Identification of genes downstream of nodal in the Ciona intestinalis embryo.

Nodal, a growth factor belonging to the TGF-beta superfamily, is required for the formation of the neural tube in Ciona intestinalis. Previous studies have revealed many genes whose expression is controlled by Nodal in the Ciona embryo; however, all of them encode transcription factors and signaling molecules. In the present study, we identified five genes upregulated or downregulated by the overexpression of Nodal in embryos of C. intestinalis. The upregulated genes included those encoding type IV collagen 1/3/5, laminin-alpha5, and Prickle. The downregulated genes included those encoding glypican and delta1-protocadherln-like. Many of these genes were expressed in the neural plate at the late gastrula stage. The present study revealed candidate effector genes that directly regulate, in response to Nodal, the morphogenesis of the neural tube in Ciona intestinalis.