title: Pdgfrα and Flk1 are direct target genes of Mixl1 in differentiating embryonic stem cells.
abstract: The Mixl1 homeodomain protein plays a key role in mesendoderm patterning during embryogenesis, but its target genes remain to be identified. We compared gene expression in differentiating heterozygous Mixl1(GFP/w) and homozygous null Mixl1(GFP/Hygro) mouse embryonic stem cells to identify potential downstream transcriptional targets of Mixl1. Candidate Mixl1 regulated genes whose expression was reduced in GFP+ cells isolated from differentiating Mixl1(GFP/Hygro) embryoid bodies included Pdgfrα and Flk1. Mixl1 bound to ATTA sequences located in the Pdgfrα and Flk1 promoters and chromatin immunoprecipitation assays confirmed Mixl1 occupancy of these promoters in vivo. Furthermore, Mixl1 transactivated the Pdgfrα and Flk1 promoters through ATTA sequences in a DNA binding dependent manner. These data support the hypothesis that Mixl1 directly regulates Pdgfrα and Flk1 gene expression and strengthens the position of Mixl1 as a key regulator of mesendoderm development during mammalian gastrulation.
authors.affiliation: Differentiation and Transcription Laboratory, Peter MacCallum Cancer Centre, East Melbourne, Victoria, 3002, Australia.
authors.forename: Lloyd A
authors.initials: LA
authors.lastname: Pereira
authors.forename: Michael S
authors.initials: MS
authors.lastname: Wong
authors.forename: Anna K
authors.initials: AK
authors.lastname: Mossman
authors.forename: Koula
authors.initials: K
authors.lastname: Sourris
authors.forename: Mary E
authors.initials: ME
authors.lastname: Janes
authors.forename: Kathy
authors.initials: K
authors.lastname: Knezevic
authors.forename: Claire E
authors.initials: CE
authors.lastname: Hirst
authors.forename: Sue Mei
authors.initials: SM
authors.lastname: Lim
authors.forename: John E
authors.initials: JE
authors.lastname: Pimanda
authors.forename: Edouard G
authors.initials: EG
authors.lastname: Stanley
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Elefanty
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002454:Cell Differentiation / Q000235:genetics*; D002460:Cell Line; D053595:Embryonic Stem Cells / Q000166:cytology* / Q000378:metabolism*; D004707:Endoderm / Q000166:cytology / Q000378:metabolism; D005434:Flow Cytometry; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000737:chemistry / Q000378:metabolism*; D008648:Mesoderm / Q000166:cytology / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000235:genetics* / Q000378:metabolism; D015533:Transcriptional Activation / Q000235:genetics; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics* / Q000378:metabolism
chemical_list: D018398:Homeodomain Proteins; C464781:Mixl1 protein, mouse; D012333:RNA, Messenger; D020796:Receptor, Platelet-Derived Growth Factor alpha; D040301:Vascular Endothelial Growth Factor Receptor-2