Metalloprotease NleC suppresses host NF-κB/inflammatory responses by cleaving p65 and interfering with the p65/RPS3 interaction.
Metalloprotease NleC suppresses host NF-κB/inflammatory responses by cleaving p65 and interfering with the p65/RPS3 interaction.
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金属蛋白酶NLEC通过切割P65并干扰P65/RPS3相互作用来抑制宿主NF-κB/炎症反应。
DOI：
10.1371/journal.ppat.1004705
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发表时间：
2015-03
期刊：
影响因子：
6.7
通讯作者：
Wan F
中科院分区：
文献类型：
--
作者：
Hodgson A;Wier EM;Fu K;Sun X;Yu H;Zheng W;Sham HP;Johnson K;Bailey S;Vallance BA;Wan F
附着/去除（A/E）病原体包括肠致病性大肠杆菌（EPEC）、肠出血性大肠杆菌（E.大肠埃希菌（EHEC）和啮齿动物等效的啮齿类柠檬酸杆菌是食源性疾病的重要病原体。在感染后，由A/E病原体编码的无数毒力蛋白（效应物）通过其保守的III型分泌系统（T3 SS）注入宿主细胞，在那里它们干扰细胞信号传导级联，特别是核因子κ B（NF-κB）信号传导通路，该通路协调用于宿主防御的先天性和适应性免疫应答。在T3 SS分泌的非LEE编码（Nle）效应物中，NleC（一种金属蛋白酶）最近被阐明通过切割NF-κB Rel亚基来调节宿主NF-κB信号传导。然而，NleC如何识别NF-κB Rel亚基以及NleC介导的切割如何影响感染细胞和动物中的宿主免疫应答仍然是难以捉摸的。在这项研究中，我们表明NleC通过与p65中独特的N-末端序列相互作用特异性靶向p65/RelA。NleC在肠上皮细胞中切割p65，尽管是小比例的分子，以在C.啮齿类感染培养细胞。此外，NleC介导的p65裂解显著影响编码促炎细胞因子/趋化因子的NF-κB靶基因亚组的表达、结肠中的免疫细胞浸润和C中的组织损伤。感染啮齿类动物的老鼠从机制上讲，NleC切割产生的p651-38片段干扰p65和核糖体蛋白S3（RPS 3）之间的相互作用，RPS 3是NF-κB的一个“指定”亚基，赋予促炎基因转录的一个子集，这放大了仅切割小百分比的p65以调节NF-κ B介导的基因表达的作用。因此，我们的研究结果揭示了一种新的机制，A/E病原体特异性阻断NF-κB信号和炎症反应，通过切割一小部分的p65和靶向宿主细胞中的p65/RPS 3相互作用，从而提供了新的见解食源性疾病的致病机制。核因子κ B（NF-κB）信号通路是宿主防御的关键，因为它协调先天性和适应性免疫应答。除了研究最多的Rel蛋白（p65、RelB、c-Rel、p50和p52）之外，RPS 3最近被鉴定为NF-κB的“特异性”组分，调节NF-κB的启动子选择性和转录特异性。特别是，RPS 3/p65赋予的信号通路最近被证明在宿主促炎转录和免疫应答中发挥关键作用。附着和消除（A/E）病原体和其他病原体已经获得了复杂的机制来调节宿主NF-κB信号通路。我们已经发现，NleC，一种由A/E病原体分泌的金属蛋白酶效应物，通过一种新的机制调节宿主NF-κB信号传导和炎症反应。NleC特异性识别并切割小百分比的p65，并且产生的p65的N末端片段干扰p65/RPS 3相互作用，从而放大仅切割小百分比的p65分子以选择性抑制NF-κB基因表达的效果。我们的研究结果突出了一个以前未被重视的机制，通过该机制，病原体编码的蛋白酶干扰宿主细胞中的信号级联和炎症反应。
Attaching/Effacing (A/E) pathogens including enteropathogenic Escherichia coli (EPEC), enterohemorrhagic E. coli (EHEC) and the rodent equivalent Citrobacter rodentium are important causative agents of foodborne diseases. Upon infection, a myriad of virulence proteins (effectors) encoded by A/E pathogens are injected through their conserved type III secretion systems (T3SS) into host cells where they interfere with cell signaling cascades, in particular the nuclear factor kappaB (NF-κB) signaling pathway that orchestrates both innate and adaptive immune responses for host defense. Among the T3SS-secreted non-LEE-encoded (Nle) effectors, NleC, a metalloprotease, has been recently elucidated to modulate host NF-κB signaling by cleaving NF-κB Rel subunits. However, it remains elusive how NleC recognizes NF-κB Rel subunits and how the NleC-mediated cleavage impacts on host immune responses in infected cells and animals. In this study, we show that NleC specifically targets p65/RelA through an interaction with a unique N-terminal sequence in p65. NleC cleaves p65 in intestinal epithelial cells, albeit a small percentage of the molecule, to generate the p651–38 fragment during C. rodentium infection in cultured cells. Moreover, the NleC-mediated p65 cleavage substantially affects the expression of a subset of NF-κB target genes encoding proinflammatory cytokines/chemokines, immune cell infiltration in the colon, and tissue injury in C. rodentium-infected mice. Mechanistically, the NleC cleavage-generated p651–38 fragment interferes with the interaction between p65 and ribosomal protein S3 (RPS3), a ‘specifier’ subunit of NF-κB that confers a subset of proinflammatory gene transcription, which amplifies the effect of cleaving only a small percentage of p65 to modulate NF-κB-mediated gene expression. Thus, our results reveal a novel mechanism for A/E pathogens to specifically block NF-κB signaling and inflammatory responses by cleaving a small percentage of p65 and targeting the p65/RPS3 interaction in host cells, thus providing novel insights into the pathogenic mechanisms of foodborne diseases. The nuclear factor kappaB (NF-κB) signaling pathway is crucial for host defense, as it orchestrates both innate and adaptive immune responses. Beyond the best-studied Rel proteins (p65, RelB, c-Rel, p50 and p52), RPS3 has been recently identified as a “specifier” component of NF-κB, modulating the promoter selectivity and transcriptional specificity of NF-κB. In particular, the RPS3/p65-conferred signaling pathway was recently shown to play a critical role in host proinflammatory transcription and immune responses. Attaching and effacing (A/E) pathogens and others have acquired sophisticated mechanisms to modulate host NF-κB signaling pathways. We have found that NleC, a metalloprotease effector secreted by A/E pathogens, modulates host NF-κB signaling and inflammatory responses through a novel mechanism. NleC specifically recognizes and cleaves a small percentage of p65 and the generated N-terminal fragment of p65 interferes with the p65/RPS3 interaction, thereby amplifying the effect of cleaving only a small percentage of p65 molecules to selectively inhibit NF-κB gene expression. Our findings highlight a previously unappreciated mechanism through which pathogen-encoded proteases interfere with signaling cascades and inflammatory responses in host cells.
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影响因子：
7
作者：
Deng, Wanyin;Yu, Hong B.;Finlay, B. Brett
通讯作者：
Finlay, B. Brett
影响因子：
6.7
作者：
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作者：
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作者：
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