The receptor for heat shock protein 60 on macrophages is saturable, specific, and distinct from receptors for other heat shock proteins
The receptor for heat shock protein 60 on macrophages is saturable, specific, and distinct from receptors for other heat shock proteins
复制标题
DOI：
10.4049/jimmunol.168.2.569
复制
发表时间：
2002-01-15
影响因子：
4.4
通讯作者：
Burkart, V
中科院分区：
文献类型：
--
作者：
Habich, C;Baumgart, K;Burkart, V
先前的研究表明，人热休克蛋白 (hsp) 60 在先天免疫系统细胞中引发强烈的促炎反应，CD14、Toll 样受体 (TLR) 2 和 TLR4 作为信号传导介质，但可能不是结合介质。在本研究中，我们直接证明了 hsp60 与巨噬细胞表面的结合，并发现 hsp60 的结合受体不同于先前描述的几种其他热休克蛋白（包括 hsp70、hsp90 和 gp96）的常见受体。荧光标记的人 hsp60 与鼠巨噬细胞系 J774 A.1 和 RAW264.7 的细胞表面以及小鼠骨髓来源的巨噬细胞结合。通过流式细胞术，我们首次证明hsp60与巨噬细胞的结合发生在亚微摩尔浓度，是可饱和的，并且可以被未标记的hsp60竞争，但不能被不相关的蛋白质竞争，从而证实了特定配体-受体相互作用的经典特征。 hsp60 在 4℃ 下结合，然后在 37℃ 下进行内吞作用。 Hsp60 与巨噬细胞的结合不能被过量的 hsp70、hsp90 或 gp96 竞争，所有这些都共享 α(2)-巨球蛋白受体作为结合位点。 Hsp60 结合发生在表面 TLR4 不存在的情况下。然而，在 TLR4 缺陷的巨噬细胞中，hsp60 没有诱导细胞因子反应。我们得出结论，hsp60 与巨噬细胞上的立体特异性受体结合，并且不同的表面分子参与结合和信号转导。此外，hsp60 的结合位点与 hsp70、hsp90 和 gp96 的常见受体分开，这表明 hsp60 作为危险 Ag 和免疫调节的独立作用。
Previous studies have shown that human heat shock protein (hsp) 60 elicits a strong proinflammatory response in cells of the innate immune system with CD14, Toll-like receptor (TLR) 2, and TLR4 as mediators of signaling, but probably not of binding. In the present study, we directly demonstrate binding of hsp60 to the macrophage surface and find the binding receptor for hsp60 different from the previously described common receptor for several other heat shock proteins, including hsp70, hsp90, and gp96. Fluorescence-labeled human hsp60 bound to cell surfaces of the murine macrophage lines J774 A.1 and RAW264.7 and to mouse bone marrow-derived macrophages. By flow cytometry, we could demonstrate for the first time that hsp60 binding to macrophages occurred at submicromolar concentrations, is saturable, and can be competed by unlabeled hsp60, but not by unrelated proteins, thus confirming the classic characteristics of specific ligand-receptor interactions. Binding of hsp60 at 4degreesC was followed by endocytosis at 37degreesC. Hsp60 binding to macrophages could not be competed by excess hsp70, hsp90, or gp96, all of which share the alpha(2)-macroglobulin receptor as binding site. Hsp60 binding occurred in the absence of surface TLR4. However, no cytokine response was induced by hsp60 in TLR4-deficient macrophages. We conclude that hsp60 binds to a stereo-specific receptor on macrophages, and that different surface molecules are engaged in binding and signal transduction. Furthermore, the binding site for hsp60 is separate from the common receptor for hsp70, hsp90, and gp96, which suggests an independent role of hsp60 as danger Ag and in immunoregulation.