E2F inhibits transcriptional activation by the retinoic acid receptor

The E2F transcription factors are thought to mediate growth-inducing signals by elevating transcription of genes required for cell proliferation. Retinoic acid receptors (RARs) mediate retinoic acid (RA)-induced expression of genes with roles in cell differentiation. We found that E2F-1 inhibited expression from RAresponsive promoters. This inhibition was specific to transcription mediated by RARs. We found no direct interaction between the E2F-1 protein and the RA response element in DNA or the RAR proteins. Our evidence suggests that E2F-1 reduces expression from RA-inducible promoters by interacting with an unidentified coactivator(s) that is required by the RARs.