The E2F family of transcription factors is believed to play a critical role in the control of cellular proliferation. These factors are encoded by distinct genes and have both tumor suppressor and oncogenic functions (1-2). Our laboratory identified E2F7 and E2F8 as the final two members of this transcription factor family (5, 6). The preliminary data presented in this proposal highlight several unique features of these two E2Fs that place them in a subclass of their own. These salient features include their ability to form homodimers and heterodimers, to associate with a large cadre of transcriptional co-repressors, to silence gene expression, and to block cellular proliferation. While they lack a typical Rb-binding domain, E2F7 can specifically interact with Rb related proteins and can thus recruit E2F8 to Rb-containing complexes. As a result, the E2F7/8 arm of the E2F network remains under the control of the cycling dependent kinase (CDK) signaling pathway. The fact that E2F7 and E2F8 have an identical pattern of cell cycle dependent and tissue- specific expression, together with their ability to homo- and hetero-dimerize, raises the possibility that they may have both unique and shared functions in the animal. A multi-faceted effort in the laboratory has yielded key technical developments, including an affinity purification strategy to purify E2F7/8-associated proteins, promoter-array technologies to identify target genes, and gene targeting approaches to disrupt E2F7 and E2F8 in mice. These advances place our research group in a strong position to make significant advances towards a mechanistic understanding of how this important arm of the E2F family of factors controls the cell cycle and cell proliferation. The overarching hypothesis of this proposal is that E2F7 and E2F8 function as transcriptional repressors to negatively control cellular proliferation.
Three specific aims utilizing biochemical, biophysical, global gene array, and genetic approaches will directly test this hypothesis:
Specific Aim 1. To identify and characterize E2F7- and E2F8-associated macromolecular protein complexes.
Specific Aim 2. To identify E2F7 and E2F8 transcriptional targets.
Specific Aim 3. To determine the mechanism of E2F7 and E2F8 action in the control of transcription. This work will elucida the individual and combinatorial contributions made by these two highly related family members towards the overall understanding of E2F transcriptional activity. Project Description Page 6

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA121275-05
Application #
8204520
Study Section
Cancer Molecular Pathobiology Study Section (CAMP)
Program Officer
Johnson, Ronald L
Project Start
2007-12-10
Project End
2012-11-30
Budget Start
2011-12-01
Budget End
2012-11-30
Support Year
5
Fiscal Year
2012
Total Cost
$301,913
Indirect Cost
$100,638
Name
Ohio State University
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
832127323
City
Columbus
State
OH
Country
United States
Zip Code
43210
Zeng, X; Shaikh, F Y; Harrison, M K et al. (2010) The Ras oncogene signals centrosome amplification in mammary epithelial cells through cyclin D1/Cdk4 and Nek2. Oncogene 29:5103-12
Trimboli, Anthony J; Cantemir-Stone, Carmen Z; Li, Fu et al. (2009) Pten in stromal fibroblasts suppresses mammary epithelial tumours. Nature 461:1084-91
Lammens, Tim; Li, Jing; Leone, Gustavo et al. (2009) Atypical E2Fs: new players in the E2F transcription factor family. Trends Cell Biol 19:111-8
Chen, Danian; Pacal, Marek; Wenzel, Pamela et al. (2009) Division and apoptosis of E2f-deficient retinal progenitors. Nature 462:925-9
Chen, Hui-Zi; Tsai, Shih-Yin; Leone, Gustavo (2009) Emerging roles of E2Fs in cancer: an exit from cell cycle control. Nat Rev Cancer 9:785-97
Tsai, Shih-Yin; Opavsky, Rene; Sharma, Nidhi et al. (2008) Mouse development with a single E2F activator. Nature 454:1137-41
Li, Jing; Ran, Cong; Li, Edward et al. (2008) Synergistic function of E2F7 and E2F8 is essential for cell survival and embryonic development. Dev Cell 14:62-75