Brain development phenotyping of IMPC lethal mutant mice

摘要：神经干细胞从简单的上皮管构建大脑的机制是 引人注目的生物学之谜。小鼠遗传学一直是发现基因的最强大工具之一 以及涉及构建健康大脑或影响大脑的神经发育障碍的过程 结构或功能。国际小鼠表型分析中心创建的靶向突变库 联盟 (IMPC) 为了解这些基因和过程提供了非常有价值的资源。很多 导致神经发育表型的突变是致命的，要么是由于大脑缺陷，要么是由于多效性 该基因在其他器官中对于生存至关重要的功能。因此，IMPC 的致死突变体库提供了 大脑发育所需的一组丰富的候选基因。然而，大脑结构的变化或 如果没有正确的工具和专业知识，就很难检测接线。我们建议将我们的专业知识应用于 根据基因表型选择可能具有神经发育缺陷的敲除系 人类发育障碍中的表达、功能和/或已知突变。这是为了回应 FOA 表征致命 IMPC 突变体的发育缺陷。我们将结合非假设驱动 对一些选定的大脑发育突变体进行假设驱动分析的总体表型分析。增加价值 以及该筛选的效率，合作研究人员还将测试突变体子集的内耳 发育表型以及胎盘、原肠胚形成或神经管缺陷。对于第一层表型分析， 将测试品系的致死年龄，并对大脑、内耳、脊髓的总体异常进行表型分析， 和身体发育。第 2 层表型分析将结合大脑、内耳和胎盘的组织病理学， 因为如果不进行切片和染色，就无法确定这些器官的许多结构缺陷。我们会 测试增殖、分层和轴突束缺陷。第 3 层表型分析将重点关注少数 具有异常脑表型和胞质分裂基因功能的突变体，以解决我们的假设： 皮质神经干细胞胞质分裂的不同缺陷是多种脑畸形的基础。我们 将利用我们建立的细胞因子皱纹和脱落定量分析方法 小鼠皮质发育缺陷。在表型分析的所有阶段，杂合子和纯合子都会 与对照进行定量和严格的统计比较。数据将与 IMPC 共享，以造福于 社区。我们的三名研究人员团队拥有超过 50 年的细胞专业知识 小鼠模型器官发育的基础，以及正向和反向遗传学。通过这个项目，我们 将发现大脑、内耳和胎盘发育障碍的新小鼠模型，并将 为神经干细胞分裂和细胞缺陷的机制提供重要的新见解 潜在的大脑畸形。

Abstract: The mechanisms by which neural stem cells build the brain from a simple epithelial tube is a compelling mystery of biology. Mouse genetics has been one of the most powerful tools to discover the genes and processes involved in building a healthy brain, or in neurodevelopmental disorders that affect brain structure or function. The library of targeted mutations created by the International Mouse Phenotyping Consortium (IMPC) provides a highly valuable resource for understanding those genes and processes. Many mutations that cause neurodevelopmental phenotypes are lethal, either due to the brain defect or to pleiotropic functions of the gene in other organs essential for viability. Thus, the bank of lethal mutants at IMPC provides an enriched set of candidate genes required for brain development. However, changes in brain structure or wiring are difficult to detect without the right tools and expertise. We propose to apply our expertise to phenotype selected knockout lines that are likely to have neurodevelopment defects, based on gene expression, function, and/or known mutation in a human developmental disorder. This is in response to an FOA to characterize developmental defects in lethal IMPC mutants. We will combine non-hypothesis driven gross phenotyping with hypothesis-driven analysis of a few selected brain development mutants. To add value and efficiency to this screen, subsets of mutants will also be tested by co-investigators for inner ear development phenotypes, and placenta, gastrulation, or neural tube defects. For the first tier of phenotyping, lines will be tested for age of lethality and phenotyped for gross abnormalities of brain, inner ear, spinal cord, and body development. Tier 2 phenotyping will incorporate histopathology of brain, inner ear, and placenta, since many structural defects in these organs cannot be ascertained without sectioning and staining. We will test for proliferation, layering, and axon tract defects. Tier 3 phenotyping will focus on a small number of mutants with both abnormal brain phenotypes and gene functions in cytokinesis, to address our hypothesis: that different defects in cytokinesis of cortical neural stem cells underlie a variety of brain malformations. We will make use of methods we have established for quantitative analysis of cytokinetic furrowing and abscission defects in developing mouse cortex. In all stages of phenotyping, heterozygotes and homozygotes will be compared to controls quantitatively and with statistical rigor. Data will be shared with IMPC for the benefit of the community. Our team of three investigators has a combined >50 years of expertise working on cellular bases of organ development in the mouse model, and forward and reverse genetics. Through this project , we will discover new mouse models for developmental disorders of the brain, inner ear, and placenta, and will provide important new insights into the mechanisms of neural stem cell divisions and cellular defects underlying brain malformations.