title: BMP-2 Induced Expression of Alx3 That Is a Positive Regulator of Osteoblast Differentiation.
abstract: Bone morphogenetic proteins (BMPs) regulate many aspects of skeletal development, including osteoblast and chondrocyte differentiation, cartilage and bone formation, and cranial and limb development. Among them, BMP-2, one of the most potent osteogenic signaling molecules, stimulates osteoblast differentiation, while it inhibits myogenic differentiation in C2C12 cells. To evaluate genes involved in BMP-2-induced osteoblast differentiation, we performed cDNA microarray analyses to compare BMP-2-treated and -untreated C2C12 cells. We focused on Alx3 (aristaless-like homeobox 3) which was clearly induced during osteoblast differentiation. Alx3, a homeobox gene related to the Drosophilaaristaless gene, has been linked to developmental functions in craniofacial structures and limb development. However, little is known about its direct relationship with bone formation. In the present study, we focused on the mechanisms of Alx3 gene expression and function during osteoblast differentiation induced by BMP-2. In C2C12 cells, BMP-2 induced increase of Alx3 gene expression in both time- and dose-dependent manners through the BMP receptors-mediated SMAD signaling pathway. In addition, silencing of Alx3 by siRNA inhibited osteoblast differentiation induced by BMP-2, as showed by the expressions of alkaline phosphatase (Alp), Osteocalcin, and Osterix, while over-expression of Alx3 enhanced osteoblast differentiation induced by BMP-2. These results indicate that Alx3 expression is enhanced by BMP-2 via the BMP receptors mediated-Smad signaling and that Alx3 is a positive regulator of osteoblast differentiation induced by BMP-2.
authors.affiliation: Department of Biochemistry, School of Dentistry, Showa University, Tokyo, Japan ; Department of Prosthodontics, School of Dentistry, Showa University, Tokyo, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Matsumoto
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yamada
authors.forename: Ryo
authors.initials: R
authors.lastname: Aizawa
authors.forename: Dai
authors.initials: D
authors.lastname: Suzuki
authors.forename: Masayuki
authors.initials: M
authors.lastname: Tsukasaki
authors.forename: Wataru
authors.initials: W
authors.lastname: Suzuki
authors.forename: Mutsuko
authors.initials: M
authors.lastname: Nakayama
authors.forename: Koutaro
authors.initials: K
authors.lastname: Maki
authors.forename: Matsuo
authors.initials: M
authors.lastname: Yamamoto
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Baba
authors.forename: Ryutaro
authors.initials: R
authors.lastname: Kamijo
mesh_terms: D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000502:physiology*; D002454:Cell Differentiation; D018398:Homeodomain Proteins / Q000378:metabolism*; D051379:Mice; D010006:Osteoblasts / Q000166:cytology*
chemical_list: C113607:Alx3 protein, mouse; D019485:Bone Morphogenetic Proteins; D018398:Homeodomain Proteins