GRK6 phosphorylates IκBα at Ser32/Ser36 and enhances TNF-α-induced inflammation
GRK6 phosphorylates IκBα at Ser32/Ser36 and enhances TNF-α-induced inflammation
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DOI：
10.1016/j.bbrc.2015.04.027
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发表时间：
2015-05-29
影响因子：
3.1
通讯作者：
Kurose, Hitoshi
中科院分区：
文献类型：
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作者：
Ohba, Yuki;Nakaya, Michio;Kurose, Hitoshi
G蛋白偶联受体激酶（GRKs）包括磷酸化激动剂活化的G蛋白偶联受体（GPCR）的7种丝氨酸/苏氨酸激酶家族。最近有报道GRKs通过细胞内蛋白的磷酸化调节GPCR非依赖性信号传导。迄今为止，已报道了GRK 2和GRK 5的几种细胞内底物。然而，对GRK 6的那些了解甚少。在这里，我们确定了I κ B α，NF-κ B信号的负调节因子，作为GRK 6的底物。GRK 6在Ser（32）/Ser（36）直接磷酸化I κ B α，并且GRK 6的激酶活性是在TNF-α刺激后促进NF-κ B信号传导所必需的。在腹腔巨噬细胞中GRK 6的敲除显著减弱了TNF-α刺激后炎性基因的转录。此外，我们开发了一种生物发光共振能量转移（BRET）探针来监测GRK 6活性。使用这种探针，我们揭示了GRK 6的构象变化是由TNF-α诱导的。总之，我们的研究表明，TNF-α诱导GRK 6活化，GRK 6通过I κ B α的磷酸化促进炎症反应。(C)2015 Elsevier Inc. All rights reserved.
G protein-coupled receptor kinases (GRKs) comprise a family of seven serine/threonine kinases that phosphorylate agonist-activated G protein-coupled receptors (GPCRs). It has recently been reported that GRKs regulate GPCR-independent signaling through the phosphorylation of intracellular proteins. To date, several intracellular substrates for GRK2 and GRK5 have been reported. However, those for GRK6 are poorly understood. Here we identified I kappa B alpha, a negative regulator of NF-kappa B signaling, as a substrate for GRK6. GRK6 directly phosphorylated I kappa B alpha at Ser(32)/Ser(36), and the kinase activity of GRK6 was required for the promotion of NF-kappa B signaling after TNF-alpha stimulation. Knockout of GRK6 in peritoneal macrophages remarkably attenuated the transcription of inflammatory genes after TNF-alpha stimulation. In addition, we developed a bioluminescence resonance energy transfer (BRET) probe to monitor GRK6 activity. Using this probe, we revealed that the conformational change of GRK6 was induced by TNF-alpha. In summary, our study demonstrates that TNF-alpha induces GRK6 activation, and GRK6 promotes inflammatory responses through the phosphorylation of I kappa B alpha. (C) 2015 Elsevier Inc. All rights reserved.