Stearyl-cell penetrating peptides (CPPs) have been proved to be efficient nonviral gene vectors. Due to the similarities between antimicrobial peptides and CPPs, we constructed a novel type of gene vectors by introducing stearyl moiety to the N-terminus of antimicrobial peptide [D]-K6L9. In this study, stearyl-[D]-K6L9 delivered plasmids into cells by clathrin- and caveolin-mediated endocytosis. Gratifyingly, stearyl-[D]-K6L9 exhibited high transfection efficiency and almost reached the level of Lipofectamine 2000. Taken together, the combination of the stearyl moiety with [D]-K6L9 provides a novel framework for the development of excellent nonviral gene vectors.     

Diaminopropionic acid lipopeptides: Characterization studies of polyplexes aimed at pDNA delivery

Here we report a novel class of peptides-d-diaminopropionic acids (Dap)-for gene delivery. These peptides have attractive properties for gene delivery, and the advantage that they can be easily manipulated in relation to their composition, abiding with tailored-design. We characterized the toxicological and biophysical properties of DNA particles resulting from the interaction of the nucleic acid with a series of Dap(8) peptides conjugated to different alkyl groups. These peptides formed small and homogenous DNA particle populations that protected against DNase I degradation at non-toxic concentrations. However, despite the similarity between these peptides and others that are arginine-rich, and efficient vectors, functional studies suggest the need for additional modifications in the carriers to improve their DNA delivery efficiency. Taken together, these studies underscore the relevance of the overall structure of the carrier and the complexity of designing from scratch a carrier.     

Analysis and Optimization of the Cationic Lipid Component of a Lipid/Peptide Vector Formulation for Enhanced Transfection In Vitro and In Vivo

We have previously described a lipopolyplex formulation comprising a mixture of a cationic peptide with an integrin-targeting motif (K₁₆GACRRETAWACG) and Lipofectin^®, a liposome consisting of DOTMA and DOPE in a 1:1 ratio. The high transfection efficiency of the mixture involved a synergistic interaction between the lipid/peptide components. The aim of this study was to substitute the lipid component of the lipopolyplex to optimize transfection further and to seek information on the structure-activity relationship of the lipids in the lipopolyplex. Symmetrical cationic lipids with diether linkages that varied in alkyl chain length were formulated into liposomes and then incorporated into a lipopolyplex by mixing with an integrin-targeting peptide and plasmid DNA. Luciferase transfections were performed of airway epithelial cells and fibroblasts in vitro and murine lung airways in vivo. The biophysical properties of lipid structures and liposome formulations and their potential effects on bilayer membrane fluidity were determined by differential scanning calorimetry and calcein-release assays. Shortening the alkyl tail from C18 to C16 or C14 enhanced lipopolyplex and lipoplex transfection in vitro but with differing effects. The addition of DOPE enhanced transfection when formulated into liposomes with saturated lipids but was more variable in its effects with unsaturated lipids. A substantial improvement in transfection efficacy was seen in murine lung transfection with unsaturated lipids with 16 carbon alkyl tails. The optimal liposome components of lipopolyplex and lipoplex vary and represent a likely compromise between their differing structural and functional requirements for complex formation and endosomal membrane destabilization.     

一种新型酿酒酵母附加型分泌表达载体的构建

用化学法合成克鲁维酵母的菊粉酶基因的信号肽序列(INU),将其嵌入酵母附加型表达质粒pYES2,得到一套新型的分泌表达载体pYES2I,pYES2Ⅱ,pYES2Ⅲ。然后用PCR方法分别扩增大肠杆菌的天冬酰胺酶基因(ASN)和短芽孢杆菌α乙酰乳酸脱羧酶(ALDC)基因,连接到INU下游,得到重组质粒pASN和pALDC。分别将这两个重组质粒转化酿酒酵母菌株INVScⅠ中表达,胞内和胞外的酶活分析表明ASN和ALDC基因都能在酿酒酵母中分泌表达,表明菊粉酶信号肽序列能很好地将酿酒酵母中的重组蛋白分泌到胞外。稳定性分析表明,重组酵母菌株在没有选择压力的条件下连续接种培养100h,未发现重组质粒的不稳定性。     

