[Analysis of a suppressor element of mouse Nodal gene in its 5' flanking sequences]

Nodal gene is a member of the TGF-beta superfamily. It is required for the formation of the primitive streak during mouse gastrulation. Mice without Nodal gene will die due to the lack of mesoderm formation. F9 cells were transiently transfected with a series of luciferase reporter constructs containing the subcones of Nodal 5' filanking sequences and their deletions. By analyzing the luciferase activity of these constructs, a suppressor element was determined at about 1 kb up stream the transcription initiation site, around an EcoR I site. Its central part was located at about 100 bp downstream of that EcoR I site. It could almost totally, suppress the Nodal gene promoter activity, though it had no effect on SV40 promoter. It behaved differently in different cell lines. In CHO cells, it had an activation activity.