University of Thessaly, Medical School, Laboratory of Cytogenetics and Molecular Genetics, Larissa, Greece.
J Orthop Res. 2010 Mar;28(3):348-53. doi: 10.1002/jor.20993.
The aim of this study was to investigate the activation of the Wnt/beta-catenin pathway in osteoarthritis and the role of low-density lipoprotein receptor-related protein 5 (LRP5) in human osteoarthritic chondrocytes. The influence of 1,25(OH)2D3 on the expression of the LRP5 gene in human chondrocytes was also assessed. Human cartilage was obtained from 11 patients with primary osteoarthritis (OA) undergoing total knee replacement surgery. Normal cartilage was obtained from five healthy individuals. Beta-catenin and LRP5 mRNA levels were investigated using real-time PCR and LRP5 protein expression using Western blot analysis. Furthermore, we evaluated the effect of 1,25(OH)2D3 on LRP5 mRNA expression levels in osteoarthritic chondrocytes. Blocking LRP5 expression was performed using small interfering RNA (siRNA) against LRP5, and subsequent MMP-13 mRNA and protein levels were evaluated by real-time PCR and Western blot analysis, respectively. We confirmed the activation of the Wnt/beta-catenin pathway in OA, as we observed significant up-regulation of beta-catenin mRNA expression in osteoarthritic chondrocytes. We also observed that LRP5 mRNA and protein expression were significantly up-regulated in osteoarthritic cartilage compared to normal cartilage, and LRP5 mRNA expression was further increased by vitamin D. Also, blocking LRP5 expression using siRNA against LRP5 resulted in a significant decrease in MMP-13 mRNA and protein expressions. Our findings suggest the catabolic role of LRP5 is mediated by the Wnt/beta-catenin pathway in human osteoarthritis.
本研究旨在探讨 Wnt/β-连环蛋白通路在骨关节炎中的激活作用，以及低密度脂蛋白受体相关蛋白 5（LRP5）在人骨关节炎软骨细胞中的作用。还评估了 1,25（OH）2D3 对人软骨细胞中 LRP5 基因表达的影响。从 11 例接受全膝关节置换术的原发性骨关节炎（OA）患者中获得人软骨，从 5 例健康个体中获得正常软骨。使用实时 PCR 检测β-连环蛋白和 LRP5 mRNA 水平，使用 Western blot 分析检测 LRP5 蛋白表达。此外，我们评估了 1,25（OH）2D3 对 OA 软骨细胞中 LRP5 mRNA 表达水平的影响。使用针对 LRP5 的小干扰 RNA（siRNA）阻断 LRP5 表达，通过实时 PCR 和 Western blot 分析分别评估随后的 MMP-13 mRNA 和蛋白水平。我们证实了 Wnt/β-连环蛋白通路在 OA 中的激活，因为我们观察到 OA 软骨细胞中β-连环蛋白 mRNA 表达显著上调。我们还观察到 LRP5 mRNA 和蛋白表达在 OA 软骨中明显高于正常软骨，并且维生素 D 进一步增加了 LRP5 mRNA 表达。此外，使用针对 LRP5 的 siRNA 阻断 LRP5 表达导致 MMP-13 mRNA 和蛋白表达显著降低。我们的研究结果表明，LRP5 的分解代谢作用是通过人骨关节炎中的 Wnt/β-连环蛋白通路介导的。