肝细胞特异性基因治疗载体的构建及活性研究

以细胞膜穿透肽 (Penetratin)基因为主要模板序列 ,融合肝细胞膜受体结合蛋白的DNA序列 ,设计一段肝细胞基因治疗载体的特异基因序列 ,构建并表达了肝细胞特异性载体体系及 3种对照体系。然后进行肝细胞的穿膜实验 ,细胞荧光显色结果提示肝细胞特异性载体体系可以有效地介导外源蛋白EGFP的基因进入肝细胞 ,并在肝细胞内表达。结论提示 ,所构建的载体体系有可能为肝细胞基因治疗提供一种新型的非病毒基因治疗载体。     

细胞穿透肽在肿瘤治疗中的应用

随着人类对基因组信息解读的不断深入,越来越多的生物大分子作为候选药物进入生物治疗领域。但细胞表面的脂质双层膜具有选择通透性,这种天然屏障作用在保护细胞的同时也限制了绝大多数生物大分子进入细胞内部发挥治疗效应。目前流行的入胞转运方式如电穿孔、脂质体转染等均存在对细胞的额外毒副作用,且作用范围局限于体外实验。细胞穿透肽是一类以非受体依赖方式,非经典内吞方式直接穿过细胞膜进入细胞的多肽。它们可以与多种生物活性物质连接并携带其进入细胞,这一特性为它们成为理想的药物载体提供了可能。本文对使用细胞穿透肽作为载体转运具有抗癌作用的生物大分子进入细胞的抗癌实验予以介绍。     

猪防御素PD基因表达载体的构建

目的：构建猪防御素PD基因表达载体。方法：化学合成经过适当改造的带有双酶切位点的PD基因,将该基因定向插入带有相同酶切位点的融合表达质粒PinPoin^TMXa-3的多克隆位点构建表达质粒。结果：构建的表达载体经双酶切电泳分析及插入基因片段序列分析,表明PD基因表达载体构建成功。结论：PD基因表达载体的构建,为进一步获得PD基因的表达产物,研究其抗菌活性、抗菌机理打下基础。     

甘蓝型油菜线粒体功能未知基因 ORF 117的载体构建与转化

本研究克隆了甘蓝型油菜线粒体功能未知基因 ORF 117,构建了带有线粒体转运信号肽序列（TP ）的植物过表达载体35S ∷TP-ORF117、35S ∷TP-EGFP 和35S ∷TP-ORF117-EGFP ,转化野生型拟南芥并进行抗除草剂筛选,共获得纯合的转基因拟南芥株系62个。qPCR 表明,ORF 117在转基因材料中得到高效过表达。用转35S ∷TP-EGFP 、35S ∷TP-ORF117-EGFP 拟南芥制备原生质体,经线粒体特异染料染色,在激光共聚焦显微镜下做线粒体、GFP 共定位检测,GFP 蛋白和 ORF117-EGFP 融合蛋白被准确定位到了线粒体。     

Isolation of targeted AAV2 vectors from novel virus display libraries

Random peptide ligands displayed on viral capsids are emerging tools for selection of targeted gene transfer vectors even without prior knowledge of the potential target cell receptor. We have previously introduced adeno-associated viral (AAV)-displayed peptide libraries that ensure encoding of displayed peptides by the packaged AAV genome. A major limitation of these libraries is their contamination with wild-type (wt) AAV. Here we describe a novel and improved library production system that reliably avoids generation of wt AAV by use of a synthetic cap gene. Selection of targeted AAV vectors from wt-containing and the novel wt-free libraries on cell types with different permissivity for wt AAV2 replication suggested the superiority of the wt-free library. However, from both libraries highly specific peptide sequence motifs were selected which improved transduction of cells with moderate or low permissivity for AAV2 replication. Strong reduction of HeLa cell transduction compared to wt AAV2 and only low level transduction of non-target cells by some selected clones showed that not only the efficiency but also the specificity of gene transfer was improved. In conclusion, our study validates and improves the unique potential of virus display libraries for the development of targeted gene transfer vectors.     

