V-erbA and c-erbA proteins enhance transcriptional activation by c-jun.
The ability of different transcription factors to interact with one another is an important means by which the eucaryotic cell can integrate separate growth and differentiation signals into a coherent response. We report here an analysis of the interactions of transcription factors that are also the products of oncogenes: the erbA, jun and fos proteins. We demonstrate that the c-jun polypeptide can functionally interact with the c-erbA protein (thyroid hormone receptor) to yield an enhanced activity greater than that of either factor individually. Although the avian erythroblastosis v-erbA allele is generally thought to act as a transcriptional repressor in vertebrate cells, we also report the existence of promoter contexts where v-erbA, as well as c-erbA, can serve as 'co-activators' of c-jun function. V-erbA appears to augment retinoic acid receptor function in the same context. Our results suggest that v-erbA may have unanticipated positive effect on transcription in the neoplastic cell in addition to the repressor functions previously characterized.
Sharif
M
M
Department of Microbiology, University of California, Davis 95616.
Privalsky
M L
ML
D001483:Base Sequence; D002352:Carrier Proteins / Q000096:biosynthesis; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D018774:Oncogene Proteins v-erbA; D010957:Plasmids; D011518:Proto-Oncogene Proteins / Q000502:physiology*; D016755:Proto-Oncogene Proteins c-jun / Q000502:physiology*; D018168:Receptors, Retinoic Acid; D011988:Receptors, Thyroid Hormone / Q000378:metabolism; D015682:Retroviridae Proteins, Oncogenic / Q000502:physiology*; D015533:Transcriptional Activation / Q000235:genetics*; D014162:Transfection
D002352:Carrier Proteins; D015345:Oligonucleotide Probes; D018774:Oncogene Proteins v-erbA; D011518:Proto-Oncogene Proteins; D016755:Proto-Oncogene Proteins c-jun; D018168:Receptors, Retinoic Acid; D011988:Receptors, Thyroid Hormone; D015682:Retroviridae Proteins, Oncogenic; D015500:Chloramphenicol O-Acetyltransferase