Hypoxia-inducible factor-1α is required for transforming growth factor-β1-induced type I collagen, periostin and α-smooth muscle actin expression in human periodontal ligament cells

Abstract Background We reported previously that hypoxia inducible factor (HIF)-1α was not degraded under normoxic condition with transforming growth factor (TGF)-β1 stimulation in human periodontal ligament (PDL) cells; however, the role of HIF-1α has been unclear. Recently, HIF-1α, working together with TGF-β1, has been reported to promote extracellular matrix accumulation under normoxic condition in renal epithelial cell. The aim of this study is to investigate the effects of HIF-1α on the expression of TGF-β1-mediated genes including type I collagen, periostin and α-smooth muscle actin (SMA) in human PDL cells. Methods The effects of TGF-β1 on HIF-1α mRNA and protein expression were analyzed by real-time RT-PCR and western blot, respectively. Next, The expression of type I collagen, periostin and α-SMA mRNA were analyzed with or without HIF-1α under normoxic condition with TGF-β1 stimulation using a real-time RT-PCR. Results TGF-β1 induced the expression of HIF-1α both in mRNA and protein levels. TGF-β1-induced mRNA expression of type I collagen, periostin and α-SMA were inhibited even with TGF-β1 stimulation when HIF-1α was knocked down. Conclusion HIF-1α is required for TGF-β1-induced type I collagen, periostin and α-SMA expression in human PDL cells.