Chordate PIAS proteins act as conserved repressors of the TRAF6 self-polyubiquitination
Chordate PIAS proteins act as conserved repressors of the TRAF6 self-polyubiquitination
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脊索动物 PIAS 蛋白充当 TRAF6 自身多泛素化的保守阻遏物
DOI：
10.1016/j.dci.2019.103554
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发表时间：
2020-03-01
影响因子：
2.9
通讯作者：
Huang, Shengfeng
中科院分区：
文献类型：
--
作者：
Fu, Xianan;Wang, Ruihua;Huang, Shengfeng
在哺乳动物中，PIAS蛋白是重要的SUMO E3连接酶，并作为60多种不同蛋白质的多功能调节剂，包括nf - κ B途径的成分。但由于其复杂的分子机制和多基因相似物的重叠作用，pas的功能尚未得到很好的理解，特别是在专门研究较少的低等脊椎动物中。文昌鱼作为一种具有单一PIAS基因的基础脊索动物，从进化角度研究PIAS是一种方便的模型。TRAF6是NF-kappa B通路的关键适配器，但目前尚不清楚TRAF6是否受PIAS的调节。本研究发现，在哺乳动物细胞中，文文鱼PIAS通过与TRAF6共定位和结合来抑制NF-kappa B的激活。这种相互作用依赖于PIAS的n端SAP和PINIT结构域。TRAF6是一种E3泛素连接酶，通过促进nf - κ B的自泛素化，启动下游nf - κ B。文文鱼SUMO1和Ubc9 （SUMO E2连接酶）均能抑制TRAF6自身泛素化和NF-kappa B的激活，表明summo1化活性竞争了TRAF6的泛素化活性。然而，我们发现野生型PIAS和没有SUMO E3连接酶活性的突变型PIAS都可以通过减少TRAF6自身泛素化来抑制TRAF6介导的NF-kappa B活化。这表明SUMO连接酶活性不是PIAS负调控TRAF6的唯一机制。最后，我们测试了人类PIAS1-4和TRAF6之间的相互作用。结果表明，人类PIAS1、3和4能够通过降低TRAF6自身泛素化来抑制NF-kappa B的激活，而不是2。综上所述，我们的研究发现了脊索动物PIAS和TRAF6之间保守的调控相互作用。因此，它揭示了PIAS在免疫调节中的复杂作用，并可能有助于了解PIAS在其他低等脊索动物（如无颌和有颌鱼类）中的功能。
In mammals, PIAS proteins are important SUMO E3 ligases and act as versatile regulators of over sixty different proteins, including components from the NF-kappa B pathways. But the PIAS functions are not well-understood due to complicated molecular mechanisms and multiple gene paralogs with overlapping roles, which is especially true in lower vertebrates where dedicated studies are scarce. As a basal chordate with a single PIAS gene, amphioxus is a convenient model to study PIAS from the evolutionary perspective. TRAF6 is a critical adaptor of the NF-kappa B pathways but it is not known whether TRAF6 is regulated by PIAS. Here we discover that in mammalian cells, amphioxus PIAS inhibited NF-kappa B activation by co-localizing and binding with TRAF6. The interaction relied on the N-terminal SAP and PINIT domains of PIAS. TRAF6 is an E3 ubiquitin ligase, which initiates downstream NF-kappa B by promoting its self-ubiquitination. Both amphioxus SUMO1 and Ubc9 (SUMO E2 ligase) could suppress TRAF6 self-ubiquitination and NF-kappa B activation, suggesting that the SUMOylation activity competed away the ubiquitination activity of TRAF6. However, we show that the wild-type PIAS and the mutant PIAS without SUMO E3 ligase activity both could inhibit TRAF6-mediated NF-kappa B activation by reducing TRAF6 self-ubiquitination. This implies that SUMO ligase activity is not the only mechanism for PIAS to negatively regulate TRAF6. Finally, we tested the interactions between human PIAS1-4 and TRAF6. It reveals that human PIAS1, 3 and 4, but not 2, were able to repress NF-kappa B activation by reducing TRAF6 self-ubiquitination. Taken together, our study discovers a conserved regulatory interaction between chordate PIAS and TRAF6. It therefore sheds light on the complicated role of PIAS in immune regulation, and may help to understand the PIAS functions in other lower chordate taxa, such as jawless and jawed fishes.