Department of Integrative Medical Biology, Section for Histology and Cell Biology, Umeå University, Umeå, Sweden.
Transfus Med Hemother. 2012 Oct;39(5):315-20. doi: 10.1159/000342537. Epub 2012 Sep 17.
The ubiquitously expressed cell surface glycoprotein CD47 is expressed by virtually all cells in the host, where it can function to regulate integrin-mediated responses, or constitute an important part of the erythrocyte band 3/Rh multi-protein complex. In addition, CD47 can protect viable cells from being phagocytosed by macrophages or dendritic cells. The latter mechanism is dependent on the interaction between target cell CD47 and SIRPα on the phagocyte. In this context, SIRPα functions to inhibit prophagocytic signaling from Fcγ receptors, complement receptors, and LDL receptor-related protein-1 (LRP-1), but not scavenger receptors. The expression level and/or distribution of CD47 may be altered on the surface of apoptotic/senescent cells, rendering the phagocytosis inhibitory function of the CD47/SIRPα interaction reduced or eliminated. Instead, the interaction between these 2 proteins may serve to enhance the binding of apoptotic/senescent target cells to the phagocyte to promote phagocytosis.
CD47 是一种广泛表达的细胞表面糖蛋白，几乎存在于宿主的所有细胞中，它可以调节整合素介导的反应，或者构成红细胞带 3/Rh 多蛋白复合物的重要部分。此外，CD47 可以保护存活细胞不被巨噬细胞或树突状细胞吞噬。后一种机制依赖于靶细胞 CD47 与吞噬细胞上 SIRPα 的相互作用。在这种情况下，SIRPα 的功能是抑制 Fcγ 受体、补体受体和 LDL 受体相关蛋白-1（LRP-1）的吞噬前信号，但不抑制清道夫受体。凋亡/衰老细胞表面的 CD47 的表达水平和/或分布可能会改变，从而降低或消除 CD47/SIRPα 相互作用的吞噬抑制功能。相反，这两种蛋白之间的相互作用可能有助于增强凋亡/衰老靶细胞与吞噬细胞的结合，从而促进吞噬作用。
