Role of ER Stress in the Pathogenesis of Primary Open Angle Glaucoma

摘要 原发性开角型青光眼(POAG)是青光眼的最常见形式，通常伴有 由于小梁网(TM)未能维持正常的眼压水平而导致的眼压升高 房水流出。我们最近建立了一种新的转基因小鼠模型(TG-MYOCY437H)，该模型 表达突变的myoclin，已知的人类POAG的主要遗传原因，并复制人类 青光眼表型。重要的是，我们将内质网(ER)应激与 TG-MYOCY437H小鼠青光眼发病机制的研究错误折叠的肌球蛋白在内质网中积聚，诱导内质网 应激并激活保护性未折叠蛋白反应(UPR)。在UPR激活的同时，突变的肌球蛋白 还会诱导自噬，这是一种已知的降解蛋白质聚集体的溶酶体降解过程。然而， 未能清除Myocin聚集体可能是由于UPR不足和自噬功能受损，TM细胞 诱导内质网应激启动的细胞凋亡转录因子CHOP，可能进一步恶化内质网稳态 并导致TM功能障碍/丢失，升高眼压，导致POAG。目前的提议将进一步 探讨慢性内质网应激在霉菌素及非霉菌素相关发病机制中的作用 普阿格。在指导阶段，拟议的研究将确定未能激活 保护性UPR(ATF-6-/-)加剧青光眼表型，而干扰内质网应激诱导 细胞凋亡(CHOP-/-)可预防TG-MYOCY437H小鼠的青光眼。此外，我们将调查ER是否 应激在POAG供者的临死TM组织中被激活。在独立阶段，我们将 观察TM中内质网应激的诱导是否与眼压升高有关 地塞米松致高眼压。此外，我们还将研究自噬在退化中的作用。 并将确定雷帕霉素诱导自噬是否能挽救青光眼 Tg-MYOCY437H小鼠。具体地说，应试者将学习并生成新的ER压力模型 ATF6和CHOP基因敲除小鼠，产生诱导多能干细胞(IPSCs)来源的小梁网- 类似POAG患者的细胞，并表征地塞米松诱导的高眼压小鼠模型 在瓦尔·谢菲尔德博士的实验室里。此外，在指导阶段，候选人将继续他的 通过咨询委员会的持续指导，实现职业发展的专业化和科学化。他 将参加科学会议，并与ER应激专家Thomas Rutkowski博士和青光眼合作 临床专家李·阿尔沃德博士。他还将获得教学经验。该项目将促进继续 对应聘者进行技术、智力和专业培训，并协助应聘者建立 一个学术研究机构的独立研究实验室。

Abstract Primary open angle glaucoma (POAG), the most common form of glaucoma, is usually accompanied by elevated intraocular pressure (IOP) due to failure of the trabecular meshwork (TM) to maintain normal levels of aqueous humor outflow. We recently generated a novel transgenic murine model (Tg-MYOCY437H) that expresses mutant myocilin, a known leading genetic cause of POAG in humans and replicates human glaucoma phenotypes. Importantly, we have associated endoplasmic reticulum (ER) stress to the pathogenesis of glaucoma in Tg-MYOCY437H mice. Misfolded myocilin accumulates in the ER, induces ER stress and activates a protective unfolded protein response (UPR). Along with UPR activation, mutant myocilin also induces autophagy, a process of lysosomal degradation known to degrade protein aggregates. However, failure to eliminate myocilin aggregates possibly due to insufficient UPR and impaired autophagy, TM cells induce the ER stress-initiated apoptotic transcriptional factor, Chop, which may further worsen ER homeostasis and cause TM dysfunction/loss, elevating IOP and resulting in POAG. The current proposal will further investigate the role of chronic ER stress in the pathogenesis of myocilin as well as non-myocilin associated POAG. During the mentored phase, the proposed studies will determine whether failure to activate the protective UPR (Atf-6¿-/-) exacerbates glaucoma phenotypes, whereas interference with ER stress-induced apoptosis (Chop-/-) prevents glaucoma in Tg-MYOCY437H mice. In addition, we will investigate whether ER stress is activated in port-mortem TM tissues from POAG donors. During the independent phase, we will examine whether induction of ER stress in the TM is associated with elevation of IOP in a mouse model of dexamethasone-induced ocular hypertension. In addition, we will examine the role of autophagy in degradation of myocilin aggregates and will determine whether inducing autophagy by rapamycin will rescue the glaucoma of Tg-MYOCY437H mice. Specifically, the candidate will learn and generate new models of ER stress using Atf6¿ and Chop knockout mice, generate induced pluripotent stem cells (iPSCs)-derived trabecular meshwork- like cells from POAG patients, and characterize a dexamethasone-induced ocular hypertension mouse model in the laboratory of Dr. Val Sheffield. Additionally, during the mentored phase, the candidate will continue his professional and scientific career development through continual guidance from the advisory committee. He will attend scientific conferences, and collaborate with ER stress expert, Dr. Thomas Rutkowski and glaucoma clinical expert, Dr. Lee Alward. He will also acquire teaching experience. This project will facilitate continued technical, intellectual, and professional training of the candidate, and assist the candidate in the establishment of an independent research laboratory at an academic research institute.