PBOND： Web Server for the Prediction of Proline and Non-Proline cis / trans Isomerization

PBOND is a web server that predicts the conformation of the peptide bond between any two amino acids. PBOND classifies the peptide bonds into one out of four classes, namely cis imide (cis-Pro), cis amide (cis-nonPro), trans imide (trans-Pro) and trans amide (trans-nonPro). Moreover, for every prediction a reliability index is computed. The underlying structure of the server consists of three stages: (1) feature extraction, (2) feature selection and (3) peptide bond clas- sification. PBOND can handle both s...     

A versatile system for the expression of nonmodified bacteriocins in Escherichia coli

AIMS: To develop a method and plasmid vectors suitable for expression of class II bacteriocins from Escherichia coli. METHODS AND RESULTS: The expression vector pSuV1 was constructed by inserting the PelB secretion signal coding sequence and a number of restriction endonuclease sites for cloning, into pTYB1. Codon optimized genes encoding the active mature region of each bacteriocin were constructed and inserted into pSuV1. Transfer of these constructs to a host expressing T7 RNA polymerase allowed for expression of secreted mature or fusion forms of the bacteriocins. Generation of the fusion, to the adjacent intein-chitin-binding domain gene, was achieved by removal of a small intervening BseRI fragment. The bacteriocins BacR1, divercin V41, enterocin P, pediocin PA-1 and piscicolin 126 were expressed from this system. For piscicolin 126, expression levels of 200 microg l(-1) in the mature form and 1100 microg l(-1) when cleaved from the fusion partner were achieved. All expressed bacteriocins displayed antimicrobial activity. CONCLUSIONS: Several class II bacteriocins have been expressed in E. coli using purpose designed plasmid vectors described here. SIGNIFICANCE AND IMPACT OF THE STUDY: This method provides a common expression system capable of producing a range of different class II bacteriocins. It allows researchers to study class II bacteriocins without access to the original producer strain, the native bacteriocin gene, or highly specific heterologous producing strains. Resulting expression levels are as high or higher than those previously reported for related bacteriocins.     

PEX慢病毒载体构建及其在293FT细胞中的分泌表达

目的 构建含人MMP-9信号肽-MMP-2-PEX片段的重组慢病毒,并在293FT细胞中分泌表达PEX蛋白.方法 利用RT-PCR、基因重组等技术,构建含MMP-9信号肽-MMP-2-PEX片段的重组慢病毒表达载体pBPLV-signal-PEX,在脂质体介导下与包装质粒（pLP1、pLP2）、包膜质粒（pLP/VSVG）共转染293FT细胞,包装产生慢病毒并进行滴度测定.慢病毒感染2931;3＂细胞后,Western印迹法检测293FI＂细胞培养上清中PEX的表达.结果 酶切和DNA测序表明慢病毒表达载pBPLV-signal-PEX构建正确,四质粒共转染293FT细胞成功获得慢病毒;慢病毒感染293FT细胞后,在细胞培养卜清中可检测到PEX蛋白的表达.结论 成功构建了含人PEX的重组慢病毒,在体外有效感染293fT细胞并持续分泌表达目的 蛋白,为进一步研究PEX在肿瘤侵袭与转移中的作用提供实验基础.     

生长激素信号肽可诱导重组蛋白外分泌表达

重组蛋白质的表达是生物医药开发、基因功能和作用机理研究中关键技术环节.虽然细菌表达体系由于表达量大、经济等而被广泛采用,但由于其不能提供许多蛋白质必需的翻译后修饰如糖基化等,所表达的蛋白又多以不可溶包涵体形式存在,变性复性过程复杂,产率低,因此真核细胞表达体系如CHO、COS等成为活性要求高的蛋白质表达的首选[1].     

