A conditional mutant of vRel containing sequences from the human estrogen receptor.
The mechanism by which the v-rel oncogene of the avian Rev-T retrovirus transforms chicken spleen cells is not known. We have created v-rel mutants that show conditional properties by fusing sequences encoding the ligand-binding domain of the human estrogen receptor (ER) in-frame at the 3' end of the v-rel oncogene. Two vRel-ER fusion proteins showed estrogen-dependent subcellular localization in chicken embryo fibroblasts (CEF): vRel-ER proteins were located in the cytoplasm of CEF in the absence of estrogen and were located in the nucleus of CEF in the presence of estrogen. Wild-type vRel was located in the nucleus of CEF in the presence or absence of estrogen. Mobility shift assays using extracts from infected CEF showed that the ability of vRel-ER to bind DNA was also dependent on estrogen. However, the ability of vRel-ER to repress transcription from kappa B site-containing promoters was not dependent on estrogen. Finally, we were able to isolate a vRel-ER-transformed avian spleen cell line whose growth is dependent on estrogen; this indicates that a vRel function is needed for both the initiation and the maintenance of the transformed state. The vRel-Er protein may be useful for determining genes controlled by vRel.
Capobianco
A J
AJ
Department of Biology, Boston University, Massachusetts 02215.
Gilmore
T D
TD
D000818:Animals; D002478:Cells, Cultured; D002642:Chick Embryo; D002645:Chickens; D004279:DNA, Viral / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000502:physiology; D006801:Humans; D009154:Mutation; D020572:Oncogene Proteins v-rel; D011960:Receptors, Estrogen / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000235:genetics; D012097:Repressor Proteins / Q000502:physiology; D015682:Retroviridae Proteins, Oncogenic / Q000235:genetics / Q000502:physiology*; D014170:Transformation, Genetic / Q000502:physiology*
D004279:DNA, Viral; D004268:DNA-Binding Proteins; D020572:Oncogene Proteins v-rel; D011960:Receptors, Estrogen; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D015682:Retroviridae Proteins, Oncogenic