骨关节炎(OA)被认为是不可逆的,因为关节软骨磨损而修复能力有限。软骨细胞肥大增强和X型胶原基因(COL10A1)表达增加与OA有关。因此,控制胶原蛋白X表达和软骨细胞肥大的调节因子可能在OA干预中起作用。这里,我们研究了无远端Homeobox5(DLX5),没有远端的homeobox家族成员,在软骨细胞模型中控制鼠Col10a1基因表达和软骨细胞肥大及其在鼠OA模型中的作用。通过qRT-PCR和Westernblot分析,与增生期相比,我们检测到增生性MCT和ATDC5细胞中COL10A1和DLX5的水平显著升高.Dlx5的强制表达进一步增加,而Dlx5的敲减会降低肥大性MCT细胞中COL10A1的表达。我们已经进行了双荧光素酶报告基因和ChIP测定,并证明DLX5通过与Col10a1顺式增强子的直接相互作用来促进报告基因活性。我们建立了小鼠OA模型,并检测到与对照组相比,OA小鼠的关节软骨和软骨下骨中的COL10A1和DLX5显着增加。值得注意的是,在肥厚性MCT细胞中强制过表达DLX5可上调RUNX2,并且先前在Col10a1顺式增强子中发现了相邻的DLX5和RUNX2结合位点。一起,我们的数据提示,DLX5可能与RUNX2协同作用以控制细胞特异性Col10a1表达和软骨细胞肥大,并且参与OA的发病机制.
Osteoarthritis (OA) has been considered non-reversible as articular cartilage wears down with limited repair capacity. Enhanced chondrocyte hypertrophy and increased type X collagen gene (COL10A1) expression have been associated with OA. Therefore, regulators controlling collagen X expression and chondrocyte hypertrophy may play a role in OA intervention. Here, we investigated how Distal-less homeobox 5 (
DLX5), the distal-less homeobox family member, controls murine Col10a1 gene expression and chondrocyte hypertrophy in chondrogenic cell models and its role in a murine OA model. Through qRT-PCR and Western blot analyses, we detected significantly increased levels of COL10A1 and
DLX5 in hypertrophic MCT and ATDC5 cells compared to their proliferative stage. Forced expression of
Dlx5 further increases, while knockdown of
Dlx5 decreases COL10A1 expression in hypertrophic MCT cells. We have performed dual-luciferase reporter and ChIP assays and demonstrated that
DLX5 promotes reporter activity through direct interaction with Col10a1 cis-enhancer. We established a murine OA model and detected markedly increased COL10A1 and DLX5 in the articular cartilage and subchondral bone of the OA mice compared with the controls. Notably, forced overexpression of
DLX5 in hypertrophic MCT cells up-regulates RUNX2, and adjacent
DLX5 and RUNX2 binding sites have previously been found within the Col10a1 cis-enhancer. Together, our data suggest that DLX5 may cooperate with RUNX2 to control cell-specific Col10a1 expression and chondrocyte hypertrophy and is involved in OA pathogenesis.