Bone and Joint Research Group, Centre for Human Development Stem Cells and Regeneration, Institute of Developmental Science, University of Southampton Medical School, Southampton, UK.
Department of Orthopaedic Surgery, Tohoku University School of Medicine, Sendai, Japan.
Sci Rep. 2017 Aug 10;7(1):7771. doi: 10.1038/s41598-017-08418-8.
The Runt-related transcription factor 2 (RUNX2) is critical for bone formation as well as chondrocyte maturation. Matrix metalloproteinase (MMP)-13 is a major contributor to cartilage degradation in osteoarthritis (OA). We and others have shown that the abnormal MMP13 gene expression in OA chondrocytes is controlled by changes in the DNA methylation status of specific CpG sites of the proximal promoter, as well as by the actions of different transactivators, including RUNX2. The present study aimed to determine the influence of the methylation status of specific CpG sites in the RUNX2 promoter on RUNX2-driven MMP13 gene expression in OA chondrocytes. We observed a significant correlation between MMP13 mRNA levels and RUNX2 gene expression in human OA chondrocytes. RUNX2 overexpression enhanced MMP13 promoter activity, independent of the MMP13 promoter methylation status. A significant negative correlation was observed between RUNX2 mRNA levels in OA chondrocytes and the percentage methylation of the CpG sites in the RUNX2 P1 promoter. Accordingly, the activity of the wild type RUNX2 promoter was decreased upon methylation treatment in vitro. We conclude that RUNX2 gene transcription is regulated by the methylation status of specific CpG sites in the promoter and may determine RUNX2 availability in OA cartilage for transactivation of genes such as MMP13.
runt 相关转录因子 2（RUNX2）对于骨形成和软骨细胞成熟至关重要。基质金属蛋白酶（MMP）-13 是骨关节炎（OA）中软骨降解的主要贡献者。我们和其他人已经表明，OA 软骨细胞中异常的 MMP13 基因表达受近端启动子特定 CpG 位点的 DNA 甲基化状态变化以及不同转录激活因子（包括 RUNX2）的作用控制。本研究旨在确定 RUNX2 启动子中特定 CpG 位点的甲基化状态对 OA 软骨细胞中 RUNX2 驱动的 MMP13 基因表达的影响。我们观察到人类 OA 软骨细胞中 MMP13 mRNA 水平与 RUNX2 基因表达之间存在显著相关性。RUNX2 过表达增强了 MMP13 启动子活性，而与 MMP13 启动子甲基化状态无关。在 OA 软骨细胞中，RUNX2 mRNA 水平与 RUNX2 P1 启动子中 CpG 位点的甲基化百分比之间存在显著负相关。因此，体外甲基化处理降低了野生型 RUNX2 启动子的活性。我们得出结论，RUNX2 基因转录受启动子中特定 CpG 位点的甲基化状态调节，并且可能决定 OA 软骨中 RUNX2 的可用性，以激活 MMP13 等基因。
