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

<p>Representative photographs of immunohistochemical analyses performed on 6 month-old Glu-ArxKO/Pax4KO pancreata using the indicated antibody combinations. A clear loss of <i>Arx</i> was evidenced in Glu-ArxKO/Pax4KO glucagon⁺ cells (<b>A</b>), such cells not ectopically expressing <i>Pax4</i> (as seen in <b><a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003934#pgen.1003934.s002" target="_blank">Figures S2</a>-<a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003934#pgen.1003934.s003" target="_blank">S3</a></b>). Interestingly, a number of insulin⁺ cells appeared Pax4⁻, such cells most likely deriving from Arx^−/Y Pax4^−/− glucagon⁺ cells (<b>A–C</b>). As noted in Glu-ArxKO and Dox+ IndGlu-ArxKO pancreata, an increase in islet size compared to controls (<a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003934#pgen-1003934-g001" target="_blank"><b>Figure 1</b></a>), caused by an insulin⁺ cell hyperplasia, was observed in Glu-ArxKO/Pax4KO pancreata (<b>A–I</b>). Non-β-cell endocrine hormone-expressing cells displayed a preferential localization at poles of the islets, adjacent to neighboring ducts (<b>E–I</b>), reminiscent of the phenotype of the sole inactivation of <i>Arx</i> in glucagon⁺ cells. (Each photograph is representative of at least three independent animals).