Chondrocyte Metabolic Stress in the Development of Osteoarthritis

骨关节炎发展中的软骨细胞代谢应激

基本信息

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
项目类别：
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

项目摘要

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) 的最重要且可预防的危险因素之一。努力找出造成这种情况的原因传统上，风险主要集中在肥胖引起的关节压力触发因素上，例如机械因素和炎症因素。然而，我们对肥胖如何损害软骨细胞防御机制，导致对关节压力的反应不适当或不足的理解存在根本性差距。申请人的长期目标是开发上调软骨保护途径或下调因肥胖和衰老而失调的细胞分解代谢途径的策略。这里的目标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分解代谢。这一焦点源于申请人令人兴奋的初步数据，该数据将线粒体脱乙酰酶 SIRT3 对线粒体蛋白乙酰化的调节与年龄相关的下降与抗氧化防御受损和 OA 联系起来。核心假设是，肥胖加剧了与年龄相关的慢性线粒体过度乙酰化的增加，导致软骨细胞氧化还原应激和软骨分解代谢。据推测，这种不平衡是由衰老依赖性 SIRT3 表达下降以及肥胖导致的乙酰辅酶 A 产生和炎症增加所驱动的。初步数据表明，线粒体抗氧化剂 SOD2 是软骨细胞过度乙酰化的关键靶标。在这些和其他初步数据的指导下，该假设将通过三个具体目标进行检验：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) 确定对软骨细胞氧化还原稳态和软骨分解代谢的正向或负向操纵 SIRT3 表达的衰老和肥胖依赖性影响； 3) 确定 SIRT3 在促炎性挑战后调节线粒体氧化还原稳态和软骨分解代谢途径激活的机制。饮食诱导的肥胖和骨关节炎的完善小鼠模型将与允许软骨中 SIRT3 有条件删除或过度表达的转基因小鼠结合使用。针对目标 1 和 2，采用有针对性的基因组、蛋白质组和代谢物检测方法来确定促进线粒体乙酰化、改变抗氧化能力和诱导 OA 的因素。目标 3 将使用离体白细胞介素 1 刺激测定来识别 SIRT3 敏感的软骨分解代谢途径。软骨特异性缺失SOD2的小鼠将为评估SOD2过度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。这种方法具有创新性，因为它将肥胖研究的重点从细胞应激触发因素转移到了应激易感性。拟议的研究意义重大，因为它将启动系统研究如何积极或消极地操纵线粒体蛋白的可逆翻译后赖氨酸乙酰化，以促进衰老和肥胖的软骨保护。