GSK3-mediated raptor phosphorylation supports amino-acid-dependent mTORC1-directed signalling.
GSK3-mediated raptor phosphorylation supports amino-acid-dependent mTORC1-directed signalling.
复制标题
GSK3介导的Raptor磷酸化支持氨基酸依赖性MTORC1定向信号传导。
DOI：
10.1042/bj20150404
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发表时间：
2015-09-01
期刊：
影响因子：
--
通讯作者：
Hundal HS
中科院分区：
文献类型：
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作者：
Stretton C;Hoffmann TM;Munson MJ;Prescott A;Taylor PM;Ganley IG;Hundal HS
糖原合成酶激酶-3（GSK 3）介导Raptor在Ser 859上的磷酸化，其关键地支持响应于氨基酸可用性的雷帕霉素（mTOR）复合物1（mTORC 1）信号传导的机械靶标的激活。GSK 3抑制与mTORC 1信号传导减少有关，其对细胞生长、蛋白质合成产生负面影响并促进细胞自噬。雷帕霉素（mTOR）复合物1（mTORC 1）的哺乳动物或机械靶标是普遍表达的多聚体蛋白激酶复合物，其整合营养和生长因子信号以协调调节细胞代谢和细胞生长。在此，我们证明，抑制糖原合成酶激酶-3（GSK 3）的细胞活性，通过使用药理学抑制剂或shRNA介导的基因沉默，导致氨基酸（AA）调节的mTORC 1介导的信号转导大幅减少，通过多个下游mTORC 1靶点的磷酸化评估。我们表明，GSK 3通过其磷酸化Ser 859上的mTOR相关支架蛋白raptor（mTOR的调节相关蛋白）的能力来调节mTORC 1活性。我们进一步证明，GSK 3抑制或S859 A突变raptor的表达导致mTOR和raptor之间的相互作用减少，并且在这些情况下，不管AA的可用性如何，mTOR底物如p70 S6 K1的磷酸化都随之丧失（核糖体S6激酶1）和非协调-51样激酶（ULK 1），其导致增加的自噬通量和减少的细胞增殖。
Glycogen synthase kinase-3 (GSK3) mediates phosphorylation of raptor on Ser859, which crucially supports activation of mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) signalling in response to amino acid availability. GSK3 inhibition is associated with reduced mTORC1 signalling that impacts negatively on cell growth, protein synthesis and promotes cellular autophagy. The mammalian or mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) is a ubiquitously expressed multimeric protein kinase complex that integrates nutrient and growth factor signals for the co-ordinated regulation of cellular metabolism and cell growth. Herein, we demonstrate that suppressing the cellular activity of glycogen synthase kinase-3 (GSK3), by use of pharmacological inhibitors or shRNA-mediated gene silencing, results in substantial reduction in amino acid (AA)-regulated mTORC1-directed signalling, as assessed by phosphorylation of multiple downstream mTORC1 targets. We show that GSK3 regulates mTORC1 activity through its ability to phosphorylate the mTOR-associated scaffold protein raptor (regulatory-associated protein of mTOR) on Ser859. We further demonstrate that either GSK3 inhibition or expression of a S859A mutated raptor leads to reduced interaction between mTOR and raptor and under these circumstances, irrespective of AA availability, there is a consequential loss in phosphorylation of mTOR substrates, such as p70S6K1 (ribosomal S6 kinase 1) and uncoordinated-51-like kinase (ULK1), which results in increased autophagic flux and reduced cellular proliferation.