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）：线粒体分裂促进蛋白Drp 1与急性和慢性神经退行性疾病的神经病理学相关。Mdivi-1是一种血脑屏障渗透性药物，被认为可以抑制Drp 1，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靶向神经元中的线粒体分裂-融合平衡是否可以改变神经疾病，但靶向非神经元脑细胞中的线粒体分裂的影响几乎完全是未知的。 未开发的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的Drp 1依赖性裂变一致。从氧化磷酸化到糖酵解的生物能量转换促进了M1的活化，活化的标志是一氧化氮（NO）和促炎细胞因子的产生。与人脑损伤中观察到的神经炎症状态相似，M1激活可以持续数月至数年，并导致额外的病理变化。更好地理解M1激活的机制将有助于发现阻断M1小胶质细胞激活的有害后果的新疗法。我们发现Drp 1抑制剂mdivi-1抑制小胶质细胞对脂多糖（LPS）±干扰素-γ的反应产生NO和TNF-α。我们还发现，mdivi-1可以抑制活性氧（ROS）的生产线粒体复合物I在一个Drp 1独立的方式。重要的是要确定是否一个或两个已知的mdivi-1的目标，Drp 1和ROS，有助于M1小胶质细胞在体内激活，从而代表真正的治疗目标。本研究将检验中心假设 在体内，Drp 1活性而不是线粒体ROS是小胶质细胞活化所必需的， 伴随着细胞生物能量学的转变。通过脑室内施用LPS将在小鼠中诱导小胶质细胞活化。为了研究Drp 1的作用，将开发一种新的小胶质细胞特异性诱导型基因敲除小鼠模型。此外，现有的异位表达基质靶向的H2 O2解毒过氧化氢酶的MCAT小鼠将用于评估对线粒体ROS的特定需求，而不依赖于其他ROS。在目标1中，我们将确定Drp 1是否是必要的生物能量转换和小胶质细胞M1激活LPS在体内诱导。在目标2中，我们将确定是否需要线粒体活性氧的生物能量转换和小胶质细胞M1激活诱导体内LPS注射。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。由于正常的Drp 1依赖性分裂是神经元中线粒体运输和质量控制所必需的，因此特异性靶向小胶质细胞中Drp 1的策略最终可能比线粒体分裂的全局抑制更可取。我们的长期目标是在缺血性和创伤性脑损伤模型中靶向小胶质细胞激活的线粒体机制，最终希望为人类开发保护性疗法。