title: The transcription factorPax6is required for pancreatic β cell identity, glucose-regulated ATP synthesis, and Ca2+dynamics in adult mice.
abstract: Heterozygous mutations in the human paired box genePAX6lead to impaired glucose tolerance. Although embryonic deletion of thePax6gene in mice leads to loss of most pancreatic islet cell types, the functional consequences ofPax6loss in adults are poorly defined. Here we developed a mouse line in whichPax6was selectively inactivated in β cells by crossing animals with floxedPax6alleles to mice expressing the inducible Pdx1CreERT transgene.Pax6deficiency, achieved by tamoxifen injection, caused progressive hyperglycemia. Although β cell mass was preserved 8 days post-injection, total insulin content and insulin:chromogranin A immunoreactivity were reduced by ∼60%, and glucose-stimulated insulin secretion was eliminated. RNA sequencing and quantitative real-time PCR analyses revealed that, although the expression of key β cell genes, includingIns2,Slc30a8,MafA, Slc2a2,G6pc2, andGlp1r, was reduced afterPax6deletion, that of several genes that are usually selectively repressed ("disallowed") in β cells, includingSlc16a1, was increased. Assessed in intact islets, glucose-induced ATP:ADP increases were significantly reduced (p< 0.05) in βPax6KOversuscontrol β cells, and the former displayed attenuated increases in cytosolic Ca2+Unexpectedly, glucose-induced increases in intercellular connectivity were enhanced afterPax6deletion, consistent with increases in the expression of the glucose sensor glucokinase, but decreases in that of two transcription factors usually expressed in fully differentiated β-cells,Pdx1andNkx6.1, were observed in islet "hub" cells. These results indicate thatPax6is required for the functional identity of adult β cells. Furthermore, deficiencies in β cell glucose sensing are likely to contribute to defective insulin secretion in human carriers ofPAX6mutations.
authors.affiliation: From the Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology, and Metabolism, Imperial College London, Du Cane Road, London W12 0NN, United Kingdom.
authors.forename: Ryan K
authors.initials: RK
authors.lastname: Mitchell
authors.affiliation: From the Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology, and Metabolism, Imperial College London, Du Cane Road, London W12 0NN, United Kingdom.
authors.forename: Marie-Sophie
authors.initials: MS
authors.lastname: Nguyen-Tu
authors.affiliation: From the Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology, and Metabolism, Imperial College London, Du Cane Road, London W12 0NN, United Kingdom.
authors.forename: Pauline
authors.initials: P
authors.lastname: Chabosseau
authors.affiliation: From the Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology, and Metabolism, Imperial College London, Du Cane Road, London W12 0NN, United Kingdom.
authors.forename: Rebecca M
authors.initials: RM
authors.lastname: Callingham
authors.affiliation: From the Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology, and Metabolism, Imperial College London, Du Cane Road, London W12 0NN, United Kingdom.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Pullen
authors.affiliation: From the Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology, and Metabolism, Imperial College London, Du Cane Road, London W12 0NN, United Kingdom.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Cheung
authors.affiliation: From the Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology, and Metabolism, Imperial College London, Du Cane Road, London W12 0NN, United Kingdom.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Leclerc
authors.affiliation: From the Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology, and Metabolism, Imperial College London, Du Cane Road, London W12 0NN, United Kingdom, d.hodson@imperial.ac.uk d.hodson@bham.ac.uk.|the Institute of Metabolism and Systems Research and Centre of Membrane Proteins and Receptors, University of Birmingham, Edgbaston B15 2TT, United Kingdom, and.|the Centre for Endocrinology, Diabetes, and Metabolism, Birmingham Health Partners, Birmingham B15 2TH, United Kingdom.
authors.forename: David J
authors.initials: DJ
authors.lastname: Hodson
authors.affiliation: From the Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology, and Metabolism, Imperial College London, Du Cane Road, London W12 0NN, United Kingdom, g.rutter@imperial.ac.uk.
authors.forename: Guy A
authors.initials: GA
authors.lastname: Rutter
mesh_terms: D000255:Adenosine Triphosphate / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D005786:Gene Expression Regulation; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D050417:Insulin-Secreting Cells / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D000071841:PAX6 Transcription Factor / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D000071841:PAX6 Transcription Factor; C000605732:Pax6 protein, mouse; D000255:Adenosine Triphosphate; D005947:Glucose; D002118:Calcium
keywords: calcium; diabetes; gene expression; imaging; insulin; islet