TBK1 Limits mTORC1 by Promoting Phosphorylation of Raptor Ser877
TBK1 Limits mTORC1 by Promoting Phosphorylation of Raptor Ser877
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DOI：
10.1038/s41598-019-49707-8
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发表时间：
2019-09-17
影响因子：
4.6
通讯作者：
Hagan, Robert S.
中科院分区：
文献类型：
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作者：
Antonia, Ricardo J.;Castillo, Johnny;Hagan, Robert S.
虽然最广为人知的是其在先天免疫系统中的作用，但现在已知tank结合激酶1 （TBK1）在调节细胞生长和自噬中发挥作用。TBK1完成这一任务的主要方式之一是通过调节雷帕霉素的机制靶标（mTOR），这是一种主调节剂，当激活时促进细胞生长并抑制自噬。然而，TBK1是否促进或抑制mTOR活性高度依赖于细胞类型和环境。为了进一步了解TBK1调节mTOR的机制，我们测试了TBK1磷酸化mTOR复合物1 （mTORC1）的关键成分Raptor的假设。利用激酶测定和质谱联用，我们绘制了体外Raptor上TBK1依赖性磷酸化位点的位置。在体外鉴定的位点中，我们发现TBK1在细胞中促进Raptor Ser877的磷酸化，并对已知诱导TBK1活性的病原体相关分子作出反应。Raptor Ser877磷酸化水平与mTOR活性水平呈负相关。不能在Ser877位点磷酸化的突变型Raptor的表达导致mTORC1活性的增加。我们得出结论，TBK1通过促进Raptor Ser877磷酸化来限制mTORC1的活性。
While best known for its role in the innate immune system, the TANK-binding kinase 1 (TBK1) is now known to play a role in modulating cellular growth and autophagy. One of the major ways that TBK1 accomplishes this task is by modulating the mechanistic Target of Rapamycin (mTOR), a master regulator that when activated promotes cell growth and inhibits autophagy. However, whether TBK1 promotes or inhibits mTOR activity is highly cell type and context dependent. To further understand the mechanism whereby TBK1 regulates mTOR, we tested the hypothesis that TBK1 phosphorylates a key component of the mTOR complex 1 (mTORC1), Raptor. Using kinase assays coupled with mass spectrometry, we mapped the position of the TBK1 dependent phosphorylation sites on Raptor in vitro. Among the sites identified in vitro, we found that TBK1 promotes Raptor Ser877 phosphorylation in cells both basally and in response to pathogen-associated molecules known to induce TBK1 activity. The levels of Raptor Ser877 phosphorylation were inversely correlated with the levels of mTOR activity. Expression of a mutant Raptor that could not be phosphorylated at Ser877 led to an increase in mTORC1 activity. We conclude that TBK1 limits mTORC1 activity by promoting Raptor Ser877 phosphorylation.