通过指数富集的配体系统进化技术筛选针对小鼠GP2的适体。

Selection of an aptamer against mouse GP2 by SELEX.

作者信息

Hanazato Misaho, Nakato Gaku, Nishikawa Fumiko, Hase Koji, Nishikawa Satoshi, Ohno Hiroshi

机构信息

Laboratory for Intestinal Ecosystem, RCAI, RIKEN Center for Integrative Medical Sciences (IMS-RCAI).

出版信息

Cell Struct Funct. 2014;39(1):23-9. doi: 10.1247/csf.13019. Epub 2013 Dec 12.

Abstract

Microfold (M) cells are intestinal epithelial cells specialized for sampling and transport of luminal antigens to gut-associated lymphoid tissue for initiation of both mucosal and systemic immune responses. Therefore, M-cell targeted vaccination has the potential to be a better immunization strategy. Glycoprotein 2 (GP2), an antigen uptake receptor for FimH(+) bacteria on M cells, can be a good target for this purpose. Aptamers are oligonucleotides that bind to a variety of target molecules with high specificity and affinity. Together with its low toxic feature, aptamers serves as a tool of molecular-targeted delivery. In this study, we used Systematic Evolution of Ligands by EXponential enrichment (SELEX) to isolate aptamers specific to murine GP2 (mGP2). After ten rounds of SELEX, eleven different aptamer sequences were selected. Among them, the most frequently appeared sequence (60%) were aptamer NO. 1 (Apt1), and the second most (7%) were aptamer NO. 5 (Apt5). In vitro binding experiment confirmed that only Apt1 and Apt5 specifically bound to mGP2 among eleven aptamers initially selected. Apt1 showed the strongest affinity with mGP2, with the Kd value of 110±2.6 nM evaluated by BIACORE. Binding assays with mutants of Apt1 suggest that, in addition to the loop structure, the nucleotide sequence, AAAUA, in the loop is important for binding to mGP2. Furthermore, this aptamer was able to bind to mGP2 expressed on the cell surface. These results suggest that this mGP2-specific aptamer could serve as a valuable tool for testing M-cell-targeted vaccine delivery in the murine model system.

摘要

微褶(M)细胞是肠道上皮细胞,专门用于摄取管腔内抗原并将其转运至肠道相关淋巴组织,以启动黏膜免疫反应和全身免疫反应。因此,靶向M细胞的疫苗接种有可能成为一种更好的免疫策略。糖蛋白2(GP2)是M细胞上FimH(+)细菌的抗原摄取受体,可成为实现这一目的的良好靶点。适体是能以高特异性和亲和力与多种靶分子结合的寡核苷酸。因其低毒性特点,适体可作为分子靶向递送工具。在本研究中,我们利用指数富集配体系统进化技术(SELEX)筛选出小鼠GP2(mGP2)特异性适体。经过十轮SELEX,共筛选出11种不同的适体序列。其中,出现频率最高的序列(约60%)是适体1号(Apt1),其次是适体5号(Apt5)(约7%)。体外结合实验证实,在最初筛选出的11种适体中,只有Apt1和Apt5能特异性结合mGP2。Apt1与mGP2的亲和力最强,通过生物传感器(BIACORE)评估其解离常数(Kd)值为110±2.6 nM。对Apt1突变体的结合试验表明,除环结构外,环内的核苷酸序列AAAUA对与mGP2的结合也很重要。此外,该适体能够结合细胞表面表达的mGP2。这些结果表明,这种mGP2特异性适体可作为在小鼠模型系统中测试靶向M细胞疫苗递送的有价值工具。

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