Molecular and Cellular Mechanisms of Chromosome 18q23 Dysmyelination

摘要 大脑的次优髓鞘形成，无论是发育还是退行性， 功能上的分歧。异常髓鞘减慢神经传导和信号同步性， 后果，如癫痫发作，智力残疾，自闭症和加速年龄相关的 认知能力下降我们已经确定了一个大约160万人口的区域， 染色体18q23，当半合子时导致髓鞘不能正常发育。 然而，目前尚不清楚这种髓鞘形成障碍的原因是否是由于单倍不足， 或在关键基因组区域中一个以上基因的协同效应。 在这个提议中，我们已经创建了一个由临床和基础科学家组成的团队来解决这个问题。 问题我们将共同获得足够的数据，以制定一个成功的实验系统 确定18q23处的因果遗传缺陷对少突胶质细胞的细胞后果 增殖、成熟和髓磷脂功能。我们将 开发一个综合管道，在人类和小鼠模型中进行救援实验 这将导致开发用于药物筛选实验的高通量测定，其中 测试成功的化合物在关键阶段纠正或改善髓鞘形成障碍缺陷 发展质量和在这个项目中，我们将从3个细胞中产生诱导多能干细胞（iPSC）。 染色体18q23缺失的嵌合体个体，从而产生一组同基因的 阳性和阴性对照线。从这些，我们将得出髓鞘皮质球体模型 与对照组相比，全面评价髓鞘形成异常， 基因组背景仅在18q23位点不同。同时，我们将使用siRNA 沉默小鼠脑细胞中保守的18q23基因以确定其在髓鞘形成中的作用 并与在人18q23模型中观察到的髓磷脂特征进行比较。相关性 人类和小鼠的数据对于开发一种能够概括 然后可以用于药物毒性和有效性筛选， 与人体外模型组合。反过来，染色体的纵向程序 18临床研究中心与最大的个体队列保持密切联系， 18号染色体异常，从而使其定位良好，以告知解释 实验结果以及基于这些结果的发现进行临床试验。

ABSTRACT Suboptimal myelination of the brain, whether developmental or degenerative, has major ramifications on function. Abnormal myelin slows nerve conduction and signal synchronicity with consequences such as seizures, intellectual disability, autism and accelerated age-related cognitive decline. We have identified an approximately 1.6 megabase region of human chromosome 18q23 that when hemizygous results in a failure of myelin to develop normally. However, it is not yet known if the cause of this dysmyelination is due to haploinsufficiency of one of the gene products or a synergistic effect of more than one gene in the critical genomic region. In this proposal, we have created a team of both clinical and basic scientists to address this question. Together, we will acquire sufficient data to formulate a successful experimental system to define the cellular consequences of the causal genetic defect(s) at 18q23 on oligodendrocyte proliferation, maturation and myelin function both in mice and in human in vitro models. We will develop an integrated pipeline to perform rescue experimentation in human and mouse models that will lead to development of high throughput assays for drug screening experiments in which to test successful compounds on correcting or improving the dysmyelination defect at key stages of development. For this project, we will generate induced pluripotent stem cells (iPSC) from 3 individuals who are mosaic for a chromosome 18q23 deletion thereby creating sets of isogenic positive and negative control lines. From these we will derive myelinating cortical spheroid models to comprehensively evaluate for myelination abnormalities as compared to their controls with genomic background that differs only at the 18q23 locus. At the same time we will use siRNA silencing of the conserved 18q23 genes in mouse brain cells to define roles in myelinogenesis and compare to the myelin characteristics observed in the human 18q23- model. Correlation of the human and mouse data are essential in order to develop a live mouse model that recapitulates the human condition and can then be used for drug toxicity and effectiveness screening in combination with the human in vitro models. In turn, the longitudinal program of the Chromosome 18 Clinical Research Center maintains close contact with the largest cohort of individuals with chromosome 18 abnormalities, thus making it well positioned to inform interpretation of experimental results as well as conduct clinical trials based on findings from these results.