Expression of osterix Is Regulated by FGF and Wnt/β-Catenin Signalling during Osteoblast Differentiation

• Published in: PloS one 2015-12, Vol.10 (12), p.e0144982-e0144982
• Main Authors: Felber, Katharina, Elks, Philip M, Lecca, Maria, Roehl, Henry H
• Format: Article
• Language: English
• Subjects: Animals; beta Catenin - genetics; beta Catenin - metabolism; Biocompatibility; Biomedical materials; Bone growth; Bone marrow; Cell Differentiation - physiology; Chemical interference; Danio rerio; Differentiation; Embryos; Fibroblast growth factors; Fibroblast Growth Factors - genetics; Fibroblast Growth Factors - metabolism; Gene expression; Kinases; Kinetics; Mesenchyme; Mutation; Osteoblastogenesis; Osteoblasts - cytology; Osteoblasts - metabolism; Osteogenesis; Osteogenesis - physiology; Pathways; Signal transduction; Signaling; Sp7 Transcription Factor; Studies; Transcription activation; Transcription factors; Transcription Factors - biosynthesis; Transcription Factors - genetics; Transgenic; Wnt protein; Wnt Signaling Pathway - physiology; Xenopus; Zebrafish; Zebrafish - genetics; Zebrafish - metabolism; Zebrafish Proteins - biosynthesis; Zebrafish Proteins - genetics; β-Catenin
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0144982

Osteoblast differentiation from mesenchymal cells is regulated by multiple signalling pathways. Here we have analysed the roles of Fibroblast Growth Factor (FGF) and canonical Wingless-type MMTV integration site (Wnt/β-Catenin) signalling pathways on zebrafish osteogenesis. We have used transgenic and chemical interference approaches to manipulate these pathways and have found that both pathways are required for osteoblast differentiation in vivo. Our analysis of bone markers suggests that these pathways act at the same stage of differentiation to initiate expression of the osteoblast master regulatory gene osterix (osx). We use two independent approaches that suggest that osx is a direct target of these pathways. Firstly, we manipulate signalling and show that osx gene expression responds with similar kinetics to that of known transcriptional targets of the FGF and Wnt pathways. Secondly, we have performed ChIP with transcription factors for both pathways and our data suggest that a genomic region in the first intron of osx mediates transcriptional activation. Based upon these data, we propose that FGF and Wnt/β-Catenin pathways act in part by directing transcription of osx to promote osteoblast differentiation at sites of bone formation.