SEARCH · PubMed Health

Results for “E2F7 Transcription Factor”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

10 recordsLinked to original sources

PubMed2005

The DP-E2F-like gene DEL1 controls the endocycle in Arabidopsis thaliana.

Endoreduplication or DNA replication without mitosis is widespread in nature. Well-known examples are fruit fly polytene chromosomes and cereal endosperm. Although endocycles are thought to be driven by the same regulators as those that control the G1-S transition of the mitotic cell cycle, the molecular mechanisms that differentiate mitotically dividing cells from endoreduplicating ones are largely unknown. A novel class of atypical E2F-like proteins has recently been identified and is designated E2F7 in mammals and DP-E2F-like (DEL) in Arabidopsis thaliana . We demonstrate that loss of DEL1 function resulted in increased ploidy levels, whereas ectopic expression of DEL1 reduced endoreduplication. Ploidy changes were correlated with altered expression of a subset of E2F target genes encoding proteins necessary for DNA replication. Because DEL1 proteins were postulated to antagonize the E2F pathway, we generated DEL1-E2Fa-DPa triple transgenics. DEL1 inhibited the endoreduplication phenotype, but not the ectopic cell divisions that resulted from the overexpression of both E2Fa and DPa, illustrating that DEL1 specifically represses the endocycle. Because DEL1 transcripts were detected exclusively in mitotically dividing cells, we conclude that DEL1 is an important novel inhibitor of the endocycle and preserves the mitotic state of proliferating cells by suppressing transcription of genes that are required for cells to enter the DNA endoreduplication cycle.

Arabidopsis↗

PubMed2005

Cloning and characterization of mouse E2F8, a novel mammalian E2F family member capable of blocking cellular proliferation.

The E2F transcription factor family plays a crucial and well established role in cell cycle progression. Deregulation of E2F activities in vivo leads to developmental defects and cancer. Based on current evidence in the field, mammalian E2Fs can be functionally categorized into either transcriptional activators (E2F1, E2F2, and E2F3a) or repressors (E2F3b, E2F4, E2F5, E2F6, and E2F7). We have identified a novel E2F family member, E2F8, which is conserved in mice and humans and has its counterpart in Arabidopsis thaliana (E2Ls). Interestingly, E2F7 and E2F8 share unique structural features that distinguish them from other mammalian E2F repressor members, including the presence of two distinct DNA-binding domains and the absence of DP-dimerization, retinoblastoma-binding, and transcriptional activation domains. Similar to E2F7, overexpression of E2F8 significantly slows down the proliferation of primary mouse embryonic fibroblasts. These observations, together with the fact that E2F7 and E2F8 can homodimerize and are expressed in the same adult tissues, suggest that they may have overlapping and perhaps synergistic roles in the control of cellular proliferation.

Amino Acid Sequence↗

PubMed2003

E2F7, a novel E2F featuring DP-independent repression of a subset of E2F-regulated genes.

The E2F family of transcription factors play an essential role in the regulation of cell cycle progression. In a screen for E2F-regulated genes we identified a novel E2F family member, E2F7. Like the recently identified E2F-like proteins of Arabidopsis, E2F7 has two DNA binding domains and binds to the E2F DNA binding consensus site independently of DP co-factors. Consistent with being an E2F target gene, we found that the expression of E2F7 is cell cycle regulated. Ectopic expression of E2F7 results in suppression of E2F target genes and accumulation of cells in G1. Furthermore, E2F7 associates with E2F-regulated promoters in vivo, and this association increases in S phase. Interestingly, however, E2F7 binds only a subset of E2F-dependent promoters in vivo, and in agreement with this, inhibition of E2F7 expression results in specific derepression of these promoters. Taken together, these data demonstrate that E2F7 is a unique repressor of a subset of E2F target genes whose products are required for cell cycle progression.

Amino Acid Sequence↗

PubMed2007

Clinical relevance of E2F family members in ovarian cancer--an evaluation in a training set of 77 patients.

