Cell specific roles of the endothelin system in glaucoma-relevant retinal ganglion cell death

青光眼是一种以视网膜神经节细胞（RGC）死亡和视神经损害为特征的视神经病变。 退化不幸的是，目前还没有专门针对神经变性的治疗方法。 确定负责疾病发作和进展的信号通路将是治疗疾病的重要一步。 开发有效的药物干预治疗神经退行性疾病。内皮素（EDN） 系统广泛表达于全身，参与生理和病理生理过程。 流程.现在有大量的证据表明EDN系统在人类和动物模型中存在 青光眼EDN系统的操作显著减少了一种遗传性和两种诱导性的RGC损失。 青光眼模型。EDN信号在视网膜和视神经乳头中也被上调， 青光眼高眼压模型中RGC死亡或功能障碍的迹象。尽管潜在的 EDN在神经退行性变中的重要性，EDN诱导RGC的分子机制 死亡是完全不确定的。特别是，上游调节器和下游效应器的作用， EDN系统未知。导致难以理解EDN信号传导如何在以下方面发挥作用： 神经退行性变是EDN受体Ednra和Ednrb在神经元上表达的事实。 视网膜和视神经头中的许多细胞类型，包括RGCs、星形胶质细胞、髓源性细胞 （小胶质细胞和巨噬细胞）和壁细胞（周细胞和平滑肌血管细胞）。此外，委员会认为， 已知EDN影响所有这些细胞的方式与在细胞中观察到的病理反应一致。 青光眼因此，为了理解青光眼中的EDN信号传导，需要EDN的组分 系统，受体和配体，必须系统地测试在肿瘤相关细胞，他们是 表示在。在这里，我们将测试这样一个假设，即定义EDN系统在RGC死亡中的作用将 识别青光眼发病机制的早期关键信号通路。为了实现这一目标， 定义EDN信号传导如何在脑卒中相关损伤后发挥作用，我们将1）定义其中的机制 EDN诱导的RGC死亡所需的RGC，2）决定受体、细胞类型和分子水平， 控制EDN诱导的RGC死亡的途径，以及3）确定哪些细胞类型和分子途径 负责产生致病性EDN配体。重要的是，此应用程序将侧重于 在单个细胞类型中的EDN系统，有条件地去除EDN组分并进行转录组学 对单个细胞类型的影响。总之，应用程序中概述的实验严格测试了一个长期存在的 关于EDN在青光眼中的作用的假设，并确定各种细胞类型和分子机制 控制肿瘤相关的致病性EDN信号传导。鉴于EDN的早期性质和已证实的作用， 这些实验将确定新的靶点， 在疾病发病的早期阶段对青光眼进行神经保护治疗。

Glaucoma is an optic neuropathy characterized by retinal ganglion cell (RGC) death and optic nerve degeneration. Unfortunately, there are no current treatments that specifically target neurodegeneration. Identifying the signaling pathways responsible for disease onset and progression will be an important step in developing effective pharmacologic interventions for glaucomatous neurodegeneration. The endothelin (EDN) system is widely expressed throughout the body and participates in both physiological and pathophysiological processes. There is now a large body of evidence implicating the EDN system in human and in animal models of glaucoma. Manipulation of the EDN system significantly lessens RGC loss in a genetic and two inducible models of glaucoma. Also EDN signaling is upregulated in both the retina and optic nerve head prior to any signs of RGC death or dysfunction in an ocular hypertensive model of glaucoma. Despite the potential importance of EDN in glaucomatous neurodegeneration, the molecular mechanisms of EDN-induced RGC death are completely undefined. In particular, the upstream regulators and the downstream effectors of the EDN system are not known. Contributing to the difficulty in understanding how EDN signaling plays a role in glaucomatous neurodegeneration is the fact that EDN receptors, Ednra and Ednrb, are expressed on numerous cell types in the retina and optic nerve head including RGCs, astrocytes, myeloid derived cells (microglia and macrophages), and mural cells (pericytes and smooth muscle vascular cells). Furthermore, EDN is known to affect all of these cells in ways that are consistent with pathological responses observed in glaucoma. Thus, in order to understand EDN signaling in glaucoma the requirement of components of the EDN system, both receptors and ligands, must be systematically tested in the glaucoma-relevant cells they are expressed in. Here, we will test the hypothesis that defining the role of the EDN system in RGC death will identify early, critical signaling pathways that underlie glaucoma pathogenesis. To accomplish this and to define how EDN signaling functions after glaucoma-relevant insults, we will 1) define the mechanisms within RGCs that are required for EDN-induced RGC death, 2) determine the receptor, cell type, and molecular pathway(s) controlling EDN-induced RGC death, and 3) determine which cell types and molecular pathways are responsible for producing pathogenic EDN ligands. Importantly, this application will focus on the role of the EDN system in individual cell types, conditionally removing EDN components and performing transcriptomics on individual cell types. Together, the experiments outlined in the application critically test a long-standing hypothesis about the role of EDN in glaucoma and identify the various cell types and molecular mechanisms controlling glaucoma-relevant pathogenic EDN signaling. Given the early nature and proven role of EDN signaling in glaucomatous neurodegeneration these experiments will identify novel targets for developing neuroprotective treatments for glaucoma at early stages of disease pathogenesis.