Externalization and recognition by macrophages of large subunit of eukaryotic translation initiation factor 3 in apoptotic cells.
Externalization and recognition by macrophages of large subunit of eukaryotic translation initiation factor 3 in apoptotic cells.
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DOI：
10.1016/j.yexcr.2005.05.006
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发表时间：
2005-09
影响因子：
3.7
通讯作者：
Y. Nakai;A. Shiratsuchi;J. Manaka;H. Nakayama;K. Takio;Jian-Ting Zhang;T. Suganuma;Y. Nakanishi
中科院分区：
文献类型：
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作者：
Y. Nakai;A. Shiratsuchi;J. Manaka;H. Nakayama;K. Takio;Jian-Ting Zhang;T. Suganuma;Y. Nakanishi
我们之前分离了一种名为PH2的单克隆抗体，可以抑制巨噬细胞对磷脂酰丝氨酸介导的凋亡细胞的吞噬作用[C]。藤井，A. Shiratsuchi， J. Manaka， S. Yonehara， Y. Nakanishi。细胞死亡杂志[j]。我们在此报告同源抗原的鉴定。Western blotting鉴定了一个与PH2结合的蛋白为真核翻译起始因子3 （eIF3 p170/eIF3a）的170 kda亚基。当eIF3a在培养细胞系中作为蛋白与绿色荧光蛋白融合表达时，只有在诱导凋亡后才能在细胞表面检测到融合蛋白。用抗eIF3a抗体测定内源性eIF3a的定位时也发现了同样的现象，eIF3a似乎在细胞凋亡过程中被部分降解。此外，细菌表达的n端一半eIF3a融合到结合在巨噬细胞表面的谷胱甘肽s -转移酶中，并在加入吞噬反应时抑制巨噬细胞对凋亡细胞的吞噬。这些结果共同表明，eIF3a在细胞凋亡时可能经过部分降解后易位到细胞表面，并架起凋亡细胞和巨噬细胞的桥梁，增强吞噬作用。
We previously isolated a monoclonal antibody named PH2 that inhibits phosphatidylserine-mediated phagocytosis of apoptotic cells by macrophages [C. Fujii, A. Shiratsuchi, J. Manaka, S. Yonehara, Y. Nakanishi. Cell Death Differ. 8 (2001) 1113–1122]. We report here the identification of the cognate antigen. A protein bound by PH2 in Western blotting was identified as the 170-kDa subunit of eukaryotic translation initiation factor 3 (eIF3 p170/eIF3a). When eIF3a was expressed in a culture cell line as a protein fused to green fluorescence protein, the fusion protein was detected at the cell surface only after the induction of apoptosis. The same phenomenon was seen when the localization of endogenous eIF3a was determined using anti-eIF3a antibody, and eIF3a seemed to be partially degraded during apoptosis. Furthermore, bacterially expressed N-terminal half of eIF3a fused to glutathione S-transferase bound to the surface of macrophages and inhibited phagocytosis of apoptotic cells by macrophages when it was added to phagocytosis reactions. These results collectively suggest that eIF3a translocates to the cell surface upon apoptosis, probably after partial degradation, and bridges apoptotic cells and macrophages to enhance phagocytosis.