The role of nyctalopin in the mammalian retina

nyctalopin 在哺乳动物视网膜中的作用

• 批准号: 7110236
• 负责人: CATHERINE W MORGANS
• 金额: $ 7.49万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-01 至 2007-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7110236
• 关键词: biological signal transduction; cell cell interaction; confocal scanning microscopy; dendrites; fluorescence microscopy; glutamate receptor; immunoelectron microscopy; immunoprecipitation; laboratory mouse; laboratory rat; leucine; neural transmission; night blindness; protein binding; protein localization; protein protein interaction; protein structure function; retina; retinal bipolar neuron; sex linked trait; visual photoreceptor; yeast two hybrid system

DESCRIPTION (provided by applicant): Complete X-linked congenital stationary night blindness (CSNB1) is a hereditary disease caused by a block in synaptic transmission in the retina between photoreceptors and ON-bipolar cells (ON-BPCs). Photoreceptors release the neurotransmitter, glutamate, in darkness, and reduce the rate of release in response to light. ON-BPCs respond to glutamate via the mGluR6 metabotropic glutamate receptor. Binding of glutamate by mGluR6 leads to the closure of a cation channel and hyperpolarization of the ON-BPC. The role of mGluR6 in transducing the action of glutamate in the ON-BPC dendrites is central to vertebrate vision, yet the steps in the mGluR6 signaling pathway are poorly understood, and the molecular identity of the ON-BPC cation channel is unknown. The human gene responsible for CSNB1, NYX, encodes a novel protein, nyctalopin, belonging to the family of leucine rich repeat (LRR) proteins. A mouse mutant, nob (no b-wave) has a similar phenotype to CSNB1 and a deletion in the nyx gene. Expression of mGluR6 appears normal in the nob mice, however their ON-BPCs fail to respond to exogenously applied glutamate, implicating nyctalopin in the mGluR6 signaling pathway. Although essential for the ON-BPC light response, the cellular function of nyctalopin is not known. Related LRR proteins in the nervous system have been implicated in neurite outgrowth and synapse formation, where they bind other proteins through their LRR domains including soluble ligands, receptors, and G proteins. We propose that nyctalopin is found at the photoreceptor to ON-BPC synapse where it interacts with components of the mGluR6 signaling pathway. To test this hypothesis, we will determine the localization of nyctalopin in the retina by immunofluorescence microscopy and immuno-electron microscopy using antibodies directed against a unique nyctalopin peptide. We will identify proteins interacting with nyctalopin by immunoprecipitation and yeast two-hybrid screening. These results will provide insight into the role of nyctalopin in synaptic transmission between photoreceptors and ON-BPCs in the retina, and may lead to the identification of other components of the ON-BPC pathway.

描述（由申请人提供）：完全X连锁先天性静止性夜盲症（CSNB1）是一种遗传性疾病，由视网膜感光细胞和ON-双极细胞（ON-BPC）之间的突触传递受阻引起。光感受器在黑暗中释放神经递质谷氨酸，并降低对光的反应释放速率。 ON-BPC 通过 mGluR6 代谢型谷氨酸受体对谷氨酸做出反应。 mGluR6 与谷氨酸的结合导致阳离子通道关闭和 ON-BPC 超极化。 mGluR6 在 ON-BPC 树突中转导谷氨酸作用中的作用是脊椎动物视觉的核心，但人们对 mGluR6 信号通路的步骤知之甚少，ON-BPC 阳离子通道的分子身份也是未知的。负责 CSNB1 的人类基因 NYX 编码一种新蛋白 Nyctalopin，属于富含亮氨酸重复序列 (LRR) 蛋白家族。小鼠突变体 nob（无 b 波）具有与 CSNB1 相似的表型，并且 nyx 基因缺失。 nob 小鼠中 mGluR6 的表达似乎正常，但它们的 ON-BPC 无法对外源施加的谷氨酸做出反应，这表明 nyctalopin 参与了 mGluR6 信号通路。尽管 nyctalopin 对于 ON-BPC 光反应至关重要，但其细胞功能尚不清楚。神经系统中相关的 LRR 蛋白与神经突生长和突触形成有关，它们通过 LRR 结构域结合其他蛋白，包括可溶性配体、受体和 G 蛋白。我们认为 nyctalopin 存在于 ON-BPC 突触的光感受器中，与 mGluR6 信号通路的成分相互作用。为了检验这一假设，我们将使用针对独特的 nyctalopin 肽的抗体，通过免疫荧光显微镜和免疫电子显微镜确定 nyctalopin 在视网膜中的定位。我们将通过免疫沉淀和酵母双杂交筛选来鉴定与 nyctalopin 相互作用的蛋白质。这些结果将深入了解 nyctalopin 在视网膜光感受器和 ON-BPC 之间突触传递中的作用，并可能导致 ON-BPC 途径其他成分的鉴定。