Epigenetic mechanisms of disrupted neurodevelopment in Menke-Hennekam syndrome

项目摘要 EP 300（一种组蛋白乙酰转移酶）的杂合变体导致两种罕见的多器官染色质病： Menke-Hennekam综合征2型（MKHK 2; MIM 618333，特别是外显子30-31中的突变）和 Rubinstein-Taybi 2型（RSTS 2; MIM 613684）。有趣的是，基于“反向”患者颅面 RSTS的特征以及MKHK 2面部特征与另一种具有重复的 CREBBP区域（EP 300的Parkinson），作者提出了导致MKHK和RSTS的突变， 可能不同的功能（即，分别获得[GOF]和损失[LOF]）。1，2此外， MKHK 2与具有皮质发育畸形（MCD）的病症具有重叠的表现， 例如，小脑畸形、癫痫发作、智力残疾、重复行为和合并诊断率增加 自闭症谱系障碍，表现出在皮层神经元功能的潜在作用。 在MKHK 2中发现的外显子30-31错义突变尚未建模，RSTS 2 LOF模型已经产生了 短枝和低兴奋性的表型变化。然而，RSTS 2 LOF大块神经元 生物信息学分析包含具有不同区域特异性的污染细胞类型，因此， EP 300特异性基因网络/通路无法解释。这一切表明，迫切需要 在MKHK 2治疗前了解EP 300在皮层兴奋性神经元成熟和功能中的作用 神经系统的问题是可以解决的。我们假设MKHK 2 EP 300突变导致加速 成熟率降低、树突形成减少和神经元功能改变。 这项提议是波特博士和巴斯基博士与Tchieu博士的合作，他们专门研究表观基因组学， 开发人类诱导多能干细胞（hPSC）分化方法的发育生物学家 神经系统细胞类型。在本研究中，我们将使用这种方法来区分MKHK 2突变的EP 300， 和相应的同基因对照hPSC转化为放射状胶质样神经干细胞和PFC兴奋性神经元。 目的：（1）鉴定神经元成熟和信号传导中的MKHK 2相关缺陷，以及（2）鉴定表观遗传缺陷。 基因表达的变化来驱动它们。 本实验项目将为研究神经皮层的机制提供坚实的基础 MKHK 2的发育缺陷，并允许鉴定用于潜在治疗的分子靶点， MKHK 2癫痫发作和其他相关的MCD样症状。此外，我们可以应用知识和技术 从该项目中获得的专业知识用于其他表观遗传蛋白质，以进一步扩展我们对表观遗传蛋白质的了解。 在皮质生成过程中的调节，特别是神经元成熟和信号传导，允许更广泛的影响 治疗MCD、神经退行性疾病、神经发育和神经炎性疾病。

Project Summary Heterozygous variants in EP300, a histone acetyltransferase, cause two rare multi-organ chromatinopathies: Menke-Hennekam syndromes type 2 (MKHK2; MIM618333, specifically mutations in exon 30-31) and Rubinstein-Taybi type 2 (RSTS2; MIM613684). Interestingly, based on “inverse” patient craniofacial characteristics with RSTS and the alignment of MKHK2 facial features with another disorder with duplicated regions of CREBBP (EP300's paralog), authors have proposed mutations causing MKHK and RSTS have potentially different functions (i.e., gain [GOF] versus loss [LOF], respectively).1,2 In addition, individuals with MKHK2 have overlapping manifestations with disorders with malformations in cortical development (MCD), such as microencephaly, seizures, intellectual disability, repetitive behaviors, and increased rates of co-diagnoses with autism spectrum disorder, demonstrating a potential role in cortical neuron function.3 While the specialized exon 30-31 missense mutations found in MKHK2 have yet to be modeled, RSTS2 LOF models have yielded phenotypic changes of shorter branches and hypo-excitability. However, the RSTS2 LOF bulk neuronal bioinformatical analyses contained contaminating cell types with differential regional specificity, therefore, EP300 specific gene network/pathways are uninterpretable. Together this demonstrates a critical need to understand EP300's role in maturation and function of cortical excitatory neurons before treatment of MKHK2 neurological issues can be tackled. We hypothesize that MKHK2 EP300 mutation causes accelerated maturation rate, decreased dendrite formation, and altered neuronal function. This proposal is a collaboration between Drs. Potter and Barski who specialize in epigenomics and Dr. Tchieu, a developmental biologist who developed methods for human induced pluripotent stem cell (hPSC) differentiation into nervous system cell types. In this study, we will use this approach to differentiate MKHK2 mutated EP300 and corresponding isogenic control hPSCs into radial glia-like neural stem cells and PFC excitatory neurons in order to: (1) identify MKHK2-related defects in neuronal maturation and signaling and (2) to identify epigenetic and gene expression changes driving them. This pilot project will provide a solid foundation for the study of the mechanism(s) behind neurocortical developmental defects in MKHK2 and allow identification of molecular targets for potential therapies for MKHK2 seizures and other related MCD-like symptoms. Further, we can apply knowledge and technical expertise gained from this project to other epigenetic proteins to further expand our knowledge of epigenetic regulation during corticogenesis, specifically neuronal maturation and signaling allowing for a broader impact on the treatment of MCD, neurodegenerative, neurodevelopment, and neuroinflammatory disorders.