Genetic Underpinnings of ipRGC Diversity

项目摘要 光是一个非常重要的调节生理和行为在广泛的生物体。光 信息通过不同的视网膜神经节细胞类型传递到大脑中大约50个不同的目标。的 表达黑视素的内在光敏视网膜神经节细胞（ipRGC）占约40-50个中的6个。 小鼠视网膜中存在的视网膜神经节细胞类型。M1-M6 ipRGC由以下的不同互补物定义： 亚型定义的形态学、生理学和转录特征。然而，这种细胞是如何 多样性在很大程度上是未知的。这项提案将调查的分子基础， ipRGC多样性。综合研资局亦是研究较大型研资局的多元化的一个极佳缩影 因为1）ipRGC可以用多种现有的遗传工具特异性地操纵，2） 转录谱分析揭示了指定ipRGC亚型的基因表达程序，和3） ipRGC亚型形态学、生理学、中枢投射和在行为中的作用的多样性是一个广泛的， RGC的亚型定义特征的代表性子样本。因此，ipRGC是可接近的， 具有代表性和遗传可塑性的人群，研究细胞多样性。在 在下面概述的实验中，我们将通过结合靶向的、单个的和/或多个的靶向的、单个的靶向的、单个的和/或多个的靶向的、单个的靶向的、单个的和/或多个的靶向的、单个的和/或多个的靶向的、单个的和/或多个的靶向的、单个的和/或多个的靶向的、单个的靶向的、单个的和/或多个的靶向的靶向的、单个的和/或多个的靶向的靶向的， 使用强大的大规模转录组学方法对ipRGC形态学和生理学进行细胞测量 在新的遗传模型中，以评估如何建立全系列ipRGC亚型。Brn 3b（Pouf 42）是一种 转录因子参与RGC特化，并且其表达在ipRGC亚型中维持到成人 阶段，在那里它准备影响发育和成人的基因表达程序，从而产生 ipRGC的子类型定义属性。这项提议将检验Brn 3b积极塑造 ipRGC亚型的形态学、生理学和转录特性。在目标1中，我们将使用新 小鼠品系，以在发育和成年期间操纵ipRGC中的Brn 3b表达， 增加或减少Brn 3b水平对ipRGC的形态生理学特征的影响。在目标2中 我们将确定Brn 3b在整个视网膜发育过程中以及在 个体ipRGC亚型。令人兴奋的是，我们的初步数据表明，在ipRGC中Brn 3b表达水平 亚型不仅与多种ipRGC特征相关，而且还积极调节ipRGC的定义特征 亚型，表明Brn 3b在整个发育和成年期被重新利用，以微调ipRGC回路。 结构和功能。这些研究将产生一个蓝图，以了解如何模式化的 转录程序在视网膜和神经系统中建立了不同的细胞身份。

PROJECT SUMMARY Light is a profoundly important regulator of physiology and behavior across a wide range of organisms. Light information is relayed via diverse retinal ganglion cell types to approximately 50 distinct targets in the brain. The melanopsin-expressing, intrinsically photosensitive retinal ganglion cells (ipRGCs) represent 6 of the ~40-50 retinal ganglion cell types present in the mouse retina. M1-M6 ipRGCs are defined by a distinct complement of subtype-defining morphological, physiological, and transcriptional characteristics. However, how this cellular diversity is achieved is largely unknown. This proposal will investigate the molecular underpinnings of ipRGC diversity. ipRGCs also represent an excellent microcosm for studying diversity in the larger RGC population because 1) ipRGCs can be specifically manipulated with multiple, existing genetic tools, 2) transcriptional profiling has revealed gene expression programs that designate ipRGC subtypes, and 3) the diversity of ipRGC subtype morphology, physiology, central projections, and roles in behavior are a broad, and representative subsample of subtype-defining features of RGCs. Thus, ipRGCs are an approachable, representative, and genetically malleable population in which to study cellular diversity. In the experiments outlined below, we will exploit the advantages of the ipRGC system by combining targeted, single cell measurements of ipRGC morphology and physiology with powerful, large-scale transcriptomic approaches in new genetic models to assess how the full range of ipRGC subtypes are established. Brn3b (Pouf42) is a transcription factor involved in RGC specification, and its expression is maintained in ipRGC subtypes into adult stages, where it is poised to influence developmental and adult gene expression programs that give rise to the subtype-defining properties of ipRGCs. This proposal will test the hypothesis that Brn3b actively shapes the morphological, physiological, and transcriptional identity of ipRGC subtypes. In Aim 1 we will use new mouse lines to manipulate Brn3b expression in ipRGCs during development and adulthood to determine the consequences of increasing or reducing Brn3b levels on the morphophysiological features of ipRGCs. In Aim 2 we will determine the roles of Brn3b in shaping gene expression patterns across retinal development and within individual ipRGC subtypes. Excitingly, our preliminary data indicate that Brn3b expression levels in ipRGC subtypes not only correlate with multiple ipRGC features, but also actively regulate defining features of ipRGC subtypes, suggesting that Brn3b is repurposed throughout development and adulthood to fine-tune ipRGC circuit structure and function. These studies will generate a blueprint for understanding how the patterning of transcriptional programs establishes diverse cellular identities in the retina and nervous system.