title: The developmental regulator Pax6 is essential for maintenance of islet cell function in the adult mouse pancreas.
abstract: The transcription factor Pax6 is a developmental regulator with a crucial role in development of the eye, brain, and olfactory system. Pax6 is also required for correct development of the endocrine pancreas and specification of hormone producing endocrine cell types. Glucagon-producing cells are almost completely lost in Pax6-null embryos, and insulin-expressing beta and somatostatin-expressing delta cells are reduced. While the developmental role of Pax6 is well-established, investigation of a further role for Pax6 in the maintenance of adult pancreatic function is normally precluded due to neonatal lethality of Pax6-null mice. Here a tamoxifen-inducible ubiquitous Cre transgene was used to inactivate Pax6 at 6 months of age in a conditional mouse model to assess the effect of losing Pax6 function in adulthood. The effect on glucose homeostasis and the expression of key islet cell markers was measured. Homozygous Pax6 deletion mice, but not controls, presented with all the symptoms of classical diabetes leading to severe weight loss requiring termination of the experiment five weeks after first tamoxifen administration. Immunohistochemical analysis of the pancreata revealed almost complete loss of Pax6 and much reduced expression of insulin, glucagon, and somatostatin. Several other markers of islet cell function were also affected. Notably, strong upregulation in the number of ghrelin-expressing endocrine cells was observed. These findings demonstrate that Pax6 is essential for adult maintenance of glucose homeostasis and function of the endocrine pancreas.
authors: Medical Research Council Human Genetics Unit at the Institute of Genetics and Molecular Medicine at the University of Edinburgh, Edinburgh, United Kingdom.
authors: Alan W
authors: AW
authors: Hart
authors: Sebastien
authors: S
authors: Mella
authors: Jacek
authors: J
authors: Mendrychowski
authors: Veronica
authors: V
authors: van Heyningen
authors: Dirk A
authors: DA
authors: Kleinjan
mesh_terms: D000818:Animals; D003920:Diabetes Mellitus / Q000235:genetics / Q000503:physiopathology; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D054439:Ghrelin / Q000235:genetics / Q000378:metabolism; D005947:Glucose / Q000235:genetics / Q000378:metabolism*; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D007515:Islets of Langerhans / Q000254:growth & development* / Q000378:metabolism; D051379:Mice; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors / Q000235:genetics / Q000378:metabolism*; D010179:Pancreas / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation; D015431:Weight Loss
chemical_list: D005136:Eye Proteins; D054439:Ghrelin; D018398:Homeodomain Proteins; D000071841:PAX6 Transcription Factor; C000605730:PAX6 protein, human; D051761:Paired Box Transcription Factors; C000605732:Pax6 protein, mouse; D012097:Repressor Proteins; D005947:Glucose