Identification of Novel E2F1-Regulated Genes by Microarray

The E2F pathway has been proposed to regulate genes involved in the transition from quiescence into DNA synthesis. However, this hypothesis has not been rigorously tested on a genomic scale. Toward this end, we have infected quiescent mouse fibroblasts, which do not express E2F1, with an E2F1-expressing adenovirus and examined the expression of more than 6000 genes using high-density microarrays. Microarray results clearly support the current paradigm; however, they suggest that E2F1 may also regulate unanticipated cellular functions including pathways involved in apoptosis, signal transduction, transcriptional control, and membrane biology. Most surprisingly, we identified a number of genes that are repressed by E2F1 expression, suggesting that E2F1 may have the potential to repress transcription of numerous genes through an unknown mechanism.