Fig. 4: NFATc1 directly bound the SOX9/MMP13 promoter region.

a Overexpression of NFATc1 upregulated SOX9 and MMP13 expression in rat NP cells. b Five constructs derived from 2000 bp upstream of the rat SOX9 promoter. c NFATc1-drived luciferase activity of the P1, P2, P3, P4, and P5 fragments in rat NP cells. d NFATc1 increasingly bound the SOX9 promotor site (bp −470 to −323) by ChIP assay. e Mutations in the putative NFATc1-binding site of the P4 fragment. f The P4 mutant decreased NFATc1-drived luciferase activity in rat NP cells. g NFATc1 could also bind sites in the MMP13 promotor (bp −1463 to −1361 and −321–216). h Similarly, NFATc1 promoted the transcriptional level by binding the MMP13 promotor region. i Hypoxia caused accumulation of the HIF-1α and NFATc1 protein complex. All experiments were performed at least three times. *P < 0.05, **P < 0.01, ***P < 0.005.