Essential requirements of Eif4a3 in brain development and disease

摘要 Eif4a3是RNA结合外显子连接复合体(EJC)的一个组成部分，与神经发育和 疾病。EJC由Eif4a3、Magoh和Rbm8a组成。EIF4A3突变与智力相关 残疾和亚型突变导致里希里-科斯塔-佩雷拉综合征(RCPS)，颅面部 伴随着小头畸形和认知障碍的发育综合征。然而，潜在的 EIF4A3介导的神经发育病理机制在很大程度上仍不清楚。此次续订 该提案旨在通过定义Eif4a3在两个关键的皮质过程中的要求来解决这一差距 发育：神经发生和神经元成熟。在这笔赠款的前一个资助期，我们发现 Magoh突变的祖细胞表现出长时间的有丝分裂，这直接改变了新生后代的命运。我们 为所有3个核心的EJC组件生成了鼠标模型。使用这些小鼠，我们发现EJC 祖细胞的单倍体功能不全导致神经发生、小头畸形和 常见转录本的失调。我们的基因和基因组发现表明，Eif4a3可能控制 神经前体细胞和通过胚胎干细胞的神经发生。相比之下，我们最近未发表的研究表明，Eif4a3 可能在神经元中具有非EJC依赖的功能。此外，我们认为微管调节在这些非 正则机制。根据我们的发现，我们假设Eif4a3使用规范的RNA调节 和非规范的微管机制，在大脑中区别控制祖细胞和神经元 发展。这项提议将通过利用独特的小鼠模型和人类IPSC来检验这一假设 模型，以及我们实验室开发的实时成像分析。我们将：(1)定义细胞和分子 Eif4a3影响神经发生的机制，(2)决定发育和分子 Eif4a3在神经元成熟中的需求，以及(3)确定Eif4A3对细胞和分子的影响 人类细胞的突变。成功完成，我们将大大推进我们对如何 Eif4a3通过规范和非规范机制控制皮质发育的关键阶段。我们 预计这一提议产生的发现将对理解大脑皮层产生广泛影响 神经发育疾病的发展和病因学。

Abstract Eif4a3 is a component of an RNA binding exon junction complex (EJC) implicated in neural development and disease. The EJC is composed of Eif4a3, Magoh, and Rbm8a. EIF4A3 mutations are associated with intellectual disability and hypomorphic mutations cause Richieri-Costa-Pereira syndrome (RCPS), a craniofacial developmental syndrome accompanied by microcephaly and cognitive disability. Yet, the underlying mechanisms of EIF4A3-mediated neurodevelopmental pathologies remain largely unknown. This renewal proposal aims to address this gap by defining requirements for Eif4a3 in two critical processes of cortical development: neurogenesis and neuronal maturation. In the prior funding period of this grant, we discovered that Magoh mutant progenitors exhibit prolonged mitosis, which directly alters fates of newborn progeny. We generated mouse models for all 3 core EJC components. Using these mice we discovered that EJC haploinsufficiency in progenitors results in strikingly similar defects in neurogenesis, microcephaly, and dysregulation of common transcripts. Our genetic and genomic discoveries indicate that Eif4a3 may control neural progenitors and neurogenesis via the EJC. In contrast, our recent unpublished work indicate that, Eif4a3 may have EJC-independent functions in neurons. Further, we implicate microtubule regulation in these non- canonical mechanisms. Based on our findings we hypothesize that Eif4a3 employs canonical RNA regulatory and non-canonical microtubule mechanisms to differentially control progenitors and neurons during brain development. This proposal will test this hypothesis by exploiting unique mouse models and human iPSC models, as well as live imaging assays developed in our lab. We will: (1) define cellular and molecular mechanisms by which Eif4a3 influences neurogenesis, (2) determine developmental and molecular requirements of Eif4a3 in neuronal maturation, and (3) determine the cellular and molecular impact of EIF4A3 mutations in human cells. Successfully completed, we will have significantly advanced our understanding of how Eif4a3 controls critical stages of cortical development, via both canonical and non-canonical mechanisms. We anticipate the discoveries resulting from this proposal will be broadly impactful for understanding cortical development and the etiology of neurodevelopmental disease.