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

Background: We reported previously that hypoxia inducible factor (HIF)-1 alpha was not degraded under normoxic condition with transforming growth factor (TGF)-beta 1 stimulation in human periodontal ligament (PDL) cells; however, the role of HIF-1 alpha has been unclear. Recently, HIP-1 alpha, working together with TGF-beta 1, 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 HIP-1 alpha on the expression of TGF-beta 1-mediated genes including type I collagen, periostin and alpha-smooth muscle actin (SMA) in human PDL cells. Methods: The effects of TGF-beta 1 on HIP-la mRNA and protein expression were analyzed by real-time RT-PCR and western blot, respectively. Next, The expression of type I collagen, periostin and alpha-SMA mRNA were analyzed with or without HIP-1 alpha under normoxic condition with TGF-beta 1 stimulation using a real-time RT-PCR. Results: TGF-beta 1 induced the expression of HIP-1 alpha both in mRNA and protein levels. TGF-beta 1-induced mRNA expression of type I collagen, periostin and alpha-SMA were inhibited even with TGF-beta 1 stimulation when HIP-1 alpha was knocked down. Conclusion: HIP-la is required for TGF-beta 1-induced type I collagen, periostin and alpha-SMA expression in human PDL cells. (C) 2014 Elsevier Ltd. All rights reserved.