PURPOSE: The major obstacle in treating ovarian cancer is the rapid development of platinum resistance during therapy. Deregulation of members of the E2F family of transcription factors is crucially involved in carcinogenesis and probably in mechanisms underlying platinum resistance. We therefore investigated the relevance of the whole set of E2F family members in predicting clinical outcome and their significance in predicting platinum resistance. EXPERIMENTAL DESIGN: Real-time PCR of all E2F family members was done from 77 ovarian carcinomas, defined as our training set, and 8 healthy control samples. The correlation with clinicopathologic characteristics, platinum resistance, and survival was investigated. Furthermore, the cross-talk of E2F family members was assessed for its value in predicting survival and platinum resistance. RESULTS: The proliferation-promoting E2F1 and E2F2 were associated with grade 3 tumors and residual disease >2 cm in diameter after initial surgery. Survival analyses showed low expression of E2F1 or E2F2 to be significantly associated with favorable disease-free and overall survival (E2F1, P = 0.039 and 0.047, respectively; E2F2, P = 0.009 and 0.006, respectively). In contrast, high expression of inhibiting E2F4 or E2F7 predicted favorable disease-free and overall survival (E2F4, P = 0.047 and 0.042, respectively; E2F7, P = 0.048 and 0.042, respectively). A high E2F2 to E2F4 ratio was the most valuable prognostic variable for disease-free survival in multivariate analysis (hazard ratio, 6.494; P = 0.002). Tumors considered platinum resistant were associated with lower E2F4 and E2F7 expression (P = 0.012 and 0.009, respectively) compared with platinum-sensitive tumors. Again, ratios of E2F1 or E2F2 to E2F7 were the most favorable variables in predicting platinum resistance. CONCLUSIONS: We here show that deregulation of both proliferation-promoting and proliferation-inhibiting E2F transcription factors and their cross-talk is crucially involved in the tumor biology of ovarian cancer and influences clinical outcome. Furthermore, down-regulation of E2F7 may contribute to mechanisms underlying platinum resistance, and calculation of ratios of proliferation-promoting E2F1 to E2F7 could serve as a putative predictor of platinum resistance.

Aged↗

PubMed2026

E2F7 promotes lung adenocarcinoma progression by affecting phosphorylation and stabilization of β-catenin.

BACKGROUND: E2F transcription factor 7 (E2F7) has been implicated in the tumorigenesis and progression of multiple cancer types; however, the molecular mechanisms through which E2F7 regulates malignant phenotypes in cancer cells remain largely undefined. In this study, we investigated the biological functions and underlying mechanisms of E2F7 in lung adenocarcinoma (LUAD). METHODS: E2F7 expression in LUAD was analyzed using The Cancer Genome Atlas (TCGA) datasets and further validated in clinical specimens via quantitative real-time polymerase chain reaction (PCR) and immunohistochemistry. The effects of E2F7 on cancer cell self‑renewal and epithelial-mesenchymal transition (EMT) were assessed using sphere formation and Transwell assays, respectively. In vivo tumorigenicity and metastasis were evaluated using xenograft models combined with extreme limiting dilution analysis to assess tumor-initiating capacity. Wnt/β‑catenin pathway activity was measured using T-cell factor optimal promoter luciferase reporter plasmid/far-from optimal promoter luciferase reporter plasmid (TOP/FOP) flash reporter assays. β‑Catenin expression, stability, and ubiquitination were examined via western blotting, cycloheximide chase assays, and ubiquitination assays. Protein-protein interactions among E2F7, β‑catenin, and glycogen synthase kinase 3 beta (GSK3β) were verified through co‑immunoprecipitation (Co‑IP), glutathione S‑transferase (GST) pull‑down, and immunofluorescence assays. Truncated mutants were generated to map the functional binding domains of E2F7. In vitro immunoprecipitation and kinase assays were further performed to confirm that E2F7 regulates GSK3β autophosphorylation and β‑catenin phosphorylation. RESULTS: Bioinformatic analyses revealed that E2F7 was significantly upregulated in LUAD tissues, and elevated E2F7 expression correlated with poor patient prognosis. Functional assays demonstrated that E2F7 promoted LUAD cell self‑renewal and EMT. Mechanistically, cytoplasmic E2F7 directly associated with β‑catenin through its DNA‑binding domain (DBD) and PHA03247 domain. E2F7 modulated β‑catenin phosphorylation at Ser675 and Ser33/37/T41, thereby inhibiting ubiquitin‑mediated degradation and enhancing β‑catenin protein stability. Furthermore, E2F7 interacted with GSK3β and suppressed its autophosphorylation at Tyr216, concomitant with reduced β-catenin phosphorylation at Ser33/37/T41 and its accumulation. CONCLUSION: Collectively, these findings indicate that E2F7 drives LUAD malignant progression through regulation of the GSK3β/β‑catenin signaling axis and stabilization of β‑catenin. This study unveils a novel oncogenic mechanism of E2F7 in LUAD and identifies E2F7 as a promising therapeutic target for clinical intervention in LUAD.

E2F7↗

PubMed2005

Characterization of E2F8, a novel E2F-like cell-cycle regulated repressor of E2F-activated transcription.

The E2F family of transcription factors are downstream effectors of the retinoblastoma protein, pRB, pathway and are essential for the timely regulation of genes necessary for cell-cycle progression. Here we describe the characterization of human and murine E2F8, a new member of the E2F family. Sequence analysis of E2F8 predicts the presence of two distinct E2F-related DNA binding domains suggesting that E2F8 and, the recently, identified E2F7 form a subgroup within the E2F family. We show that E2F transcription factors bind the E2F8 promoter in vivo and that expression of E2F8 is being induced at the G1/S transition. Purified recombinant E2F8 binds specifically to a consensus E2F-DNA-binding site indicating that E2F8, like E2F7, binds DNA without the requirement of co-factors such as DP1. E2F8 inhibits E2F-driven promoters suggesting that E2F8 is transcriptional repressor like E2F7. Ectopic expression of E2F8 in diploid human fibroblasts reduces expression of E2F-target genes and inhibits cell growth consistent with a role for repressing E2F transcriptional activity. Taken together, these data suggest that E2F8 has an important role in turning of the expression of E2F-target genes in the S-phase of the cell cycle.

