[Delineation of the cis-regulatory sequences of the nodal gene]

In mouse embryo development, nodal is expressed in the node during the gastrulation. It is involved in mesoderm formation and left-right axis determination. The expression of the nodal gene has a restricted spatial and temporal specificity. Studies on the function of the nodal first intron in the gene expression regulation have shown that a 220 bp fragment at the 5' end of the first intron has an enhancer activity. Rather unexpectedly, the transient transfection assays in F9 cells indicate that this fragment also displayed a promoter activity when it is cloned upstream of basic luciferase reporter gene only in sense orientation. We present here the nucleotide sequence of this 220 bp fragment, and discuss its possible role in the nodal gene regulation.