Specificity of TRAF3 in its negative regulation of the noncanonical NF-κB pathway
Specificity of TRAF3 in its negative regulation of the noncanonical NF-κB pathway
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DOI：
10.1074/jbc.m610271200
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发表时间：
2007-02-09
影响因子：
4.8
通讯作者：
Cheng, Genhong
中科院分区：
文献类型：
--
作者：
He, Jeannie Q.;Saha, Supriya K.;Cheng, Genhong
肿瘤坏死因子受体相关因子(TRAF)是肿瘤坏死因子受体和白介素1受体/Toll样受体超家族中许多受体下游的重要信号转导因子。TRAF2、5和6是典型的核因子-kappa B信号通路的激活剂，而TRAF3是非典型的核因子-kappaB途径的抑制因子。TRAF中不同结构域对各自功能的贡献尚不清楚。为了阐明TRAF3的结构和功能的特殊性，我们用一系列TRAF3突变体重组了TRAF3缺陷细胞，并通过检测核因子-kappa B诱导激酶(NIK)蛋白水平和P100到p52的处理来评估它们恢复TRAF3介导的非规范核转录因子-kappa B途径抑制的能力。我们发现，TRAF3的结构完整的环指结构域是抑制非规范的NF-kappa B途径所必需的。此外，高度同源的TRAF5的三个N-末端结构域，而不是C-末端的TRAF结构域，可以在功能上取代TRAF3的相应结构域，从而抑制非规范的NF-kappa B途径。这种功能特异性与TRAF3，而不是TRAF5与先前报道的NIK中TRAF3结合基序的特异性结合有关。我们的研究表明，TRAF结构域的活性和TRAF结构域与Nik的特异性结合是TRAF3抑制Nik蛋白水平和加工P100到P52的两个关键成分。
Tumor necrosis factor (TNF) receptor-associated factors (TRAFs) are critical signaling adaptors downstream of many receptors in the TNF receptor and interleukin-1 receptor/Toll-like receptor superfamilies. Whereas TRAF2, 5, and 6 are activators of the canonical NF-kappa B signaling pathway, TRAF3 is an inhibitor of the noncanonical NF-kappa B pathway. The contribution of the different domains in TRAFs to their respective functions remains unclear. To elucidate the structural and functional specificities of TRAF3, we reconstituted TRAF3-deficient cells with a series of TRAF3 mutants and assessed their abilities to restore TRAF3-mediated inhibition of the noncanonical NF-kappa B pathway as measured by NF-kappa B-inducing kinase (NIK) protein levels and processing of p100 to p52. We found that a structurally intact RING finger domain of TRAF3 is required for inhibition of the noncanonical NF-kappa B pathway. In addition, the three N-terminal domains, but not the C-terminal TRAF domain, of the highly homologous TRAF5 can functionally replace the corresponding domains of TRAF3 in suppression of the noncanonical NF-kappa B pathway. This functional specificity correlates with the specific binding of TRAF3, but not TRAF5, to the previously reported TRAF3 binding motif in NIK. Our studies suggest that both the RING finger domain activity and the specific binding of the TRAF domain to NIK are two critical components of TRAF3 suppression of NIK protein levels and the processing of p100 to p52.