Unité de Signalisation Moléculaire et Activation Cellulaire and 2 Laboratoire Trafic Membranaire et Division Cellulaire, Institut Pasteur, Centre National de la Recherche Scientifique URA 2582, Paris 75015, France.
J Cell Biol. 2014 Jan 20;204(2):231-45. doi: 10.1083/jcb.201307172.
Nuclear factor κB (NF-κB) essential modulator (NEMO), a regulatory component of the IκB kinase (IKK) complex, controls NF-κB activation through its interaction with ubiquitin chains. We show here that stimulation with interleukin-1 (IL-1) and TNF induces a rapid and transient recruitment of NEMO into punctate structures that are anchored at the cell periphery. These structures are enriched in activated IKK kinases and ubiquitinated NEMO molecules, which suggests that they serve as organizing centers for the activation of NF-κB. These NEMO-containing structures colocalize with activated TNF receptors but not with activated IL-1 receptors. We investigated the involvement of nondegradative ubiquitination in the formation of these structures, using cells deficient in K63 ubiquitin chains or linear ubiquitin chain assembly complex (LUBAC)-mediated linear ubiquitination. Our results indicate that, unlike TNF, IL-1 requires K63-linked and linear ubiquitin chains to recruit NEMO into higher-order complexes. Thus, different mechanisms are involved in the recruitment of NEMO into supramolecular complexes, which appear to be essential for NF-κB activation.
核因子 κB（NF-κB）必需调节剂（NEMO）是 IκB 激酶（IKK）复合物的调节成分，通过与泛素链的相互作用控制 NF-κB 的激活。我们在这里表明，白细胞介素 1（IL-1）和肿瘤坏死因子（TNF）的刺激诱导 NEMO 迅速和短暂地募集到位于细胞外周的点状结构中。这些结构富含激活的 IKK 激酶和泛素化的 NEMO 分子，这表明它们作为 NF-κB 激活的组织中心。这些含有 NEMO 的结构与激活的 TNF 受体共定位，但与激活的 IL-1 受体不共定位。我们使用缺乏 K63 泛素链或线性泛素链组装复合物（LUBAC）介导的线性泛素化的细胞，研究了非降解泛素化在这些结构形成中的作用。我们的结果表明，与 TNF 不同，IL-1 需要 K63 连接的和线性泛素链来将 NEMO 招募到高级别复合物中。因此，NEMO 被招募到超分子复合物中涉及不同的机制，这对于 NF-κB 激活似乎是必不可少的。
