Mitochondrial Structural and Functional Remodeling in Microglial Activation

小胶质细胞激活中的线粒体结构和功能重塑

• 批准号: 9093229
• 负责人: BRIAN M POLSTER
• 金额: $ 23.1万
• 依托单位: UNIVERSITY OF MARYLAND BALTIMORE
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-03-01 至 2018-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9093229
• 关键词: Acute; Affect; Agonist; Alzheimer' s Disease; Animal Model; Belief; Bioenergetics; Blinded; Blood - brain barrier anatomy; Brain; Brain Injuries; Cardiac; Cells; Chronic; Complex; Data; Electron Microscopy; Equilibrium; Figs - dietary; Flow Cytometry; Genus Hippocampus; Glycolysis; Goals; Heart Arrest; Human; Hydrogen Peroxide; ITGAM gene; Individual; Injection of therapeutic agent; Injury; Interferon Type II; Interferons; Knock-out; Knockout Mice; Label; Link; Lipopolysaccharides; Measures; Microglia; Mitochondria; Modeling; Morphology; Mus; NADPH Oxidase; Nerve Degeneration; Neurodegenerative Disorders; Neurons; Nitric Oxide; Oxidative Phosphorylation; PTPRC gene; Parkinson Disease; Pathology; Pharmaceutical Preparations; Population; Pre-Clinical Model; Production; Proteins; Quality Control; Reactive Oxygen Species; Respiration; Reverse Transcriptase Polymerase Chain Reaction; Role; Secondary to; Signal Transduction; Staining method; Stains; Stroke; TLR4 gene; TNF gene; Testing; The Jackson Laboratory; Thinking; Time; Traumatic Brain Injury; brain cell; brain tissue; catalase; cellular imaging; cytokine; in vivo; in vivo Model; inhibitor/antagonist; mouse model; neuroinflammation; neuropathology; novel; novel therapeutics; public health relevance; research study; response; small molecule inhibitor; targeted treatment; trafficking

 DESCRIPTION (provided by applicant): The mitochondrial fission-promoting protein Drp1 is linked to neuropathology in acute and chronic neurodegenerative disorders. Mdivi-1, a blood-brain barrier permeable drug thought to inhibit Drp1, protects the brain in preclinical models of stroke, cardiac arrest, and Parkinson's disease. While major efforts are underway to test whether targeting the mitochondrial fission-fusion balance in neurons can modify neurodisease, the implications of targeting mitochondrial fission in non-neuronal brain cells are almost entirely unexplored. We see a mitochondrial structural remodeling consistent with Drp1-dependent fission in microglia when they enter a proinflammatory activation state termed M1. A bioenergetic shift from oxidative phosphorylation to glycolysis promotes M1 activation, and activation is marked by production of nitric oxide (NO) and proinflammatory cytokines. Resembling the neuroinflammatory state seen in human brain injury, M1 activation can persist for months to years and result in additional pathology. A better understanding of the mechanisms contributing to M1 activation will help discover novel therapeutics that block the deleterious consequences of M1 microglial activation. We find that the Drp1 inhibitor mdivi-1 suppresses microglial NO and TNF-α production in response to lipopolysaccharide (LPS) ± interferon-γ. We also find that mdivi-1 can inhibit reactive oxygen species (ROS) production by mitochondrial complex I in a Drp1-independent fashion. It is important to determine whether one or both of the known mdivi-1 targets, Drp1 and ROS, contribute to M1 microglial activation in vivo, and thus represent bona fide targets for therapy. This study will test the central hypothesis that in vivo, Drp1 activity but not mitochondrial ROS is required for microglial activation and the accompanying shift in cellular bioenergetics. Microglial activation will be induced in mice by intracerebroventricular administration of LPS. To investigate the role of Drp1, a novel microglia-specific inducible knockout mouse model will be developed. In addition, the existing MCAT mouse ectopically expressing matrix-targeted, H2O2-detoxifying catalase will be used to evaluate a specific requirement for mitochondrial ROS independent of other ROS. In Aim 1, we will determine whether Drp1 is necessary for the bioenergetic shift and microglial M1 activation induced by LPS in vivo. In Aim 2, we will determine whether mitochondrial ROS are required for the bioenergetic shift and microglial M1 activation induced by in vivo LPS injection. Our studies will take a crucial step toward determining whether microglial mitochondria can be targeted for therapy. Since normal Drp1-dependent fission is required for mitochondrial trafficking and quality control in neurons, a strategy specifically targeting Drp1 in microglia may ultimately be more desirable than global inhibition of mitochondrial fission. Our long-term goal is to target mitochondrial mechanisms of microglial activation in models of ischemic and traumatic brain injury, with the ultimate hope of developing a protective therapy for humans.

 描述（由申请人提供）：线粒体裂变促进蛋白 Drp1 与急性和慢性神经退行性疾病的神经病理学有关。 Mdivi-1 是一种血脑屏障渗透性药物，被认为可以抑制 Drp1，在中风、心脏骤停和帕金森病的临床前模型中保护大脑。虽然正在进行重大努力来测试针对神经元中的线粒体裂变-融合平衡是否可以改变神经疾病，但针对非神经元脑细胞中的线粒体裂变的影响几乎完全是 未经探索。当小胶质细胞进入称为 M1 的促炎激活状态时，我们看到线粒体结构重塑与小胶质细胞中 Drp1 依赖性裂变一致。从氧化磷酸化到糖酵解的生物能转变促进 M1 激活，而激活的标志是一氧化氮 (NO) 和促炎细胞因子的产生。类似于人类脑损伤中看到的神经炎症状态，M1 激活可以持续数月至数年，并导致额外的病理。更好地了解 M1 激活机制将有助于发现阻止 M1 小胶质细胞激活有害后果的新疗法。我们发现 Drp1 抑制剂 mdivi-1 抑制小胶质细胞响应脂多糖 (LPS) ± 干扰素-γ 产生 NO 和 TNF-α。我们还发现 mdivi-1 可以以不依赖于 Drp1 的方式抑制线粒体复合物 I 产生活性氧 (ROS)。确定已知的 mdivi-1 靶点 Drp1 和 ROS 之一或两者是否有助于体内 M1 小胶质细胞激活，从而代表真正的治疗靶点非常重要。本研究将检验中心假设 在体内，小胶质细胞激活需要 Drp1 活性，而不是线粒体 ROS，并且 伴随着细胞生物能量学的转变。通过脑室内注射 LPS 可诱导小鼠小胶质细胞活化。为了研究 Drp1 的作用，将开发一种新型小胶质细胞特异性诱导敲除小鼠模型。此外，现有的 MCAT 小鼠异位表达基质靶向 H2O2 解毒过氧化氢酶将用于评估独立于其他 ROS 的线粒体 ROS 的特定需求。在目标 1 中，我们将确定 Drp1 是否是 LPS 体内诱导的生物能转变和小胶质细胞 M1 激活所必需的。在目标 2 中，我们将确定体内 LPS 注射诱导的生物能转变和小胶质细胞 M1 激活是否需要线粒体 ROS。我们的研究将朝着确定小胶质细胞线粒体是否可以作为治疗目标迈出关键一步。由于神经元中的线粒体运输和质量控制需要正常的 Drp1 依赖性裂变，因此专门针对小胶质细胞中的 Drp1 的策略最终可能比全面抑制线粒体裂变更可取。我们的长期目标是针对缺血性和创伤性脑损伤模型中小胶质细胞激活的线粒体机制，最终希望为人类开发一种保护性疗法。