P1otentiation of Glycine Receptors by Ethanol

乙醇对甘氨酸受体的 P1 增强作用

• 批准号: 6944786
• 负责人: LUIS GERARDO AGUAYO
• 金额: $ 17.55万
• 依托单位: UNIVERSITY OF CONCEPCION
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-09-01 至 2007-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6944786
• 关键词: G protein; alcoholism /alcohol abuse; biological signal transduction; brain electrical activity; brain stem; cell line; electrophysiology; ethanol; glycine receptors; laboratory mouse; molecular cloning; neurons; phosphorylation; receptor binding; receptor expression; receptor sensitivity; spinal cord; spinal ganglion; stoichiometry; tissue /cell culture; toxicant interaction; transfection; voltage /patch clamp; western blottings

DESCRIPTION (provided by applicant): Glycine receptors (GlyRs), together with GABAA and nicotinic ACh receptors, form part of the ligand-activated ion channel superfamily and play an important role in the excitability of the mammalian brain stem and spinal cord. For instance, the activation of glycine receptors (GlyRs) in brain stem, spinal cord and brain provides a main inhibitory control for neuronal excitability. Studies from our and other laboratories have shown that clinically relevant concentrations of ethanol (1-1 O0 mM) enhanced the function of these receptors in hippocampal, cortical and spinal neurons. We have recently published that GlyRs are regulated by G protein activation. In addition, our study indicated that this novel modulation of GlyR was via the G-beta-gamma dimer. The mechanisms by which ethanol is able to affect GlyRs had remained largely unknown. An important line of research has dealt with the search of sites that permit the binding of ethanol within the GlyR. For instance, single residue mutations in S267 within the alpha1 GlyR was reported to change the sensitivity to 200 mM ethanol by more than 50%. Overall, these studies concluded that ethanol effects on GlyRs could be related to the amino acid sequence inTM2 andTM3: Based on our recent paper and preliminary results, we have proposed the hypothesis that the effects of low ethanol concentrations depend on the activation of G proteins, more than the presence of sites that directly bind the ethanol molecule, For example, GlyR sensitivity to ethanol was significantly modified by changing the stoichiometry of the heterotrimeric complex: More importantly, the potentiation of the GlyR was completely blocked by overexpression of Gl3y subunits (occlusion), as well as a G-beta-gamma scavenger peptide (ct-GRK). In order to characterize the importance- of G protein activation on ethanol sensitivity; we will study G protein modulators using heterologous expression of G protein subunits in HEK cells, electrophysiology, receptor mutagenesis and Western blot techniques. Key experiments will be performed in cultured spinal and dorsal root ganglion (DRG) neurons to confirm the major effects in a neuronal substrate. Such information will help us to understand the mechanisms by which ethanol affects these inhibitory receptors, which are important in functions such as convulsions, sensory integration, muscle tone and respiration. In summary, this proposal may provide support for a novel mechanism of ethanol effects in motor and sensory functions.

描述（由申请方提供）：甘氨酸受体（GlyR）与GABAA和烟碱ACh受体一起构成配体激活离子通道超家族的一部分，在哺乳动物脑干和脊髓的兴奋性中发挥重要作用。例如，脑干、脊髓和脑中甘氨酸受体（GlyR）的激活提供了对神经元兴奋性的主要抑制控制。我们和其他实验室的研究表明，临床相关浓度的乙醇（1- 100 mM）增强了海马，皮层和脊髓神经元中这些受体的功能。我们最近发表了GlyRs受G蛋白激活的调节。此外，我们的研究表明，这种新的调节GlyR是通过G-β-γ二聚体。 乙醇能够影响GlyR的机制在很大程度上仍然未知。一个重要的研究方向是寻找允许乙醇在GlyR内结合的位点。例如，据报道，α 1 GlyR内S267中的单残基突变使对200 mM乙醇的敏感性改变超过50%。总之，这些研究得出结论，乙醇对GlyR的影响可能与TM 2和TM 3中的氨基酸序列有关：基于我们最近的论文和初步结果，我们提出了这样的假设，即低乙醇浓度的影响取决于G蛋白的活化，而不是直接结合乙醇分子的位点的存在，例如，通过改变异源三聚体复合物的化学计量，GlyR对乙醇的敏感性被显著改变：更重要的是，Gl 3 γ亚基（闭塞）以及G-β-γ清除肽（ct-GRK）的过表达完全阻断了GlyR的增强作用。 为了表征G蛋白活化对乙醇敏感性的重要性，我们将使用HEK细胞中G蛋白亚基的异源表达、电生理学、受体诱变和Western印迹技术来研究G蛋白调节剂。将在培养的脊髓和背根神经节（DRG）神经元中进行关键实验，以确认在神经元基质中的主要作用。这些信息将有助于我们了解乙醇影响这些抑制性受体的机制，这些抑制性受体在惊厥、感觉整合、肌肉张力和呼吸等功能中很重要。总之，这一提议可能为乙醇对运动和感觉功能影响的新机制提供支持。