Role of TRIM71 in neural stem cell biology and congenital hydrocephalus

项目摘要 先天性脑积水（CH）是最常见的脑发育畸形， 1/1000出生。CH已被经典地归因于失败的脑脊液（CSF）稳态， 因此通过手术脑脊液分流治疗，具有高发病率和失败率。后的坚持， 许多患者的外科脑室扩大，通常神经发育结果较差， 关于我们目前的CH及其治疗的范例。我们对分子生物学的理解 CH的发病机制阻碍了预防措施的发展，靶向治疗，并改善 精确化。通过全外显子组测序，Kahle实验室已经鉴定出杂合子从头 TRIM 71/lin-41中的突变是人类散发性CH的最常见遗传原因（Jin et al. 2020，Nature Medicine）。TRIM 71编码一种RNA结合蛋白，该蛋白首先在C.优雅作为一个 调节表皮干细胞发育时间的异时基因。尽管其卓越的 在胚胎发育过程中的进化保守性和产前神经干细胞（NSC）的稳健表达， TRIM 71在哺乳动物脑发育和CH中的作用基本上是未知的。在前期工作中，我 已经显示具有人TRIM 71 CH突变R608 H的鼠同源物的小鼠系 （Trim 71 R595 H/+）或具有条件性NSC特异性Trim 71缺失（Nestin-Trim 71 fl/fl）两者都概括了 携带TRIM 71的人类患者的严重脑出血发作交通性脑积水 突变我的建议的目的是进一步描述这些模型，以增加对 脑发育与脑出血发病机制我假设TRIM 71突变型脑室扩大的结果 来自原发性脑脊液（CSF）过度积聚，而是来自与以下相关的神经发生受损 减少NSC增殖和早熟NSC分化。目标1将描述神经解剖学特征， 使用脑磁共振成像（MRI）和直接MRI检查TRIM 71突变型脑积水的CSF生理学 CSF流体动力学的测量。目的2阐明TRIM 71突变体的细胞机制 在Trim 71 CH突变小鼠中使用免疫荧光研究并辅以体外测定的脑积水 使用原代NSC培养物。证明神经发生失调而不是原发性CSF 一些CH案例的过度积累可能会改变范式， 改善诊断、预后和治疗策略，包括预测哪些CH患者 可能受益于或可能不受益于神经外科脑脊液分流术。这些研究将作为我们 长期目标是为CH开发精确的医学疗法。

PROJECT SUMMARY Congenital hydrocephalus (CH) is the most common developmental malformation of the brain affecting 1/1000 births. CH has been classically attributed to failed cerebrospinal fluid (CSF) homeostasis and therefore treated by surgical CSF diversion, with high morbidity and failure rates. The persistence of post- surgical ventriculomegaly in many patients, often with poor neurodevelopmental outcomes, raises questions about our current paradigms of CH and its treatment. Significant gaps in our understanding of the molecular pathogenesis of CH impede the development of preventive measures, targeted therapies, and improved prognostication. By whole exome sequencing, the Kahle lab has identified heterozygous de novo mutations in the TRIM71/lin-41 as the most common genetic cause of human sporadic CH (Jin et al. 2020, Nature Medicine). TRIM71 encodes an RNA-binding protein first discovered in C. elegans as a heterochronic gene that regulates developmental timing of epidermal stem cells. Despite its remarkable evolutionary conservation across phylogeny and robust expression in prenatal neural stem cells (NSCs), the roles of TRIM71 in mammalian brain development and CH are essentially unknown. In preliminary work, I have shown that mouse lines with the murine homolog of the human TRIM71 CH mutation R608H (Trim71R595H/+) or with conditional NSC-specific Trim71 deletion (Nestin-Trim71fl/fl) both recapitulate the severe neonatal-onset communicating hydrocephalus of human patients harboring TRIM71 mutations. The objective of my proposal is to further characterize these models to increase knowledge of human brain development and CH pathogenesis. I hypothesize TRIM71 mutant ventriculomegaly results not from primary cerebrospinal fluid (CSF) over-accumulation, but rather from impaired neurogenesis related to reduced NSC proliferation and precocious NSC differentiation. Aim 1 will characterize the neuroanatomy and CSF physiology of TRIM71-mutant hydrocephalus using brain magnetic resonance imaging (MRI) and direct measurements of CSF hydrodynamics. Aim 2 will elucidate the cellular mechanisms of TRIM71-mutant hydrocephalus using immunofluorescent studies in Trim71 CH mutant mice complemented by in vitro assays using primary NSC cultures. The demonstration that dysregulated neurogenesis rather than primary CSF over-accumulation underlies some CH cases could have paradigm-changing implications that could lead to improved diagnostic, prognostic, and therapeutic strategies, including the prediction of which CH patients may or may not benefit from neurosurgical CSF shunting. These studies will be conducted as part of our long-term goal to develop precision medicine therapies for CH.