Interaction between the Purα and E2F-1 transcription factors

Background: Cell proliferation is regulated by E2F-1 which facilitates expression of genes involved in entry into S-phase. Release of E2F-1 from binding partners, e.g. pRb, is critical for G1/S progression. However ectopic E2F-1 overexpression activates p53 and inhibits growth. Previously, the multifunctional Purα protein was found to bind to E2F-1 and inhibit E2F-1 transcriptional activity. Materials and Methods: Purα deletion mutants were assayed for: in vitro binding to E2F-1, inhibition of E2F-1-induced promoter activation and effects on cell proliferation. Two RNA species with specific binding to E2F-1 and Purα were analyzed for their effects on E2F-1/Purα binding and cell growth. Results: The N-terminal 72 amino acids of Purα were involved in E2F-1 binding, inhibition of promoter activation by E2F-1 and reversal of E2F-mediated growth inhibition. The RNA species disrupted Purα/E2F-1 interaction and affected cell growth. Conclusion: E2F-1/Purα interaction has a role in the control of cell proliferation.