Here we report the characterization of 12 kb genomic DNA upstream of the human PIT1/GHF1 promoter. Different regions involved in the modulation of human PIT1/GHF1 gene expression were defined by transient transfection studies. Two regions, one proximal (-7.1/-2.3) and one distal (-11.8/-10.9), presented an enhancer activity in pituitary cells when placed upstream of the SV40 promoter. The 0.9 kb distal region was analysed further and found to decrease the basal transcriptional activity of the human PIT1/GHF1 minimal promoter, indicating that this region behaves as a silencer for its own promoter. Three Pit-1/GHF-1-binding sites and two ubiquitous nuclear factor 1 (NF-1)-binding sites were identified by DNase I footprinting in the distal regulatory region. Deletion analysis indicated that NF-1 or NF-1-related protein(s) participate in the down-regulation of human PIT1/GHF1 gene expression by interacting with an NF-1-binding site within the distal regulatory region.
The nucleotide sequence data reported will appear in DDBJ, EMBL and GenBank Nucleotide Sequence Databases under the accession number X97489.
Present address: INSERM U449, Faculté de Médecine Laënnec, Rue Guillaume Paradin, 69372 Lyon Cedex 08, France
Present address: Department of Pharmacology, School of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0636, U.S.A.