title: Hypoxia decreases Runx2/Cbfa1 expression in human osteoblast-like cells.
abstract: To elucidate the molecular mechanism in relation to vascular supply and osteoporosis, we investigated the effect of hypoxia on Runx2 expression in MG63 cells. Also investigated was expression of type I collagen and osteocalcin, which are regulated by Runx2, alkaline phosphatase (ALPase) to see if they are affected by hypoxia. Quiescent cultures of MG63 cells were exposed to hypoxia (2% O(2)) and normoxia (18% O(2)) for 24, 48, 72 and 96 h. In cells exposed to hypoxia, reverse transcription-polymerase chain reaction (RT-PCR) analysis showed that mRNA expression of Runx2, type I collagen, osteocalcin, and ALPase were decreased in a time dependent manner to 96 h. Activity of ALPase was also reduced in the same manner. Western blotting showed a marked decrease in Runx2 protein at 96 h in cells under hypoxia compared to normoxia. These data indicate that Runx2 expression in osteoblasts is reduced by hypoxia, and may be a mechanism of osteoporosis by decreased vascular supply.
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Chonbuk National University Medical School and Research Institute of Clinical Medicine, #634-18, Keumam Dong, Dukjin Gu, Chonju, 561-712, Chonbuk, Republic of Korea.
authors.forename: J H
authors.initials: JH
authors.lastname: Park
authors.forename: B H
authors.initials: BH
authors.lastname: Park
authors.forename: H K
authors.initials: HK
authors.lastname: Kim
authors.forename: T S
authors.initials: TS
authors.lastname: Park
authors.forename: H S
authors.initials: HS
authors.lastname: Baek
mesh_terms: D000469:Alkaline Phosphatase / Q000096:biosynthesis / Q000235:genetics; D001842:Bone and Bones / Q000098:blood supply; D015687:Cell Hypoxia / Q000235:genetics*; D002478:Cells, Cultured / Q000187:drug effects; D003094:Collagen / Q000096:biosynthesis / Q000235:genetics; D050659:Core Binding Factor Alpha 1 Subunit; D004790:Enzyme Induction / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D009363:Neoplasm Proteins; D010006:Osteoblasts / Q000187:drug effects / Q000378:metabolism*; D015675:Osteocalcin / Q000096:biosynthesis / Q000235:genetics; D010024:Osteoporosis / Q000097:blood*; D010100:Oxygen / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D015398:Signal Transduction; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology
chemical_list: D050659:Core Binding Factor Alpha 1 Subunit; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D015675:Osteocalcin; D003094:Collagen; D000469:Alkaline Phosphatase; D010100:Oxygen