Correlation between E2F-1 Requirement in the S Phase and E2F-1 Transactivation of Cell Cycle-related Genes in Human Cells

Abstract The mammalian nuclear protein E2F-1 has recently been cloned based on its ability to bind the retinoblastoma protein. To determine whether E2F-1 plays a role in the control of the cell proliferation, we introduced an inducible construct expressing an E2F-1 antisense RNA into the human glioblastoma T98G cell line and assessed DNA synthesis during the cell cycle. Expression of the antisense transcripts during the G 1 -S transition resulted in a marked delay in the completion of DNA synthesis. Band-shift analysis of bacterially produced E2F-1 showed that this protein bound to the promoters of human DNA polymerase-α, cyclin D1, and c- myb but not to the cdc2 gene promoter. E2F-1 also transactivated the bound promoters in transient transfection assays. These results suggest a major role for E2F-1 in the control of cell cycle progression via transcriptional regulation of proliferation-associated genes.