Oxygen Tension Regulates Pancreatic β-Cell Differentiation Through Hypoxia-Inducible Factor 1α

OBJECTIVE-Recent evidence indicates that low oxygen tension (pO(2)) or hypoxia controls the differentiation of several cell types during development. Variations of pO(2) 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 pO(2) in beta-cell differentiation. RESEARCH DESIGN AND 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 pO(2). An inhibitor of the prolyl hydroxylases, dimethyloxaloylglycine (DMOG), was used to stabilize HIF1 alpha protein in normoxia. RESULTS-When cultured in collagen, embryonic pancreatic cells were hypoxic and expressed HIF1 alpha and rare beta-cells differentiated. In pancreata cultured on filter (normoxia), HIF1 alpha expression decreased and numerous beta-cells developed. During pancreas development, HIF1 alpha levels were elevated at early stages and decreased with time. To determine the effect of pO(2) on beta-cell differentiation, pancreata were cultured in collagen at increasing concentrations of O-2. Such conditions repressed HIF1 alpha. expression, fostered development of Ngn3-positive endocrine progenitors, and induced beta-cell differentiation by O-2 in a dose-dependent manner. By contrast, forced expression of HIF1 alpha 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 pO(2) through HIF1 alpha. Modifying pO(2) should now be tested in protocols aiming to differentiate beta-cells from embryonic stem cells. Diabetes 59:662-669, 2010