Meeting Abstract
The early specification and patterning of cell fates along the primary body axis of many metazoan embryos relies on a gradient of Wnt signaling. In most embryos this patterning mechanism depends primarily on high levels of localized canonical Wnt/&beta-catenin signaling around one pole of this embryonic axis, which will form endoderm/endomesoderm, and localized Wnt signaling antagonists around the opposite pole that typically aid in specifying the ectodermal and neuroectodermal territories. We have recently shown for the first time in any embryo that the deuterostome sea urchin integrates information from three different Wnt signaling branches (Wnt/&beta-catenin, Wnt/JNK, and Wnt/PKC pathways) to specify and pattern early regulatory states along the embryonic anterior-posterior axis. Here, we present new functional evidence suggesting that the three Wnt branches interact through several extracellular Wnt signaling modulators (Wnt1, Wnt8, Wnt16, sFRP1/5, sFRP1, Dkk1, Dkk3 and Wif-1) and receptors (Fzl5/8 and Fzl1/2/7). Our data also suggest these Wnt branches also interact through intracellular transduction molecules (e.g. PKC, NFAT, and ATF2) and the transcriptional gene regulatory networks they activate. These data represent the first steps in our strategy to use a combination of high-throughput genome-wide assays, molecular manipulations, and gene regulatory network analysis to produce a systems-level model of how this Wnt signaling network governs anterior-posterior axis specification in the sea urchin embryo. Importantly, evidence from functional and expression studies in other embryos strongly suggests that aspects of this fundamental developmental mechanism are conserved in deuterostome embryos.
