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Structure and function of a lectin-like protein of macrophage cell membrane that recognizes oxidized cells

识别氧化细胞的巨噬细胞膜凝集素样蛋白的结构和功能

基本信息

批准号：
11672187
负责人：
BEPPU Masatoshi
金额：
$ 2.3万
依托单位：
Tokyo University of Pharmacy and Life Science
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11672187/
关键词：
macrophage lectin oxidative stress apoptosis carbohydrate recognition cell recognition host defense CD43 細胞接着

项目摘要

We have carried out studies on the molecular mechanism of macrophage recognition of oxidized cells in the following aspects. 1) Elucidation of structure and function of 50 kDa lectin-like protein which we had isolated previously as a candidate for a receptor molecule of macrophage surface, and 2) elucidation of the mechanism of appearance of the carbohydrate ligands for the recognition on the oxidized cells. Furthermore, in the course of the above studies, we have found that this recognition mechanism works not only in the recognition of oxidized cells but also of the cells dying by apotosis. The findings are as follows.1. A candidate protein for the receptor molecule was cloned from human cell cDNA library by PCR, based on the partial amino acid sequence of isolated p50. Identification of the protein coded by the cloned cDNA as the oxidized-cell recognizing protein is now in progress.2. Presence of p50 on macrophage surface was confirmed microscopically by immunofluorescence usig the antibody against the partial amino acid sequence of p50. In addition, macrophage recognition of oxidized cells was inhibited by the antibody, comfirming p50 as a receptor for the oxidized cells.3. It was found that T cells at an early apoptotic stage were recognized by macrophages through the same mechanism, involving sialyl polylactosaminyl chains on the cell surface, as the recognition of oxidized cells. Interestingly, this carbohydrate-dependent recognition mechanism worked earlier than phosphatidylserine-recognizing mechanism.4. The carbohydrate chains recognized were found to be those of CD43 glycoprotein of the cell membrane. Moreover, CD43 of oxidized cells or early apoptotic cells were found to undergo clustering. This finding substantiated our hypothesis that clustering of membrane glycoproteins of oxidized or apoptotic cells would generate carbohydrate ligands for the cell recognition.

我们从以下几个方面对巨噬细胞识别氧化细胞的分子机制进行了研究。1)阐明了我们以前分离的作为巨噬细胞表面受体分子候选物的50 kDa凝集素样蛋白的结构和功能; 2）阐明了在氧化细胞上识别的碳水化合物配体的出现机制。此外，在上述研究的过程中，我们发现这种识别机制不仅在氧化细胞的识别中起作用，而且在因凋亡而死亡的细胞的识别中也起作用。研究结果如下：1.根据分离的p50的部分氨基酸序列，通过PCR从人细胞cDNA文库中克隆了受体分子的候选蛋白。目前正在鉴定克隆的cDNA编码的蛋白质为氧化细胞识别蛋白.用抗p50部分氨基酸序列的抗体通过免疫荧光显微镜证实巨噬细胞表面p50的存在。此外，该抗体抑制了巨噬细胞对氧化细胞的识别，证实p50是氧化细胞的受体.发现处于早期凋亡阶段的T细胞通过与氧化细胞的识别相同的机制被巨噬细胞识别，所述机制涉及细胞表面上的唾液酸聚乳糖胺链。有趣的是，这种碳水化合物依赖的识别机制比磷脂酰丝氨酸识别机制更早起作用.发现识别的糖链是细胞膜的CD 43糖蛋白的糖链。此外，发现氧化细胞或早期凋亡细胞的CD 43经历聚集。这一发现证实了我们的假设，即氧化或凋亡细胞的膜糖蛋白的聚集将产生用于细胞识别的糖配体。