Impact of the DNA Methylome in Chondrocyte Hypertrophy in Osteoarthritis

 描述(由申请人提供)：本申请涉及计划公告R21PA-13-303。我们的重点是了解控制发育模式的表观遗传机制如何有助于骨关节炎的发生和发展。虽然骨关节炎(OA)是最常见的关节炎形式，影响着数以千万计的美国人，但人们对该疾病早期阶段所涉及的机制(S)知之甚少。由于我们对骨性关节炎的理解很差，目前还没有经过验证的疾病修正疗法。骨性关节炎的特征是软骨基质的破坏，这对维持关节表面的完整性是必不可少的。在OA疾病中，软骨细胞是关节软骨的独特细胞类型，经历了类似于发育过程中观察到的肥大样变化。在某种程度上，这些变化包括DNA甲基化状态的改变，导致基因表达和细胞功能异常。我们推测，在体内观察到的骨关节炎软骨细胞中的异常基因表达与DNA甲基化的改变有关，该改变概括了发育事件，不适当地导致关节软骨细胞进入肥大样状态。在这个项目中，我们将利用增强的亚硫酸氢盐转化的简化代表来描述生长板软骨细胞的DNA甲基化状态，并通过RNA测序来确定与软骨细胞肥大分化相关的DNA甲基化模式以及与基因表达变化相关的DNA甲基化模式。然后，我们将使用人类骨性关节炎软骨样本和手术诱导的骨性关节炎小鼠模型，建立与骨性关节炎疾病进展阶段发生的DNA甲基化和基因表达变化的相似之处。这些方法将使我们能够定义导致骨性关节炎疾病发生和发展的表观基因组改变。最终，我们的实验的成功完成应该会导致针对疾病相关的表观基因组调节变化的早期骨性关节炎的新治疗策略的开发。

 DESCRIPTION (provided by applicant): This application addresses the program announcement R21 PA-13-303. Our focus is on understanding how epigenetic mechanisms controlling developmental patterns contribute to the onset and progression of osteoarthritis. While osteoarthritis (OA) is the most prevalent form of arthritis, affecting tens of millions of Americans, relatively little is known about the mechanism(s) implicated in the early stages of the disease. As a consequence of our poor understanding of OA, there is no proven disease-modifying therapy available. OA is characterized by the destruction of the cartilage matrix, which is essential for maintaining the integrity of the joint surfaces. In OA disease, chondrocytes, the unique cell type of articular cartilage, undergo hypertrophic- like changes that resemble patterns observed during development. To some extent, those changes comprise alterations of the DNA methylation status that lead to abnormal gene expression and cell function. We hypothesize that the abnormal gene expression observed in OA chondrocytes in vivo relates to alterations in DNA methylation that recapitulate developmental events, inappropriately leading articular chondrocytes to a hypertrophic-like state. In this project, we will utilize Enhanced Reduced Representation of Bisulfite Conversion to profile the DNA methylation status of growth plate chondrocytes, and to define DNA methylation patterns associated with chondrocyte hypertrophic differentiation and linked to changes in gene expression, assessed by RNA sequencing. We will then establish parallels with alterations in DNA methylation and gene expression that occur at progressive stages of OA disease, using human OA cartilage samples and a mouse model of surgically-induced OA. These approaches will allow us to define epigenomic alterations that lead to OA disease initiation and progression. Ultimately, the successful completion of our experiments should lead to the development of novel therapeutic strategies for early OA by targeting disease-related alterations in epigenomic regulation.