The inactivation of <i>Pax4</i> in <i>Arx</i>-deficient glucagon-expressing cells does not impact β-like cell neogenesis.

Representative photographs of immunohistochemical analyses performed on 6 month-old Glu-ArxKO/Pax4KO pancreata using the indicated antibody combinations. A clear loss of Arx was evidenced in Glu-ArxKO/Pax4KO glucagon+ cells (A), such cells not ectopically expressing Pax4 (as seen in Figures S2-S3). Interestingly, a number of insulin+ cells appeared Pax4−, such cells most likely deriving from Arx−/Y Pax4−/− glucagon+ cells (A–C). As noted in Glu-ArxKO and Dox+ IndGlu-ArxKO pancreata, an increase in islet size compared to controls (Figure 1), caused by an insulin+ cell hyperplasia, was observed in Glu-ArxKO/Pax4KO pancreata (A–I). Non-β-cell endocrine hormone-expressing cells displayed a preferential localization at poles of the islets, adjacent to neighboring ducts (E–I), reminiscent of the phenotype of the sole inactivation of Arx in glucagon+ cells. (Each photograph is representative of at least three independent animals).