title: The mammal-specific Pdx1 Area II enhancer has multiple essential functions in early endocrine cell specification and postnatal β-cell maturation.
abstract: The transcription factor Pdx1 is required for multiple aspects of pancreatic organogenesis. It remains unclear to what extent Pdx1 expression and function depend upon trans-activation through 5' conserved cis-regulatory regions and, in particular, whether the mammal-specific Area II (-2139 to -1958 bp) affects minor or major aspects of organogenesis. We show that Area II is a primary effector of endocrine-selective transcription in epithelial multipotent cells, nascent endocrine progenitors, and differentiating and mature β cells in vivo Pdx1ΔAREAII/-mice exhibit a massive reduction in endocrine progenitor cells and progeny hormone-producing cells, indicating that Area II activity is fundamental to mounting an effective endocrine lineage-specification program within the multipotent cell population. Creating an Area II-deleted state within already specified Neurog3-expressing endocrine progenitor cells increased the proportion of glucagon+α relative to insulin+β cells, associated with the transcriptional and epigenetic derepression of the α-cell-determining Arx gene in endocrine progenitors. There were also glucagon and insulin co-expressing cells, and β cells that were incapable of maturation. Creating the Pdx1ΔAREAIIstate after cells entered an insulin-expressing stage led to immature and dysfunctional islet β cells carrying abnormal chromatin marking in vital β-cell-associated genes. Therefore, trans-regulatory integration through Area II mediates a surprisingly extensive range of progenitor and β-cell-specific Pdx1 functions.
authors.affiliation: Vanderbilt University Program in Developmental Biology and Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37232 USA.|Vanderbilt Center for Stem Cell Biology, Vanderbilt University, Nashville, TN 37232, USA.
authors.forename: Yu-Ping
authors.initials: YP
authors.lastname: Yang
authors.affiliation: Vanderbilt University Program in Developmental Biology and Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37232 USA.|Vanderbilt Center for Stem Cell Biology, Vanderbilt University, Nashville, TN 37232, USA.|Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Magnuson
authors.affiliation: Vanderbilt University Program in Developmental Biology and Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37232 USA.|Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA.
authors.forename: Roland
authors.initials: R
authors.lastname: Stein
authors.affiliation: Vanderbilt University Program in Developmental Biology and Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37232 USA chris.wright@vanderbilt.edu.|Vanderbilt Center for Stem Cell Biology, Vanderbilt University, Nashville, TN 37232, USA.
authors.forename: Christopher V E
authors.identifier: 0000-0002-9260-4009
authors.initials: CV
authors.lastname: Wright
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002454:Cell Differentiation / Q000235:genetics*; D004622:Embryo, Mammalian; D004742:Enhancer Elements, Genetic; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000378:metabolism*; D050417:Insulin-Secreting Cells / Q000166:cytology / Q000502:physiology*; D007515:Islets of Langerhans / Q000196:embryology* / Q000254:growth & development / Q000378:metabolism; D008322:Mammals / Q000196:embryology / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D038081:Organogenesis / Q000235:genetics; D013045:Species Specificity; D015534:Trans-Activators / Q000378:metabolism*
chemical_list: D018398:Homeodomain Proteins; D015534:Trans-Activators; C084010:pancreatic and duodenal homeobox 1 protein
keywords: Cis-regulatory function; Lineage diversification; Mouse; Pancreatic endocrine progenitors; Pdx1 enhancer Area II