Molecular cloning of the chick Nau gene and analysis of its expression patterns during neurogenesis

We have previously identified a novel gene, Nau (Neuron-specific gene, which has a number of AU-rich RNA instability motifs), from a quail spinal cord cDNA library. Nau expression was observed mainly in post-mitotic neuroblasts, especially in the stage of axonogenesis. In this study, we cloned its chick orthologue (cNau, 5069 bp), which encodes 369 amino acid residues. cNau's open reading frame has three highly conserved regions with rat STOP (stable tubule-only polypeptide). cNau may be an orthologue of STOP gene considering its uniqueness in zoo blot analysis and its sequence similarity. Both the genetic structure and temporo-spatial expression patterns indicate that the cNau gene may be related to axonogenesis. In the hindbrain, cNau mRNA was accumulated in rhombomere boundary regions and in the rhombomere 2, 4 and 6. These observations suggest a specific role of cNau in the hindbrain or the difference in development between the hindbrain and spinal cord.