Mechanism of Cone Degeneration Resulting from CNG Channel Deficiency

CNG通道缺陷导致锥体退化的机制

• 批准号: 8301722
• 负责人: XI-QIN DING
• 金额: $ 35.52万
• 依托单位: UNIVERSITY OF OKLAHOMA HLTH SCIENCES CTR
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-01 至 2015-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8301722
• 关键词: Accounting; Apoptosis; Blindness; Cell Death; Cellular biology; Cessation of life; Color Visions; Complex; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Defect; Development; Disease; Experimental Designs; Gene Expression; Generations; Genes; Genetic; Goals; Guanylate Cyclase; Hand; In Situ Nick-End Labeling; Inherited; Knock-out; Knowledge; Label; Longevity; Mammals; Methods; Microarray Analysis; Modeling; Mus; Mutation; Normal Cell; Pathology; Patients; Photoreceptors; Phototransduction; Population; Proteins; RNA Interference; Retina; Retinal; Retinal Cone; Role; Technology; Testing; Therapeutic Intervention; Vision Disorders; Visual Acuity; achromatopsia; cGMP production; cyclic-nucleotide gated ion channels; cytotoxic; density; gene replacement therapy; improved; inhibitor/antagonist; insight; mouse model; prevent; public health relevance; research study; response; retinal rods; therapeutic development; tool; treatment strategy

DESCRIPTION (provided by applicant): The cone cyclic nucleotide-gated (CNG) channel is essential for central and color vision and for visual acuity. Mutations in the two channel subunits, CNGA3 and CNGB3, are associated with achromatopsia and progressive cone dystrophy. Cones degenerate in mouse models of CNGA3 and CNGB3 deficiency and in patients with achromatopsia or cone dystrophy. There are currently no curative treatments for these diseases, in part due to a lack of understanding of the mechanisms underlying the disease pathobiology. The overarching objective of this study is to understand the mechanism(s) of cone degeneration resulting from loss of CNG channel function. Specifically, we will determine whether the accumulation of cGMP in models of CNG channel deficiency causes cone degeneration. We will perform the proposed studies using the CNGA3-/-/Nrl-/- and CNGB3-/-/Nrl-/- mouse lines. Using these mouse models provides a unique opportunity to study cone degeneration in a retina that contains only cones. Three specific aims are proposed. The first specific aim is to determine whether the accumulation of cGMP is responsible for cone degeneration in CNGA3 deficiency. We will test the ability of guanylate cyclase (GC) inhibitors to reduce cone degeneration in the channel-deficient mice. In a corroborating experiment, we will also test this hypothesis by abolishing expression of retGC-1 (retinal guanlyate cyclase) in channel deficient cones by utilizing RNAi and/or genetic methods (generation of CNGA3-/-/Nrl-/-/retGC-1-/-). The second specific aim is to determine how cones die in CNGA3 deficiency. If cGMP is responsible for cone cell death, we will examine how the accumulation of cGMP leads to cone cell death. We will investigate the role of cGMP- dependent protein kinase (PKG) in cone degeneration. We will determine whether PKG activity is higher in the CNGA3-/-/Nrl-/- retina compared to the Nrl-/- retina, and will test whether the use of PKG inhibitors/knockdown of PKG expression can ameliorate cone degeneration. Alternate mechanisms for cone degeneration will also be investigated by studying altered gene expression in channel deficient mice (compared to WT) by using microarray analysis. The third specific aim is to determine whether CNGB3 deficiency leads to an accumulation of cGMP in cones by using CNGB3-/-/Nrl-/- mice. Upon completion of the proposed study we will have a better understanding of the mechanism(s) underlying cone degeneration resulting from CNG channel deficiency. Improving the lifespan of degenerating cones is necessary for successful treatment of inherited cone diseases. The knowledge gained in this study is crucial for the development of therapeutic strategies to prevent or retard this degeneration, both in cases in which the causative gene is one of the channel proteins and in more general cases of cone dystrophy. PUBLIC HEALTH RELEVANCE: Congenital achromatopsia and progressive cone dystrophy are debilitating hereditary vision disorders for which there are currently no curative treatments. Mutations in genes encoding the cone cyclic nucleotide- gated (CNG) channel subunits account for 70% of all known cases of achromatopsia. The proposed study will probe the mechanisms underlying the cone degeneration that leads to loss of vision in CNG channel- associated achromatopsia. The results will provide significant insights into both the normal cell biology of cones and the pathobiology of cone dominant inherited disease. This knowledge is essential for developing therapeutic interventions to treat cone diseases and retard or rescue vision loss.

