title: Runx2 determines bone maturity and turnover rate in postnatal bone development and is involved in bone loss in estrogen deficiency.
abstract: Runx2 is an essential transcription factor for osteoblast differentiation. However, the functions of Runx2 in postnatal bone development remain to be clarified. Introduction of dominant-negative (dn)-Runx2 did not inhibit Col1a1 and osteocalcin expression in mature osteoblastic cells. In transgenic mice that expressed dn-Runx2 in osteoblasts, the trabecular bone had increased mineralization, increased volume, and features of compact bone, and the expression of major bone matrix protein genes was relatively maintained. After ovariectomy, neither osteolysis nor bone formation was enhanced and bone was relatively conserved. In wild-type mice, Runx2 was strongly expressed in immature osteoblasts but downregulated during osteoblast maturation. These findings indicate that the maturity and turnover rate of bone are determined by the level of functional Runx2 and Runx2 is responsible for bone loss in estrogen deficiency, but that Runx2 is not essential for maintenance of the expression of major bone matrix protein genes in postnatal bone development and maintenance.
authors.affiliation: Department of Cell Biology, Unit of Basic Medical Sciences, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
authors.forename: Zenjiro
authors.initials: Z
authors.lastname: Maruyama
authors.forename: Carolina A
authors.initials: CA
authors.lastname: Yoshida
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Furuichi
authors.forename: Norio
authors.initials: N
authors.lastname: Amizuka
authors.forename: Masako
authors.initials: M
authors.lastname: Ito
authors.forename: Ryo
authors.initials: R
authors.lastname: Fukuyama
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Miyazaki
authors.forename: Hideki
authors.initials: H
authors.lastname: Kitaura
authors.forename: Kouhei
authors.initials: K
authors.lastname: Nakamura
authors.forename: Takashi
authors.initials: T
authors.lastname: Fujita
authors.forename: Naoko
authors.initials: N
authors.lastname: Kanatani
authors.forename: Takeshi
authors.initials: T
authors.lastname: Moriishi
authors.forename: Kei
authors.initials: K
authors.lastname: Yamana
authors.forename: Wenguang
authors.initials: W
authors.lastname: Liu
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kawaguchi
authors.forename: Kozo
authors.initials: K
authors.lastname: Nakamura
authors.forename: Toshihisa
authors.initials: T
authors.lastname: Komori
mesh_terms: D000818:Animals; D001846:Bone Development / Q000502:physiology*; D001862:Bone Resorption / Q000378:metabolism*; D001842:Bone and Bones / Q000378:metabolism*; D002460:Cell Line; D050659:Core Binding Factor Alpha 1 Subunit / Q000502:physiology*; D004967:Estrogens / Q000172:deficiency*; D051379:Mice; D008822:Mice, Transgenic; D010006:Osteoblasts / Q000378:metabolism
chemical_list: D050659:Core Binding Factor Alpha 1 Subunit; D004967:Estrogens; C493716:Runx2 protein, mouse