Oxygen tension regulates pancreatic [beta]-cell differentiation through hypoxia-inducible factor 1[alpha].(ORIGINAL ARTICLE)

OBJECTIVE--Recent evidence indicates that low oxygen tension (p[O.sub.2]) or hypoxia controls the differentiation of several cell types during development. Variations of p[O.sub.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 p[O.sub.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 p[O.sub.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 p[O.sub.2] on [beta]-cell differentiation, pancreata were cultured in collagen at increasing concentrations of [O.sub.2]. Such conditions repressed HIF1[alpha] expression, fostered development of Ngn3-positive endocrine progenitors, and induced [beta]-cell differentiation by [O.sub.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)l expression to repress [beta]-cell differentiation. CONCLUSIONS--These data demonstrate that [beta]-cell differentiation is controlled by p[O.sub.2] through HIF1[alpha]. Modifying p[O.sub.2] should now be tested in protocols aiming to differentiate [beta]-cells from embryonic stem cells. Diabetes 59:662-669, 2010