Supplement to: Transcription control of retinal neuron specification and maturation

补充：视网膜神经元规范和成熟的转录控制

• 批准号: 10429697
• 负责人: Kevin Wright
• 金额: $ 7.32万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-01-01 至 2024-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10429697
• 关键词: ATAC-seq; Adopted; Affect; Amacrine Cells; Axon; Cellular Morphology; Defect; Development; Disease; Genes; Genetic; Genomic approach; Individual; Injury; Inner Plexiform Layer; Morphology; Nervous system structure; Neurons; Pathway interactions; Pattern; Population; Property; Regulator Genes; Retina; Shapes; Signal Transduction; Specific qualifier value; Stereotyping; Stratification; Testing; Transcriptional Regulation; Visual; experimental study; gain of function; homeodomain; inhibitory neuron; insight; programs; public health relevance; regenerative therapy; retinal neuron; selective expression; starburst amacrine cell; transcription factor; transcriptome sequencing; virtual

PROJECT SUMMARY/ABSTRACT Amacrine cells (ACs) are the principle inhibitory neurons of the inner retina, with at least 45 morphologically distinct subtypes that can be distinguished by the size, shape, and stratification of their dendritic arbors within the inner plexiform layer (IPL). Most ACs do not have axons, and instead integrate signaling across their dendritic arbors. This unique arrangement means that form and function are intimately related in ACs, perhaps more so than in any other neuron type. However, we know virtually nothing about how individual AC subtypes are specified during development, or how their adopt their stereotyped morphologies. We hypothesize that selectively expressed transcription factors (TFs) are well poised to direct subtype-specific genetic programs that specify and direct the morphological maturation of ACs. Within the AC population, the homeodomain TF Isl1 is only expressed in starburst amacrine cells (SACs) and Gbx2 is only expressed in a previously unidentified population of medium-field non-GABAeric, non-Glycinergic ACs (MF-nGnGs). Our preliminary results show that early deletion of Isl1 or Gbx2 from AC precursors results in defects in SAC and MF-nGnG subtype specification, respectively. Later deletion of Isl1 or Gbx2 in post-migratory SACs or MF-nGnGs alters their dendritic morphology and stratification patterns. Therefore, Isl1 and Gbx2 appear to be required for the initial specification and the subsequent morphological maturation of their respective AC subtypes. We will test this in the following Specific Aims: 1) Determine whether Isl1 and Gbx2 are necessary and sufficient for AC subtype specification and maturation. We will use conditional loss- and gain-of function approaches to determine whether Isl1 and Gbx2 are both necessary and sufficient to initiate and maintain terminal differentiation in SACs and MF-nGnGs, respectively. Furthermore, we will use a combination of genomic approaches (RNASeq, ATACseq) to identify the Isl1 and Gbx2 gene regulator networks in the respective AC subtypes. 2) Define how Isl1 and Gbx2 regulate SAC and MF-nGnG morphology and functional connectivity. We will first identify how the loss of Isl1 in SACs and Gbx2 in MF-nGnGs affects the development of their stereotyped dendritic morphology and stratification patterns. Then we will test candidate effector genes and pathways for their involvement in the establishment of dendritic arbors. Finally, we will determine how the loss of Isl1 and Gbx2 affects the functional connectivity of SACs and MF-nGnGs in visual circuits. Together, these experiments are expected to reveal how selectively expressed transcription factors specify AC subtypes and drive terminal differentiation programs that endow ACs with their unique morphological properties. We expect that these findings will reveal principles that are broadly applicable across the developing nervous system.

项目摘要/摘要 无长束细胞（ACS）是内部视网膜的原理抑制性神经元，至少45个形态学 不同的亚型可以通过其树突状乔木的大小，形状和分层来区分 内丛状层（IPL）。大多数AC没有轴突，而是整合了信号 树突状乔木。这种独特的安排意味着形式和功能在ACS中密切相关， 也许比其他任何神经元类型都更重要。但是，我们几乎不知道个人AC 在开发过程中指定了亚型，或者如何采用其刻板印象的形态。我们假设 选择性表达的转录因子（TFS）已很好地直接指导亚型特异性遗传程序 指定和指导ACS的形态成熟。在AC人群中，同源域TF ISL1仅在Starburst Amacrine细胞（SAC）中表达，而GBX2仅在先前未识别的 中型非gabaeric，非糖激素ACS（MF-NGNGS）的种群。我们的初步结果显示 从交流前体中ISL1或GBX2的早期删除会导致SAC和MF-NGNG亚型的缺陷 规格分别。后来删除术后囊中的ISL1或GBX2或MF-NGNGS改变了它们 树突形态和分层模式。因此，ISL1和GBX2似乎是必需的 规格和随后的AC亚型的形态成熟。我们将在此测试 以下特定目的：1）确定ISL1和GBX2是否需要AC亚型的必要且足够 规范和成熟。我们将使用有条件的损失和获取功能方法来确定 ISL1和GBX2是否必要且足以启动和维持终端分化 SAC和MF-NGNGS。此外，我们将使用基因组方法的组合（RNASEQ， atacseq）识别相应的AC亚型中的ISL1和GBX2基因调节器网络。 2）定义如何 ISL1和GBX2调节SAC和MF-NGNG形态和功能连接性。我们将首先确定如何 MF-NGNG中SAC和GBX2中ISL1的损失会影响其定型树突状的发展 形态和分层模式。然后，我们将测试候选效应子基因和途径 参与树突状乔木的建立。最后，我们将确定ISL1和GBX2的损失 影响视觉电路中SAC和MF-NGNG的功能连通性。在一起，这些实验是 期望揭示如何选择性表达的转录因子指定AC亚型和驱动端子 分化程序赋予其独特的形态学特性。我们希望这些 调查结果将揭示在发展中神经系统中广泛适用的原则。