Two novel functions associated with the Rel oncoproteins: DNA replication and cell-specific transcriptional activation.

The v-Rel oncoprotein and its cellular homolog c-Rel belong to the Rel/kappa B family of transcription factors. Members of this family share extensive sequence similarity in their N-terminal halves, a region referred to as the Rel Homology Region (RHR), bind to NF-kappa B DNA motifs and form heterodimers with one another. Whereas c-Rel activates transcription of kappa B-linked genes, v-Rel behaves as a dominant-interfering mutant of c-Rel- and kappa B-mediated transcription activation. Here we describe two novel activities of the Rel oncoproteins. One induces kappa B-site dependent stimulation of polyomavirus (Py) DNA replication and maps to the N-terminus of the RHR, a region where no transcription activation function was detected. This activity is common to v-Rel, c-Rel, p52 (p49/lyt10), RelA (p65) and the p50 subunit of NF-kappa B. The second promotes transcriptional activation in undifferentiated F9 cells and maps 3' to the RHR, a region essential for the transforming activity of v-Rel.