Autophagy and Mechanotransduction in the Trabecular Meshwork

摘要 小梁网络(TM)常规流出通路的功能衰竭导致 眼压(IOP)，从而增加患原发性开角型青光眼(POAG)和 与年龄有关的疾病是不可逆转失明的第二大原因。负责的动态平衡机制 对于眼压的调节及其在青光眼中的相关变化，目前还知之甚少。 由于眼压升高和其他力量，小梁网(TM)中的细胞不断受到 对机械疲劳的影响。为了保持细胞功能和恢复动态平衡，细胞必须感知和适应 这些形态上的变化。我们和其他人已经证明，机械应力可以触发 TM细胞的广泛反应；然而，对TM细胞使用的策略了解很少 对这种压力做出反应，这样它们才能适应并生存下来。 自噬，一种溶酶体的降解途径，已经成为一种重要的细胞内稳态机制。 促进细胞存活和适应一系列细胞毒性应激。我们的实验室已经报告了 TM细胞在静态双轴应变和高压下自噬的激活。而且，我们最新的 数据还表明，伴侣辅助的选择性自噬激活，这是最近发现的一种紧张- 在周期性机械应力作用下，TM细胞发生机械转导所必需的自噬。 我们假设自噬是TM细胞对应变的综合反应的一部分， 在修复和机械转导中发挥双重作用。我们进一步假设，这种失调 反应有助于青光眼流出物中ECM沉积和僵硬的增加 路径。因此，我们认为激活自噬可以代表一种新的治疗方法。 高眼压和青光眼的治疗。为了检验这一假设，我们将(1)描述 机械应力和高压诱导TM细胞自噬并确定其 在TM细胞中对拉伸诱导的反应的贡献；(2)评估自噬在调节 转化生长因子β介导的机械性损伤促纤维化反应；(3)药理作用评价 自噬激活剂，以减少ECM沉积，恢复流出途径功能。我们预料到 该项目的完成将有助于进一步了解自噬在人类免疫系统中的作用 流出途径、组织生理学和病理生理学。最重要的是，我们的研究有可能 寻找治疗高眼压和青光眼的新靶点。

ABSTRACT Functional failure of the trabecular meshwork (TM) conventional outflow pathway causes elevation in intraocular pressure (IOP), thus increasing the risk for developing primary open angle glaucoma (POAG) an age-related disease second leading cause of irreversible blindness. The homeostatic mechanisms responsible for IOP regulation and those associated with its alteration in glaucoma remain yet poorly understood. Because of elevation in IOP and other forces, cells in the trabecular meshwork (TM) are constantly subjected to mechanical strain. In order to preserve cellular function and regain homeostasis, cells must sense and adapt to these morphological changes. We and others have already shown that mechanical stress can trigger a broad range of responses in TM cells; however, very little is known about the strategies that TM cells use to respond to this stress, so they can adapt and survive. Autophagy, a lysosomal degradation pathway, has emerged as an important cellular homeostatic mechanism promoting cell survival and adaptation to a number of cytotoxic stresses. Our laboratory has reported the activation of autophagy in TM cells in response to static biaxial strain and high pressure. Moreover, our newest data also suggest the activation of chaperon-assisted selective autophagy, a recently identified tension- induced autophagy essential for mechanotransduction, in TM cells under cyclic mechanical stress. We hypothesize that autophagy is part of an integrated response triggered in TM cells in response to strain, exerting a dual role in repair and mechanotransduction. We further hypothesize that dysregulation of this response contributes to the increased ECM deposition and stiffness reported in the glaucomatous outflow pathway. We propose that activation of autophagy can, therefore, represent a novel therapeutic approach for the treatment of ocular hypertension and glaucoma. To test this hypothesis, we will (1) characterize the induction of autophagy in TM cells in response to mechanical stress and high pressure and determine its contribution to the stretch-induced response in TM cells; (2) assess a role of autophagy in modulating the TGFβ-mediated pro-fibrotic response to mechanical injury, and (3) evaluate the ability of pharmacological activators of autophagy to decrease ECM deposition and restore outflow pathway function. We anticipate that completion of this project will definitively contribute to a further understanding of the role of autophagy in outflow pathway tissue physiology and pathophysiology. Most importantly, our studies have the potential of identifying a novel therapeutic target for the treatment of ocular hypertension and glaucoma.