BMP signaling regulates dorsal skeletal growth in the sea urchin embryo

While several signaling pathways have been shown to regulate gene expression and biomineral formation by sea urchin skeletogenic cells, important gaps in our understanding remain. Here, we focused on signals regulate skeletogenesis along the dorsal/ventral axis of the late-stage embryo.

We used specific inhibitor of Type I BMP receptors, K02288, to show that BMP signaling regulates skeletal growth selectively in the dorsal region. K02288 treatment led to dorsal skeletal defects and inhibited the expression of genes typically expressed specifically in the dorsal skeletogenic cells, including biomineralization genes. Using RNA-seq, we identified genes that were uniquely downstream of either the BMP or a ventral signaling pathway (the VEGF pathway) at late developmental stages and genes downstream of both pathways.