title: Endodermal expression of Nkx6 genes depends differentially on Pdx1.
abstract: Nkx family members are essential for normal development of many different tissues such as the heart, lungs, thyroid, prostate, and CNS. Here, we describe the endodermal expression pattern of three Nkx6 family genes of which two shows conserved expression in the early pancreatic epithelium. In chicken, Nkx6.1 expression is not restricted to the presumptive pancreatic area but is more broadly expressed in the endoderm. In mice, expression of Nkx6.1 is restricted to the pancreatic epithelium. In both mice and chicken, Nkx6.2 and Pdx1 are expressed in very similar domains, identifying Nkx6.2 as a novel marker of pancreas endoderm. Additionally, our results show that Nkx6.3 is expressed transiently in pancreatic endoderm in chicken but not mouse embryos. At later stages, Nkx6.3 is found in the caudal stomach and rostral duodenum in both species. Finally, we demonstrate that Pdx1 is required for Nkx6.1 but not Nkx6.2 expression in mice and that ectopic Pdx1 can induce Nkx6.1 but not Nkx6.2 or Nkx6.3 expression in anterior chicken endoderm. These results demonstrate that Nkx6.1 lies downstream of Pdx1 in a genetic pathway and that Pdx1 is required and sufficient for Nkx6.1 expression in the early foregut endoderm.
authors.affiliation: Department of Developmental Biology, Hagedorn Research Institute, Niels Steensensvej 6, DK-2820, Gentofte, Denmark.
authors.forename: Jesper K
authors.initials: JK
authors.lastname: Pedersen
authors.forename: Shelley B
authors.initials: SB
authors.lastname: Nelson
authors.forename: Mette C
authors.initials: MC
authors.lastname: Jorgensen
authors.forename: Korinna D
authors.initials: KD
authors.lastname: Henseleit
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Fujitani
authors.forename: Chris V E
authors.initials: CV
authors.lastname: Wright
authors.forename: Maike
authors.initials: M
authors.lastname: Sander
authors.forename: Palle
authors.initials: P
authors.lastname: Serup
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002642:Chick Embryo; D004707:Endoderm / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008817:Mice, Mutant Strains; D008969:Molecular Sequence Data; D010179:Pancreas / Q000196:embryology / Q000378:metabolism*; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D018398:Homeodomain Proteins; C491328:Nkx6-1 protein, mouse; C436827:Nkx6.2 protein, vertebrate; D015534:Trans-Activators; D014157:Transcription Factors; C084010:pancreatic and duodenal homeobox 1 protein