Functional follow-up of a genetic variant associated with high risk of osteoarthritis

项目摘要 全基因组关联研究（GWAS）为基因治疗的潜在靶点提供了一个公正的来源。 骨关节炎（OA）治疗的发展。然而，在以下机制方面存在知识差距： 这些基因变异导致细胞和组织功能障碍。当以纯合状态存在时， Chondroadherin-like（CHADL）基因变异导致全髋关节置换术的风险增加7.7倍。 Chadl是一种小的富含亮氨酸的蛋白聚糖（SLRP），其表达模式仅限于关节炎。 软骨8bp移码突变（rs 532464664）使转录本易于降解，我们的研究表明， 数据表明还产生了新的蛋白质片段。这一建议的总体假设是， 功能性CHADL蛋白的丧失和新蛋白片段的产生都有助于OA的增强 破坏软骨细胞外基质本提案的目的是确定 负责CHADL变异和OA风险之间的关联，长期目标是使用这些 在一般（非变异）人群中开发特发性OA治疗方法的见解。第一个目标是 确定Chadl敲除和新的“8bp变体”小鼠加速OA发展的程度， 在6个月和12个月大时评估OA。“8bp变体”小鼠通过重现人类基因组产生。 在小鼠基因组的匹配的、高度保守的位置中的变异。第二个目标是确定如何 CHADL破坏改变软骨细胞外基质的组成、结构和功能。除了 来自Chadl敲除小鼠和8bp变体小鼠的软骨外植体，具有过表达的原代人软骨细胞 正常或8bp变体形式的人CHADL将用于产生用于分析的工程化组织。 将分析组织的胶原交联程度、质谱法测定的蛋白质组成， 机械性能的原子力显微镜。所提出的目标是创新的，因为它们在 体内鼠和人软骨细胞系统直接询问未充分研究的GWAS变体， OA的风险拟议实验的结果将包括OA的综合分析， 在CHADL损失和特定变体表达的情况下，软骨特性。未来的发展方向 该项目的目的是将从这种特定变体中获得的见解转化为对特发性 OA。这种方法的一个例子是研究细胞外基质裂解产物， 概括了由CHADL变体产生的蛋白片段的功能。这些捐款 预期将对社会产生积极影响，促进采取更有效的预防战略， 治疗OA。

PROJECT SUMMARY Genome-wide association studies (GWAS) provide an unbiased source of potential targets for the development of osteoarthritis (OA) therapies. However, there is a knowledge gap regarding the mechanisms by which identified genetic variants drive cellular and tissue dysfunction. When present in a homozygous state, a genetic variant in Chondroadherin-like (CHADL) results in a 7.7 fold increased risk of total hip replacement. Chadl is a small leucine rich proteoglycan (SLRP) with an expression pattern that is restricted to articular cartilage. The 8 bp frameshift mutation (rs532464664) makes the transcript susceptible to degradation and our data indicates that a novel protein fragment is also produced. The overall hypothesis of this proposal is that the loss of functional CHADL protein and the generation of a novel protein fragment both contribute to enhanced OA by disrupting the cartilage extra-cellular matrix. The objective of this proposal is to determine the mechanisms responsible for the association between the CHADL variant and OA risk, with the long-term goal of using these insights to develop therapies for idiopathic OA in the general (non-variant) population. The first aim is to determine the extent to which Chadl knockout and a novel “8 bp variant” mouse accelerate OA development by assessing OA at 6 and 12 months of age. The “8 bp variant” mice were generated by recapitulating the human variant in a matched, highly conserved location of the mouse genome. The second aim is to establish how CHADL disruption alters the composition, structure, and function of cartilage extra-cellular matrix. In addition to cartilage explants from Chadl knockout and 8 bp variant mice, primary human chondrocytes with over-expression of the normal or 8 bp variant forms of human CHADL will be used to generate engineered tissues for analysis. Tissues will be analyzed for the extent of collagen crosslinking, protein composition by mass spectrometry, and mechanical properties by atomic force microscopy. The proposed aims are innovative in that they use both in vivo murine and human chondrocyte systems to directly interrogate an understudied GWAS variant with high risk of OA. The outcomes of the proposed experiments will include the comprehensive analysis of OA and cartilage properties in the case of CHADL loss and expression of the specific variant. Future directions of this project are to translate the insights gained from this specific variant into a greater understanding of idiopathic OA. One example of this approach would be to investigate extra-cellular matrix cleavage products that may recapitulate the function of the protein fragment generated by the CHADL variant. These contributions are expected to have a positive impact on society by stimulating more effective strategies for the prevention and treatment of OA.