Isolation of congenital stationary night blindness genes

描述(申请人提供)：在暗适应条件下，谷氨酸在视杆状感光细胞和视锥感光细胞的末端以最大速率释放。外节感光色素吸收光的最终结果是使感光器超极化，并降低谷氨酸的释放速率。这种减少是由视网膜二级神经元上的谷氨酸受体检测到的，这些神经元是水平和双极细胞。由于水平和超极化双极细胞使用离子型谷氨酸受体，这两种类型的细胞在黑暗中都保持去极化状态，并对光做出反应而超极化。相比之下，去极化双极细胞(DBCS)含有一种代谢性谷氨酸受体mGluR6。由于一个不完全确定的信号转导级联，DBCs在黑暗中超极化，并在光响应时去极化。到目前为止，只鉴定了这一过程中的两个关键蛋白：mGluR6和Galpha/0，并且DBC信号转导过程的大部分仍有待阐明。Nyctalopin是一种新发现的蛋白，似乎在DBC信号转导中发挥关键作用。已知nyctalopin的突变是人类CSNB1和nob突变小鼠的基础，这两种疾病的特征都是缺乏DBC功能。本项目的总体目标是确定夜他罗平在DBC活动中的功能作用。这个问题将在几个互补的实验中得到解决。有三个特定的目标：1)确定nyctalopin蛋白的细胞和亚细胞位置，2)确定nob小鼠DBCS的电生理特性，3)识别与nyctalopin相互作用的蛋白质。在这个项目完成后，我们希望对nyctalopin在DBC信号转导中所起的作用有一个透彻的了解，并确定参与这一重要过程的更多蛋白质。

DESCRIPTION (provided by applicant): Under dark-adapted conditions, glutamate is released at a maximal rate at the terminals of rod and cone photoreceptors. The net result of light absorption by outer segment photopigments is to hyperpolarize the photoreceptor and to reduce the rate of glutamate release. This reduction, is detected by glutamate receptors on the second order neurons of the retina, the horizontal and bipolar cells. As ionotropic glutamate receptors are used by horizontal and hyperpolarizing bipolar cells, both of these cell types are maintained in a depolarized state in darkness and are hyperpolarized in response to light. In comparison, depolarizing bipolar cells (DBCs) incorporate a metabotropic glutamate receptor, mGluR6. As a result of an incompletely defined signal transduction cascade, DBCs are hyperpolarized in darkness and depolarize in response to light. To date, only two key proteins of this process have been identified, mGluR6 and Galpha/0, and much of the DBC signal transduction process remains to be elucidated. Nyctalopin is a newly identified protein that appears to play some key role in DBC signal transduction. Mutations in nyctalopin are known to underlie human CSNB 1 and the nob mutant mouse, and both disorders are characterized by a lack of DBC function. The overall goal of the present project is to define the functional role of nyctalopin in DBC activity. This question will be addressed in several complementary experiments. There are three specific aims; 1) Determine the cellular and subcellular location of the nyctalopin protein, 2) Determine the electrophysiological properties of DBCs from nob mice, and 3) Identify proteins that interact with nyctalopin. At the completion of this project, we expect to have a thorough understanding of the role that nyctalopin plays in DBC signal transduction, and to have identified additional proteins involved in this important process.