The role of BARHL2 in the mosaic pattering and dendritic tiling of retinal amacri

项目总结 我们准确的视觉依赖于通过精确的有线连接的视觉信息流 在不同视网膜神经元的轴突和树突之间。在视网膜中，神经元占据空间域和 树枝的树枝，这需要它们的细胞体和树枝的适当分布。细胞 同一类型神经元的胞体以一种称为镶嵌图案的过程隔开，它们的树突 建立一个区域，在其中排除相同类型的其他单元格，这一过程称为平铺。此外， 单个细胞的神经突起表现出自我回避特性。与在中国取得的出色进展形成对比的是 关于决定视网膜细胞命运和分化的基因和机制的发现，人们知之甚少 关于视网膜中镶嵌图案和瓷砖过程的分子机制以及 在其他神经系统中。直到最近，研究表明在唐氏综合症细胞突变的小鼠中 黏附分子(DSCAM)、DSCAM样蛋白1(DSCAML1)、MEG10和PCDH，某些类型的视网膜 无长突细胞和神经节细胞在胞体间距和树突分枝方面存在缺陷，这 开始涉及特殊类别的细胞黏附分子(CAM)在调节这些方面的作用 脊椎动物视网膜中的突起。然而，我们还没有发现与这些有关的其他分子。 在近80种视网膜细胞类型和亚型中的每一种中进行处理，更重要的是，识别和 描述控制功能神经回路形成的整个基因和遗传路径。在……里面 过去，由于缺乏合适的分子，这个问题很难解决。在这里，我们在 缺乏BARHL2的小鼠，神经节细胞中的无长突细胞星状破裂 层内有聚集的树突和成团的细胞体，表明Barhl2‘S在自我回避中的作用。成为最好的 第一个参与神经元镶嵌图案化和拼接过程的转录因子，BARHL2提供了一个独特的 最终确定神经元镶嵌图案和瓦片形成的遗传路径的机会。在这 建议，我们将充分表征星暴无长突细胞的马赛克图案和瓦片表型。 Barhl2缺失视网膜的神经节细胞层。第二，为了恢复自我回避的遗传途径，我们 将Barhl2野生型和空星爆型无长突细胞的RNA-Seq和BARHL2芯片-Seq进行筛选 寻找Barhl2的下游靶基因，并鉴定调控TILLING和TILL的转录网络。 星爆无长突细胞的镶嵌图案化过程。总之，这些研究将确定Barhl2的作用 在调节星爆无长突细胞的瓦片和镶嵌图案过程中，并阐明了 发生在Barhl2下游的转录事件。

PROJECT SUMMARY Our accurate vision depends on the flow of visual information through precisely wired connections between axons and dendrites of different retinal neurons. In the retina, neurons occupy spatial domains and arborize their dendrites, which require the proper distribution of their cell bodies and dendritic arbors. Cell bodies of the same type of neurons are spaced out in a process called mosaic patterning, and their dendrites establish a zone within which other cells of the same type are excluded, a process called tiling. In addition, the neurites from an individual cell display self-avoidance properties. In contrast to the excellent progress made in discovering genes and mechanisms of retinal cell fate determination and differentiation, relatively little is known about the molecular mechanisms underlying the mosaic patterning and tiling processes in the retina as well as in other nervous systems. Not until recently, studies show that in mice mutant for Down syndrome cell adhesion molecule (DSCAM), DSCAM-LIKE1 (DSCAML1), MEG10, and PCDH, certain types of retinal amacrine and ganglion cells exhibit defects in the spacing of cell bodies and in the dendritic arborization, which begins to implicate the roles of unique classes of cell adhesion molecules (CAMs) in regulating these processes in the vertebrate retina. Nevertheless, we have yet to uncover the other molecules involved in these processes in each of the nearly 80 retinal cell types and subtypes, and more importantly, to identify and characterize the entire genes and genetic pathways that govern the formation of functional neural circuitry. In the past, this question has been hard to address due to the lack of a suitable molecule. Here, we show that in mice lacking BARHL2, a BAR-homeodomain transcription factor, starburst amacrine cells in the ganglion cell layer have aggregated dendrites and clumped cell bodies, indicating Barhl2's role in self-avoidance. Being the first transcription factor implicated in neuronal mosaic patterning and tiling processes, BARHL2 offers a unique opportunity to ultimately identify genetic pathways of neuronal mosaic patterning and tiling formation. In this proposal, we will fully characterize the mosaic patterning and tiling phenotypes of starburst amacrine cells in the ganglion cell layer of the Barhl2-null retina. Second, to recover the genetic pathway of self-avoidance, we will perform RNA-Seq of Barhl2 wild type and null starburst amacrine cells and BARHL2 ChIP-Seq to screen for downstream target genes of Barhl2 and to identify the transcriptional network regulating the tiling and mosaic patterning processes of starburst amacrine cells. Together, these studies will define the role of Barhl2 in regulating the tiling and mosaic patterning processes of starburst amacrine cells and elucidate the transcriptional events that occur downstream of Barhl2.