Novel actions of neurosteroids on GABA (A) receptor trafficking

神经类固醇对 GABA (A) 受体运输的新作用

基本信息

批准号：
10218279
负责人：
Paul Andrew Davies
金额：
$ 36.19万
依托单位：
TUFTS UNIVERSITY BOSTON
依托单位国家：
美国
项目类别：
财政年份：
2012
资助国家：
美国
起止时间：
2012-12-01 至 2023-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10218279
关键词：
Address Agonist Alanine Allopregnanolone Anti-Anxiety Agents Anticonvulsants Antidepressive Agents Anxiety Anxiety Disorders Behavior Behavioral Behavioral Paradigm Biochemical Brain Cell membrane Chemosensitization Development Electroencephalography Electrophysiology (science)Epilepsy G-Protein-Coupled Receptors GABA-A Receptor Glutamine Homozygote Image Lead Measurement Mediating Membrane Mental Depression Methionine Modification Molecular Mood Disorders Mouse Strains Mus Mutant Strains Mice Mutate Mutation Neurons PRKCA gene Phenotype Phosphorylation Play Premenstrual syndrome Process Progesterone Progesterone Receptors Property Receptor Activation Role Serine Signal Transduction Status Epilepticus System Testing Therapeutic autism spectrum disorder comparative efficacy efficacious treatment experimental study gamma-Aminobutyric Acid hypnotic kainate neuronal circuitry neuronal excitability neurosteroids novel novel therapeutic intervention positive allosteric modulator prevent receptor receptor expression sedative tool trafficking

项目摘要

Neuroactive steroids (NASs) such as allopregnanolone (ALLO) play a central role in regulating behavior via their potent anxiolytic, anticonvulsant, sedative, and hypnotic actions. Accordingly, modifications in the levels of NASs contribute to anxiety, autism spectrum disorders, depression, epilepsy, and premenstrual syndrome. Classically, NASs are thought to act by rapidly boosting neuronal inhibition by positive allosteric modulation of the activity of γ-aminobutyric acid type A receptors (GABAARs). In addition to their allosteric actions, we have recently shown that NASs act via a protein kinase C-dependent mechanism to enhance the phosphorylation of residues including Serine’s 408 and 409 in the β3 subunit (S408/9), a process that increases GABAAR number on the plasma membrane leading to a sustained increase in the efficacy of GABAergic inhibition. Although we have shown that NASs do not directly activate PKC, the mechanism by which NASs lead to changes in phosphorylation of GABAAR subunits are unknown. It is emerging that in addition to their positive allosteric modulation of GABAARs, NASs can directly activate membrane progesterone receptors (mPRs); G-protein coupled receptors that regulate PKC signaling. However, no information is available on the role that mPRs play in regulating GABAAR activity. Likewise, the behavioral significance of the sustained mPR-mediated metabotropic actions of NASs remains unexplored. To address these issues we have created mice in which S408/9 in the β3 subunit have been mutated to alanines, mutations that are predicted to reduce the metabotropic actions of NASs on GABAAR function. Preliminary studies using these tools have allowed us to formulate a central hypothesis that will be tested here; NASs activate mPRs to enhance the phosphorylation of GABAARs on residues including S408/9 in the β3 subunit, a mechanism that underlies their anticonvulsant efficacy. In contrast, their anxiolytic efficacy is mediated via allosteric potentiation of GABAAR activity, a process dependent upon Q241 in the α2 subunit. Our experiments will focus on the following aims. Aim 1. To test the hypothesis that the ability of NAS to induce sustained effects on GABAergic inhibition is dependent upon S408/9A in the β3 subunit. Aim 2. To test the hypothesis that the anxiolytic, and anticonvulsant efficacy of NASs is dependent upon S408/9 in the β3 subunit. Aim 3. To test the hypothesis that NASs mediate their metabotropic effects on GABAARs via the activation of mPRs. Collectively, our proposal will identify the molecular mechanisms by which NAS exert their therapeutic actions. This information may aid the development of new therapeutic strategies to alleviate the burdens of anxiety, autism spectrum disorders, depression, epilepsy, and premenstrual syndrome.

神经活性类固醇 (NAS)，例如四氢孕酮 (ALLO)，通过以下方式在调节行为中发挥核心作用：它们具有强大的抗焦虑、抗惊厥、镇静和催眠作用，相应地，其水平也会发生变化。 NAS 会导致焦虑、自闭症谱系障碍、抑郁症、癫痫和经前综合症。传统上，NAS 被认为通过正变构调节快速增强神经元抑制来发挥作用。 γ-氨基丁酸 A 型受体 (GABAAR) 的活性除了其变构作用外，我们还具有其变构作用。最近表明，NAS 通过蛋白激酶 C 依赖性机制发挥作用，增强 β3 亚基 (S408/9) 中的丝氨酸 408 和 409 等残基，这是增加 GABAAR 数量的过程尽管我们发现质膜上的GABA能抑制作用持续增加。已经表明 NAS 不会直接激活 PKC，而 PKC 是 NAS 导致变化的机制 GABAAR 亚基的磷酸化除了其正变构之外还不清楚。调节GABAAR、NAS可以直接激活膜孕酮受体（mPR）；然而，没有关于 mPR 所发挥作用的信息。同样，持续 mPR 介导的行为意义。 NAS 的代谢作用尚未被探索，为了解决这些问题，我们培育了小鼠。 β3 亚基中的 S408/9 已突变为丙氨酸，预计该突变会减少使用这些工具的初步研究使我们能够了解 NAS 对 GABAAR 功能的代谢作用。制定将在此处进行测试的中心假设； GABAAR 在 β3 亚基中包括 S408/9 在内的残基上的磷酸化，这一机制相反，它们的抗焦虑功效是通过变构介导的。 GABAAR 活性的增强，这一过程依赖于 α2 亚基中的 Q241。重点关注以下目标。目标 1. 检验 NAS 对 GABA 能产生持续影响的能力这一假设抑制作用取决于 β3 亚基中的 S408/9A。目标 2. 检验 NAS 的抗焦虑和抗惊厥功效具有依赖性的假设 β3 亚基中的 S408/9 上。目标 3. 检验 NAS 通过 GABAAR 介导其代谢作用的假设 mPR 的激活。总的来说，我们的提案将确定 NAS 发挥治疗作用的分子机制。这些信息可能有助于开发新的治疗策略，以减轻焦虑的负担，自闭症谱系障碍、抑郁症、癫痫症和经前综合症。