The Brain's Valium: Investigating the Role of DBI in Regulating GABA-mediated Inhibition

大脑的安定：研究 DBI 在调节 GABA 介导的抑制中的作用

• 批准号: 9397064
• 负责人: Jennifer Sara BORCHARDT
• 金额: $ 3.23万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9397064
• 关键词: 5' Untranslated Regions; Address; Alzheimer' s Disease; Anti-Anxiety Agents; Anticonvulsants; Anxiety; Astrocytes; Autistic Disorder; Benzodiazepines; Binding; Biological Assay; Brain; Brain region; Cell Nucleus; Cytoplasmic Protein; Diazepam; Diazepam Binding Inhibitor; Disease; Electrodes; Electrophysiology (science); Epilepsy; Essential Drugs; Foundations; Fragile X Syndrome; Functional disorder; GABA A Receptor Binding; GABA Modulators; GABA-A Receptor; Gated Ion Channel; Genes; Glutamates; Human; Interneurons; Ion Channel Gating; Knock-out; Ligands; Link; Mass Spectrum Analysis; Measures; Mediating; Mental disorders; Modification; Molecular; Muscle relaxants; Neurologic; Neurons; Neurotransmitter Receptor; Peptide Fragments; Peptides; Pharmaceutical Preparations; Pharmacology; Phosphopeptides; Physiological; Play; Population; Process; Property; Protein Isoforms; Proteins; Radiolabeled; Recombinants; Role; Schizophrenia; Scientist; Signal Transduction; Sleeplessness; Testing; Thalamic structure; Therapeutic; Transcript; Variant; Work; World Health Organization; cell type; experimental study; gamma-Aminobutyric Acid; gene product; in vivo; induced pluripotent stem cell; knock-down; lateral ventricle; neural circuit; neurogenesis; neurotransmission; overexpression; polypeptide; positive allosteric modulator; receptor; receptor function; rho; sedative; subventricular zone; voltage clamp

Project Summary: First synthesized in the 1950s, benzodiazepines (BZDs) are widely prescribed drugs that exert their anxiolytic, muscle relaxant, sedative, and anticonvulsant actions by binding to GABA-A receptors (GABAARs), the main inhibitory ligand-gated ion channel in the brain. Since their synthesis, many scientists have theorized that there exists an endogenous BZD, or endozepine, in the brain. In 1983, a candidate polypeptide that displaced BZDs in a GABAAR binding assay was isolated from brain homogenates . However, proof that this 1 peptide called diazepam-binding inhibitor (DBI) had functional effects in the brain was lacking. Recently, using DBI knock-down experiments it was demonstrated in the subventricular zone of the lateral ventricles that DBI and one of its peptide fragments, ODN, inhibit GABA-induced currents and promote neurogenesis , indicating that DBI and ODN work as negative allosteric modulators of GABAARs in vivo. 2 However, in the thalamic reticular nucleus (a nucleus that plays an important role in controlling epileptic seizures), DBI and/or a DBI-derived peptide was found to enhance GABAAR currents and suppress epileptic activity . Thus, depending on the brain region, DBI can potentiate or inhibit GABAAR activity. Little, however, is 3 known about how DBI exerts these actions. How do products from a single protein elicit positive versus negative effects on GABAAR currents? Do DBI- derived peptides such as ODN elicit the same functional effects as DBI? Do different cell types make and process distinct DBI peptide(s)? Is DBI modified post-translationally (e.g. phosphorylated, acylated) and can these modifications alter DBI's physiological effects? The proposed experiments will address these fundamental questions and will 1) determine if specific GABAAR subunit combinations mediate the positive and negative actions of DBI and ODN; 2) determine if astrocytes and neurons release different DBI peptides and/or post-translationally process DBI differently, which impact its functional effects and 3) determine if astrocytes and neurons express different DBI transcript variants. Successful completion of these experiments will validate DBI's role as an endogenous BZD and will lay the foundation for understanding how DBI regulates GABA- mediated inhibition in the brain.

项目摘要： 苯二氮卓类药物（BZD）是1950年代首次合成的，是广泛的处方药，可发挥其 通过与GABA-A受体（GABAARS）结合，抗焦虑，肌肉松弛，镇静剂和抗惊厥作用， 大脑中的主要抑制配体门控离子通道。自从他们的合成以来，许多科学家已经理论上了 在大脑中存在内源性BZD或插入的内源。 1983年，候选多肽 从脑匀浆中分离出GABAAR结合测定中的位移BZD。但是，证明这一点 1 缺乏称为地西he肌结合抑制剂（DBI）的肽在大脑中具有功能作用。 最近，使用DBI敲低实验，在侧面的室室区域证明了这一点 DBI及其肽片段之一ODN的心室，抑制GABA诱导的电流并促进 神经发生，表明DBI和ODN是体内GABAARS的负变构调节剂。 2 然而，在丘脑网状核中（在控制癫痫中起重要作用的核 癫痫发作），DBI和/或DBI衍生的肽可增强加巴电流并抑制癫痫 活动 。因此，根据大脑区域，DBI可以增强或抑制Gabaar活性。但是，很少 3 知道DBI如何施加这些行为。 来自单个蛋白质的产品如何引起对Gabaar电流的阳性和负面影响？做dbi- 诸如ODN之类的衍生肽会引起与DBI相同的功能效应？做不同的单元格类型， 处理不同的DBI肽？是DBI经过翻译后修改的（例如磷酸化，酰化），可以 这些修饰会改变DBI的生理影响？拟议的实验将解决这些 基本问题并将确定特定的Gabaar亚基组合是否介导了阳性和 DBI和ODN的负面作用； 2）确定星形胶质细胞和神经元是否释放不同的DBI肽和/或 翻译后处理DBI的不同，这会影响其功能效应，3）确定星形胶质细胞是否存在 和神经元表达不同的DBI转录物变体。这些实验的成功完成将验证 DBI作为内源性BZD的作用，将奠定基础，以了解DBI如何调节GABA- 介导的大脑抑制作用。