描述(申请人提供)：锥体环核苷酸门控(CNG)通道对于中枢和色觉以及视力来说是必不可少的。CNGA3和CNGB3这两个通道亚基的突变与色盲和进行性视锥细胞营养不良有关。在CNGA3和CNGB3缺乏的小鼠模型中，以及在色盲或视锥细胞营养不良的患者中，视锥细胞退化。目前还没有治愈这些疾病的方法，部分原因是缺乏对疾病病理生物学基础的机制的了解。本研究的主要目的是了解CNG通道功能丧失导致视锥细胞变性的机制(S)。具体地说，我们将确定cGMP在CNG通道缺陷模型中的积聚是否会导致锥体变性。我们将使用CNGA3-/-/NRL-/-和CNGB3-/-/NRL-/-小鼠进行拟议的研究。使用这些小鼠模型为研究只含有视锥细胞的视网膜中的视锥细胞变性提供了一个独特的机会。提出了三个具体目标。第一个特定的目的是确定cGMP的积累是否与CNGA3缺乏症的锥体变性有关。我们将测试鸟苷环化酶(GC)抑制剂减少通道缺陷小鼠视锥细胞变性的能力。在一个确证的实验中，我们还将利用RNAi和/或遗传方法(产生CNGA3-/-/NRL-/retGC-1-/-)，通过取消通道缺陷视锥细胞中retGC-1(视网膜鸟氨酸环化酶)的表达来验证这一假说。第二个具体目标是确定在CNGA3缺乏的情况下锥体是如何死亡的。如果cGMP是导致锥体细胞死亡的原因，我们将研究cGMP的积累如何导致锥体细胞死亡。我们将探讨cGMP依赖的蛋白激酶(PKG)在锥体退变中的作用。我们将确定与NRL-/-视网膜相比，CNGA3-/-/NRL-/-视网膜的PKG活性是否更高，并将测试使用PKG抑制剂/下调PKG表达是否可以改善视锥细胞退行性变。还将通过利用微阵列分析研究通道缺陷小鼠(与WT相比)中基因表达的变化来研究锥体退化的替代机制。第三个具体目的是通过CNGB3-/-/NRL-/-小鼠来确定CNGB3缺乏是否导致cGMP在锥体中积累。研究完成后，我们将更好地了解CNG通道缺陷导致视锥细胞退行性变的机制(S)。延长退化视锥细胞的寿命是成功治疗遗传性视锥细胞疾病所必需的。在这项研究中获得的知识对于开发预防或延缓这种退化的治疗策略至关重要，无论是在致病基因是通道蛋白之一的情况下，还是在更一般的视锥细胞营养不良的情况下。 与公共卫生相关：先天性色盲和进行性视锥细胞营养不良是使人衰弱的遗传性视力障碍，目前尚无根治方法。编码锥体环核苷酸门控(CNG)通道亚单位的基因突变占所有已知色盲病例的70%。这项拟议的研究将探索导致CNG通道相关性色盲视力丧失的视锥细胞变性的潜在机制。这些结果将为锥体正常细胞生物学和锥体显性遗传病的病理生物学提供重要的见解。这些知识对于开发治疗视锥细胞疾病和延缓或挽救视力丧失的治疗干预措施是必不可少的。