Calcineurin-mediated YB-1 Dephosphorylation Regulates CCL5 Expression during Monocyte Differentiation
Calcineurin-mediated YB-1 Dephosphorylation Regulates CCL5 Expression during Monocyte Differentiation
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DOI：
10.1074/jbc.m114.562991
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发表时间：
2014-08-01
影响因子：
4.8
通讯作者：
Raffetseder, Ute
中科院分区：
文献类型：
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作者：
Alidousty, Christina;Rauen, Thomas;Raffetseder, Ute
Y-box（YB）蛋白-1是基因转录和mRNA翻译的主要调节因子。YB-1本身在各个层面上受到调控，例如。G.通过翻译后修饰。在我们以前的工作中，我们确定了RANTES/CCL 5作为YB-1的转录靶点。我们以前证明，YB-1蛋白是瞬时上调单核细胞/巨噬细胞分化过程中证明单核细胞（THP-1细胞），使用佛波醇肉豆蔻酸酯醋酸酯（PMA）分化。在这里，我们提供了证据表明，PMA处理后THP-1细胞以及分化的原代人单核细胞中的YB-1磷酸化，特别是其丝氨酸残基102（Ser-102）的磷酸化在早期增加。这个过程是通过Akt信号通路介导的。Ser-102-磷酸化的YB-1在CCL 5基因启动子处表现出更强的结合亲和力和反式激活能力。值得注意的是，Ser-102-磷酸化的YB-1在单核细胞/巨噬细胞分化过程的后期阶段消失。我们证明，丝氨酸-苏氨酸磷酸酶钙调磷酸酶（CN）去磷酸化YB-1阻止它结合和反式激活的CCL 5启动子。免疫共沉淀试验证明了YB-1/CN的直接相互作用。此外，对用CN抑制剂环孢菌素A处理的小鼠的肾组织的分析揭示了CN对YB-1磷酸化状态的体内影响。我们的结论是，YB-1磷酸化的Ser-102是一个重要的先决条件，在巨噬细胞分化过程中CCL 5启动子激活。我们的研究结果表明，YB-1在炎症过程的解决中起着关键作用，这可能主要是由于CN介导的去磷酸化。
Y-box (YB) protein-1 serves as a master regulator in gene transcription and mRNA translation. YB-1 itself is regulated at various levels, e. g. through post-translational modifications. In our previous work, we identified RANTES/CCL5 as a transcriptional target of YB-1. We previously demonstrated that YB-1 protein is transiently up-regulated during monocyte/macrophage differentiation evidenced in monocytic cells (THP-1 cells) that were differentiated using phorbol myristate acetate (PMA). Here we provide evidence that YB-1 phosphorylation, specifically at its serine residue 102 (Ser-102), increases early on in THP-1 cells following PMA treatment as well as in differentiated primary human monocytes. This process is mediated through the Akt signaling pathway. Ser-102-phosphorylated YB-1 displays stronger binding affinity and trans-activating capacity at the CCL5 gene promoter. Notably, Ser-102-phosphorylated YB-1 disappears at later stages of the monocyte/macrophage differentiation process. We demonstrate that serine-threonine phosphatase calcineurin (CN) dephosphorylates YB-1 preventing it from binding to and trans-activating the CCL5 promoter. Co-immunoprecipitation assays prove a direct YB-1/CN interaction. Furthermore, analyses in kidney tissues from mice that were treated with the CN inhibitor cyclosporine A revealed an in vivo effect of CN on the YB-1 phosphorylation status. We conclude that YB-1 phosphorylation at Ser-102 is an important prerequisite for CCL5 promoter activation during macrophage differentiation. Our findings point to a critical role of YB-1 in the resolution of inflammatory processes which may largely be due to CN-mediated dephosphorylation.