Hormone-regulated v-rel estrogen receptor fusion protein: reversible induction of cell transformation and cellular gene expression.
We describe the construction of a v-rel estrogen receptor fusion protein (v-relER) which allows the regulation of v-rel oncoprotein activity by hormone. In the presence of estrogen, v-relER readily transformed primary chicken fibroblasts and bone marrow cells in vitro. In both cell types, v-rel-specific transformation was critically dependent on the presence of estrogen or the estrogen agonist 4-hydroxytamoxifen (OHT). Withdrawal of estrogen or application of an estrogen antagonist, ICI164,384 (ICI) caused a reversal of the transformed phenotype. We also demonstrate that the v-relER protein binds to NF-kappa B sites in an estrogen-dependent manner, thereby showing that sequence-specific DNA binding of v-relER is critical for the activation of its transforming capacity. In transient transfection experiments, we failed to demonstrate a clear repressor or activator function of the v-rel moiety in v-relER. However, in v-relER-transformed bone marrow cells, estrogen and OHT induced elevated mRNA levels of two cellular genes whose expression is constitutive and high in v-rel-transformed cells. These results suggest that v-rel might exert part of its activity as an activator of rel-responsive genes.
Boehmelt
G
G
Institute of Molecular Pathology (IMP), Vienna, Austria.
Walker
A
A
Kabrun
N
N
Mellitzer
G
G
Beug
H
H
Zenke
M
M
Enrietto
P J
PJ
D000818:Animals; D001853:Bone Marrow / Q000187:drug effects; D001854:Bone Marrow Cells; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D002645:Chickens; D046508:Culture Techniques; D004277:DNA, Single-Stranded; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology; D004965:Estrogen Antagonists / Q000494:pharmacology; D004967:Estrogens / Q000494:pharmacology; D005786:Gene Expression Regulation; D006801:Humans; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism; D020572:Oncogene Proteins v-rel; D053284:Polyunsaturated Alkamides; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011960:Receptors, Estrogen / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015682:Retroviridae Proteins, Oncogenic / Q000235:genetics* / Q000378:metabolism; D013629:Tamoxifen / Q000031:analogs & derivatives / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects
D004277:DNA, Single-Stranded; D004965:Estrogen Antagonists; D004967:Estrogens; D016328:NF-kappa B; D020572:Oncogene Proteins v-rel; D053284:Polyunsaturated Alkamides; D012333:RNA, Messenger; D011960:Receptors, Estrogen; D011993:Recombinant Fusion Proteins; D015682:Retroviridae Proteins, Oncogenic; D013629:Tamoxifen; C016601:afimoxifene; D004958:Estradiol; C051781:ICI 164384; D011505:Protein-Tyrosine Kinases