Neuromodulators and Signaling Cascades in Retina

视网膜中的神经调节剂和信号级联

• 批准号: 7171781
• 负责人: P Michael Iuvone
• 金额: $ 33.43万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-01-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7171781
• 关键词: Adenosine; Adenylate Cyclase; Afferent Neurons; Animals; Biochemical; Calmodulin; Cell membrane; Cell physiology; Cells; Couples; Cyclic AMP; Dark Adaptation; Data; Dopamine; Enzymes; Experimental Models; Exposure to; Gene Expression; Glutamates; Goals; Lead; Learning; Light; Lighting; Link; Mammals; Melatonin; Membrane Potentials; Metabolism; Molecular; Molecular Profiling; Mus; Nature; Neuromodulator; Neurotransmitters; Nitric Oxide; Photoreceptors; Physiology; Play; Post-Translational Protein Processing; Proteins; Regulation; Retina; Retinal; Role; Signal Pathway; Signal Transduction; Somatostatin; Structure of retinal pigment epithelium; Synapses; Testing; Vertebrate Photoreceptors; Vertebrates; Visual system structure; adenylyl cyclase 4; base; dopamine D4 receptor; phosducin; receptor; research study; response; retinal adaptation

DESCRIPTION (provided by applicant): Photoreceptor cells are the primary sensory neurons of the visual system. In addition to being regulated by light, aspects of photoreceptor physiology are subject to control by neuromodulators, such as dopamine, adenosine, somatostatin, and nitric oxide. Much of the data supporting a role for these substances in photoreceptor cell function is pharmacological in nature, obtained from non-mammalian vertebrates, and much remains to be learned about the signaling mechanisms involved. Our preliminary data in mouse led to the hypothesis that dopamine, acting on dopamine D4 receptors, plays a major role in regulating cAMP metabolism in photoreceptor cells by Ca 2+ -dependent regulation of adenylyl cyclase and by regulating gene expression for components of the signaling cascade that links light exposure to inhibition of cAMP formation. Preliminary data also show that dopamine plays a major role in adaptive responses of mouse retina to changing illumination, possibly through a cAMP-dependent mechanism. The present goal is to test these hypotheses and to thereby elucidate the signaling mechanisms whereby dopamine produces it's effects on photoreceptor gene expression and retinal function during light- and dark-adaptation. Using mouse retina as an experimental model, we will test the following predictions of hypotheses: (1) Dopamine D4 receptors on photoreceptor cells regulate gene expression of one or more components of the signaling pathway that couples light-exposure to suppression of cAMP synthesis. (2) Dysfunctional cAMP regulation in photoreceptors of dopamine D4 receptor deficient mice alters photoreceptor gene expression profiles and posttranslational modification of key gene products, such as phosducin. (3) Dopamine and light decrease photoreceptor cAMP levels by reducing the activity of Ca 2+ / calmodutin-stimulated adenylyl cyclases. (4) Decreased expression of Ca 2+ / calmodulin-stimulated adenylyl cyclase(s) leads to the abnormalities of light and dark adaptation seen in dopamine D4 receptor deficient mice. The results of these experiments will significantly enhance our understanding of how dopamine and cAMP modulate photoreceptor function, especially light- and dark-adaptation.

描述（由申请人提供）：感光细胞是视觉系统的主要感觉神经元。除了受光调节外，光感受器生理学的各个方面还受到神经调节剂的控制，例如多巴胺、腺苷、生长抑素和一氧化氮。支持这些物质在感光细胞功能中发挥作用的许多数据本质上是药理学的，是从非哺乳动物脊椎动物中获得的，并且关于所涉及的信号传导机制还有很多有待了解。我们在小鼠中的初步数据得出这样的假设：多巴胺作用于多巴胺 D4 受体，通过 Ca 2+ 依赖性腺苷酸环化酶的调节以及调节将光暴露与抑制 cAMP 形成联系起来的信号级联成分的基因表达，在调节感光细胞中的 cAMP 代谢中发挥重要作用。初步数据还表明，多巴胺在小鼠视网膜对光照变化的适应性反应中发挥着重要作用，这可能是通过 cAMP 依赖性机制实现的。目前的目标是测试这些假设，从而阐明多巴胺在光适应和暗适应过程中对光感受器基因表达和视网膜功能产生影响的信号传导机制。使用小鼠视网膜作为实验模型，我们将测试以下假设预测：（1）感光细胞上的多巴胺 D4 受体调节信号通路中一个或多个组件的基因表达，该信号通路将光暴露与抑制 cAMP 合成耦合起来。 (2) 多巴胺 D4 受体缺陷小鼠的光感受器中 cAMP 调节功能失调会改变光感受器基因表达谱和关键基因产物（如磷酸蛋白）的翻译后修饰。 (3) 多巴胺和光通过降低 Ca 2+ /钙调蛋白刺激的腺苷酸环化酶的活性来降低光感受器 cAMP 水平。 (4) Ca 2+ /钙调蛋白刺激的腺苷酸环化酶表达减少导致多巴胺D4受体缺陷小鼠的光适应和暗适应异常。这些实验的结果将显着增强我们对多巴胺和 cAMP 如何调节光感受器功能，特别是光适应和暗适应的理解。