Ion Conductances in the Retinal Pigment Epithelium

视网膜色素上皮中的离子电导

• 批准号: 7583760
• 负责人: BRET A HUGHES
• 金额: $ 38.63万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-01-01 至 2013-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7583760
• 关键词: Affect; Apical; Arachidonic Acids; Biochemical; Calcium; Calmodulin; Carrier Proteins; Cell Volumes; Cells; Chemicals; Choroid; Cyclic AMP-Dependent Protein Kinases; Cytoplasm; Diffuse; Environment; Epithelium; Genes; Goals; Health; Hydrogen Peroxide; Image; Immunohistochemistry; Immunoprecipitation; Ion Channel; Ion Transport; Ions; Learning; Liquid substance; Location; Mediating; Membrane; Membrane Potentials; Metabolism; Molecular; Neurons; Outcome Study; Phagocytosis; Phosphatidylinositol 4,5-Diphosphate; Phospholipase C; Phosphorylation; Photoreceptors; Physiological; Physiology; Play; Potassium; Potassium Channel; Preparation; Process; Pump; Regulation; Retinal; Retinal Diseases; Role; Signal Pathway; Signal Transduction; Structure; Structure of retinal pigment epithelium; Swelling; Techniques; Testing; Transport Process; Tyrosine Phosphorylation; Vascular blood supply; Vitamin A; Water; Western Blotting; basolateral membrane; extracellular; insight; monolayer; oxidation; pH Homeostasis; public health relevance; receptor; receptor coupling; src-Family Kinases

DESCRIPTION (provided by applicant): The health and integrity of photoreceptors critically depend on the composition and volume of their extracellular microenvironment. Regulation of the ionic composition and volume of the subretinal space is accomplished by the transport of ions and water across the retinal pigment epithelium (RPE), a multifunctional monolayer of cells juxtaposed between the photoreceptor outer segments and the choroidal blood supply. RPE transport is the result of the coordinated activity of a diverse group of ion transport proteins and channels residing in its apical and basolateral membranes. With changes in retinal activity, chemical signals released by retinal cells diffuse to the RPE and initiate adjustments in its transport to compensate for alterations in the photoreceptor microenvironment. Disruption of these transport processes or their regulation may cause adverse changes in the subretinal space, contributing to retinal disease. These channels and transporters are also responsible for maintaining the intracellular composition of the RPE cell, which, if disturbed, could adversely affect other key RPE functions such as phagocytosis, the degradation of photoreceptor outer segments, and vitamin A transport and metabolism. Our overall goal is to understand the mechanisms by which potassium (K+) channels participate in the regulation of the volume and ionic composition of the fluid in both the subretinal space and the RPE cytoplasm. Recent studies have identified in the RPE an outwardly rectifying K+ current that resembles the M-type current in neurons. The specific aims of this proposal are to: (1) determine the subunit composition of KCNQ channels that underlie the M-type conductance in the RPE; (2) determine whether the M-type conductance is localized to the apical or basolateral membrane; (3) determine whether the M-type conductance is modulated by pharmacologic agents and signaling pathways known to modulate specific types of KCNQ channels; and (4) determine the role of the M-type conductance in the regulation of RPE cell volume. These aims will be pursued using a combination of molecular, biochemical, immunohistochemical, imaging, and electrophysiological techniques to investigate M-type channel structure, function, and regulation. The outcome of these studies will result in a better understanding of how these critically important transport proteins operate in the RPE to help maintain a healthy photoreceptor microenvironment. PUBLIC HEALTH RELEVANCE: The health and integrity of photoreceptors critically depend on the composition and volume of their extracellular microenvironment. Regulation of the ionic composition and volume of the subretinal space is accomplished by the transport of ions and water across the retinal pigment epithelium (RPE), a monolayer of cells juxtaposed between the photoreceptor outer segments and the choroidal blood supply. RPE transport is the result of the coordinated activity of a diverse group of ion transport proteins and channels residing in its membranes. With changes in retinal activity, chemical signals released by retinal cells diffuse to the RPE and initiate adjustments in its transport to compensate for alterations in the photoreceptor microenvironment. Disruption of these transport processes or their regulation may cause adverse changes in the subretinal space, contributing to retinal disease.

描述（由申请人提供）：光感受器的健康和完整性主要取决于其细胞外微环境的组成和体积。视网膜下腔的离子组成和体积的调节是通过离子和水穿过视网膜色素上皮（RPE）的运输来实现的，视网膜色素上皮是并置在光感受器外节和脉络膜血液供应之间的多功能单层细胞。RPE转运是位于其顶膜和基底外侧膜中的不同离子转运蛋白和通道组的协调活性的结果。随着视网膜活动的变化，视网膜细胞释放的化学信号扩散到RPE，并启动其运输的调整，以补偿感光细胞微环境的改变。这些运输过程或其调节的中断可能导致视网膜下腔的不利变化，从而导致视网膜疾病。这些通道和转运蛋白还负责维持RPE细胞的细胞内组成，如果受到干扰，可能会对其他关键RPE功能产生不利影响，例如吞噬作用、光感受器外节的降解以及维生素A转运和代谢。我们的总体目标是了解钾（K+）通道参与调节视网膜下腔和RPE细胞质中液体的体积和离子组成的机制。最近的研究已经确定在RPE中的向外整流K+电流，类似于神经元中的M型电流。本研究的具体目的是：（1）确定RPE中M型电导的基础KCNQ通道的亚基组成;（2）确定M型电导是否定位于顶膜或基底侧膜;（3）确定M型电导是否由已知调节特定类型KCNQ通道的药理学试剂和信号通路调节;（4）确定M型电导在RPE细胞体积调节中的作用。这些目标将使用分子，生物化学，免疫组织化学，成像和电生理技术的组合来研究M型通道的结构，功能和调节。这些研究的结果将有助于更好地了解这些至关重要的转运蛋白如何在RPE中发挥作用，以帮助维持健康的感光细胞微环境。公共卫生关系：光感受器的健康和完整性关键取决于其细胞外微环境的组成和体积。视网膜下腔的离子组成和体积的调节是通过离子和水穿过视网膜色素上皮（RPE）的运输来实现的，视网膜色素上皮是感光体外节和脉络膜血液供应之间并置的单层细胞。RPE转运是多种离子转运蛋白和存在于其膜中的通道的协调活性的结果。随着视网膜活动的变化，视网膜细胞释放的化学信号扩散到RPE，并启动其运输的调整，以补偿感光细胞微环境的改变。这些运输过程或其调节的中断可能导致视网膜下腔的不利变化，从而导致视网膜疾病。