Novel Target for Ciliary Epithelium Transport Regulation

睫状上皮运输调节的新目标

• 批准号: 6899784
• 负责人: Kathleen J Sweadner
• 金额: $ 17.3万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-05-01 至 2006-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6899784
• 关键词: biological signal transduction; epithelium; glaucoma; immunoprecipitation; intraocular aqueous flow; laboratory mouse; laboratory rat; membrane proteins; molecular pathology; optic nerve; phosphorylation; protein binding; protein kinase; protein purification; protein structure function; sodium potassium exchanging ATPase; uvea ciliary body

DESCRIPTION (provided by applicant): Once high intraocular pressure is detected, one way that glaucoma can be prevented and treated is by reducing the rate of secretion of intraocular fluid in an effort to reduce net intraocular pressure. Current drug therapies have some shortcomings, however, and it would be preferable to have a target that has a more unique role in the control of intraocular fluid secretion. This pilot research grant application proposes to test the new hypothesis that phospholemann, a small membrane protein that is phosphorylated by multiple protein kinases, could be such a target. We show that in the anterior segment of the eye, phospholemann is expressed specifically in the non-pigmented layer of the ciliary epithelium and co-localizes with Na,K-A TPase, the active transport enzyme that provides the driving force for fluid secretion. In the similar secretory organ of the brain ventricles, the choroid plexus, phospholemann is associated in a complex with the Na,K-ATPase. Phospholemman is a homolog of two other proteins that have been shown to associate with and modulate Na,K-ATPase in the kidney. We will test the hypothesis that phospholemann binds to Na,K-ATPase in ciliary epithelium, and that it is phosphorylated by protein inases that are implicated in the regulation of intraocular fluid secretion. Two different strains of mutant mice will be used to evaluate phospholemann's role in glaucoma. In one strain, DBA/2J, progressive symptoms of glaucoma develop because of blockage of the outflow pathway, mimicking human glaucomas. We will assess compensatory and pathological changes in phospholemman and in the Na,K-ATPase itself. The other strain is a knockout of phospholemann. We will investigate the ciliary body, retina, and optic nerve for evidence of damage from a deficiency in the regulation of intraocular fluid secretion. The idea that phospholemann and its homologs may be regulators of Na,K-ATPase is quite new, and as an intermediate of signal transduction, phospholemman may integrate the activation of multiple signaling pathways. If successful the work promises to lead to a new paradigm for understanding the regulation and pharmacological control of intraocular fluid secretion.

描述（由申请人提供）：一旦检测到高眼内压，预防和治疗青光眼的一种方法是通过降低眼内液的分​​泌速率来努力降低净眼内压。然而，目前的药物疗法存在一些缺点，最好有一个在控制眼内液分泌方面具有更独特作用的靶点。这项试点研究拨款申请旨在测试新的假设，即磷酸化曼（一种被多种蛋白激酶磷酸化的小膜蛋白）可能是这样的目标。我们发现，在眼睛的前段，phospholemann 在睫状上皮的非色素层中特异性表达，并与 Na,K-A TPase（为液体分泌提供驱动力的主动转运酶）共定位。在脑室的类似分泌器官脉络丛中，磷化氢与 Na,K-ATP 酶形成复合物。 Phospholemman 是另外两种蛋白质的同源物，这两种蛋白质已被证明与肾脏中的 Na,K-ATP 酶相关并对其进行调节。我们将检验这样的假设：phospholemann 与睫状上皮中的 Na,K-ATP 酶结合，并且它被参与眼内液分泌调节的蛋白酶磷酸化。两种不同品系的突变小鼠将用于评估 Phosolemann 在青光眼中的作用。在一种菌株 DBA/2J 中，由于流出途径的阻塞而出现青光眼的进行性症状，类似于人类青光眼。我们将评估磷酸膜和 Na,K-ATP 酶本身的代偿性和病理性变化。另一种菌株是 Phosholemann 的敲除菌株。我们将检查睫状体、视网膜和视神经，寻找因眼内液分泌调节缺陷而受损的证据。 Phosolemann 及其同系物可能是 Na,K-ATPase 调节剂的观点是相当新的，作为信号转导的中间体，Phospolemann 可能整合多个信号通路的激活。如果成功，这项工作有望为理解眼内液分泌的调节和药理学控制提供一个新的范式。