Regulation of Neurotransmission in the Retina

描述（由申请人提供）：本提案的目的是描述一种基本的钙信号传导机制，该机制调节长时间的细胞内对光刺激的适应性反应，当异常时，导致光感受器变性。我们将确定细胞内钙储存的消耗如何通过光感受器质膜上的储存操作钙通道触发钙流入。存储操作通道的分子同工型将被识别，并确定它们在调节自发突触反应和光诱发反应的振幅和频率中的作用。病理性钙流入通过储存操作通道杀死光感受器的机制将在小鼠遗传性视网膜变性模型系统和缺乏储存操作（TRPC）通道异构体的小鼠中进行表征。

DESCRIPTION (provided by applicant): The objective of this proposal is to characterize a fundamental calcium signaling mechanism that regulates long lasting intracellular adaptive responses to light stimulation and, when abnormal, causes photoreceptor degeneration. We will determine how depletion of intracellular calcium stores triggers calcium influx through store-operated calcium channels in the plasma membrane of photoreceptors. The molecular isoforms of store-operated channels will be identified and their role in regulating the amplitude and frequency of spontaneous synaptic responses and light-evoked responses, determined. The mechanisms, through which pathological calcium influx through store-operated channels kills photoreceptors will be characterized in mouse model systems for inherited retinal degeneration and in mice lacking store-operated (TRPC) channel isoforms. Two Specific Aims are proposed: Specific Aim 1: To characterize the roles of store-operated calcium channel entry in photoreceptor calcium homeostasis and neurotransmission Specific Aim 2: To identify expression of transient receptor potential channels (TRPCs) in the retina, and to determine their role in store-operated calcium entry and visual signaling The experiments in isolated cells, retinal slices and TRPC knockout mice will combine high-resolution calcium imaging techniques with patch clamp electrophysiology, immunocytochemistry, RT-PCR, gene chip and RNAi technology. Depletion of calcium stores and dysfunctional calcium influx kill photoreceptors. Thus, the proposed studies will help us understand how photoreceptors adjust their calcium levels to maintain optimal signaling range and will also help us identify potential candidate cellular targets for therapeutic interventions during retinal disease.