SELEX与适配体在蛋白质研究中的应用

指数富集的配基系统进化(SELEX)是一种从大容量寡核苷酸文库中经反复分离扩增步骤得到针对靶分子的高亲和力高特异性核酸配基—适配体的体外筛选技术。SELEX技术自1990年发展至今,已涌现出多种筛选模式和分离方法。筛选特异结合蛋白质的SELEX技术发展直接影响和指导了适配体在蛋白质功能调控方面的应用。文章综述了多种SELEX技术在筛选蛋白质方面的发展近况,适配体在蛋白质功能研究中的应用,筛选过程中关键性因素的确定及适配体的前后期修饰。     

特异性结合白色念珠菌（1，3）-β-D-葡聚糖单链 DNA 适配子的筛选及其应用

目的：通过指数富集的配基系统进化技术（systematic evolution of ligands by exponential enrichment ,SELEX）筛选能与高亲和力（1,3）‐β‐D‐葡聚糖特异性结合的适配子,并用该适配子建立双适配子夹心酶联寡聚核苷酸吸附试验（enzyme‐linked oligonucleotide assay ,ELONA）来对深部真菌感染血浆进行辅助诊断。方法提取白色念珠菌 ATCC10231株细胞壁（1,3）‐β‐D‐葡聚糖,通过 SELEX 筛选获得能与（1,3）‐β‐D‐葡聚糖特异性结合的高亲和力单链 DNA 适配子,并用该适配子建立双适配子夹心ELONA 来检测深部真菌感染血浆中的（1,3）‐β‐D‐葡聚糖。结果从白色念珠菌细胞壁中成功提取了高聚合度（1,3）‐β‐D‐葡聚糖,并通过体外酶解获得可溶性低聚合度（1,3）‐β‐D‐葡聚糖作为筛选靶标。用SELEX 进行12轮筛选后,从初始单链 DNA 文库中获得2个高亲和力适配子 AU1和 AD1,检测发现它们并非结合于（1,3）‐β‐D‐葡聚糖的同一表位。双适配子夹心 ELONA 检测深部真菌感染血浆中（1,3）‐β‐D‐葡聚糖的特异性和敏感度分别为91．94％和92．31％。结论从初始单链 DNA 文库中成功获得可与（1,3）‐β‐D‐葡聚糖特异结合的高亲和力适配子,为深部真菌感染新型诊断试剂的研发奠定了基础。     

靶向乳腺癌的核酸适配体应用研究进展

乳腺癌是女性最常见的恶性肿瘤,实现乳腺癌的早期诊断和早期治疗意义重大.核酸适配体是经过指数富集配体系统进化技术(systematic evolution of ligands by exponential enrichment, SELEX)筛选得到的寡核苷酸序列,在肿瘤诊断及治疗方面拥有良好的应用前景.本文对靶向乳腺癌的核酸适配体及适配体作为载体和探针在乳腺癌诊疗中的作用进行综述.     

幽门螺杆菌ssDNA适配子的筛选及其应用

目的通过富集的配基系统进化技术(SELEX)筛选出与幽门螺杆菌(HP)菌体具有高亲和性适配子,并且利用其检测组织和活体内HP的感染。方法培养HP细菌,利用SELEX筛选获得HP菌体的适配子。在HP感染患者活检组织验证其结合。结果从第6轮筛选所得ssDNA中筛选出一条高结合力的适配子命名为HP1,将适配子HP1区别于其他筛选出的适配子,并检测其与幽门螺旋杆菌的亲和力。结论初步获得了针对HP菌体筛选出高亲和性适配子,为开发HP诊断试剂奠定了基础。     

新型HER2适配体的筛选及鉴定

目的研发能特异性结合人表皮生长因子受体2(HER2)的DNA适配体,为开发针对HER2的新型肿瘤靶向诊疗技术提供依据。方法体外合成全长86个碱基并含有40个随机寡核苷酸的单链DNA文库,以HER2表位肽为靶标,利用指数富集的配体系统进化技术(SELEX),从单链DNA文库中筛选能够选择性结合HER2多肽的核酸适配体;流式细胞术检测富集进度、适配体与HER2蛋白及HER2阳性细胞的结合特性;MFold软件预测二级结构。结果经多轮筛选获得了能够识别HER2多肽的DNA适配体HA5,其能够选择性地结合HER2蛋白及HER2阳性的乳腺癌细胞,而不结合胰蛋白酶和HER2阴性细胞。结论 DNA适配体HA5能选择性地识别HER2阳性的乳腺癌细胞,在研发针对HER2的新型肿瘤靶向诊疗技术方面具有应用潜能。     

Metastasis‐focused cell‐based SELEX generates aptamers inhibiting cell migration and invasion

Metastasis, the capacity of tumour cells to disseminate and grow at distant sites, is the main factor in cancer mortality. Compounds inhibiting migration and invasion of cancer cells are promising candidates for anticancer therapy strategies. We have generated nuclease‐resistant RNA ligands (aptamers) recognizing highly metastatic cells with high affinity and specificity, and inhibiting their migratory and invasive potentials. Aptamers were generated by a cell‐based subtractive SELEX technology using isogenic cell lines with similar tumorigenic potentials but opposite metastatic aggressiveness. Two aptamers, E37 and E10, bound specifically to the metastatically aggressive cell line and altered the phosphorylation of several tyrosine kinases. Fluorescent microscopy showed intracellular uptake of E37, in contrast to membrane binding of E10. Both aptamers inhibited migration of tumour cells in culture (50 and 85% inhibition with respect to control pool for E10 and E37, respectively) while only E10 inhibited cell invasion (?75% with respect to control pool). This proof‐of‐concept study demonstrates the potential of cell‐based SELEX to yield ligands that selectively recognize aggressive metastatic cells and inhibit phenotypes linked to metastatic potential.     

ATP-Responsive Drug Delivery Systems

The combination of targeted drug delivery and controlled-release technology may pave the road for more effective yet safer chemotherapeutic options for cancer therapy. Drug-encapsulated polymeric nanoparticle–aptamer bioconjugates represent an emerging technology that can facilitate the delivery of chemotherapeutics to primary and metastatic tumours. Aptamers are short nucleic acid molecules with binding properties and biochemical characteristics that may make them suitable for use as targeting molecules. The goal of this review is to summarise the key components that are required for creating effective cancer targeting nanoparticle–aptamer bioconjugates. The field of controlled release and the structure and properties of aptamers, as well as the criteria for constructing effective conjugates, will be discussed.     

B淋巴细胞活化因子特异的单链DNA适体的人工进化

目的: 进化筛选与B淋巴细胞活化因子（B cell activating factor belonging to the TNF family，BAFF）特异结合的单链DNA适体，鉴定其结合力。方法:应用指数方式富集的配体系统进化（systematic evolution of ligands by exponential enrichment, SELEX）技术，将随机序列寡核