Yang Yong-Kang, Yang Chao, Chan Waipan, Wang Zhaoquan, Deibel Katelynn E, Pomerantz Joel L
From the Department of Biological Chemistry and Institute for Cell Engineering, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
From the Department of Biological Chemistry and Institute for Cell Engineering, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
J Biol Chem. 2016 Dec 9;291(50):25921-25936. doi: 10.1074/jbc.M116.754028. Epub 2016 Oct 24.
The activation of NF-κB downstream of T cell receptor (TCR) engagement is a key signaling step required for normal lymphocyte function during the adaptive immune response. During TCR signaling, the adaptor protein Bcl10 is inducibly recruited to the CARD11 scaffold protein as part of a multicomponent complex that induces IκB kinase (IKK) activity and NF-κB activation. Here, we show that a consequence of this recruitment is the TCR-induced conjugation of Bcl10 with linear-linked polyubiquitin chains to generate the signaling intermediate Lin(Ub)-Bcl10, which is required for the association of Bcl10 with the NEMO subunit of the IKK complex. The TCR-induced generation of Lin(Ub)-Bcl10 requires Bcl10 lysines 17, 31, and 63, CARD11, MALT1, and the HOIP subunit of the linear ubiquitin chain assembly complex (LUBAC) but not the HOIP accessory protein SHARPIN. CARD11 promotes signal-induced Lin(Ub)-Bcl10 generation by co-recruiting Bcl10 with HOIP, thereby bringing substrate to enzyme. The CARD11-HOIP interaction is rendered TCR-inducible by the four autoinhibitory repressive elements in the CARD11 inhibitory domain and involves the CARD11 coiled-coil domain and two independent regions of HOIP. Interestingly, oncogenic CARD11 variants associated with diffuse large B cell lymphoma spontaneously induce Lin(Ub)-Bcl10 production to extents that correlate with their abilities to activate NF-κB and with their enhanced abilities to bind HOIP and Bcl10. Our results define molecular determinants that control the production of Lin(Ub)-Bcl10, an important signaling intermediate in TCR and oncogenic CARD11 signaling.
T细胞受体（TCR）激活后，NF-κB的激活是适应性免疫反应中正常淋巴细胞功能所需的关键信号步骤。在TCR信号传导过程中，衔接蛋白Bcl10被诱导募集到CARD11支架蛋白上，形成多组分复合物的一部分，该复合物诱导IκB激酶（IKK）活性和NF-κB激活。在这里，我们表明这种募集的一个结果是TCR诱导Bcl10与线性连接的多聚泛素链结合，生成信号中间体Lin(Ub)-Bcl10，这是Bcl10与IKK复合物的NEMO亚基结合所必需的。TCR诱导的Lin(Ub)-Bcl10生成需要Bcl10的赖氨酸17、31和63、CARD11、MALT1以及线性泛素链组装复合物（LUBAC）的HOIP亚基，但不需要HOIP辅助蛋白SHARPIN。CARD11通过与HOIP共同募集Bcl10来促进信号诱导的Lin(Ub)-Bcl10生成，从而将底物带到酶处。CARD11-HOIP相互作用通过CARD11抑制域中的四个自抑制性阻遏元件而被TCR诱导，并且涉及CARD11卷曲螺旋结构域和HOIP的两个独立区域。有趣的是，与弥漫性大B细胞淋巴瘤相关的致癌性CARD11变体自发诱导Lin(Ub)-Bcl10的产生，其程度与它们激活NF-κB的能力以及它们结合HOIP和Bcl10的增强能力相关。我们的结果定义了控制Lin(Ub)-Bcl10产生的分子决定因素，Lin(Ub)-Bcl10是TCR和致癌性CARD11信号传导中的重要信号中间体。
