[en] We have performed transfection and DNase I footprinting experiments to investigate pituitary-specific
expression of the human prolactin (hPRL) gene. When fused to the chloramphenicol acetyltransferase (CAT)
reporter gene, 5,000 base pairs of the 5'-flanking sequences of the hPRL gene were able to drive high cat gene
expression in prolactin-expressing GH3B6 cells specifically. Deletion analysis indicated that this pituitaryspecific
expression was controlled by three main positive regulatory regions. The first was located just upstream
from the TATA box between coordinates -40 and -250 (proximal region). We have previously shown that
three motifs of this region bind the pituitary-specific Pit-l factor. The second positive region was located in the
vicinity of coordinates -1300 to -1750 (distal region). DNase I footprinting assays revealed that eight DNA
motifs of this distal region bound protein Pit-l and that two other motifs were recognized by ubiquitous factors,
one of which seems to belong to the AP-1 (jun) family. The third positive region was located further upstream,
between -3500 and -5000 (superdistal region). This region appears to enhance transcription only in the
presence of the distal region.
