Fig. 4

Klf10 regulates Fzd9 to improve chondrocyte extracellular matrix calcification induced by TBHP. A–C Q-PCR was used to detect the expression of Fzd9 (n = 3). D Mouse articular chondrocytes were treated with siRNA (Fzd9) for 48 h. The expressions of Fzd9 was detected by western blot. E, F Alizarin red dye is used to stain calcium nodules formed by treated chondrocytes (n = 3). Scale bar: 100 μm. G The alkaline phosphatase kit was used to measure the alkaline phosphatase activity of chondrocytes (n = 3). H, I Relative calcification related gene mRNA expressions of murine chondrocytes were detected using RT-qPCR (n = 3). J Serially truncated and mutated Fzd9 promoter constructs were cloned and transfected into cells. The relative luciferase activities were determined after Klf10 overexpression. K Selective mutation (left panel) analyses identified Klf10-responsive regions in the Fzd9 promoter (right panel)