Wong M, Uddin S, Majchrzak B, Huynh T, Proudfoot A E, Platanias L C, Fish E N
Toronto General Research Institute, University Health Network, Toronto and Department of Immunology, University of Toronto, Ontario M5G 2M1, Canada.
J Biol Chem. 2001 Apr 6;276(14):11427-31. doi: 10.1074/jbc.M010750200. Epub 2001 Jan 18.
The chemokine RANTES (regulated on activation normal T cell expressed and secreted) and its cognate receptor CC chemokine receptor 5 (CCR5) have been implicated in regulating immune cell function. Previously we reported that in T cells, RANTES activation of CCR5 results in Stat1 and Stat3 phosphorylation-activation, leading to Stat1:1 and Stat1:3 dimers that exhibit DNA binding activity and the transcriptional induction of a Stat-inducible gene, c-fos. Given that RANTES and CCR5 have been implicated in T cell activation, we have studied RANTES-induced signaling events in a CCR5-expressing T cell line, PM1. RANTES treatment of PM1 T cells results in the rapid phosphorylation-activation of CCR5, Jak2, and Jak3. RANTES-inducible Jak phosphorylation is insensitive to pertussis toxin inhibition, indicating that RANTES-CCR5-mediated tyrosine phosphorylation events are not coupled directly to Galpha(i) protein-mediated events. In addition to Jaks, several other proteins are rapidly phosphorylated on tyrosine residues in a RANTES-dependent manner, including the Src kinase p56(lck), which associates with Jak3. Additionally our data confirm that the amino-terminally modified RANTES proteins, aminooxypentane-RANTES and Met-RANTES, are agonists for CCR5 and induce early tyrosine phosphorylation events that are indistinguishable from those inducible by RANTES with similar kinetics. Our data also demonstrate that RANTES activates the p38 mitogen-activated protein (MAP) kinase pathway. This is evidenced by the rapid RANTES-dependent phosphorylation and activation of p38 MAP kinase as well as the activation of the downstream effector of p38, MAP kinase-activated protein (MAPKAP) kinase-2. Pharmacological inhibition of RANTES-dependent p38 MAP kinase activation blocks MAPKAP kinase-2 activity. Thus, activation of Jak kinases and p38 MAP kinase by RANTES regulates the engagement of multiple signaling pathways.
趋化因子RANTES（活化正常T细胞表达和分泌时上调）及其同源受体CC趋化因子受体5（CCR5）参与调节免疫细胞功能。此前我们报道，在T细胞中，RANTES激活CCR5会导致Stat1和Stat3磷酸化激活，产生具有DNA结合活性的Stat1:1和Stat1:3二聚体以及Stat诱导基因c-fos的转录诱导。鉴于RANTES和CCR5与T细胞活化有关，我们研究了RANTES在表达CCR5的T细胞系PM1中诱导的信号事件。用RANTES处理PM1 T细胞会导致CCR5、Jak2和Jak3迅速磷酸化激活。RANTES诱导的Jak磷酸化对百日咳毒素抑制不敏感，表明RANTES-CCR5介导的酪氨酸磷酸化事件不直接与Gα(i)蛋白介导的事件偶联。除了Jaks，其他几种蛋白质也会以RANTES依赖的方式在酪氨酸残基上迅速磷酸化，包括与Jak3相关的Src激酶p56(lck)。此外，我们的数据证实，氨基末端修饰的RANTES蛋白，氨氧基戊烷-RANTES和Met-RANTES，是CCR5的激动剂，并诱导早期酪氨酸磷酸化事件，其动力学与RANTES诱导的事件相似。我们的数据还表明RANTES激活p38丝裂原活化蛋白（MAP）激酶途径。这表现为RANTES依赖的p38 MAP激酶迅速磷酸化和激活以及p38的下游效应器MAP激酶激活蛋白（MAPKAP）激酶-2的激活。对RANTES依赖的p38 MAP激酶激活的药理学抑制会阻断MAPKAP激酶-2的活性。因此，RANTES对Jak激酶和p38 MAP激酶的激活调节了多个信号通路的参与。
