Regulation of lipopolysaccharide-induced translation of tumor necrosis factor-alpha by the toll-like receptor 4 adaptor protein TRAM.
Regulation of lipopolysaccharide-induced translation of tumor necrosis factor-alpha by the toll-like receptor 4 adaptor protein TRAM.
复制标题
Toll 样受体 4 接头蛋白 TRAM 对脂多糖诱导的肿瘤坏死因子-α 翻译的调节。
DOI：
10.1159/000324833
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发表时间：
2011
影响因子：
5.3
通讯作者：
Cherayil,BobbyJ
中科院分区：
文献类型：
--
作者：
Wang,Lijian;Trebicka,Estela;Fu,Ying;Waggoner,Lisa;Akira,Shizuo;Fitzgerald,KatherineA;Kagan,JonathanC;Cherayil,BobbyJ
脂多糖（LPS）诱导的肿瘤坏死因子（TNF）-α的产生需要两对衔接子募集到Toll样受体4胞质结构域。一对-Toll-白细胞介素-1受体结构域诱导干扰素-β（TRIF）和TRIF相关衔接分子（TRAM）-对TNF-α表达的贡献尚未充分了解。为了澄清这个问题，我们研究了TRAM敲除的骨髓源性巨噬细胞（BMDM）。LPS刺激的TRAM缺陷型BMDM即使在TNF-α mRNA水平正常的情况下，TNF-α蛋白表达也降低，表明翻译受损。与这一观点一致，在RAW264.7巨噬细胞中敲低TRAM减少了由TNF-α 3′非翻译区控制的报告基因的翻译，而在HEK 293 T细胞中转染TRAM增加了该报告基因的翻译。与TRAM在TNF-α翻译中的作用一致，LPS诱导的MK2（参与该过程的激酶）活化在TRAM缺陷的BMDM中受损。TRIF在HEK 293 T细胞中表达时不增加TNF-α 3′非翻译区报告基因的翻译。然而，缺乏功能性TRIF的BMDM在响应LPS时产生降低水平的TNF-α蛋白，尽管mRNA的量正常。与BMDM不同，LPS刺激的TRAM缺陷型腹腔巨噬细胞显示TNF-α蛋白和mRNA的同等降低。我们的研究结果表明，TRAM和TRIF依赖性信号在调节TNF-α翻译中具有以前未被认识到的细胞类型特异性作用。
Lipopolysaccharide (LPS)-induced production of tumor necrosis factor (TNF)-α requires the recruitment of two pairs of adaptors to the Toll-like receptor 4 cytoplasmic domain. The contribution of one pair – Toll-interleukin-1 receptor domain-containing adaptor inducing interferon-β (TRIF) and TRIF-related adaptor molecule (TRAM) – to TNF-α expression is not well understood. To clarify this issue, we studied TRAM knockout bone marrow-derived macrophages (BMDM). LPS-stimulated TRAM-deficient BMDM had decreased TNF-α protein expression even at times when TNF-α mRNA levels were normal, suggesting impaired translation. Consistent with this idea, knockdown of TRAM in RAW264.7 macrophages decreased translation of a reporter controlled by the TNF-α 3′ untranslated region, while transfection of TRAM in HEK293T cells increased translation of this reporter. Also consistent with a role for TRAM in TNF-α translation, LPS-induced activation of MK2, a kinase involved in this process, was impaired in TRAM-deficient BMDM. TRIF did not increase translation of the TNF-α 3′ untranslated region reporter when expressed in HEK293T cells. However, BMDM that lacked functional TRIF produced reduced levels of TNF-α protein in response to LPS despite normal amounts of the mRNA. Unlike BMDM, LPS-stimulated TRAM-deficient peritoneal macrophages displayed equivalent reductions in TNF-α protein and mRNA. Our results indicate that TRAM- and TRIF-dependent signals have a previously unappreciated, cell type-specific role in regulating TNF-α translation.