Reciprocal role of PLAP-1 in HIF-1α-mediated responses to hypoxia.

Journal of periodontal research 2022 Jun

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To investigate the mutual regulation of hypoxia-inducible factor (HIF)-1α activity and periodontal ligament-associated protein-1 (PLAP-1) expression in human periodontal ligament cells (HPDLs). Cellular responses to hypoxia regulate various biological events (e.g., inflammation and tissue regeneration) through activation of HIF-1α. PLAP-1, an extracellular matrix protein preferentially expressed in the periodontal ligament, plays important roles in the functions of HPDLs. Although PLAP-1 expression has been demonstrated in hypoxic regions, the involvement of PLAP-1 in responses to hypoxia has not been revealed. HPDLs were cultured under normoxic (20% O2 ) or hypoxic (1% O2 ) conditions with or without deferoxamine mesylate (chemical hypoxia inducer) or chetomin (HIF signaling inhibitor). Expression levels of PLAP-1 and HIF-1α were examined by real-time reverse transcription-polymerase chain reaction and western blot analysis. Luciferase reporter assays of HIF-1α activity were performed using 293T cells stably transfected with a hypoxia response element (HRE)-containing luciferase vector in the presence or absence of recombinant PLAP-1 or PLAP-1 gene transfection. Cultivation under hypoxic conditions elevated the gene and protein expression levels of PLAP-1 in HPDLs. Deferoxamine mesylate treatment also enhanced PLAP-1 expression in HPDLs. Hypoxia-induced PLAP-1 expression was significantly suppressed in the presence of chetomin. PLAP-1-suppressed HPDLs showed increased HIF-1α accumulation in the nucleus during culture under hypoxic conditions, but not in the presence of recombinant PLAP-1. In the presence of recombinant PLAP-1, hypoxia-induced HRE activity of 293T cells was significantly suppressed in a dose-dependent manner. Transfection of the PLAP-1 gene resulted in a significant reduction of HRE activity during culture under hypoxic conditions. PLAP-1 expression is upregulated under hypoxic conditions through HIF-1α activation. Moreover, hypoxia-induced PLAP-1 expression regulates HIF-1α signaling. © 2022 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Citation

Masahide Takedachi, Satomi Yamamoto, Kohsuke Kawasaki, Junpei Shimomura, Mari Murata, Chiaki Morimoto, Asae Hirai, Kazuma Kawakami, Phan Bhongsatiern, Tomoaki Iwayama, Keigo Sawada, Satoru Yamada, Shinya Murakami. Reciprocal role of PLAP-1 in HIF-1α-mediated responses to hypoxia. Journal of periodontal research. 2022 Jun;57(3):470-478