Chondrocyte Metabolic Stress in the Development of Osteoarthritis

骨关节炎发展中的软骨细胞代谢应激

• 批准号: 9432273
• 负责人: TIMOTHY M GRIFFIN
• 金额: $ 11.34万
• 依托单位: OKLAHOMA MEDICAL RESEARCH FOUNDATION
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-04-15 至 2020-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9432273
• 关键词: Acetyl Coenzyme A; Acetylation; Aging; Animal Model; Antioxidants; Biological Assay; Cartilage; Cartilage Matrix; Catabolism; Cell Death; Cells; Cellular Stress; Chemicals; Chondrocytes; Chronic; Coupled; Data; Deacetylase; Defense Mechanisms; Degenerative polyarthritis; Detection; Development; Diet; Disease; Extracellular Matrix; Functional disorder; Gene Expression; Genomics; Glycolysis; Goals; Head; Homeostasis; Human; Image; Impairment; Inflammation; Inflammatory; Interleukin-1; Isotope Labeling; Knee Osteoarthritis; Knockout Mice; Knowledge; Lead; Link; Lysine; Mechanics; Mediating; Mediator of activation protein; Metabolic; Metabolic stress; Metabolism; Methods; Mission; Mitochondria; Mitochondrial Proteins; Modeling; Mus; Obese Mice; Obesity; Oxidation-Reduction; Oxidative Stress; Pathway interactions; Peptide Hydrolases; Pharmaceutical Preparations; Positioning Attribute; Predisposition; Process; Production; Protein Acetylation; Proteolysis; Proteomics; Public Health; Rattus; Regulation; Research; Resolution; Risk; Risk Factors; Rodent Model; Role; SOD2 gene; Signal Pathway; Sirtuins; Stress; Testing; Thinness; Tissues; Trauma; United States National Institutes of Health; age related; aggrecan; antioxidant enzyme; articular cartilage; disability; experimental study; fatty acid oxidation; in vivo; innovation; joint loading; joint stress; metabolic phenotype; mitochondrial dysfunction; mouse model; novel; overexpression; oxidation; prevent; protein expression; public health relevance; response; stressor

DESCRIPTION (provided by applicant): Obesity is among the most significant and preventable risk factors for developing osteoarthritis (OA). Efforts to identify the causes of this risk have traditionally focused on obesity-induced triggers of joint stress, such as mechanical and inflammatory factors. However, there is a fundamental gap in our understanding about how obesity impairs chondrocyte cellular defense mechanisms resulting in inappropriate or insufficient responses to joint stresses. The applicant's long-term goal is to develop strategies t either up-regulate chondroprotective pathways or down-regulate cell catabolic pathways that become dysregulated with obesity and aging. The objective here is to determine how obesity increases the acetylation of mitochondrial proteins that ultimately regulate cartilage catabolism under aging and inflammatory conditions. This focus is derived from the applicant's exciting preliminary data linking an age-related decline in the regulation of mitochondrial protein acetylation by the mitochondrial deacetylase SIRT3 to impaired antioxidant defense and OA. The central hypothesis is that obesity exacerbates an age-related increase in chronic mitochondrial hyper-acetylation resulting in chondrocyte redox stress and cartilage catabolism. It is proposed that this imbalance is driven by an aging-dependent decline in SIRT3 expression coupled with an obesity-driven increase in acetyl-CoA production and inflammation. Preliminary data show that the mitochondrial antioxidant, SOD2, is a key target of hyper-acetylation in chondrocytes. Guided by these and additional preliminary data, the hypothesis will be tested by three specific aims: 1) Determine how obesity induces metabolic changes that promote mitochondrial protein acetylation; 2) Determine the aging and obesity-dependent effects of manipulating SIRT3 expression, positively or negatively, on chondrocyte redox homeostasis and cartilage catabolism; and 3) Identify the mechanisms by which SIRT3 regulates mitochondrial redox homeostasis and activation of cartilage catabolic pathways following a pro-inflammatory challenge. Well-established mouse models of diet-induced obesity and OA will be used in combination with genetically modified mice that allow for the conditional deletion or over- expression of SIRT3 in cartilage. Targeted genomic, proteomic, and metabolite detection methods are in place for aims 1 and 2 to determine the factors that promote mitochondrial acetylation, alter antioxidant capacity, and induce OA. Aim 3 will use ex vivo interleukin-1 stimulation assays to identify SIRT3-sensitive cartilage catabolic pathways. Mice with cartilage-specific deletion of SOD2 will provide a reference for evaluating the effect of SOD2 hyper-acetylation on chondrocyte oxidative stress and activation of downstream catabolic pathways. This approach is innovative because it shifts the focus of obesity research on OA from cellular stress triggers to stress susceptibility. The proposed research is significant because it will initiate the systematic study of how reversible post-translational lysine acetylation of mitochondrial proteins may be manipulated, either positively or negatively, to promote chondroprotection with aging and obesity.

描述（由申请人提供）：肥胖是发生骨关节炎（OA）的最重要和可预防的风险因素之一。查明原因的努力 风险传统上集中在肥胖引起的关节压力触发因素，如机械和炎症因素。然而，我们对肥胖如何损害软骨细胞防御机制，导致对关节应力的反应不适当或不足的理解存在根本性的差距。申请人的长期目标是开发上调软骨保护途径或下调随着肥胖和衰老而失调的细胞分解代谢途径的策略。本研究的目的是确定肥胖如何增加线粒体蛋白的乙酰化，从而最终调节衰老和炎症条件下的软骨细胞增殖。这一重点来自申请人令人兴奋的初步数据，该数据将线粒体脱乙酰酶SIRT 3对线粒体蛋白乙酰化的调节中与年龄相关的下降与受损的抗氧化防御和OA联系起来。核心假设是肥胖加剧了慢性线粒体过度乙酰化的年龄相关性增加，导致软骨细胞氧化还原应激和软骨细胞增殖。有人提出，这种不平衡是由SIRT 3表达的衰老依赖性下降以及肥胖驱动的乙酰辅酶A产生和炎症增加驱动的。初步数据显示，线粒体抗氧化剂SOD 2是软骨细胞中超乙酰化的关键目标。在这些和额外的初步数据的指导下，该假设将通过三个特定的目标进行测试：1）确定肥胖如何诱导促进线粒体蛋白乙酰化的代谢变化; 2）确定操纵SIRT 3表达的衰老和肥胖依赖性影响，积极或消极地，对软骨细胞氧化还原稳态和软骨细胞增殖的影响;和3）鉴定SIRT 3调节线粒体氧化还原稳态和在促炎性攻击后软骨分解代谢途径的激活的机制。饮食诱导的肥胖和OA的良好建立的小鼠模型将与允许软骨中SIRT 3的条件性缺失或过表达的遗传修饰的小鼠组合使用。针对目标1和目标2，采用了靶向基因组、蛋白质组和代谢物检测方法，以确定促进线粒体乙酰化、改变抗氧化能力和诱导OA的因素。目的3将使用离体白细胞介素-1刺激试验来鉴定SIRT 3敏感的软骨分解代谢途径。软骨特异性缺失SOD 2的小鼠将为评价SOD 2过乙酰化对软骨细胞氧化应激和下游分解代谢途径激活的影响提供参考。这种方法是创新的，因为它将肥胖研究的重点从OA细胞应激触发转移到应激易感性。这项研究意义重大，因为它将启动线粒体蛋白可逆的翻译后赖氨酸乙酰化的系统研究，无论是积极的还是消极的，以促进衰老和肥胖的软骨保护。