Ion Conductances in the Retinal Pigment Epithelium

视网膜色素上皮中的离子电导

• 批准号: 8197365
• 负责人: BRET A HUGHES
• 金额: $ 36.71万
• 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/8197365
• 关键词: Affect; 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; apical membrane; basolateral membrane; extracellular; insight; monolayer; oxidation; pH Homeostasis; receptor; receptor coupling; src-Family Kinases

ABSTRACT 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.

摘要 光感受器的健康和完整性关键取决于其细胞外基质的组成和体积。 微环境。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， 在感光器外节和脉络膜血液供应之间并列的细胞。RPE运输是 这是一组不同的离子转运蛋白和位于其上的通道的协调活性的结果。 顶膜和基底外侧膜。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的改变 微环境这些运输过程或其调节的中断可能会导致 视网膜下间隙，导致视网膜疾病。这些渠道和运输商还负责 维持RPE细胞的细胞内组成，如果受到干扰，可能会对其他关键因素产生不利影响。 RPE功能如吞噬作用、光感受器外节的降解和维生素A 运输和新陈代谢。我们的总体目标是了解钾（K+） 通道参与调节视网膜下和视网膜下的流体的体积和离子组成。 空间和RPE细胞质。最近的研究已经确定在RPE中存在向外整流的K+电流 类似于神经元中的M型电流本提案的具体目标是：（1）确定 KCNQ通道的亚基组成是RPE中M型电导的基础;（2）确定 M型电导是否位于顶膜或基底侧膜;（3）确定M型电导是否位于顶膜或基底侧膜。 M型电导是由药理学试剂和已知的调节信号通路调节的。 特定类型的KCNQ通道;（4）确定M型电导在调节 RPE细胞体积。这些目标将使用分子，生物化学， 免疫组织化学、成像和电生理技术来研究M型通道结构， 功能和监管。这些研究的结果将使人们更好地了解这些 一种至关重要的转运蛋白在RPE中起作用，以帮助维持健康的感光细胞 微环境。