TY - JOUR
T1 - Estrogen-induced retinoic acid receptor α1 gene expression
T2 - Role of estrogen receptor-Sp1 complex
AU - Sun, G.
AU - Porter, W.
AU - Safe, S.
N1 - Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 1998
Y1 - 1998
N2 - Retinoic acid receptor α1 (RARα1) gene expression is induced by 17β-estradiol (E2) in estrogen receptor (ER)-positive breast cancer cells, and the -100 to -49 region of the RARα1 gene promoter was previously shown to be required for E2-responsiveness. This region of the RARα1 promoter was further analyzed using the following oligonucleotides: - 100 to -49 (RAR4); -79 to -56 (RAR3); -79 to -49 (RAR2); -100 to -58 (RAR1); and their derived promoter reporter constructs (pRAR4, pRAR3, pRAR2, and pRAR1). In transient transfection studies in MCF-7 human breast cancer cells, pRAR2 and pRAR1 were E2-responsive; both of the RARα1 gene promoter inserts contained two GC-rich sites and bound Sp1 protein in gel mobility shift assays. Using wild-type [32P]RAR2 and oligonucleotides mutated in one or both GC-rich sites, it was shown that ER enhanced Sp1 binding to both sites, but a ternary ER-Sp1-DNA complex was not observed in gel mobility shift assays. In transient transfection assays, each of the GC-rich motifs were sufficient for E2-induced transactivation. In ER-negative MDA-MB-231 cells transiently transfected with pRAR2, E2 responsiveness was observed only in cells cotransfected with wild-type ER or 11C-ER containing a deletion of the DNA-binding domain but not with ER variants that express activation function-1 (AF-1) or AF-2. Using a similar approach, it was shown that the GC-rich sites in RAR1 were also sufficient for ER activation. These results demonstrate that interaction of a transcriptionally active ER/Sp1 complex with GC-rich motifs is required for hormone inducibility of the downstream region of the RARα1 gene promoter.
AB - Retinoic acid receptor α1 (RARα1) gene expression is induced by 17β-estradiol (E2) in estrogen receptor (ER)-positive breast cancer cells, and the -100 to -49 region of the RARα1 gene promoter was previously shown to be required for E2-responsiveness. This region of the RARα1 promoter was further analyzed using the following oligonucleotides: - 100 to -49 (RAR4); -79 to -56 (RAR3); -79 to -49 (RAR2); -100 to -58 (RAR1); and their derived promoter reporter constructs (pRAR4, pRAR3, pRAR2, and pRAR1). In transient transfection studies in MCF-7 human breast cancer cells, pRAR2 and pRAR1 were E2-responsive; both of the RARα1 gene promoter inserts contained two GC-rich sites and bound Sp1 protein in gel mobility shift assays. Using wild-type [32P]RAR2 and oligonucleotides mutated in one or both GC-rich sites, it was shown that ER enhanced Sp1 binding to both sites, but a ternary ER-Sp1-DNA complex was not observed in gel mobility shift assays. In transient transfection assays, each of the GC-rich motifs were sufficient for E2-induced transactivation. In ER-negative MDA-MB-231 cells transiently transfected with pRAR2, E2 responsiveness was observed only in cells cotransfected with wild-type ER or 11C-ER containing a deletion of the DNA-binding domain but not with ER variants that express activation function-1 (AF-1) or AF-2. Using a similar approach, it was shown that the GC-rich sites in RAR1 were also sufficient for ER activation. These results demonstrate that interaction of a transcriptionally active ER/Sp1 complex with GC-rich motifs is required for hormone inducibility of the downstream region of the RARα1 gene promoter.
UR - http://www.scopus.com/inward/record.url?scp=0032230246&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0032230246&partnerID=8YFLogxK
U2 - 10.1210/mend.12.6.0125
DO - 10.1210/mend.12.6.0125
M3 - Article
C2 - 9626663
AN - SCOPUS:0032230246
SN - 0888-8809
VL - 12
SP - 882
EP - 890
JO - Molecular Endocrinology
JF - Molecular Endocrinology
IS - 6
ER -