title: Novel basic helix-loop-helix transcription factor hes4 antagonizes the function of twist-1 to regulate lineage commitment of bone marrow stromal/stem cells.
abstract: Basic helix-loop-helix (bHLH) transcription factors are pivotal regulators of cellular differentiation and development. The bHLH factor, Twist-1 has previously been found to control bone marrow stromal/stem cells (BMSC) self-renewal, life span, and differentiation, however not much is known about its mechanism of action. In this study, we have discovered a novel Twist-1 regulated bHLH gene, Hes4, expressed in humans, but not in mice. Its closest homologue in both humans and mice is Hes1. Overexpression and knockdown studies demonstrated that Hes4 promotes osteogenesis resulting in an increase in Runx2, osteocalcin, osteopontin, and bone sialoprotein expression. Conversely, Hes4 was found to inhibit adipogenesis accompanied by a decrease in PPARγ2, adiponectin, and adipsin expression. In vitro studies indicate that Hes4 employs a mechanism to counteract the negative function of Twist-1 on osteogenesis by binding to Twist-1 and inhibiting the ability of Twist-1 to bind and inhibit Runx2. In vivo chromatin immunoprecipitation and in vitro reporter assays illustrated that Runx2 recruitment to the osterix promoter, was found to be enhanced in the presence of Hes4 and inhibited in the presence of Twist-1. Therefore, Hes4 antagonizes the function of Twist-1 to regulate lineage commitment of BMSC. These studies highlight the potential differences in molecular mechanisms that regulate BMSC osteogenic differentiation between human and mouse.
authors.affiliation: 1Mesenchymal Stem Cell Laboratory, School of Medical Sciences, Faculty of Health Sciences, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Cakouros
authors.affiliation: 1Mesenchymal Stem Cell Laboratory, School of Medical Sciences, Faculty of Health Sciences, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: Sandra
authors.initials: S
authors.lastname: Isenmann
authors.affiliation: 1Mesenchymal Stem Cell Laboratory, School of Medical Sciences, Faculty of Health Sciences, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: Sarah Elizabeth
authors.initials: SE
authors.lastname: Hemming
authors.affiliation: 1Mesenchymal Stem Cell Laboratory, School of Medical Sciences, Faculty of Health Sciences, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: Danijela
authors.initials: D
authors.lastname: Menicanin
authors.affiliation: 1Mesenchymal Stem Cell Laboratory, School of Medical Sciences, Faculty of Health Sciences, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: Esther
authors.initials: E
authors.lastname: Camp
authors.affiliation: 2Myeloma Research Laboratory, School of Medical Sciences, Faculty of Health Sciences, University of Adelaide, Adelaide, South Australia, Australia.|3Cancer Theme, South Australian Health and Medical Research Institute, Adelaide, South Australia, Australia.
authors.forename: Andrew Christopher William
authors.initials: AC
authors.lastname: Zannetinno
authors.affiliation: 1Mesenchymal Stem Cell Laboratory, School of Medical Sciences, Faculty of Health Sciences, University of Adelaide, Adelaide, South Australia, Australia.|3Cancer Theme, South Australian Health and Medical Research Institute, Adelaide, South Australia, Australia.
authors.forename: Stan
authors.initials: S
authors.lastname: Gronthos
mesh_terms: D050156:Adipogenesis; D052242:Adiponectin / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D019070:Cell Lineage; D002478:Cells, Cultured; D011416:Complement Factor D / Q000235:genetics / Q000378:metabolism; D050659:Core Binding Factor Alpha 1 Subunit / Q000235:genetics / Q000378:metabolism; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism*; D015675:Osteocalcin / Q000235:genetics / Q000378:metabolism; D053495:Osteopontin / Q000235:genetics / Q000378:metabolism; D047495:PPAR gamma / Q000235:genetics / Q000378:metabolism; D013045:Species Specificity; D051879:Twist-Related Protein 1 / Q000235:genetics / Q000378:metabolism*
chemical_list: D052242:Adiponectin; D051792:Basic Helix-Loop-Helix Proteins; D011416:Complement Factor D; D050659:Core Binding Factor Alpha 1 Subunit; D009687:Nuclear Proteins; D015675:Osteocalcin; D053495:Osteopontin; D047495:PPAR gamma; D051879:Twist-Related Protein 1; C000604917:Hes4 protein, human; C493709:RUNX2 protein, human; C103173:TWIST1 protein, human