Ubiquitin-specific Protease 20 Regulates the Reciprocal Functions of β-Arrestin2 in Toll-like Receptor 4-promoted Nuclear Factor κB (NFκB) Activation
Ubiquitin-specific Protease 20 Regulates the Reciprocal Functions of β-Arrestin2 in Toll-like Receptor 4-promoted Nuclear Factor κB (NFκB) Activation
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DOI：
10.1074/jbc.m115.687129
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发表时间：
2016-04-01
影响因子：
4.8
通讯作者：
Shenoy, Sudha K.
中科院分区：
文献类型：
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作者：
Jean-Charles, Pierre-Yves;Zhang, Lisheng;Shenoy, Sudha K.
Toll 样受体 4 (TLR4) 可促进血管炎症性疾病，例如内膜增生和动脉粥样硬化。 TLR4 通过泛素连接酶 TRAF6（肿瘤坏死因子受体相关因子 6）触发 NF kappa B 信号传导。 TRAF6 活性可以通过去泛素化酶（如泛素特异性蛋白酶 20 (USP20)）以及与多功能接头蛋白 β-arrestin2 的结合来阻碍，该酶可以逆转 TRAF6 自身泛素化。虽然 β-arrestin2 对 TRAF6 的影响表明具有抗炎作用，但生理性 β-arrestin2 会促进动脉粥样硬化和新内膜增生中的炎症。我们假设 β-arrestin2 活性的抗炎和促炎作用可能由 β-arrestin2 的泛素化状态决定，这与其将活化的 ERK1/2 支架和定位到信号体的能力有关。在纯化的蛋白质和完整细胞中，我们的蛋白质相互作用研究表明 TRAF6/USP20 关联和随后的 USP20 介导的 TRAF6 去泛素化是 beta-arrestin2 依赖性的。平滑肌细胞特异性表达 USP20 或其催化失活突变体的转基因小鼠的产生揭示了 USP20 体内和体外的抗炎作用。颈动脉内皮剥脱表明，拮抗平滑肌细胞 USP20 活性可增加 NF kappa B 激活和新内膜增生。我们发现 TLR4 促进 β-arrestin2 泛素化，并被 USP20 逆转。当β-arrestin2泛素化被阻止时，USP20与β-arrestin2的关联性增强；当β-arrestin2泛素化呈现组成型时，USP20与β-arrestin2的关联性降低。组成型 β-arrestin2 泛素化也增强了 NF kappa B 的激活。我们推断β-arrestin2的促炎和抗炎活性是由β-arrestin2泛素化决定的，因此USP20表达和/或活性的变化可以通过定义β-arrestin2的泛素化状态至少部分地调节炎症反应。
Toll-like receptor 4 (TLR4) promotes vascular inflammatory disorders such as neointimal hyperplasia and atherosclerosis. TLR4 triggers NF kappa B signaling through the ubiquitin ligase TRAF6 (tumor necrosis factor receptor-associated factor 6). TRAF6 activity can be impeded by deubiquitinating enzymes like ubiquitin-specific protease 20 (USP20), which can reverse TRAF6 autoubiquitination, and by association with the multifunctional adaptor protein beta-arrestin2. Although beta-arrestin2 effects on TRAF6 suggest an anti-inflammatory role, physiologic beta-arrestin2 promotes inflammation in atherosclerosis and neointimal hyperplasia. We hypothesized that anti-and proinflammatory dimensions of beta-arrestin2 activity could be dictated by beta-arrestin2's ubiquitination status, which has been linked with its ability to scaffold and localize activated ERK1/2 to signalosomes. With purified proteins and in intact cells, our protein interaction studies showed that TRAF6/USP20 association and subsequent USP20-mediated TRAF6 deubiquitination were beta-arrestin2-dependent. Generation of transgenic mice with smooth muscle cell-specific expression of either USP20 or its catalytically inactive mutant revealed anti-inflammatory effects of USP20 in vivo and in vitro. Carotid endothelial denudation showed that antagonizing smooth muscle cell USP20 activity increased NF kappa B activation and neointimal hyperplasia. We found that beta-arrestin2 ubiquitination was promoted by TLR4 and reversed by USP20. The association of USP20 with beta-arrestin2 was augmented when beta-arrestin2 ubiquitination was prevented and reduced when beta-arrestin2 ubiquitination was rendered constitutive. Constitutive beta-arrestin2 ubiquitination also augmented NF kappa B activation. We infer that pro-and anti-inflammatory activities of beta-arrestin2 are determined by beta-arrestin2 ubiquitination and that changes in USP20 expression and/or activity can therefore regulate inflammatory responses, at least in part, by defining the ubiquitination status of beta-arrestin2.