Vision defects associated with loss of C-Vps function

摘要 白质营养不良(LD)和遗传性白质脑病(GLE)是影响白人的遗传性疾病 中枢神经系统中的物质(髓鞘)。LDS和GLES逐渐影响运动和感觉 系统，包括视觉系统。受影响儿童的父母首先注意到视力问题是逐渐丧失的 他们的孩子跟踪视觉线索的能力。视力在接下来的几年里慢慢恶化，很可能是由于 由于视神经和大脑中髓鞘的丧失，被称为皮质盲。核磁共振成像通常对 髓鞘缺陷，但明确诊断疾病特异性LDS和GLES仍然是一个挑战， 大多数LDS和GLE的遗传来源不明。我们最近发现VPS11的一个突变是 来自三个无血缘关系的德系犹太人(AJ)的五个个体的GLE表型中的致病等位基因 家人。我们的分析表明，AJ患者的携带率为1：250。VPS11在四个C-复合体中的函数 VPS蛋白，从酵母到人类都是保守的，控制着关键的细胞过程 内溶体和自噬途径。这些过程才刚刚开始在 分子水平，主要在酵母中。事实上，在我们最近的报告之前，没有已知的人类突变 C-VPS蛋白的任何一种。然而，我们之前鉴定了斑马鱼vps11突变体，最近 发现它有许多人类突变体的表型，包括内溶酶体缺陷 自噬途径，中枢神经系统髓鞘缺陷，视网膜和中枢神经系统神经元丢失，以及运动缺陷。 这项建议旨在利用斑马鱼模型来表征基础的病理 与C-VPS功能丧失相关的视力丧失。目标1将进一步描述视力和运动缺陷的特征 与我们斑马鱼模型中Vps11功能的丧失相关，并表征相关的Gle表型 伴随着其他C-VPS蛋白的丢失。目标2将分析特定VPS11的细胞间后果 GLE表型下的突变和筛选将拯救自噬通量的化合物 与这种疾病相关的缺陷。Aim 3利用哺乳动物细胞培养模型进行共培养 以测试VPS11在髓鞘形成中的作用，这是对 VPS11在任何物种的少突胶质细胞中都有功能。通过将哺乳动物体外技术与 斑马鱼突变模型的力量，这些目标的成功完成将大大促进我们的 长期目标是阐明VPS11介导性视力丧失的机制。

ABSTRACT Leukodystrophies (LD) and genetic Leukoencephalopathies (gLE) are genetic disorders affecting the white matter (myelin) in the central nervous system. LDs and gLEs progressively affect the motor and sensory systems, including the visual systems. Parents of affected children first note visual problems as a gradual loss in the ability of their child/children to track visual cues. Vision slowly worsens over subsequent years, likely due to the loss of myelin in the optic nerve and brain, termed cortical blindness. An MRI is typically diagnostic for myelination defects, but a clear diagnosis of disease-specific LDs and gLEs remains a challenge, and the majority of LDs and gLEs have an unknown genetic origin. We recently identified a mutation in VPS11 as a causative allele in the gLE phenotypes observed in five individuals from three unrelated Ashkenazi Jewish (AJ) families. Our analysis indicates a carrier rate of 1:250 AJ individuals. VPS11 functions in a complex of four C- VPS proteins, which are conserved from yeast to humans, and control critical cellular processes in the endolysosomal and autophagy pathways. These processes are only beginning to be investigated at the molecular level, mainly in yeast. Indeed, prior to our recent report, there were no known human mutations of any of the C-VPS proteins. However, we previously characterized a zebrafish vps11 mutant and have recently discovered that it shares many of the phenotypes of the human mutant, including defects in endolysosomal and autophagy pathways, myelination defects in the CNS, loss of retinal and CNS neurons, and motor defects. This proposal aims to take advantage of the zebrafish model to characterize the pathology underlying the vision loss associated with loss of C-Vps function. Aim 1 will further characterize the vision and motor defects associated with loss of Vps11 function in our zebrafish model and characterize the gLE phenotypes associated with loss of other C-Vps proteins. Aim 2 will analyze the intercellular consequences of the specific VPS11 mutation that underlies the gLE phenotypes and screen for compounds that will rescue the autophagy flux defects associated with this disease. Aim 3 utilizes a mammalian cell culture model to co-culture oligodendrocytes and neurons to test the role of VPS11 in myelin formation, which is the first investigation of VPS11 function in oligodendrocytes in any species. By combining mammalian in vitro techniques with the power of the zebrafish mutant model, the successful completion of these aims will significantly advance our long-term goal of elucidating the mechanism that underlies VPS11-mediated vision loss.