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Tale-Family Homeodomain Proteins Regulate Endodermal Sonic Hedgehog Expression And Pattern The Anterior Endoderm, Philip Diiorio, Kristen Alexa, Seong-Kyu Choe, Letitiah Etheridge, Charles Sagerstrom

Philip J diIorio Jr

sonic hedgehog (shh) is expressed in anterior endoderm, where it is required to repress pancreas gene expression and to pattern the endoderm, but the pathway controlling endodermal shh expression is unclear. We find that expression of meis3, a TALE class homeodomain gene, coincides with shh expression in the endoderm of zebrafish embryos. Using a dominant negative construct or anti-sense morpholino oligos (MOs) to disrupt meis3 function, we observe ectopic insulin expression in anterior endoderm. This phenotype is also observed when meis3 MOs are targeted to the endoderm, suggesting that meis3 acts within the endoderm to restrict insulin expression. We also …