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

• 批准号: 8438898
• 负责人: Paul Andrew Davies
• 金额: $ 43.97万
• 依托单位: TUFTS UNIVERSITY BOSTON
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-12-01 至 2017-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8438898
• 关键词: Address; Affinity; Aminobutyric Acids; Animals; Anxiety; Autistic Disorder; Barbiturates; Behavior; Benzodiazepines; Binding; Brain; Bungarotoxins; Cell Surface Receptors; Cell membrane; Cell surface; Corpus striatum structure; Data; Dependovirus; Development; Disease; Endocytosis; Epilepsy; Event; GABA-A Receptor; General anesthetic drugs; Goals; Hippocampus (Brain); Intervention; Knockout Mice; Lead; Long-Term Effects; Measures; Mediating; Membrane; Membrane Protein Traffic; Membrane Proteins; Mental Depression; Microscopy; Modification; Neocortex; Neurons; Parahippocampal Gyrus; Pathway interactions; Phosphorylation; Play; Population; Premenstrual syndrome; Process; Protein Kinase C; Research; Role; Schizophrenia; Serine; Site; Slice; Stress; Substance abuse problem; Surface; Synapses; Testing; Thalamic structure; Time; Translating; barbituric acid salt; comparative efficacy; dentate gyrus; gamma-Aminobutyric Acid; mutant; neuronal excitability; neuropsychiatry; neurosteroids; neurotransmission; novel; novel therapeutic intervention; public health relevance; receptor; research study; residence; synaptic inhibition; trafficking

DESCRIPTION (provided by applicant): Tonic inhibition determines the excitability of neurons and the activity of neuronal circuits through the persistent activity of specialized populations of high affinity extrasynaptic ?-aminobutyric acid A receptors (GABAARs), that are the principle targets of neurosteroids. Neurosteroids are widely accepted as endogenous regulators of GABAergic inhibition. Fluctuations in the levels of neurosteroids are accepted to play a critical role in epilepsy, and are also relevant to autism, anxiety, depression, premenstrual syndrome and schizophrenia. However, to date, there is a fundamental gap in understanding how fluctuations in the levels of neurosteroids change extrasynaptic GABAAR subunit expression levels, which are a significant factor in the changes in GABAergic inhibition that occur in a plethora of neuropsychiatric disorders. Our long-term goal is to fully understand the mechanism by which neurosteroids influence the expression levels of extrasynaptic GABAARs. In this proposal we will address the role that neurosteroids play in protein kinase C (PKC)-dependent phosphorylation of ¿4 subunit-containing GABAARs. We will determine how this influences the cell surface accumulation of the GABAAR subtypes that mediate tonic inhibition. Our central hypothesis is that neurosteroids modulate the phosphorylation of GABAARs assembled from ¿4¿3 and ? subunits, which mediate the majority of tonic inhibition in the dentate gyrus and thalamus. Neurosteroids specifically potentiate PKC-dependent phosphorylation of serine 443 (S443) in the ¿4 subunit. This increased phosphorylation leads to enhanced insertion of receptors composed of ¿4¿3 and ? subunits into the plasma membrane that originate within the secretory pathway. These enhancements of receptor cell surface stability are responsible for sustained increases in the efficacy of tonic inhibition. Guided by strong preliminary data, this hypothesis will be tested by pursuing three specific aims: (1) Determining the role of PKC-dependent phosphorylation in modulating the specific cell surface accumulation of GABAARs that mediate tonic inhibition (2) Visualizing neurosteroid- mediated changes in cell surface stability and membrane trafficking of GABAARs and (3) Ascertaining the effects of neurosteroid-dependent phosphorylation on the activity of GABAARs and the efficacy of tonic inhibition. In summary this proposal will demonstrate a new and unexpected mechanism by which neurosteroids exert persistent and sustained changes in the efficacy of tonic inhibition. Understanding neurosteroid-mediated changes in phosphorylation and cell surface expression of GABAARs has the potential to translate into better understanding of neuropsychiatric disorders. Moreover such information is likely to lead to the development of more efficacious treatments for anxiety, depression, premenstrual syndrome, schizophrenia and substance abuse.

描述（由申请人提供）：强直抑制通过特定群体的持续活动来决定神经元的兴奋性和神经元回路的活动。 高亲和力突触外 β-氨基丁酸 A 受体 (GABAAR) 是神经类固醇的主要靶标，神经类固醇被广泛认为是 GABA 能抑制的内源性调节剂，并且神经类固醇水平的波动在癫痫中发挥着关键作用。也与自闭症、焦虑症、抑郁症、经前综合症和精神分裂症有关，但迄今为止，人们在认识上还存在根本性的差距。神经类固醇水平的波动如何改变突触外 GABAAR 亚基表达水平，这是许多神经精神疾病中发生的 GABA 能抑制变化的重要因素。我们的长期目标是充分了解神经类固醇影响神经类固醇的机制。突触外 GABAAR 的表达水平 在本提案中，我们将讨论神经类固醇在蛋白激酶 C (PKC) 依赖性磷酸化中发挥的作用。我们将确定这如何影响介导强直抑制的 GABAAR 亚型的细胞表面积累。我们的中心假设是神经类固醇调节由 ¿ 组装的 GABAAR 的磷酸化。 4¿3 和 ? 亚基，介导齿状回和丘脑中的大部分强直性抑制，神经类固醇特异性增强 ¿3 和 ? 中丝氨酸 443 (S443) 的 PKC 依赖性磷酸化。 4 亚基的这种增加的磷酸化导致由 ¿ 组成的受体的插入增强。 4¿3 和 ? 亚基进入质膜，起源于分泌途径，这些增强的受体细胞表面稳定性是导致强直抑制功效持续增加的原因，该假设将通过三个方面进行检验。具体目标： (1) 确定 PKC 依赖性磷酸化在调节介导强直性抑制的 GABAAR 特定细胞表面积累中的作用 (2) 可视化神经类固醇介导的细胞表面稳定性和细胞膜变化(3) 确定神经类固醇依赖性磷酸化对 GABAAR 活性和强直抑制功效的影响 总之，该提案将展示一种新的、意想不到的机制，神经类固醇通过该机制对 GABAAR 的功效发挥持久和持续的变化。了解神经类固醇介导的 GABAAR 磷酸化和细胞表面表达变化有可能转化为更好地理解神经精神疾病。此外，这些信息可能会导致疾病的发展。针对焦虑、抑郁、经前综合症、精神分裂症和药物滥用的更有效的治疗方法。