title: BMP-4 induction of arrest and differentiation of osteoblast-like cells via p21 CIP1 and p27 KIP1 regulation.
abstract: Cell cycle regulation by differentiation signals is critical for eukaryote development. We investigated the roles of bone morphogenetic protein (BMP)-4, an important stimulator of osteoblast differentiation and bone formation, in regulating cell cycle distribution in four osteoblast-like cell lines and mouse primary osteoblasts, and the underlying mechanisms. In all cells used, BMP-4 induced G(0)/G(1) arrest. The molecular basis of the BMP-4 effect was analyzed, and the presentation on molecular mechanism is focused on human MG63 cells. BMP-4 induced p21(CIP1) and p27(KIP1) expressions and hence cell differentiation but had no effects on the expressions of cyclins A, B1, D1, and E, cyclin-dependent protein kinase-2, -4, and -6. Using specific small interfering RNA (siRNA), we found that BMP-4-induced G(0)/G(1) arrest, and p21(CIP1) and p27(KIP1) expressions were mediated by BMP receptor type IA (BMPRIA)-specific Sma- and Mad-related protein (Smad)1/5. BMP-4 induced transient phosphorylations of ERK; transfection of MG63 cells with ERK2, but not ERK1, -specific siRNA inhibited the BMP-4-induced responses in MG63 cells. Pretreatment of MG63 cells with Arg-Gly-Asp-Ser, which blocks the cell-extracellular matrix interaction, or transfection with beta(3) integrin-specific siRNA inhibited BMP-4-induced ERK and Smad1/5 phosphorylations. BMP-4 induced transient increases in associations of beta(3)-integrin with focal adhesion kinase and Shc, the dominant-negative mutants of which inhibited BMP-4-induced ERK and Smad1/5 phosphorylations. Our results indicate that BMP-4 induces G(0)/G(1) arrest and hence differentiation in osteoblast-like cells through increased expressions of p21(CIP1) and p27(KIP1), which are mediated by BMPRIA-specific Smad1/5. The extracellular matrix/beta(3) integrin/ focal adhesion kinase/Shc/ERK2 signaling pathway is involved in these BMP-4-induced responses in osteoblast-like cells.
authors.affiliation: Division of Medical Engineering Research, National Chiao Tung University, Hsinchu 30010, Taiwan.
authors.forename: Shun-Fu
authors.initials: SF
authors.lastname: Chang
authors.forename: Ting-Kuo
authors.initials: TK
authors.lastname: Chang
authors.forename: Hsin-Hsin
authors.initials: HH
authors.lastname: Peng
authors.forename: Yi-Ting
authors.initials: YT
authors.lastname: Yeh
authors.forename: Ding-Yu
authors.initials: DY
authors.lastname: Lee
authors.forename: Chiuan-Ren
authors.initials: CR
authors.lastname: Yeh
authors.forename: Jing
authors.initials: J
authors.lastname: Zhou
authors.forename: Cheng-Kung
authors.initials: CK
authors.lastname: Cheng
authors.forename: Cheng Allen
authors.initials: CA
authors.lastname: Chang
authors.forename: Jeng-Jiann
authors.initials: JJ
authors.lastname: Chiu
mesh_terms: D016475:3T3 Cells; D000818:Animals; D055415:Bone Morphogenetic Protein 4 / Q000378:metabolism*; D002453:Cell Cycle; D002454:Cell Differentiation; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism*; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D051379:Mice; D008954:Models, Biological; D010006:Osteoblasts / Q000378:metabolism*
chemical_list: C525809:BMP4 protein, human; D055415:Bone Morphogenetic Protein 4; C493956:CDKN1A protein, human; C436291:CDKN1B protein, human; C493957:Cdkn1a protein, mouse; C493961:Cdkn1b protein, mouse; D050759:Cyclin-Dependent Kinase Inhibitor p21; D047908:Intracellular Signaling Peptides and Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27