BINDING OF A MEMBER OF THE NF1 FAMILY OF TRANSCRIPTION FACTORS TO 2 DISTINCT CIS-ACTING ELEMENTS IN THE PROMOTER AND 5'-FLANKING REGION OF THE HUMAN CELLULAR RETINOL-BINDING PROTEIN-1 GENE
W. Eskild et al., BINDING OF A MEMBER OF THE NF1 FAMILY OF TRANSCRIPTION FACTORS TO 2 DISTINCT CIS-ACTING ELEMENTS IN THE PROMOTER AND 5'-FLANKING REGION OF THE HUMAN CELLULAR RETINOL-BINDING PROTEIN-1 GENE, Molecular endocrinology, 8(6), 1994, pp. 732-745
We studied the interaction of nuclear proteins with the 5'-flanking an
d promoter region of the human cellular retinol binding protein 1 (hCR
BP1) gene and identified seven specific sequences that interacted with
nuclear proteins from liver and prostate. Two of these sequences, foo
tprint 1 (Fp1) and footprint 5 (Fp5), were highly homologous, sharing
the core sequence GGCCAAC, which has a certain similarity to the conse
nsus sequence for the NF1 binding site. Competition experiments in gel
mobility shift assays and DNasel footprinting indicated that a common
protein interacted with both elements. Immunological and biochemical
data indicated that this protein belongs to the nuclear factor 1 (NF1)
family of transcription factors. The ability of the Fp1 and Fp5 seque
nces to control gene expression was studied by transient transfections
of several cell types. In the wild type promoter, both Fp1 and Fp5 ac
ted as repressors of human (h) CRBP1 gene transcription. Once inserted
upstream of the basal promoter from the heterologous p12 gene, the fu
nction of both Fp1 and Fp5 was reverted to that of transcriptional act
ivators, although Fp5 exerted only moderate transcriptional activation
of the chloramphenicol acetyl transferase (CAT) reporter gene. Hence,
the position of these NF1 binding sites and the nature of the flankin
g sequences appear to direct their effect on transcription. Despite cl
ose sequence homology, a common core sequence, and a similar ability t
o bind nuclear proteins in vitro, these results indicate that Fp1 and
Fp5 exert similar regulatory functions but to different levels in vivo
. In conclusion, these results indicate that a member of the NF1 famil
y plays a significant role in regulating CRBP1 gene expression.