Spemann organizer transcriptome induction by early β-Catenin, Wnt, Nodal and Siamois signals in Xenopus laevis

During Xenopus gastrulation, dorsal stabilization of β-Catenin at the earliest stage and subsequent target genes expression are critical for dorsal-ventral axis determination. However, many β-Catenin targets that mediate this process are still unkown. Here through RNA-seq analysis of β-Catenin knockdown embryos and self-regulating dorsal and ventral half embryos at early gastrula, we define an early β-Catenin gene signature that is downregulated by β-Catenin MO and enriched in dorsal gastrula tissues. This gene signature includes classic Spemann organizer genes, as well as other novel genes. Further analyses revealed that the early β-Catenin gene signature is positively correlated with LiCl treated, Wnt8 and Siamois mRNA-induced genes, consistent with their early role in dorsal-ventral axis formation. Our results also show that St 10.5 is the appropriate stage to uncover β-Catenin target genes that regulate dorsal-ventral patterning than St 9. Meanwhile, the multi-growth factor antagonist Cerberus inhibits part of the early β-Catenin gene signature and also controls the expression of a unique set of genes. Our findings provide new insight into the pivotal role of β-catenin in dorsal-ventral axis determination and can serve a fruitful resource for this field. A genome-wide study of the effects of depleting the early dorsal b-Catenin signal which is responsible for the induction of the body axis.