Far upstream sequences regulate the @entity1 XXXX promoter transcription.

@entity1 @entity10914 @entity15757 @entity4090 @entity35 @entity6863
The @entity1 @entity4090 gene is mainly expressed in pituitary lactotrope cells, but transcription from an alternative, far upstream promoter was detected in lymphoid, placental and mammary cells. We describe the transcriptional activity in @entity35 pituitary cells of the complete region separating the two promoters, using transient transfection experiments. A far upstream activating region was only functional in combination with the @entity4090 promoter. DNaseI protection experiments revealed, in addition to binding sites for the pituitary-specific factor @entity10914 , sites (e.g. @entity15757 ) for several ubiquitous factors and one lymphoid-specific factor (SD4). A single copy of the ubiquitous site @entity15757 or the lymphoid-specific site SD4 was unable to activate transcription of a heterologous promoter in pituitary cells. However, @entity15757 activated transcription in nonpituitary cells and SD4 was functional specifically in lymphoid cells. Five copies of a distal site (D8) activated transcription in each cell type tested. Gel retardation experiments show that this site binds the specific factor @entity6863 in liver and a distinct factor in other cell types. Our results suggest that different elements within this large region direct specific expression from each promoter via a complex interplay between cell-specific and ubiquitous transcription factors.
