Phosphatase activity of small C-terminal domain phosphatase 1 (SCP1) controls the stability of the key neuronal regulator RE1-silencing transcription factor (REST)
Phosphatase activity of small C-terminal domain phosphatase 1 (SCP1) controls the stability of the key neuronal regulator RE1-silencing transcription factor (REST)
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小 C 端结构域磷酸酶 1 (SCP1) 的磷酸酶活性控制关键神经元调节器 RE1 沉默转录因子 (REST) 的稳定性
DOI：
10.1074/jbc.ra118.004722
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发表时间：
2018-10-26
影响因子：
4.8
通讯作者：
Zhang, Yan Jessie
中科院分区：
文献类型：
--
作者：
Burkholder, Nathaniel Tate;Mayfield, Joshua E.;Zhang, Yan Jessie
RE1沉默转录因子(REST)是组装神经元基因沉默复合体的主要支架蛋白，通过调节周围的染色质结构来抑制基因转录。REST抑制干细胞和非神经细胞中神经基因的表达，但在神经细胞中表达最低，以确保神经元的正常发育。静息功能失调与几种癌症和神经系统疾病有关。调节REST基因沉默是具有挑战性的，因为细胞和发育差异会影响其活性。因此，我们考虑了通过其调节蛋白来调节REST活性的可能性。人小C-末端结构域磷酸酶1(SCP1)调节作为REST降解检查点的位点上REST的磷酸化状态。利用动力学分析和X射线结晶学的直接可视化，我们发现SCP1对两个降解的REST亚磷酸盐进行去磷酸化，并对磷酸丝氨酸861(pSer-861)有明显的偏好。此外，我们发现SCP1稳定了REST蛋白水平，从而维持了REST在HEK293细胞中的基因沉默功能。综上所述，我们的发现有力地表明，REST是体内SCP1的真实底物，SCP1磷酸酶活性保护REST免受降解。这些观察表明，通过其调节蛋白SCP1靶向REST可以调节其活性并改变这一重要发育途径中的信号转导。
The RE1-silencing transcription factor (REST) is the major scaffold protein for assembly of neuronal gene silencing complexes that suppress gene transcription through regulating the surrounding chromatin structure. REST represses neuronal gene expression in stem cells and non-neuronal cells, but it is minimally expressed in neuronal cells to ensure proper neuronal development. Dysregulation of REST function has been implicated in several cancers and neurological diseases. Modulating REST gene silencing is challenging because cellular and developmental differences can affect its activity. We therefore considered the possibility of modulating REST activity through its regulatory proteins. The human small C-terminal domain phosphatase 1 (SCP1) regulates the phosphorylation state of REST at sites that function as REST degradation checkpoints. Using kinetic analysis and direct visualization with X-ray crystallography, we show that SCP1 dephosphorylates two degron phosphosites of REST with a clear preference for phosphoserine 861 (pSer-861). Furthermore, we show that SCP1 stabilizes REST protein levels, which sustains REST's gene silencing function in HEK293 cells. In summary, our findings strongly suggest that REST is a bona fide substrate for SCP1 in vivo and that SCP1 phosphatase activity protects REST against degradation. These observations indicate that targeting REST via its regulatory protein SCP1 can modulate its activity and alter signaling in this essential developmental pathway.