Cross-talk between MECP2 post-translational modifications and MECP2 function upon glucocorticoid stress hormone stimulation

甲基CpG结合蛋白2（methyl CpG binding protein 2，MECP 2）是一种重要的表观遗传调节因子，它通过与甲基化DNA结合并募集组蛋白修饰酶，在全基因组水平上控制染色质结构和转录状态。MECP 2对中枢神经系统的正常功能起着至关重要的作用，MECP 2基因的突变与人类严重的神经系统疾病有关（如Rett综合征，女性中第二常见的人类精神发育迟滞疾病）。重要的是，翻译后MECP 2修饰已被确定为该蛋白质调控的关键水平。值得注意的是，MECP 2磷酸化与神经元活性和应激有关。在MECP 2相互作用蛋白的蛋白质组学筛选中，我们发现MECP 2与PARP-1相互作用并被PARP-1聚（ADP-核糖基）化。我们表明，这种修饰调节MECP 2结合和浓缩染色质的能力。在对MECP 2修饰的单独筛选中，我们发现除了其他修饰之外，MECP 2在脑组织中是精氨酸甲基化的。翻译后修饰的类型和不同修饰的MECP 2蛋白的基因组定位是在整个基因组中微调和多样化神经元细胞中MECP 2功能的方法，这是非常有可能的。然而，对特定MECP 2修饰的影响知之甚少。在这个项目中，我们将调查，在一个系统的方式，MECP 2的翻译后修饰，糖皮质激素应激激素刺激后发生，并研究它们在调节染色质结构和海马细胞的基因活性的作用。基于我们的初步结果，我们将集中在聚（ADP-核糖基）化和精氨酸甲基化，并与磷酸化这些。我们的具体目标是：i）表征MECP 2翻译后修饰（PTM）及其在应激激素处理后的变化; ii）分析PTM是否以及如何影响MECP 2蛋白相互作用; iii）测试这些修饰对于MECP 2染色质结合、染色质结构和转录调控的功能相关性; iv）分析PTM如何受疾病突变型MECP 2基因产生的MECP 2蛋白的影响或影响疾病突变型MECP 2基因产生的MECP 2蛋白的功能。这项工作应显着有助于阐明MECP 2在生理和病理生理条件下的作用，并提供重要的线索，MECP 2相关的神经系统疾病的病因。由于翻译后修饰非常适合药理学抑制，因此还应概述新的治疗方法。

MECP2 (methyl CpG binding protein 2) is a central epigenetic regulator, it controls chromatin structure and transcriptional state at a genome-wide level by binding to methylated DNA and recruiting histone modifying enzymes. MECP2 plays an essential role for the proper functioning of the central nervous system and mutations in the MECP2 gene are linked to severe neurological disorders in humans (such as Rett syndrome, the second most common human mental retardation disorder in females). Importantly, post-translational MECP2 modifications have been identified as a critical level of regulation of this protein. Notably, MECP2 phosphorylation has been linked to neuronal activity and stress. In a proteomic screen for MECP2 interacting proteins we have found that MECP2 interacts with and is poly(ADP-ribosyl)ated by PARP-1. We showed that this modification modulates MECP2 ability to bind to and condense chromatin. In a separate screen for MECP2 modifications we found, amongst other modifications, that MECP2 is arginine methylated in brain tissue. It is highly conceivable that the type of posttranslational modification and the genomic localization of differently modified MECP2 proteins are ways to fine tune and diversify MECP2 function in neuronal cells across the genome. However, very little is known about the effects of specific MECP2 modifications. In this project, we will investigate, in a systematic way, MECP2 post-translational modifications that occur upon stimulation with glucocorticoid stress hormones and study their role in regulating chromatin structure and gene activity in hippocampal cells. Building upon our preliminary results, we will focus on poly(ADP-ribosyl)ation and arginine methylation and relate these with phosphorylation. Our specific aims are to: i) characterize MECP2 post-translational modifications (PTMs) and their change upon stress hormone treatment; ii) analyze whether and how PTMs affect MECP2 protein interactions; iii) test the functional relevance of these modifications for MECP2 chromatin binding, chromatin structure and transcriptional regulation; iv) analyze how PTMs are affected by or affect the function of MECP2 proteins produced by disease mutant MECP2 genes. This work should significantly contribute to the elucidation of the role of MECP2 under physiological and pathophysiological conditions and provide important clues as to the etiology of MECP2-related neurological disorders. As post-translational modifications are very suited to pharmacological inhibition, it should also outline new therapeutic approaches.