Translational Regulation in Adult Neural Stem Cells

描述(由申请人提供)：“干细胞研究为治疗一系列无法治愈的先天性、发育性、精神性或退行性疾病提供了巨大的潜力(NIH PA-04-101)。”然而，深入了解调控成体神经干细胞(NSC)增殖和分化的分子机制是其治疗应用的先决条件。干细胞领域的进展扩大了我们对成年NSC功能转录调控的了解。最近，microRNA(MiRNA)途径被证明在干细胞的增殖和分化中发挥重要作用，这表明对成年神经干细胞的翻译调控，尽管了解得较少，但在成年神经干细胞的功能中同样重要，甚至更重要。这个项目的长期目标是了解翻译调节在成人神经发生中的作用。脆性X智力低下蛋白(FMRP)是一种选择性RNA结合蛋白，与多聚核糖体形成信使核糖核蛋白(MRNP)复合体，是脆性X综合征中缺失的蛋白。FMRP调节蛋白质的翻译，FMRP的缺失导致选择性mRNAs的异常翻译，树突棘的延迟成熟，以及神经元中微管的异常稳定性。我们发现，FMRP在成人大脑来源的神经干细胞/祖细胞(NSPC)中也高表达。我们最近的研究和其他团队的研究证明了FMRP与miRNA途径的组成部分之间的生化和遗传相互作用，包括DICER和ArgAerte蛋白质，表明成年NSCs中特定mRNAs的翻译调控可以通过miRNA途径和FMRP之间的协同作用来实现。我们从野生型(野生型)和Fmr1基因敲除(KO)的成年小鼠中分离出NSPC，发现FMRP的缺失在体外既影响成年NSPC的增殖，也影响其命运。我们假设成年神经干细胞的增殖和分化受miRNA途径和RNA结合蛋白FMRP在翻译水平上的调控。因此，我们建议：首先确定NSPC特异性mRNAs的翻译是否受miRNAs的调控(目标1)；然后确定成人NSCs的翻译调控是否对体内NSC的功能至关重要(目标2)；最后确定FMRP和miRNA途径是否协同调节成年NSCs的增殖和分化(目标3)。我们提议的工作将由在成人神经发生方面拥有专业知识的PI赵博士和在翻译调控和miRNA方面拥有丰富经验的共同PI金博士的努力共同完成。这项工作的结果将为我们对成年大脑中NSC调节的知识增加一个新的维度。我们的前提是，更好地了解这些调控机制是成人神经干细胞治疗人类疾病的先决条件。

DESCRIPTION (provided by applicant): "Stem cell research offers enormous potential for treating a host of congenital, developmental, psychiatric or degenerative diseases for which there are no cures (NIH PA-04-101)." However, a thorough understanding of the molecular mechanisms that regulate adult neural stem cell (NSC) proliferation and differentiation is a pre-requisite for their therapeutic applications. Advances in the stem cell field have expanded our knowledge of transcriptional regulations in adult NSC functions. Recently, microRNA (miRNA) pathway has been shown to play important roles in the proliferation and differentiation of stem cells, indicating that translational regulation of adult NSCs, though less understood, is equally, if not more important in adult NSC function. The long-term goal of this project is to understand the role of translational regulation in adult neurogenesis. Fragile X mental retardation protein (FMRP), the protein that is lost in Fragile X syndrome, is a selective RNA-binding protein that forms a messenger ribonucleoprotein (mRNP) complex associating with polyribosomes. FMRP regulates protein translation and the loss of FMRP leads to abnormal translation of selective mRNAs, delayed maturation of dendritic spines, and abnormal microtubule stability in neurons. We found that FMRP is also highly expressed in neural stem/progenitor cells (NSPCs) derived from adult brains. Our recent studies and those of other groups have demonstrated the biochemical and genetic interactions between FMRP and the components of the miRNA pathway, including Dicer and Argonaute proteins, suggesting that translational regulation of specific mRNAs in adult NSCs could be achieved by collaborative actions between miRNA pathway and FMRP. We have isolated NSPCs from both wild type (wildtype) and Fmr1 knockout (KO) adult mice, and found that the loss of FMRP affects both proliferation and fate- specification of adult NSPCs in vitro. We hypothesize that the proliferation and differentiation of adult NSCs is regulated at the translational level by miRNA pathway and RNA binding protein, FMRP. Therefore, we propose: first to determine whether the translation of NSPC-specific mRNAs is regulated by miRNAs (Aim 1); then to determine whether translational regulation of adult NSCs is critical for NSC function in vivo (Aim 2); and finally to determine whether FMRP and miRNA pathway collaboratively regulate the proliferation and differentiation of adult NSCs (Aim 3). Our proposed work will be carried out by combining the efforts of the PI, Dr. Zhao, who has expertise in adult neurogenesis, and the Co-Pi, Dr. Jin, who has extensive experience in translational regulation and miRNA. The outcome of this work would add a new dimension to our knowledge of NSC regulation in the adult brain. It is our premise that a better understanding of these regulatory mechanisms is a pre-requisite for the therapeutic application of adult NSCs for human diseases.