title: Attenuation of prostaglandin E1‑induced osteoprotegerin synthesis in osteoblasts by normoxic HIF inducers.
abstract: Mimosine, which is a natural plant amino acid present in the Leucaena genus, is able to induce hypoxia‑inducible factors (HIFs). Previous evidence has indicated that HIF regulates angiogenesis‑osteogenesis coupling in bone metabolism, and it has previously been reported that mimosine inhibits prostaglandin (PG)F2α‑induced osteoprotegerin (OPG) synthesis without affecting interleukin‑6 (IL‑6) production in osteoblast‑like MC3T3‑E1 cells. In addition, PGE1 has been demonstrated to induce OPG synthesis via activation of p38 mitogen‑activated protein (MAP) kinase and stress‑activated protein kinase/c‑Jun N‑terminal kinase (SAPK/JNK) in these cells, and PGE1 stimulates IL‑6 production via the activation of protein kinase A. In the present study, the effects of mimosine on the PGE1‑stimulated synthesis of OPG and IL‑6 were investigated in osteoblast‑like MC3T3‑E1 cells. The concentrations of OPG and IL‑6 were measured using relevant ELISA kits. OPG mRNA was measured by semi‑quantitative reverse transcription polymerase chain reaction. The phosphorylation of p38 MAP kinase and SAPK/JNK was analyzed by western blotting. Mimosine significantly reduced PGE1‑induced release of OPG and OPG mRNA expression levels without affecting the release of IL‑6. In addition, deferoxamine, which is also a normoxic HIF inducer, significantly inhibited PGE1‑induced OPG release and OPG mRNA expression levels; however, it had little effect on IL‑6 release. Furthermore, mimosine and deferoxamine failed to affect PGE1‑stimulated phosphorylation of p38 MAP kinase or SAPK/JNK. These results strongly suggest that normoxic HIF inducers attenuate PGE1‑stimulated OPG synthesis without affecting IL‑6 production in osteoblasts.
authors.affiliation: Department of Orthopedic Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi 467‑8601, Japan.
authors.forename: Gen
authors.initials: G
authors.lastname: Kuroyanagi
authors.affiliation: Department of Pharmacology, Gifu University Graduate School of Medicine, Gifu 501‑1194, Japan.
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Tokuda
authors.affiliation: Department of Orthopedic Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi 467‑8601, Japan.
authors.forename: Naohiro
authors.initials: N
authors.lastname: Yamamoto
authors.affiliation: Department of Orthopedic Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi 467‑8601, Japan.
authors.forename: Shingo
authors.initials: S
authors.lastname: Kainuma
authors.affiliation: Department of Orthopedic Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi 467‑8601, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Fujita
authors.affiliation: Department of Orthopedic Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi 467‑8601, Japan.
authors.forename: Reou
authors.initials: R
authors.lastname: Ohguchi
authors.affiliation: Department of Pharmacology, Gifu University Graduate School of Medicine, Gifu 501‑1194, Japan.
authors.forename: Rie
authors.initials: R
authors.lastname: Matsushima-Nishiwaki
authors.affiliation: Department of Pharmacology, Gifu University Graduate School of Medicine, Gifu 501‑1194, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Kozawa
authors.affiliation: Department of Orthopedic Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi 467‑8601, Japan.
authors.forename: Takanobu
authors.initials: T
authors.lastname: Otsuka
mesh_terms: D000527:Alprostadil / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D003676:Deferoxamine / Q000494:pharmacology*; D007887:Fabaceae / Q000737:chemistry; D051793:Hypoxia-Inducible Factor 1 / Q000819:agonists* / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D048670:MAP Kinase Kinase 4 / Q000378:metabolism; D051379:Mice; D008898:Mimosine / Q000737:chemistry / Q000494:pharmacology*; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D053244:Osteoprotegerin / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D051793:Hypoxia-Inducible Factor 1; D015850:Interleukin-6; D053244:Osteoprotegerin; D012333:RNA, Messenger; D008898:Mimosine; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D000527:Alprostadil; D003676:Deferoxamine