RRC ID 62092
Author Fujita T, Fukuyama R, Izumo N, Hirai T, Meguro T, Nakamuta H, Koida M.
Title Transactivation of core binding factor alpha1 as a basic mechanism to trigger parathyroid hormone-induced osteogenesis.
Journal Jpn J Pharmacol
Abstract During 28-day culture of bone marrow- and calvaria-derived osteoblasts, the constant presence of parathyroid hormone (PTH)(1-34) retarded differentiation and nodule formation (NF) in a dose-dependent fashion (C-phase). In contrast, addition of PTH(1-34) in late stage cultures (from day 10 to 21) accelerated NF (A-phase). The stable production of such an A-phase allowed us to study the mechanism of bone anabolic action of PTH(1-34). Subcellular localization studies of core binding factor alpha1 (Cbfa1) and reporter assays provided the results indicating that in the A-phase, PTH(1-34) triggers its bone anabolic action via enhancement of Cbfa1 transactivation. RT-PCR and Northern blot analyses revealed that alkaline phosphatase, osteocalcin and bone sialoprotein expression decreased in the C-phase and increased in the A-phase; however, expression of other bone proteins (Cbfa1, PTH/PTH-related peptide-receptor, osteopontin, collagen I alpha1, collagen I alpha2, vitamin K-dependent gamma-glutamyl carboxylase) did not change in a phase transition-related manner. Ovariectomized osteopenic mice, treated with PTH(1-34) (4 and 40 microg/kg, s.c., every other day, 4 or 6 weeks), recovered lost bone, displayed elevated nuclear localization of Cbfal in tibiae without alteration of its cytosolic level and exhibited upregulation of expressions of the same set of proteins (alkaline phosphatase, osteocalcin and bone sialoprotein) in femora. These results obtained by a concerted study in vitro and in vivo suggest that PTH triggers its osteogenic action via promotion of the transactivation of Cbfa1.
Volume 86(4)
Pages 405-16
Published 2001-8-1
DOI 10.1254/jjp.86.405
PMID 11569614
MeSH Alkaline Phosphatase / analysis Animals Animals, Newborn Body Weight Bone Diseases, Metabolic / surgery Cells, Cultured Core Binding Factor Alpha 1 Subunit Core Binding Factors Dose-Response Relationship, Drug Female Femur / drug effects Immunohistochemistry Injections, Subcutaneous Integrin-Binding Sialoprotein Mice Neoplasm Proteins* Osteoblasts / chemistry Osteoblasts / drug effects* Osteoblasts / physiology Osteocalcin / analysis Osteogenesis / drug effects* Osteogenesis / physiology Ovariectomy Sialoglycoproteins / analysis Teriparatide / administration & dosage Teriparatide / pharmacology* Tibia / drug effects Time Factors Transcription Factors / immunology Transcription Factors / metabolism* Transcription Factors / physiology* Transcriptional Activation Up-Regulation
Human and Animal Cells MC3T3-E1(RCB1126)