Regulation of Signaling in the Retina by RGS Proteins

项目摘要 视网膜中的G蛋白信号通路在视觉信号的接收和转导中起着重要的作用。 刺激。这些通路的生理操作依赖于调节器提供的严格控制 G蛋白信号传导（RGS）蛋白。我们的长期目标是阐明分子和细胞机制 RGS蛋白在塑造视网膜信号中的功能是理解视觉的必要前提 功能障碍及其治疗方法。在第一个视觉突触处，G蛋白级联反应由 mGluR 6受体介导ON双极细胞对光诱导的神经递质变化的反应 从感光器释放谷氨酸。ON-双极通路信号传递的失调 导致先天性静止性夜盲症，一种以视力模糊为特征的视觉疾病。 RGS蛋白R7亚家族的成员RGS 7和RGS 11特异性地集中在 ON-双极细胞突触，在那里它们与它们的辅助亚基G5、R7 BP和 R9 AP以及主要受体mGluR 6。R7 RGS蛋白或mGluR 6的破坏导致 突触缺陷，并消除了双极细胞对光的反应。这些观察导致了 R7 RGS复合物的组分在调节中起重要作用的建议的中心假设 mGluR 6通路和介导突触稳态。 这一假设将通过追求三个互补的具体目标来检验：（1）建立一个角色 RGS复合体在第一视觉突触功能稳态中的作用，（2）确定机制 RGS复合物向ON-BC树突的潜在选择性递送，以及（3）为了理解动力学 在mGluR 6级联中G蛋白失活的要求。为实现这些目标而提出的战略 将需要生物化学、分子生物学、电生理学和生理学的协同组合， 方法，每一个都利用了一系列强大的试剂和动物模型的存在。 更好地了解RGS蛋白的功能和mGluR 6通路的调控将产生重要的 深入了解G蛋白参与突触传递事件的一般原则，并可能表明 为治疗遗传性夜盲症而设计的治疗策略提供了新的干预节点。

PROJECT SUMMARY G protein signaling pathways in the retina are critically involved in reception and transduction of visual stimuli. The physiological operation of these pathways depends on the tight control provided by the Regulators of G protein signaling (RGS) proteins. Our long term goal is to elucidate molecular and cellular mechanisms of RGS protein function in shaping retina signaling as a necessary prerequisite to understanding visual dysfunctions and therapeutic means of their treatment. At the first visual synapse, G protein cascade driven by mGluR6 receptor, mediates the responses of ON-bipolar cells to light induced changes in neurotransmitter glutamate release from the photoreceptors. The dysregulation of signal transmission in ON-bipolar pathway causes congenital stationary night blindness, a visual disease characterized by the loss of dim vision. The members of the R7 subfamily of RGS protein, RGS7 and RGS11, are specifically concentrated at the ON-bipolar cell synapses where they form physical complexes with their auxiliary subunits G 5, R7BP, and R9AP as well as with the principal receptor, mGluR6. Disruption of R7 RGS proteins or mGluR6 leads to synaptic deficits and abolishes the responses of ON-bipolar cells to light. These observations lead to the central hypothesis of the proposal that components of R7 RGS complexes play essential role in regulating mGluR6 pathway and mediating synapse homeostasis. This hypothesis will be tested by pursuing three complementary Specific Aims: (1) To establish a role of the RGS complexes in functional homeostasis of the first visual synapse, (2) To determine mechanisms underlying selective delivery of the RGS complexes to the ON-BC dendrites, and (3) To understand kinetic requirements of G protein inactivation in the mGluR6 cascade. The strategy proposed to address these aims will entail a synergistic combination of biochemical, molecular biological, electrophysiological, and physiological approaches, each exploiting the existence of a powerful array of reagents and animal models. Better understanding of the RGS protein function and mGluR6 pathway regulation will yield important insights into the general principles of G protein involvement in synaptic transmission events and may suggest novel nodes of intervention for therapeutic strategies designed to treat inherited types of night blindness.