Regional expression of the Cwnt-4 Gene in developing chick central nervous system in relationship to the diencephalic neuromere D2 and a dorsal domain of the spinal-cord

Members of the Wnt gene family code for cysteine-rich, secreted proteins, which are differentially expressed in the developing brain and possibly act as an intercellular signaling molecule. A Wnt gene, e.g., Wnt-1 is known to be essential for specification of the midbrain cell fate. Since other members of the Wnt genes are likely to be also involved in development of the brain, we searched chick Wnt members expressing in specific domains of the brain. We found several novel Wnt members expressing specifically in the central nervous system of chick embryos. One of the genes was intensely expressed in a segment of the diencephalon at stages 14 and 20 and in a dorsal region of the spinal cord at stage 20. Although the expression patterns differ from those of mouse or Xenopus Wnt-4, the gene is highly homologous to the mouse or frog Wnt-4. Thus, we designated the gene as Cwnt-4 (chick Wnt-4). Our results suggested that Cwnt-4 is involved in segmentation of the forebrain into the neuromere D2 and in differentiation of the dorsal region of the spinal cord.