title: miR-124 negatively regulates osteogenic differentiation and in vivo bone formation of mesenchymal stem cells.
abstract: MicroRNAs are novel key regulators of cellular differentiation. Dlx transcription factors play an important role in osteoblast differentiation, and Dlx5 and Dlx2 are known targets of miR-124. Therefore, in the present study, we investigated the regulatory effects of miR-124 on the osteogenic differentiation and in vivo bone formation of mesenchymal stem cells (MSCs). During osteogenic induction by BMP2, the expression levels of miR-124 were inversely correlated with those of osteogenic differentiation marker genes in human and mouse bone marrow-derived MSCs, MC3T3-E1 cells and C2C12 cells. The overexpression of a miR-124 mimic significantly decreased the expression levels of Dlx5, Dlx3, and Dlx2, whereas the silencing of miR-124 with hairpin inhibitors significantly increased the expression of these Dlx genes. Luciferase reporter assays demonstrated that miR-124 directly targets the 3'UTRs of Dlx3, Dlx5, and Dlx2. The overexpression of a miR-124 mimic suppressed the osteogenic marker gene expression levels, alkaline phosphatase activity and matrix mineralization, which were all significantly increased by the overexpression of a miR-124 inhibitor. When ectopic bone formation was induced by the subcutaneous transplantation of human bone marrow-derived MSCs in nude mice, MSCs overexpressing a miR-124 inhibitor significantly enhanced woven bone formation compared with control MSCs. However, MSCs overexpressing a miR-124 mimic exhibited increased adipocyte differentiation at the expense of ectopic bone formation. These results suggest that miR-124 is a negative regulator of osteogenic differentiation and in vivo bone formation and that the targeting of Dlx5, Dlx3, and Dlx2 genes partly contributes to this inhibitory effect exerted by miR-124.
authors.affiliation: Department of Molecular Genetics, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, 110-744, Korea.
authors.forename: Abdul S
authors.initials: AS
authors.lastname: Qadir
authors.forename: Soyoun
authors.initials: S
authors.lastname: Um
authors.forename: Heesu
authors.initials: H
authors.lastname: Lee
authors.forename: Kyunghwa
authors.initials: K
authors.lastname: Baek
authors.forename: Byoung Moo
authors.initials: BM
authors.lastname: Seo
authors.forename: Gene
authors.initials: G
authors.lastname: Lee
authors.forename: Gwan-Shik
authors.initials: GS
authors.lastname: Kim
authors.forename: Kyung Mi
authors.initials: KM
authors.lastname: Woo
authors.forename: Hyun-Mo
authors.initials: HM
authors.lastname: Ryoo
authors.forename: Jeong-Hwa
authors.initials: JH
authors.lastname: Baek
mesh_terms: D020413:3' Untranslated Regions; D017667:Adipocytes / Q000166:cytology / Q000378:metabolism; D000818:Animals; D000954:Antigens, Surface / Q000235:genetics / Q000378:metabolism; D055396:Bone Morphogenetic Protein 2 / Q000378:metabolism; D001842:Bone and Bones / Q000166:cytology / Q000378:metabolism*; D002454:Cell Differentiation; D002478:Cells, Cultured; D055785:Gene Knockdown Techniques; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000378:metabolism; D008810:Mice, Inbred C57BL; D008819:Mice, Nude; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism*; D010006:Osteoblasts / Q000166:cytology* / Q000378:metabolism; D010012:Osteogenesis; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D020413:3' Untranslated Regions; D000954:Antigens, Surface; C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; C100596:DLX5 protein, human; C088334:Distal-less homeobox proteins; D018398:Homeodomain Proteins; C509207:MIRN124 microRNA, human; D035683:MicroRNAs; D014157:Transcription Factors; C092261:antigen Dlx-2
keywords: BONE FORMATION; Dlx TRANSCRIPTION FACTORS; OSTEOGENIC DIFFERENTIATION; miR-124