Abstract
E2F2 is essential for the maintenance of T lymphocyte quiescence. To identify the full set of E2F2 target genes, and to gain further understanding of the role of E2F2 in transcriptional regulation, we have performed ChIP-chip analyses across the genome of lymph node–derived T lymphocytes. Here we show that during quiescence, E2F2 binds the promoters of a large number of genes involved in DNA metabolism and cell cycle regulation, concomitant with their transcriptional silencing. A comparison of ChIP-chip data with expression profiling data on resting E2f2−/− T lymphocytes identified a subset of 51 E2F2-specific target genes, most of which are upregulated on E2F2 loss. Luciferase reporter assays showed a retinoblastoma-independent role for E2F2 in the negative regulation of these target genes. Importantly, we show that the DNA binding activity of the transcription factor CREB contributes to E2F2-mediated repression of Mcm5 and Chk1 promoters. siRNA-mediated CREB knockdown, expression of a dominant negative KCREB mutant or disruption of CREB binding by mutating a CRE motif on Mcm5 promoter, relieved E2F2-mediated transcriptional repression. Taken together, our data uncover a new regulatory mechanism for E2F-mediated transcriptional control, whereby E2F2 and CREB cooperate in the transcriptional repression of a subset of E2F2 target genes.
Highlights
Mammalian E2F is a family of transcription factors, originally discovered for their crucial role in the control of cell cycle progression through the activation or suppression of a group of responsive genes [1,2]
Using genome-wide assays for transcription factor binding (ChIP-chip) in combination with expression profiling and classical biochemical approaches, we have uncovered a novel partner in the regulation of E2F2-mediated transcriptional repression
We show that E2F2 and CREB are recruited to a subset of E2F target genes to co-regulate their expression at the transcriptional level, providing new insights into E2F regulatory complexity
Summary
Mammalian E2F is a family of transcription factors, originally discovered for their crucial role in the control of cell cycle progression through the activation or suppression of a group of responsive genes [1,2]. Specific regulation of different sets of target genes by individual E2Fs may account for the phenotypes observed in the absence of these proteins. In this regard, chromatin immunoprecipitation assays coupled to DNA microarray analysis (ChIP-chip) or to whole-genome sequencing technology (ChIP-Seq), and microarray expression profiling analyses in cells overexpressing individual E2Fs, have revealed that E2F factors regulate genes necessary for G1/S transition and a wide spectrum of genes with diverse biological functions, including regulation of apoptosis, autophagy, mitosis, chromosome organization, macromolecule metabolism or differentiation [2,10]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
