Novel Target for Ciliary Epithelium Transport Regulation

睫状上皮运输调节的新目标

• 批准号: 6735625
• 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/6735625
• 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，可以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以努力降低净眼内压。然而，目前的药物疗法具有一些缺点，并且优选具有在控制眼内流体分泌中具有更独特作用的靶标。这项试点研究资助申请提出了一个新的假设，即磷脂曼，一种被多种蛋白激酶磷酸化的小膜蛋白，可能是这样一个目标。我们发现，在眼前段的眼睛，磷脂是专门表达在睫状体上皮的非色素层和共定位与钠，钾-A凝血酶，主动运输酶，提供了流体分泌的驱动力。在脑室的类似分泌器官脉络丛中，磷脂曼与Na，K-ATP酶复合。Phospholemman是另外两种蛋白质的同源物，已显示其与肾脏中的Na，K-ATP酶相关并调节该酶。我们将检验磷脂酶与睫状体上皮中的Na，K-ATP酶结合的假设，以及磷脂酶被参与眼内液分泌调节的蛋白激酶磷酸化的假设。两种不同品系的突变小鼠将被用来评估磷脂曼在青光眼中的作用。在一种菌株DBA/2 J中，由于流出通路的阻塞，青光眼的进行性症状发展，模仿人类青光眼。我们将评估磷脂酶和Na，K-ATP酶本身的代偿和病理变化。另一种是敲除磷脂曼的菌株。我们将研究睫状体、视网膜和视神经，以寻找眼内液体分泌调节缺陷造成损害的证据。磷脂曼及其同系物可能是Na，K-ATP酶的调节因子，这一观点较新，磷脂曼作为信号转导的中间体，可能整合了多种信号通路的激活。如果成功的话，这项工作有望为理解眼内液体分泌的调节和药理学控制提供一个新的范例。