title: YY1 activates Msx2 gene independent of bone morphogenetic protein signaling.
abstract: Msx2 is a homeobox gene expressed in multiple embryonic tissues which functions as a key mediator of numerous developmental processes. YY1 is a bi-functional zinc finger protein that serves as a repressor or activator to a variety of promoters. The role of YY1 during embryogenesis remains unknown. In this study, we report that Msx2 is regulated by YY1 through protein-DNA interactions. During embryogenesis, the expression pattern of YY1 was observed to overlap in part with that of Msx2. Most notably, during first branchial arch and limb development, both YY1 and Msx2 were highly expressed, and their patterns were complementary. To test the hypothesis that YY1 regulates Msx2 gene expression, P19 embryonal cells were used in a number of expression and binding assays. We discovered that, in these cells, YY1 activated endogenous Msx2 gene expression as well as Msx2 promoter-luciferase fusion gene activity. These biological activities were dependent on both the DNA binding and activation domains of YY1. In addition, YY1 bound specifically to three YY1 binding sites on the proximal promoter of Msx2 that accounted for this transactivation. Mutations introduced to these sites reduced the level of YY1 transactivation. As bone morphogenetic protein type 4 (BMP4) regulates Msx2 expression in embryonic tissues and in P19 cells, we further tested whether YY1 is the mediator of this BMP4 activity. BMP4 did not induce the expression of YY1 in early mouse mandibular explants, nor in P19 cells, suggesting that YY1 is not a required mediator of the BMP4 pathway in these tissues at this developmental stage. Taken together, these findings suggest that YY1 functions as an activator for the Msx2 gene, and that this regulation, which is independent of the BMP4 pathway, may be required during early mouse craniofacial and limb morphogenesis.
authors.affiliation: Craniofacial Development Section, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, 6 Center Drive, MSC 2745, Building 6, Room 324, Bethesda, MD 20892, USA.
authors.forename: D P
authors.initials: DP
authors.lastname: Tan
authors.forename: K
authors.initials: K
authors.lastname: Nonaka
authors.forename: G H
authors.initials: GH
authors.lastname: Nuckolls
authors.forename: Y H
authors.initials: YH
authors.lastname: Liu
authors.forename: R E
authors.initials: RE
authors.lastname: Maxson
authors.forename: H C
authors.initials: HC
authors.lastname: Slavkin
authors.forename: L
authors.initials: L
authors.lastname: Shum
mesh_terms: D000818:Animals; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology*; D001934:Branchial Region / Q000196:embryology / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D024202:Electrophoretic Mobility Shift Assay; D050981:Erythroid-Specific DNA-Binding Factors; D005121:Extremities / Q000196:embryology; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D018398:Homeodomain Proteins; D017403:In Situ Hybridization; D008334:Mandible / Q000187:drug effects / Q000196:embryology / Q000378:metabolism; D051379:Mice; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000096:biosynthesis; D015398:Signal Transduction; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics / Q000502:physiology; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D015533:Transcriptional Activation; D014162:Transfection; D014407:Tumor Cells, Cultured; D050986:YY1 Transcription Factor
chemical_list: C525810:Bmp4 protein, mouse; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins; D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D018398:Homeodomain Proteins; C084119:MSX2 protein; D012333:RNA, Messenger; D015534:Trans-Activators; D014157:Transcription Factors; D050986:YY1 Transcription Factor; C494699:Yy1 protein, mouse