Amino Acid Sequence↗

PubMed2005

E2F-8: an E2F family member with a similar organization of DNA-binding domains to E2F-7.

E2F is a family of transcription factors implicated in cell cycle control. To understand the role of E2F in controlling cell cycle progression, it is necessary to clarify the breadth of the E2F family. To date, seven E2F subunits have been identified. We report here the characterization of a new E2F subunit, E2F-8, which resembles the organization of E2F-7 in the presence of two separate DNA-binding domains, the integrity of which is required for E2F-8 to bind to DNA. Furthermore, like E2F-7, we find that E2F-8 can repress transcription and delay cell cycle progression. The similarities between E2F-7 and E2F-8 define a new subgroup of the E2F family, and further imply that E2F-7 and E2F-8 may act through overlapping mechanisms in mediating cell cycle control.

Amino Acid Sequence↗

PubMed2004

E2F-7: a distinctive E2F family member with an unusual organization of DNA-binding domains.

The E2F family of transcription factors play an important role in regulating cell cycle progression. We report here the characterization and functional properties of a new member of the human E2F family, referred to as E2F-7. E2F-7 has two separate DNA-binding domains, a feature that distinguishes E2F-7 from other mammalian E2F proteins, but resembling the organization of recently isolated E2F-like proteins from Arabidopsis. E2F-7 binds to DNA independently of a DP partner and delays cell cycle progression. Interestingly, E2F-7 modulates the transcription properties of other E2F proteins. A mutational analysis indicates that the integrity of both DNA-binding domains is required for cell cycle delay and transcriptional modulation. Biochemical results and protein modelling studies suggest that in binding to DNA interactions occur between the two DNA-binding domains, most probably as a homodimer, thereby mimicking the organization of an E2F/DP heterodimer. These structural and functional properties of E2F-7 imply a unique role in regulating cellular proliferation.

Amino Acid Motifs↗

PubMed2003

Identification and characterization of E2F7, a novel mammalian E2F family member capable of blocking cellular proliferation.

The mammalian E2F family of transcription factors plays a crucial role in the regulation of cellular proliferation, apoptosis, and differentiation. Consistent with its biological role in a number of important cellular processes, E2F regulates the expression of genes involved in cell cycle, DNA replication, DNA repair, and mitosis. It has proven difficult, however, to determine the specific roles played by the various known family members in these cellular processes. The work presented here now extends the complexity of this family even further by the identification of a novel E2F family member, which we now term E2F7. Like the expression of the known E2F activators, E2F1, E2F2, and E2F3, the expression of E2F7 is growth-regulated, at least in part, through E2F binding elements on its promoter, and its protein product is localized to the nucleus and associates with DNA E2F recognition sites with high affinity. A number of salient features, however, make this member unique among the E2F family. First, the E2F7 gene encodes a protein that possesses two distinct DNA-binding domains and that lacks a dimerization domain as well as a transcriptional activation and a retinoblastoma-binding domain. In contrast to the E2F activators, E2F7 can block the E2F-dependent activation of a subset of E2F target genes as well as mitigate cellular proliferation of mouse embryo fibroblasts. These findings identify E2F7 as a novel member of the mammalian E2F transcription factor family that has properties of a transcriptional repressor capable of negatively influencing cellular proliferation.

Animals↗

PubMed2026

Cdk1 and PP2A constitute a molecular switch controlling orderly degradation of atypical E2Fs.

Dynamic oscillations in the phosphorylation and ubiquitination of key proliferative regulators are defining features of the eukaryotic cell cycle. Resetting the cell cycle at the mitosis-to-G1 transition requires activation of the E3 ubiquitin ligase Anaphase-Promoting Complex/Cyclosome (APC/C), which ensures cell cycle irreversibility by targeting dozens of substrates for degradation, safeguarding genome integrity. However, the overall coupling of substrate phosphorylation with target recognition and degradation by the APC/C remains relatively unexplored. As a paradigm for further defining these rules, we focused on E2F7 and E2F8-atypical E2F-family proteins that coordinate cell cycle gene expression by restraining the pro-proliferative transcriptional activity of E2F1. Leveraging complementary cell and cell-free systems, we demonstrate that flexible domains at the amino-termini of E2F7 and E2F8 contain APC/C recognition motifs adjacent to critical Thr residues, whose phosphorylation by Cdk1 is rate-limiting for degradation. The removal of this phosphorylation by PP2A serves as a molecular switch, coupling the degradation of E2F7 and E2F8 to the G1 phase, coinciding with the rise of E2F1. Collectively, these findings highlight a critical role for Cdk1-PP2A signaling in controlling the orderly degradation of APC/C substrates, ensuring precisely timed assembly of the transcriptional infrastructure that coordinates cell cycle commitment and progression.

Protein Phosphatase 2↗