title: Oxygen tension regulates pancreatic beta-cell differentiation through hypoxia-inducible factor 1alpha.
abstract: OBJECTIVE
  Recent evidence indicates that low oxygen tension (pO2) or hypoxia controls the differentiation of several cell types during development. Variations of pO2 are mediated through the hypoxia-inducible factor (HIF), a crucial mediator of the adaptative response of cells to hypoxia. The aim of this study was to investigate the role of pO2 in beta-cell differentiation.
  
  
  METHODS
  We analyzed the capacity of beta-cell differentiation in the rat embryonic pancreas using two in vitro assays. Pancreata were cultured either in collagen or on a filter at the air/liquid interface with various pO2. An inhibitor of the prolyl hydroxylases, dimethyloxaloylglycine (DMOG), was used to stabilize HIF1alpha protein in normoxia.
  
  
  RESULTS
  When cultured in collagen, embryonic pancreatic cells were hypoxic and expressed HIF1alpha and rare beta-cells differentiated. In pancreata cultured on filter (normoxia), HIF1alpha expression decreased and numerous beta-cells developed. During pancreas development, HIF1alpha levels were elevated at early stages and decreased with time. To determine the effect of pO2 on beta-cell differentiation, pancreata were cultured in collagen at increasing concentrations of O2. Such conditions repressed HIF1alpha expression, fostered development of Ngn3-positive endocrine progenitors, and induced beta-cell differentiation by O2 in a dose-dependent manner. By contrast, forced expression of HIF1alpha in normoxia using DMOG repressed Ngn3 expression and blocked beta-cell development. Finally, hypoxia requires hairy and enhancer of split (HES)1 expression to repress beta-cell differentiation.
  
  
  CONCLUSIONS
  These data demonstrate that beta-cell differentiation is controlled by pO2 through HIF1alpha. Modifying pO2 should now be tested in protocols aiming to differentiate beta-cells from embryonic stem cells.
authors.affiliation: INSERM U845, Research Center Growth and Signalling, Université Paris Descartes, Hôpital Necker, Paris, France.
authors.forename: Mylène
authors.initials: M
authors.lastname: Heinis
authors.forename: Marie-Thérèse
authors.initials: MT
authors.lastname: Simon
authors.forename: Karine
authors.initials: K
authors.lastname: Ilc
authors.forename: Nathalie M
authors.initials: NM
authors.lastname: Mazure
authors.forename: Jacques
authors.initials: J
authors.lastname: Pouysségur
authors.forename: Raphael
authors.initials: R
authors.lastname: Scharfmann
authors.forename: Bertrand
authors.initials: B
authors.lastname: Duvillié
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology; D053595:Embryonic Stem Cells / Q000166:cytology / Q000378:metabolism; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D000860:Hypoxia / Q000378:metabolism* / Q000473:pathology; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism*; D050417:Insulin-Secreting Cells / Q000166:cytology* / Q000378:metabolism*; D007515:Islets of Langerhans / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D009924:Organ Culture Techniques; D010100:Oxygen / Q000378:metabolism* / Q000494:pharmacology; D011247:Pregnancy; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000502:physiology; D000072056:Transcription Factor HES-1
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D018398:Homeodomain Proteins; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009419:Nerve Tissue Proteins; D010100:Oxygen; D000072056:Transcription Factor HES-1; C489735:Hes1 protein, rat; C497444:Hif1a protein, rat; C498696:Neurog3 protein, rat