Early retinal development in pigmented and albino mice: Factors in the CMZ and RPE controlling RGC specification

项目摘要 来自每只眼睛的视网膜神经节细胞（RGC）将其轴突同侧和对侧延伸到大脑， 建立双目视觉电路。研资局的预测缺乏适当的偏侧性， 遗传性疾病，如白化病，其中视网膜色素上皮（RPE）的色素减退与 导致视神经走错从而改变了立体视觉这项赠款的进展包括确定 ipsi和contra RGC的特化和分化的转录调节因子; 腹侧睫状缘区（CMZ）作为ipsi RGCs的来源; 腹侧CMZ;以及ipsi RGC投射对细胞周期蛋白D2的依赖性。在白化病视网膜中，这些过程 和RPE的细胞完整性，被破坏，使白化病成为一个很好的比较模型， 建议的研究。 在这里，我们探索了CMZ在神经视网膜发育和RGC特化中的新作用，并寻求 发现潜在的信令网络，以建立正确的RGC连接。我们建议将联合收割机研究 用CMZ、RPE和神经视网膜的转录组学进行神经发生和命运作图， 深入了解白化病动物RPE中黑色素的损失如何导致细胞命运从ipsi转变为contra， 双目电路的建立。为此，我们将确定细胞周期蛋白D2在细胞的节奏中的作用。 周期，细胞分裂平面，以及从CMZ向神经视网膜的迁移（Aim 1）;研究CMZ和神经视网膜之间的信号传导。 RPE和CMZ，从Wnt途径开始，作为调节RGC命运的途径（目的2）;确定 通过对CMZ，神经视网膜， 和RPE（目标3）。在整个过程中，我们将比较白化病和色素视网膜。我们假设， CMZ控制神经发生的时间，其指定RGC投射命运，并且RPE中的因子提供 对CMZ和神经视网膜的指令用于ipsi/contra RGC命运获取。 意义：探索早期神经视网膜发育，解析神经发生和细胞命运的调节因子 从CMZ和RPE发出的信号提供了一个新的机械切入点， 色素和RPE影响视交叉处的细胞命运和RGC轴突分离。鉴别基因 关于ipsi/contra RGC多样性如何产生的节目揭示了交叉系统，如双眼回路， 已经建立。这些信息对于将干细胞驱动到RGC中进行替代治疗和指导治疗至关重要。 损伤和退化视觉通路中的轴突再生。

PROJECT SUMMARY Retinal ganglion cells (RGCs) from each eye extend their axons ipsi- and contralaterally to the brain to establish the circuit for binocular vision. The lack of appropriate sidedness of RGC projections is debilitating in genetic disorders such as albinism, in which hypopigmentation of the retinal pigment epithelium (RPE) is linked to optic nerve misrouting and therefore altered stereo vision. Progress on this grant includes the identification of transcriptional regulators of the specification and differentiation of ipsi and contra RGCs; demonstration of the ventral ciliary margin zone (CMZ) as a source of ipsi RGCs; expression of the cell cycle regulator Cyclin D2 in the ventral CMZ; and dependence of the ipsi RGC projection on Cyclin D2. In the albino retina, these processes and the cellular integrity of the RPE, are disrupted, making the albino an excellent comparative model for the proposed studies. Here we explore a novel role for the CMZ in neural retinal development and RGC specification, and seek to uncover potential signaling networks for establishing proper RGC connections. We propose to combine studies of neurogenesis and fate mapping with transcriptomics of the CMZ, RPE, and neural retina to gain mechanistic insight into how loss of melanin in the RPE of albino animals causes a shift in cell fate from ipsi to contra during the establishment of the binocular circuit. To this end, we will establish a role for Cyclin D2 in the pace of the cell cycle, plane of cell division, and migration from the CMZ to the neural retina (Aim 1); study signaling between the RPE and CMZ, starting with the Wnt pathway, as a route to regulate RGC fate (Aim 2); identify the transcriptional networks that regulate RGC cell fate by performing single-cell RNA-Seq of the CMZ, neural retina, and RPE (Aim 3). Throughout, we will compare albino and pigmented retina. We hypothesize that events in the CMZ control timing of neurogenesis, which specifies RGC projection fate and that factors in the RPE provide directives to the CMZ and neural retina for ipsi/contra RGC fate acquisition. Significance: Probing early neural retinal development and parsing regulators of neurogenesis and cell fate emanating from the CMZ and RPE offer a novel mechanistic entry point to the long-standing enigma of how pigment and the RPE influences cell fate and RGC axon segregation at the optic chiasm. Identifying gene programs on how ipsi/contra RGC diversity arises reveals how decussating systems such as the binocular circuit are established. Such information is critical for driving stem cells into RGCs for replacement therapy and directing axon regeneration in injured and degenerating visual pathways.