v-rel oncoproteins in the nucleus and in the cytoplasm transform chicken spleen cells.
The transforming protein encoded by the v-rel oncogene of the highly oncogenic avian retrovirus reticuloendotheliosis virus strain T (Rev-T) is a 59,000-dalton protein, p59v-rel. The mechanism by which p59v-rel induces transformation of early lymphoid cells is unknown. As a step towards understanding the mechanism of v-rel-induced transformation, we sought to establish the subcellular site of action of p59v-rel. In this report, we show that p59v-rel contains sequences that are necessary for its efficient localization in the nucleus of infected chicken embryo fibroblasts. These v-rel sequences when added to the normally cytoplasmic protein, beta-galactosidase, directed that protein to the nucleus. A mutation in the v-rel nuclear-localizing sequence did not affect the transforming function, although it did alter the nuclear-localizing function. The addition of a supplemental nuclear-localizing sequence from simian virus 40 large T-antigen to v-rel resulted in the expression of a transforming rel protein which was located exclusively in the nucleus of transformed spleen cells, in contrast to wild-type p59v-rel, which was largely cytoplasmic in transformed spleen cells. Our results support the hypothesis that v-rel encodes a protein which can act either in the nucleus or in the cytoplasm to transform spleen cells.
Gilmore
T D
TD
McArdle Laboratory for Cancer Research, University of Wisconsin, Madison 53706.
Temin
H M
HM
D000818:Animals; D002451:Cell Compartmentation; D002467:Cell Nucleus / Q000032:analysis*; D002472:Cell Transformation, Viral; D002645:Chickens; D003593:Cytoplasm / Q000032:analysis*; D005347:Fibroblasts / Q000032:analysis; D006378:Helper Viruses / Q000235:genetics; D006801:Humans; D020572:Oncogene Proteins v-rel; D011499:Protein Processing, Post-Translational; D011994:Recombinant Proteins / Q000032:analysis; D001356:Reticuloendotheliosis virus / Q000235:genetics / Q000502:physiology*; D012190:Retroviridae / Q000502:physiology*; D012191:Retroviridae Proteins / Q000235:genetics / Q000502:physiology*; D013154:Spleen / Q000166:cytology
D020572:Oncogene Proteins v-rel; D011994:Recombinant Proteins; D012191:Retroviridae Proteins