G-proteins and mechanisms of signal transduction in vision

描述（由申请人提供）：视网膜视杆细胞中的光转导依赖于由异源三聚体G蛋白转导素介导的高产量信号放大的原型机制。单个光激活的视紫红质分子激活数百个转导蛋白分子，其将关于来自视紫红质的传入视觉信号的信息传递给第二信使系统的酶，cGMP-磷酸二酯酶。转导素α亚基功能的所有方面，特别是其与视紫红质和视紫红质催化的核苷酸交换的主要相互作用，需要转导素β-γ亚基复合物。二十多年前发现的transducin beta-gamma几乎完全通过体外实验进行研究。这种蛋白复合物在正常功能或其参与视网膜疾病期间的真正体内作用仍然未知。我们已经开发了一种新的工具来研究G蛋白在视觉中的机制-缺乏视杆细胞特异性转导素γ亚基的小鼠模型。为了表征这个模型系统，我们将提供给广泛的视觉研究界，我们建议测试光转导，视网膜发育和蛋白质分布的主要方面。关键目标是确定视觉信号的激活是否可能在没有转导素β-γ复合物的情况下进行，这是目前体外研究尚未解决的问题。在未来，这个模型也将有助于回答这样的重要问题，如光适应机制，杆和锥信号之间的差异，突触传递，视网膜变性和其他。G蛋白β-γ复合物最近成为药物设计和治疗干预的新靶点。因此，该小鼠模型的功能表征对于理解人类眼部疾病和潜在的新疗法将非常有价值。 公共卫生相关性：该项目的重点是小鼠模型系统的第一个特征，其中一个关键的视网膜蛋白，transducin β-γ复合物，已被删除。该模型正在开发中，供视觉研究界使用，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.