Transient Receptor Potential Channels and Retinal Ganglion Cell Death in Glaucoma

青光眼中的瞬时受体电位通道和视网膜神经节细胞死亡

• 批准号: 7870313
• 负责人: David J. Calkins
• 金额: $ 30.39万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-01 至 2011-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7870313
• 关键词: Affect; Aging; Agonist; Apoptosis; Applied Genetics; Axon; Blindness; Capsaicin; Cell Death; Cessation of life; Degenerative Disorder; Dependence; Disease; Event; Exposure to; Genes; Glaucoma; Goals; Hydrostatic Pressure; Image; In Vitro; Individual; Injury; Knock-out; Knockout Mice; Laboratories; Length; Link; Measures; Molecular; Neurodegenerative Disorders; Neurons; Physiologic Intraocular Pressure; Population; Predisposition; Preparation; Relative (related person); Retina; Retinal; Retinal Ganglion Cells; Risk Factors; Site; Somatic Cell; Spatial Distribution; System; TRPV1 gene; Testing; Time; Translating; Vanilloid; Work; axonal degeneration; base; extracellular; gain of function; loss of function; neurobiological mechanism; neuronal cell body; new therapeutic target; pressure; prevent; public health relevance; receptor; response; standard care; tool

DESCRIPTION (provided by applicant): Our long-term objective is to understand the early molecular events leading to the death of retinal ganglion cells (RGCs) and their axons in glaucoma. The defining feature of glaucoma is sensitivity to intraocular pressure (IOP), and elevated IOP represents a significant risk factor for the disease. Lowering IOP pharmacologically is the standard treatment to slow the disease, but there is no cure because the neurobiological mechanisms linking RGC degeneration to pressure remain unresolved. The death of RGCs in glaucoma demonstrates key aspects of neuronal death in other degenerative diseases, most prominently somatic (cell body) loss via apoptosis and axonal degeneration. In other diseases, somatic and axonal degenerative are often linked to elevated intracellular Ca2+, and Ca2+-dependent cascades are also likely to contribute to RGC degeneration in glaucoma. Our studies demonstrate that for RGCs exposed to elevated pressure in culture, rapidly increased intracellular Ca2+ predicates both somatic and axonal loss. These observations raise the questions of whether pressure-induced RGC death is dependent on increased intracellular Ca2+ and, if so, what is the mechanism of this dependence. We have hypothesized that pressure-induced RGC degeneration involves the activation of a mechanosensitive channel that directly gates an increase in intracellular Ca2+. In support of this hypothesis, we recently identified in RGCs the capsaicin-sensitive, vanilloid-1 transient receptor potential (TRPV1) channel. TRPV1 is characterized by a robust Ca2+ conductance that contributes to pressure sensitivity and Ca2+-dependent cell death in other systems. Here we will probe the relationships between pressure-induced changes in intracellular Ca2+, RGC death and TRPV1 activation using an in vitro preparation of purified RGCs optimized for studying somatic degeneration and a retinal explant preparation optimized for studying axonal degeneration ex vivo. By applying pharmacological tools to these systems we will (1) test the Ca2+-dependence of pressure-induced RGC degeneration and the contribution of TRPV1 to pressure-induced increases in RGC intracellular Ca2+ and (2) determine the dependence of pressure-induced RGC degeneration on TRPV1 activation. Finally, by applying genetic tools for gene inhibition and over-expression developed in our laboratory and a TRPV1 knock-out mouse we will (3) test the relationship between TRPV1 expression and RGC susceptibility to pressure-induced degeneration. PUBLIC HEALTH RELEVANCE:. With the aging of the population, glaucoma will afflict nearly 80 million people worldwide by 2020, making the disease the leading cause of irreversible blindness. Glaucoma remains incurable, largely because our understanding of how pressure sensitivity translates to RGC degeneration is incomplete. The work proposed here will explore a viable molecular mechanism for contributing to RGC susceptibility to pressure-related injury and test its relevance as a novel therapeutic target.

描述（由申请人提供）：我们的长期目标是了解导致视网膜神经节细胞（RGC）及其轴突在青光眼中死亡的早期分子事件。青光眼的定义特征是对眼内压（IOP）的敏感性，IOP升高代表了该疾病的重要危险因素。在药理学上降低IOP是减慢疾病的标准治疗方法，但是无法治愈，因为将RGC变性与压力联系起来的神经生物学机制仍然无法解决。 RGC在青光眼中的死亡证明了其他退化性疾病中神经元死亡的关键方面，这是通过细胞凋亡和轴突变性而显着的细胞（细胞体）丧失。在其他疾病中，体细胞和轴突变性通常与细胞内Ca2+升高有关，而Ca2+依赖性级联反应也可能导致青光眼的RGC变性。我们的研究表明，对于暴露于培养的压力升高的RGC，迅速增加了细胞内Ca2+谓词，均可体细胞和轴突损失。这些观察结果提出了压力诱导的RGC死亡是否取决于增加的细胞内Ca2+的问题，如果是的，则该依赖性的机制是什么。我们假设压力诱导的RGC变性涉及一个直接大门增加细胞内Ca2+的机械敏感通道的激活。为了支持这一假设，我们最近在RGC中鉴定出辣椒素敏感的香草-1瞬态受体电位（TRPV1）通道。 TRPV1的特征是强大的Ca2+电导，在其他系统中有助于压力灵敏度和Ca2+依赖性细胞死亡。在这里，我们将使用优化用于研究躯体变性的纯化RGC的体外制备，探测压力诱导的细胞内Ca2+，RGC死亡和TRPV1激活之间的关系，以研究轴突变性，以研究轴突变性，以研究轴突变性。通过将药理学工具应用于这些系统，我们将（1）测试压力诱导的RGC变性的Ca2+依赖性，以及TRPV1对RGC细胞内Ca2+的压力诱导增加的贡献，并（2）确定压力诱导的RGC变性对TRPV1激活的依赖性。最后，通过在我们的实验室和TRPV1敲除小鼠中开发的基因抑制和过表达来应用遗传工具，我们将（3）测试TRPV1表达与RGC对压力诱导变性的敏感性之间的关系。公共卫生相关性：随着人口的衰老，到2020年，青光眼将在全球范围内将近8000万人折磨，这使该疾病成为不可逆转的失明的主要原因。青光眼仍然无法治愈，这主要是因为我们对压力敏感性如何转化为RGC变性的理解是不完整的。这里提出的工作将探索一种可行的分子机制，以导致RGC易感性损伤的敏感性，并将其作为一种新型治疗靶标的相关性。