Identification of optineurin as an interleukin-1 receptor-associated kinase 1-binding protein and its role in regulation of MyD88-dependent signaling
Identification of optineurin as an interleukin-1 receptor-associated kinase 1-binding protein and its role in regulation of MyD88-dependent signaling
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DOI：
10.1074/jbc.m117.813899
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发表时间：
2017-09
期刊：
影响因子：
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通讯作者：
Mitsuyoshi Tanishima;S. Takashima;A. Honda;Daisuke Yasuda;T. Tanikawa;S. Ishii;T. Maruyama
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文献类型：
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作者：
Mitsuyoshi Tanishima;S. Takashima;A. Honda;Daisuke Yasuda;T. Tanikawa;S. Ishii;T. Maruyama
在用各种微生物配体刺激Toll样受体后，通过激活髓样分化初级反应蛋白88（MyD 88）依赖性信号传导途径引起各种炎症基因的诱导。白细胞介素-1（IL-1）受体相关激酶1（IRAK 1）通过激活核因子κB（NF-κB）和丝裂原活化激酶（MAPK）在该通路中起重要作用。在这里，我们确定视神经磷酸酶（OPTN）作为IRAK 1结合蛋白的酵母双杂交筛选使用IRAK 1作为诱饵。OPTN的C-末端片段具有泛素结合结构域，与IRAK 1共免疫沉淀。在报告基因分析中，OPTN过表达抑制IL-1β、IRAK 1和LPS诱导的NF-κB活化。因此，OPTN缺陷导致NF-κB活化增加，响应于IL-1β/LPS刺激。为了阐明OPTN对NF-κB信号转导的抑制作用的潜在机制，我们将重点放在肿瘤坏死因子（TNF）受体相关因子6（TRAF 6）上，TRAF 6是IRAK 1的衔接蛋白，在多聚泛素化后在NF-κB活化过程中起关键作用。OPTN的过表达阻止TRAF 6多聚泛素化。此外，不能募集去泛素化酶CYLD的OPTN H486 R突变体不能抑制IRAK 1诱导的NF-κB活化。这些结果表明，IRAK 1结合蛋白OPTN通过阻止TRAF 6的多聚泛素化来负调节IL-1β/LPS诱导的NF-κB活化。
Upon stimulation of toll-like receptors with various microbial ligands, induction of a variety of inflammatory genes is elicited by activation of a myeloid differentiation primary-response protein 88 (MyD88)-dependent signaling pathway. Interleukin-1 (IL-1) receptor-associated kinase 1 (IRAK1) plays an essential role in this pathway by activating nuclear factor κB (NF-κB) and mitogen-activated kinases (MAPKs). Here, we identified optineurin (OPTN) as an IRAK1-binding protein by yeast two-hybrid screening using IRAK1 as bait. A C-terminal fragment of OPTN harboring a ubiquitin-binding domain was co-immunoprecipitated with IRAK1. In reporter analyses, overexpression of OPTN inhibited IL-1β-, IRAK1-, and LPS-induced NF-κB activation. Consistently, OPTN deficiency resulted in increased NF-κB activation in response to IL-1β/LPS stimulation. To address the mechanisms underlying the inhibitory effect of OPTN on NF-κB signaling, we focused on tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6), which is an adaptor protein of IRAK1 and upon polyubiquitination plays a crucial role during NF-κB activation. Overexpression of OPTN prevented TRAF6 polyubiquitination. Furthermore, OPTN H486R mutant, which is unable to recruit the deubiquitinase CYLD, failed to inhibit IRAK1-induced NF-κB activation. These results suggest that the IRAK1-binding protein OPTN negatively regulates IL-1β/LPS-induced NF-κB activation by preventing polyubiquitination of TRAF6.