Investigating the role of MeCP2 in activity-dependent gene expression

描述(申请人提供)：Rett综合征(RTT)是一种X连锁的进行性神经发育障碍，是女孩严重智力残疾和自闭症样症状的常见原因。MECP2是一种甲基CpG结合蛋白，它的突变导致了大多数RTT病例。MeCP2是一种甲基CpG结合蛋白，通过与NCoR/HDAC3组蛋白脱乙酰酶复合体结合而抑制转录。精氨酸306突变为胞嘧啶(R306C)会引起RTT，并破坏MeCP2与NCoR复合体的结合，这表明MeCP2-NCoR相互作用对大脑发育至关重要，破坏这一复合体会导致RTT。格林伯格实验室在其对神经元活性依赖的基因转录的研究中发现，作为对感觉体验的响应，MeCP2在苏氨酸308(T308)处被磷酸化，这一磷酸化事件扰乱了NCoR与MeCP2的相互作用。此外，初步实验表明，MeCP2 T308突变为丙氨酸(T308A)会导致活性调节基因Npas4的诱导减弱。Npas4基因编码一种转录因子，控制兴奋性神经元上抑制性突触的形成。因此，我们的初步数据表明，MeCP2和NCoR之间的相互作用可能是Npas4表达的关键，并且在RTT中被错误调控。为了验证这一假说，我们提出了以下具体目标：(1)进一步研究MeCP2-NCoR复合体是否调节神经元活性依赖的基因表达；(2)确定MeCP2-NCoR复合体是否通过与Npas4基因的调节区以活性依赖的方式结合来调节基因表达。我们希望这些拟议的实验将提供对MeCP2功能的更好理解，并将为治疗RTT提供潜在的治疗策略。

DESCRIPTION (provided by applicant): Rett Syndrome (RTT) is an X-linked progressive neurodevelopmental disorder and is a common cause of severe intellectual disability and autistic-like symptoms in girls. Mutations in MECP2, a methyl-CpG-binding protein, cause of the majority of RTT cases. MeCP2 is a methyl-CpG-binding protein that represses transcription by binding the NCoR/HDAC3 histone deacetylase complex. Mutation of arginine 306 to cytosine (R306C) causes RTT and disrupts binding of MeCP2 to the NCoR complex, suggesting that MeCP2-NCoR interaction is critical for brain development and that disrupting this complex leads to RTT. The Greenberg laboratory, in its studies of neuronal activity-dependent gene transcription, discovered that in response to sensory experience MeCP2 becomes phosphorylated at threonine 308 (T308) and that this phosphorylation event perturbs the interaction of NCoR with MeCP2. Furthermore, preliminary experiments suggest that mutation of MeCP2 T308 to alanine (T308A) leads to attenuation of the induction of the activity-regulated gene Npas4. The Npas4 gene encodes a transcription factor that controls inhibitory synapse formation onto excitatory neurons. Thus, our preliminary data suggest that the interaction between MeCP2 and NCoR may be critical for Npas4 expression and is misregulated in RTT. To test this hypothesis we propose the following specific aims: (1) to further investigate if MeCP2-NCoR complex regulates neuronal activity-dependent gene expression and (2) to determine if the MeCP2-NCoR complex regulates gene expression by associating with the regulatory region of the Npas4 gene in an activity-dependent manner. It is our hope that these proposed experiments will provide a better understanding of MeCP2 function and will suggest potential therapeutic strategies for treating RTT.