Regulation of Cyclic GMP Synthesis in Photoreceptors

项目总结 环状cGMP(CGMP)能够在脊椎动物的视杆和视锥中进行光转导。视网膜合成cGMP的研究进展 鸟苷酸环化酶(RetGC)是光感受器生理学中最重要的过程之一。 受钙、鸟苷酸环化酶激活蛋白(GCAPs)和视网膜变性3(RD3)蛋白控制。 CGMP信号的异常导致光感受器功能障碍和死亡。其中，不足之处 RetGC的活性和调节导致各种隐性和显性形式的先天性失明。这个 RetGC调控的基本原理及其对光感受器信号和信号转导的重要意义 存活率已经确定，第一批与RetGC相关的失明的临床试验现在已经开始，并取得了进展 来自早期的分子研究。然而，RetGC调控的一些关键的分子和细胞方面仍然存在 还不够了解，包括分子结构和RetGC与调节因子的相互作用 在光感受器中定义其生物学功能的蛋白质。这项建议符合NEI的使命，以 支持有关失明眼病、视力障碍和视觉功能机制的研究， 建立在理解RetGC如何使光感受器功能的最新进展的基础上：(I) 鉴定影响RetGC与GCAPs和RD3相互作用的突变；(Ii)建立 RD3及其RetGC结合界面的鉴定；(Iii)建立新的小鼠遗传模型 RetGC1、GCAP1、GCAP1基因突变引起的信号转导机制及其异常的研究 以及RD3；(Iv)确定RD3在光感受器功能和存活中的复杂生理作用。我们 这里提出了一项多样化的研究，旨在通过将蛋白质生物化学、分子生物学 和分子遗传学，更好地从机制上理解控制cGMP的调控过程 光感受器的合成，是其功能和疾病的基础。目标1寻求建立目前的 光感受器中cGMP的主要来源RetGC1的结构未知，其突变导致严重的形式 失明的恐惧。目标2阐述了RD3的分子决定因素，它控制着RetGC在 使用转基因小鼠模型的光感受器。目标3将描述RetGC复合体的动力学 GCAPs和RD3使RetGC能够在体内发挥作用。通过完成这些具体目标，我们希望实现 更深入、更可靠地理解定义了 RetGC在光感受器生物学中的作用，并导致先天性视网膜疾病的生理异常。

PROJECT SUMMARY Cyclic cGMP (cGMP) enables phototransduction in vertebrate rods and cones. The cGMP synthesis by retinal guanylyl (guanylate) cyclase (RetGC), one of the most essential processes in the photoreceptor physiology, is controlled by calcium, guanylyl cyclase activating proteins (GCAPs), and retinal degeneration 3 (RD3) protein. The abnormalities in cGMP signaling cause photoreceptor dysfunction and death. Among them, deficiency in RetGC activity and regulation leads to a variety of recessive and dominant forms of congenital blindness. The basic principles of the RetGC regulation and its fundamental importance for the photoreceptor signaling and survival have been established, and the first clinical trials for RetGC-linked blindness now have begun, evolved from the earlier molecular studies. Yet, some key molecular and cellular aspects of RetGC regulation still remain insufficiently understood, including the molecular structure and the interactions of RetGC with the regulatory proteins that define its biological function in photoreceptors. This proposal, conforming to the NEI mission to support research with respect to blinding eye diseases, visual disorders and mechanisms of visual function, is built on recent advancements in understanding of how RetGC enables the photoreceptor function: (i) identification of mutations that affect RetGC interactions with GCAPs and RD3; (ii) establishing the structure on RD3 and identification of its RetGC-binding interface; (iii) development of new mouse genetic models for studying mechanisms of signal transduction and their abnormalities caused by mutations in RetGC1, GCAP1, and RD3; (iv) establishing the complex physiological role of RD3 in photoreceptor function and survival. We here propose a diversified study designed to achieve, by integrating protein biochemistry, molecular biology, and molecular genetics, better mechanistic understanding of the regulatory processes that control cGMP synthesis in photoreceptors and underlie their function and diseases. Aim 1 seeks establishing the presently unknown structure of RetGC1, the main source of cGMP in photoreceptors, whose mutants cause severe forms of blindness. Aim 2 addresses the molecular determinant of RD3 that controls RetGC trafficking in photoreceptors using transgenic mouse models. Aim 3 will delineate the dynamics of RetGC complexes with GCAPs and RD3 that enable RetGC to function in vivo. By completing these specific aims, we expect to achieve deeper and more reliable understanding of the mechanistic interactions that define the fundamental role of RetGC in photoreceptor biology and cause physiological abnormalities in congenital retinal diseases.