Function of stimulus-induced MeCP2 phosphorylation

刺激诱导MeCP2磷酸化的功能 摘要 MeCP2是识别甲基化DNA和解释编码的表观遗传信息的关键角色 不同的DNA甲基化模式。X-连锁的人MECP2基因序列或拷贝数的改变 基因导致Rett综合征(RTT)或MECP2重复综合征。除了引起RTT之外 突变，在MECP2中发现了许多功能未知的错义突变 人类的基因。其中两个突变位于或接近丝氨酸80或丝氨酸421，它们的磷酸化 状态是调节MeCP2功能的重要因素。要充分理解MECP2在人类基因组中的重要作用 为了调节神经系统的发育和功能，研究MeCP2的各个方面都很重要 功能。我们以前已经证明，丝氨酸421(S421)的磷酸化可以通过 空间学习，以及S421磷酸化在调节MeCP2与基因的结合中起关键作用 启动子，神经基因转录，兴奋性突触发生，两种类型的突触可塑性(长期 增强和突触伸缩)、运动、学习和记忆。最近，我们发现S421 在从海马区分离的成年神经前体细胞(ANPC)中也被磷酸化。有趣的是， ANPC中S421磷酸化的刺激、调节和功能与其他基因完全不同 在有丝分裂后神经元中。在aNPC中，MeCP2 S421的磷酸化是由与细胞相连的生长因子诱导的 周期，由极光激酶B直接调节，并在调节细胞增殖和 通过Notch信号通路诱导aNPC的分化。这些新发现进一步概括了甲基氯化石蜡2 磷酸化是细胞功能中常见的调节模块。更有趣的是，磷酸化在 在有丝分裂后神经元中，丝氨酸80(S80)似乎与S421处的磷酸化调控不同， 并且在有丝分裂后神经元和aNPC中都扮演着相反的功能，对抗S421的磷酸化。 总的来说，这些研究提出了MeCP2上多个位点的动态磷酸化状态的可能性 可能形成一个组合密码，除了DNA外，还提供另一个表观遗传调控模块 甲基化和组蛋白密码。为了验证这一假设，我们建议生成几个新的MeCP2敲打 携带在S80和S421取消或模拟磷酸化的点突变组合的等位基因， 并研究了在公认的神经发生范式中每个组合代码的功能输出 无论是老鼠模型还是人类模型。我们的具体目标是：1)研究S80和S80双突变的影响 S421对小鼠鼻咽癌模型增殖和分化的影响2)研究单、双联对鼻咽癌的影响 S80和S421突变对人类干细胞模型中鼻咽癌增殖和分化的影响 明确MeCP2磷酸化与其功能输出之间的分子机制。学习 MeCP2的翻译后修饰为理解MeCP2的基本功能提供了一个重要角度 MeCP2，这将使我们对MeCP2的了解超越RTT和MECP2重复综合征。

Function of stimulus-induced MeCP2 phosphorylation Abstract MeCP2 is a key player in recognizing methylated DNA and interpreting the epigenetic information encoded in different DNA methylation patterns. Alterations in sequence or copy number of the X-linked human MECP2 gene cause either Rett syndrome (RTT) or MECP2 duplication syndrome. In addition to RTT-causing mutations, many missense mutations with unknown functional significance have been identified in the MECP2 gene in humans. Two of those mutations are at or close to serine 80 or serine 421, whose phosphorylation status is important for regulating MeCP2 function. To fully understand the significant role of MECP2 in regulating the development and function of the nervous system, it is important to study all aspects of MeCP2 function. We have previously demonstrated that phosphorylation at serine 421 (S421) can be induced by spatial learning, and that S421 phosphorylation plays critical roles in regulating MeCP2 binding to gene promoters, neuronal gene transcription, excitatory synaptogenesis, two types of synaptic plasticity (long-term potentiation and synaptic scaling), locomotion, learning and memory. Most recently, we discovered that S421 is also phosphorylated in adult neural progenitor cells (aNPC) isolated from the hippocampus. Interestingly, the stimulus, the regulation and the function of S421 phosphorylation in aNPCs are completely different from those in post-mitotic neurons. In aNPCs, MeCP2 S421 phosphorylation is induced by growth factors, linked to cell cycle, directly regulated by aurora kinase B, and plays critical roles in regulating the proliferation and differentiation of aNPCs through the Notch signaling pathway. These new findings further generalize MeCP2 phosphorylation as a common regulatory module in cellular functions. More interestingly, phosphorylation at serine 80 (S80) appears to be regulated differentially from phosphorylation at S421 in post-mitotic neurons, and plays opposing functional roles against S421 phosphorylation in both post-mitotic neurons and aNPCs. Collectively, these studies raise the possibility that dynamic phosphorylation states at multiple sites on MeCP2 may form a combinatorial code, presenting another epigenetic regulatory module in addition to DNA methylation and histone codes. To test this hypothesis, we propose to generate several novel Mecp2 knockin alleles carrying combinations of point mutations that either abolish or mimic phosphorylation at S80 and S421, and study the functional output of each combinatorial code in the well-established paradigm of neurogenesis in both mouse and human models. Our specific aims are: 1) To study the effects of double mutations at S80 and S421 on aNPC proliferation and differentiation in mouse models, 2) To study the effects of single and double mutations at S80 and S421 on NPC proliferation and differentiation in human stem cell models, and 3) To define the molecular mechanism linking MeCP2 phosphorylation with its functional output. Studying posttranslational modification of MeCP2 provides a critical angle of understanding the basic function of MeCP2, which will expand our knowledge of MeCP2 beyond RTT and MECP2 duplication syndrome.