HEY1 functions are regulated by its phosphorylation at Ser-68.
HEY1 functions are regulated by its phosphorylation at Ser-68.
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DOI：
10.1042/bsr20160123
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发表时间：
2016-07
影响因子：
4
通讯作者：
Belandia B
中科院分区：
文献类型：
--
作者：
López-Mateo I;Arruabarrena-Aristorena A;Artaza-Irigaray C;López JA;Calvo E;Belandia B
通过对位于bHLH结构域的HEY1的Ser - 68位点进行直接磷酸化，可抑制HEY1依赖的p53肿瘤抑制通路的激活。STK38和STK38L丝氨酸/苏氨酸激酶能够磷酸化HEY1的Ser - 68位点，并可能调节其生物学功能。
HEY1（含YRPW基序1的毛发/分裂增强相关蛋白）是介导Notch信号传导的碱性螺旋 - 环 - 螺旋 - 橙色（bHLH - O）转录抑制因子家族的成员。HEY1通过尚不明确的机制作为肿瘤抑制因子p53的正向调节因子。基质辅助激光解吸电离飞行时间/飞行时间质谱（MALDI - TOF/TOF MS）分析揭示了在Ser - 68位点的一种新的HEY1调节性磷酸化事件。显著的是，这种单一的磷酸化事件控制着HEY1的稳定性和功能：模拟HEY1的Ser - 68磷酸化可增加HEY1蛋白的稳定性，但抑制其增强p53转录活性的能力。与野生型HEY1不同，模拟磷酸化突变体HEY1 - S68D的表达未能诱导p53依赖的细胞周期停滞，且未使U2OS细胞对激活p53的化疗药物敏感。我们已经鉴定出两种相关激酶，STK38（丝氨酸/苏氨酸激酶38）和STK38L（类丝氨酸/苏氨酸激酶38），它们与HEY1相互作用并在Ser - 68位点磷酸化HEY1。在有丝分裂期间，HEY1在Ser - 68位点被磷酸化，并在有丝分裂细胞的中心体中积累，这表明HEY1依赖的信号传导可能与中心体功能整合。此外，HEY1与一部分激活p53的核糖体蛋白相互作用。核糖体应激导致HEY1从核质重新定位到被称为核仁帽的核仁周围结构。HEY1与至少一种核糖体蛋白RPL11发生物理相互作用，并且这两种蛋白在抑制MDM2介导的p53降解方面相互协作，从而对p53转录活性产生协同的正向作用。HEY1自身也直接与MDM2相互作用，并受到MDM2介导的降解。模拟HEY1的Ser - 68磷酸化可阻止其与p53、RPL11和MDM2的相互作用，并在核糖体应激时消除HEY1向核仁帽的迁移。我们的研究结果揭示了Notch信号传导和核仁应激之间相互作用的一种新机制。
HEY1-dependent activation of the p53 tumour suppressor pathway can be inhibited through direct phosphorylation of HEY1 at Ser-68 located in the bHLH domain. STK38 and STK38L serine/threonine kinases can phosphorylate HEY1 Ser-68 and could modulate its biological function. HEY1 (hairy/enhancer-of-split related with YRPW motif 1) is a member of the basic helix–loop–helix-orange (bHLH-O) family of transcription repressors that mediate Notch signalling. HEY1 acts as a positive regulator of the tumour suppressor p53 via still unknown mechanisms. A MALDI-TOF/TOF MS analysis has uncovered a novel HEY1 regulatory phosphorylation event at Ser-68. Strikingly, this single phosphorylation event controls HEY1 stability and function: simulation of HEY1 Ser-68 phosphorylation increases HEY1 protein stability but inhibits its ability to enhance p53 transcriptional activity. Unlike wild-type HEY1, expression of the phosphomimetic mutant HEY1-S68D failed to induce p53-dependent cell cycle arrest and it did not sensitize U2OS cells to p53-activating chemotherapeutic drugs. We have identified two related kinases, STK38 (serine/threonine kinase 38) and STK38L (serine/threonine kinase 38 like), which interact with and phosphorylate HEY1 at Ser-68. HEY1 is phosphorylated at Ser-68 during mitosis and it accumulates in the centrosomes of mitotic cells, suggesting a possible integration of HEY1-dependent signalling in centrosome function. Moreover, HEY1 interacts with a subset of p53-activating ribosomal proteins. Ribosomal stress causes HEY1 relocalization from the nucleoplasm to perinucleolar structures termed nucleolar caps. HEY1 interacts physically with at least one of the ribosomal proteins, RPL11, and both proteins cooperate in the inhibition of MDM2-mediated p53 degradation resulting in a synergistic positive effect on p53 transcriptional activity. HEY1 itself also interacts directly with MDM2 and it is subjected to MDM2-mediated degradation. Simulation of HEY1 Ser-68 phosphorylation prevents its interaction with p53, RPL11 and MDM2 and abolishes HEY1 migration to nucleolar caps upon ribosomal stress. Our findings uncover a novel mechanism for cross-talk between Notch signalling and nucleolar stress.