Retinal degeneration and chloride channels

视网膜变性和氯离子通道

• 批准号: 8425046
• 负责人: H. CRISS HARTZELL
• 金额: $ 33.13万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-08-01 至 2015-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8425046
• 关键词: Adult; Affect; Anions; Blindness; CLCA2 gene; Categories; Cell Line; Cells; Chloride Channels; Chloride Ion; Chlorides; Clinical Pathology; Conflict (Psychology); Coupled; Data; Defect; Degenerative Disorder; Disease susceptibility; Etiology; Eye; Family; Functional disorder; Gene Mutation; Genes; Genetic Models; Goals; Homeostasis; Human; Image; Inherited; Ion Channel; Knock-out; Knowledge; Light; Measures; Mental Health; Modeling; Molecular; Monkeys; Mus; Mutation; Pathway interactions; Persons; Physiological; Physiology; Play; Primates; Property; Proteins; RNA Splicing; Regulation; Research; Retina; Retinal; Retinal Degeneration; Retinal Diseases; Role; Signal Pathway; Signal Transduction; Structure of retinal pigment epithelium; Testing; Time; Transgenic Mice; Variant; Vision; Visual impairment; Vitelliform macular dystrophy; Work; base; basolateral membrane; economic impact; fetal; inherited retinal degeneration; inhibitor/antagonist; innovation; insight; mouse model; mutant mouse model; patch clamp; voltage

DESCRIPTION (provided by applicant): Retinal diseases affect an estimated 1 in 28 people in the US, and have a huge personal and economic impact. This application will investigate a rapidly-growing category of inherited retinal degenerations termed bestrophinopathies. Bestrophinopathies are caused by mutations in the human bestrophin-1 gene (hBest1). hBest1 mutations produce a panoply of both dominantly- and recessively-inherited retinal degenerations presenting a diverse range of clinical pathologies. It is well-established that hBest1 encodes a Ca-activated chloride channel (CaCC) that is expressed in the basolateral membrane of the retinal pigment epithelium (RPE) and that bestrophinopathies are characterized by a reduction in the electro-oculogram light peak that is generated by an RPE CaCC. These observations have led to the "CaCC hypothesis" for bestrophinopathies. Although considerable data supports the idea that bestrophinopathies are caused by defects in chloride transport by Best1, studies on knockout and knockin-mutant mouse models have provided strongly conflicting conclusions. The goal of this project is to examine in depth the CaCC hypothesis of bestrophinopathies. We will explore in detail the molecular mechanisms of the light peak to establish the ionic mechanisms underlying the light peak, from the Ca signals that initiate it to the anion channels that generate it. Our hypothesis is that the CRAC channel Orai-1 is responsible for the Ca influx that activates the Ca-activated anion channel Tmem16a/Ano1 to generate the light peak. We hypothesize that Best1 mutations reduce the light peak by two mechanisms: interacting with and regulating Ano1 activity and by altering Ca signaling. These studies will be accomplished using a combination of patch clamp recording and state-of-the-art Ca imaging of isolated RPE from wild type and transgenic mice and from monkey. These studies are innovative because they investigate fundamental properties of RPE cells that are poorly understood. Although it is clear that chloride channels are indispensible for normal RPE function, they remain inadequately investigated, both with regard to their regulation and their physiological roles in the retina. These studies are significant because understanding the ionic mechanisms of RPE function is essential to understanding retinal physiology and because it is becoming apparent that Best1 dysfunction plays a much larger role in retinopathies than previously recognized. In addition to being a prime player in causing bestrophinopathies, Best1 mutations may also contribute disease susceptibility or Best1 protein may be a downstream target in other retinopathies of unknown etiology.

描述（由申请人提供）：在美国，估计每28人中就有1人患有视网膜疾病，并且对个人和经济造成巨大影响。本应用程序将研究一种快速增长的遗传性视网膜变性，称为双虹膜病变。bestrophinopathy是由人类bestrophin-1基因（hBest1）突变引起的。hBest1突变产生一系列显性和隐性遗传的视网膜变性，呈现多种临床病理。hBest1编码在视网膜色素上皮（RPE）基底外侧膜中表达的钙活化的氯离子通道（CaCC），并且视网膜色素上皮病的特征是由RPE CaCC产生的眼电图光峰减少。这些观察结果导致了对视性疾病的“CaCC假说”。尽管大量数据支持besstrophinopathies是由Best1的氯离子运输缺陷引起的观点，但对敲除和敲除突变小鼠模型的研究提供了强烈矛盾的结论。本项目的目的是深入研究两性疾病的CaCC假说。我们将详细探讨光峰的分子机制，以建立光峰背后的离子机制，从启动它的Ca信号到产生它的阴离子通道。我们的假设是CRAC通道Orai-1负责Ca内流，激活Ca激活的阴离子通道Tmem16a/Ano1产生光峰。我们假设Best1突变通过两种机制降低光峰：与Ano1活性的相互作用和调节，以及通过改变Ca信号。这些研究将结合膜片钳记录和最先进的Ca成像来完成从野生型和转基因小鼠以及猴子身上分离的RPE。这些研究具有创新性，因为它们研究了人们对RPE细胞知之甚少的基本特性。虽然氯离子通道对于RPE的正常功能是必不可少的，但它们在视网膜中的调节和生理作用仍然没有得到充分的研究。这些研究意义重大，因为了解RPE功能的离子机制对于理解视网膜生理学至关重要，而且越来越明显的是，Best1功能障碍在视网膜病变中的作用比以前认识到的要大得多。除了是引起视网膜病变的主要因素外，Best1突变也可能导致疾病易感性，或者Best1蛋白可能是其他病因不明的视网膜病变的下游靶点。