Mellado M, Rodríguez-Frade J M, Aragay A, del Real G, Martín A M, Vila-Coro A J, Serrano A, Mayor F, Martínez-A C
Department of Immunology and Oncology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científica-Universidad Autónoma de Madrid, Spain.
J Immunol. 1998 Jul 15;161(2):805-13.
The chemokines are a growing family of low m.w., 70- to 80-residue proinflammatory cytokines that operate by interacting with G protein-coupled receptors. Chemokines are involved in cell migration and in the activation of specific leukocyte subsets. Using the Mono Mac 1 monocytic cell line, we show that monocyte chemotactic protein 1 (MCP-1) triggers activation of the Janus kinase 2 (JAK2)/STAT3 pathway and CCR2 receptor tyrosine phosphorylation. Both Ca2+ mobilization and cell migration are blocked in Mono Mac 1 cells by tyrphostin B42, a specific JAK2 kinase inhibitor. Within seconds of MCP-1 activation, JAK2 phosphorylates CCR2 at the Tyr139 position and promotes JAK2/STAT3 complex association to the receptor. This MCP-1-initiated phosphorylation and association to JAK2 is also observed in CCR2B-transfected HEK293 cells. In contrast, when a CCR2B Tyr139Phe mutant is expressed in HEK293 cells, it is not phosphorylated in tyrosine and triggers neither JAK2/STAT3 activation nor Ca2+ mobilization in response to MCP-1. These results implicate the tyrosine kinase pathway in early chemokine signaling, suggesting a key role for this kinase in later events.
趋化因子是一个不断增加的低分子量家族，由70至80个氨基酸残基组成，是促炎细胞因子，通过与G蛋白偶联受体相互作用发挥作用。趋化因子参与细胞迁移和特定白细胞亚群的激活。利用单核细胞系Mono Mac 1，我们发现单核细胞趋化蛋白1（MCP-1）可触发Janus激酶2（JAK2）/信号转导和转录激活因子3（STAT3）途径的激活以及CCR2受体酪氨酸磷酸化。特异性JAK2激酶抑制剂 tyrphostin B42可阻断Mono Mac 1细胞中的Ca2+动员和细胞迁移。在MCP-1激活后的数秒内，JAK2在Tyr139位点使CCR2磷酸化，并促进JAK2/STAT3复合物与该受体结合。在转染CCR2B的人胚肾293（HEK293）细胞中也观察到这种由MCP-1引发的磷酸化以及与JAK2的结合。相反，当在HEK293细胞中表达CCR2B Tyr139Phe突变体时，它不会发生酪氨酸磷酸化，并且在响应MCP-1时既不会触发JAK2/STAT3激活也不会引发Ca2+动员。这些结果表明酪氨酸激酶途径参与早期趋化因子信号传导，提示该激酶在后续事件中起关键作用。
