G-proteins and mechanisms of signal transduction in vision

描述(申请人提供)：视网膜视杆感光细胞中的光传导依赖于由异源三聚体G蛋白转导蛋白介导的高产量信号放大的典型机制。一个光激活的视紫红质分子激活数百个转导分子，这些转导分子将有关从视紫红质传入的视觉信号的信息传递到第二信使系统cGMP-磷酸二酯酶的酶上。转导蛋白α亚基功能的方方面面，特别是它与视紫红质和视紫红质催化的核苷酸交换的初级相互作用，都需要转导蛋白β-伽马亚单位复合体。20多年前发现的转导蛋白β-伽马几乎只通过体外实验进行研究。这种蛋白复合体在正常功能过程中的真正体内作用或在视网膜疾病中的参与尚不清楚。我们开发了一种新的工具来研究视觉中G蛋白的机制--一个缺乏杆状特异转导蛋白伽马亚单位的小鼠模型。为了描述这个模型系统的特征，我们将提供给广泛的视觉研究社区，我们建议测试光传导、视网膜发育和蛋白质分布的主要方面。关键目标是确定在没有转导蛋白β-伽马复合体的情况下，视觉信号的激活是否可能，这是一个目前的体外研究还没有解决的问题。在未来，这个模型还将有助于回答诸如光适应机制、视杆细胞和视锥细胞信号的差异、突触传递、视网膜退化等重要问题。G蛋白-β-伽马复合体最近成为药物设计和治疗干预的新靶点。因此，这种小鼠模型的功能特征对于了解人类眼病和潜在的新疗法将是非常有价值的。 与公共卫生相关：该项目专注于小鼠模型系统的第一个特征，在该模型系统中，关键的视网膜蛋白-转导蛋白β-伽马复合体已经被删除。这一模型正在开发中，供视力研究界使用，以帮助了解人类视网膜疾病的潜在机制，并促进新的治疗策略。

DESCRIPTION (provided by applicant): Phototransduction in retinal rod photoreceptor cells relies on the prototypical mechanism of high-yield signal amplification mediated by the heterotrimeric G-protein transducin. A single light activated rhodopsin molecule activates several hundred transducin molecules, which relay the information about incoming visual signal from rhodopsin to the enzyme of the second messenger system, cGMP-phosphodiesterase. All aspects of transducin alpha subunit functions, especially its primary interactions with rhodopsin and rhodopsin catalyzed nucleotide exchange, require the transducin beta-gamma subunit complex. Discovered more than two decades ago, transducin beta-gamma has been studied by in-vitro experiments almost exclusively. The true in-vivo role of this protein complex during normal functioning or its involvement in retina diseases remains unknown. We have developed a novel tool to study the mechanisms of G-proteins in vision - a mouse model lacking the rod specific transducin gamma subunit. To characterize this model system, which we will make available to the broad vision research community, we propose to test major aspects of phototransduction, retina development and protein distribution. The key goal is to determine whether activation of visual signaling is possible at all without transducin beta-gamma complex, a problem that is not resolved by current in-vitro studies. In the future this model will also help to answer such important questions, as mechanisms of light adaptation, differences between rod and cone signaling, synaptic transmission, retina degeneration and others. G-protein beta-gamma complexes have recently emerged as new targets of drug design and therapeutic intervention. Thus, the functional characterization of this mouse model will be very valuable for understanding eye disease and potential new therapies in humans. PUBLIC HEALTH RELEVANCE: This project focuses on the first characterization of the mouse model system in which a key retinal protein, transducin beta-gamma complex, has been deleted. This model is being developed for use by the vision research community to help understand underlying mechanisms of retinal diseases in humans and facilitate novel therapeutic strategies.