跨膜蛋白基因克隆载体pMBL的构建及验证

自行设计一对引物,从质粒pUC18上扩增一段无启动子和信号肽的β-内酰胺酶基因(△P△SP Amp),以作为最终构建的载体克隆到带跨膜信号基因片段的报告基因。所设计的上游引物中依次带有分别处于3个不同阅读框架、且形成匹配粘性末端的3个酶切位点BglⅡ、BclI、BamHI,以便最终构建的载体捕获基因时的对位融合和表达。pET-28经BglI、Bst1107I双酶切,去除约2．5kh的lac I等基因的冗余片段,保留Kan抗性基因、复制原点、多克隆位点等结构,并消除BglⅡ位点,获得作为最终构建载体的抗性基因和基本骨架的过渡质粒pKan。△p△SP Amp基因经pGEM-T-EASY载体,克隆到pKan的EcoRI和XbaI间,得到在Kan平板中生长而在Amp和Kan双抗平板中不能生长的转化子pMBL-E质粒;经部分酶切补平自连,筛选得到消除HindⅢ位点端EcoRI位点的质粒,即得到用于跨膜蛋白信号基因片段捕获克隆的目的载体pMBL,大小为3．46kb。经酶切鉴定和测序,证明构建的载体与预期设计的一致。应用四环素抗性基因(Tet)片段对构建的跨膜蛋白基因克隆载体pMBL．的有效性进行了验证,在克隆人EcoRI和BglⅡ双酶切(0位)的载体中,Kan和Amp双抗平板筛选到阳性克隆子,经酶切和测序均显示Tet基因已对位插人,并启动了β-内酰胺酶的表达和跨膜分泌。由此证明：构建的跨膜蛋白克隆载体pMBL能有效捕获含启动子和信号肽序列的跨膜蛋白基因。     

Production of a biologically active human basic fibroblast growth factor using silkworm-baculovirus expression vector system

As a therapeutic treatment, recombinant human basic fibroblast growth factor (rhbFGF) is usually employed in tissue regeneration, and as an essential component in culture medium for maintaining the induced pluripotent stem (iPS) cell and embryonic stem (ES) cell in an undifferentiated state. Therefore, a large amount of biologically active rhbFGF is required. In this study, silkworm-baculovirus expression vector system (silkworm-BEVS) is employed to achieve a high productivity of recombinant rhbFGF with two small affinity tags (His-tag and STREP-tag) at the N or C-terminus. It is observed that rhbFGF with 30?K signal peptide of silkworm were successfully expressed but are not sufficiently secreted into the culture medium of cultured insect cells. Then we purified the N- or C-tagged intracellular rhbFGF protein and obtained a yield of about 0.7?mg/larva and 1.2?mg/larva, respectively. Although the final yield of the C-tagged rhbFGF is higher than that of the N-tagged, rhbFGF with N-tag demonstrated promising and comparable biological activity, which is evaluated through a mammalian cell proliferation assay. Taken together, these results indicate that silkworm-BEVS could contribute to the mass-production of the biologically active rhbFGF for medical uses.     

利用自裂解多肽T2A在牛耳皮肤成纤维细胞中实现多基因共同表达

目的:探讨利用自裂解多肽2A构建的多顺反子载体能否在牛耳皮肤成纤维细胞中实现多基因的有效表达。方法:利用来自一点褐翅蛾病毒(TaV)的2A元件(T2A)将GFP和Neo基因连接到同一载体中,构建pCMV-GFP-T2A-Neo质粒,将其转染牛耳皮肤成纤维细胞,以FACS检测GFP基因的表达,RT-qPCR检测GFP、T2A和Neo的表达。结果:由T2A连接的GFP和Neo基因在mRNA水平上都有显著表达,且表达水平相当。结论:以T2A连接的基因在转入细胞后能正常翻译和表达,显示T2A在牛耳皮肤成纤维细胞中具有自裂解功能,可作为一种构建多顺反子载体的有效工具用于牛耳皮肤成纤维细胞的基因转移,为其将来在转基因牛研制中的应用奠定了基础。