Dev105775 2462..2472

The anteroposterior patterning of the embryonic gut represents one of the most intriguing biological processes in development. A dynamic control of gene transcription regulation and cell movement is perfectly orchestrated to shape a functional gut in distinct specialized parts. Two ParaHox genes, Xlox and Cdx, play key roles in vertebrate and sea urchingut patterning throughmolecularmechanismsthat arestillmostly unclear. Here, we have combined functional analysis methodologies with high-resolution imaging and RNA-seq to investigateXlox andCdx regulation and function. We reveal part of the regulatory machinery responsible for the onset of Xlox and Cdx transcription, uncover a Wnt10 signal that mediates Xlox repression in the intestinal cells, and provide evidence of Xloxand Cdx-mediated control of stomach and intestine differentiation, respectively. Our findings offer a novel mechanistic explanation of how the control of transcription is linked to cell differentiation and morphogenesis for the development of a perfectly organized biological system such as the sea urchin larval gut.