Impact of the DNA Methylome in Chondrocyte Hypertrophy in Osteoarthritis

 描述（由申请人提供）：本申请涉及程序公告R21 PA-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促进骨关节炎的发生和进展。虽然骨关节炎（OA）是最普遍的关节炎形式，影响了数千万美国人，但对该疾病早期阶段涉及的机制知之甚少。由于我们对OA的认识不足，目前还没有经过证实的疾病改善疗法。OA的特征在于软骨基质的破坏，这对于维持关节表面的完整性至关重要。在OA疾病中，软骨细胞（关节软骨的独特细胞类型）经历类似于在发育期间观察到的模式的肥大样变化。在某种程度上，这些变化包括导致异常基因表达和细胞功能的DNA甲基化状态的改变。我们推测，在体内OA软骨细胞中观察到的异常基因表达与DNA甲基化的改变有关，这种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，我们将利用增强的还原亚硫酸氢盐转化来分析生长板软骨细胞的DNA甲基化状态，并定义与软骨细胞肥大分化相关的DNA甲基化模式，并与基因表达的变化相关，通过RNA测序进行评估。然后，我们将建立平行的DNA甲基化和基因表达的变化，发生在OA疾病的进展阶段，使用人类OA软骨样本和小鼠模型的骨关节炎诱导的OA。这些方法将使我们能够定义导致OA疾病发生和进展的表观基因组改变。最终，我们的实验的成功完成将导致通过靶向表观基因组调控中的疾病相关改变来开发早期OA的新治疗策略。

 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.