Rodríguez-Frade J M, Vila-Coro A J, de Ana A M, Albar J P, Martínez-A C, Mellado M
Department of Immunology and Oncology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas/Universidad Autónoma de Madrid, Campus de Cantoblanco, E-28049 Madrid, Spain.
Proc Natl Acad Sci U S A. 1999 Mar 30;96(7):3628-33. doi: 10.1073/pnas.96.7.3628.
Cytokines interact with hematopoietin superfamily receptors and stimulate receptor dimerization. We demonstrate that chemoattractant cytokines (chemokines) also trigger biological responses through receptor dimerization. Functional responses are induced after pairwise crosslinking of chemokine receptors by bivalent agonistic antichemokine receptor mAb, but not by their Fab fragments. Monocyte chemoattractant protein (MCP)-1-triggered receptor dimerization was studied in human embryonic kidney (HEK)-293 cells cotransfected with genes coding for the CCR2b receptor tagged with YSK or Myc sequences. After MCP-1 stimulation, immunoprecipitation with Myc-specific antibodies revealed YSK-tagged receptors in immunoblotting. Receptor dimerization also was validated by chemical crosslinking in both HEK-293 cells and the human monocytic cell line Mono Mac 1. Finally, we constructed a loss-of-function CCR2bY139F mutant that acted as a dominant negative, blocking signaling through the CCR2 wild-type receptor. This study provides functional support for a model in which the MCP-1 receptor is activated by ligand-induced homodimerization, allowing discussion of the similarities between bacterial and leukocyte chemotaxis.
细胞因子与造血因子超家族受体相互作用并刺激受体二聚化。我们证明趋化因子细胞因子（趋化因子）也通过受体二聚化触发生物学反应。通过二价激动性抗趋化因子受体单克隆抗体对趋化因子受体进行成对交联后可诱导功能性反应，但其Fab片段则不能。在用编码带有YSK或Myc序列标签的CCR2b受体的基因共转染的人胚肾（HEK）-293细胞中研究了单核细胞趋化蛋白（MCP）-1触发的受体二聚化。MCP-1刺激后，用Myc特异性抗体进行免疫沉淀，在免疫印迹中显示出带有YSK标签的受体。在HEK-293细胞和人单核细胞系Mono Mac 1中通过化学交联也验证了受体二聚化。最后，我们构建了一个功能丧失的CCR2bY139F突变体，它作为显性负性分子，阻断通过CCR2野生型受体的信号传导。本研究为MCP-1受体通过配体诱导的同源二聚化激活的模型提供了功能支持，从而可以讨论细菌趋化性和白细胞趋化性之间的相似性。
