TRANSCRIPTOME DYNAMICS DURING ANTERO- POSTERIOR PATTERNING OF ENDODERMAL CELLS AND TOWARDS THEIR SPECIFICATION TO A PANCREATIC FATE

It is known that retinoic acid (RA) plays an important role in the antero-posterior patterning of the embryo in vertebrates. RA is synthesized in the mesoderm and diffuses to the endoderm where it acts by binding the nuclear RA receptors, these receptors binds regulatory elements that will regulate the transcription of different genes. It is unclear which are the signals that act to localize pancreas in the mid-gut Some studies have shown that RA signaling during gastrulation is required for pancreatic cell differentiation. Indeed, incubation of zebrafish gastrulae with RA produces anterior ectopic pancreatic cells, and inversely, the inhibition of this signaling pathway by adding RA antagonist prevents pancreas formation. Besides, expression of cdx4 in a gradient from high posteriorly to low anteriorly functions within the endoderm to localize pancreas. However, not much information is available on the genes activated by RA in the endoderm and controlling its antero-posterior patterning. Our goal is to identify these genes and better understand the mechanism by which the RA is regulating pancreas formation in zebrafish.