Constitutive expression of the E2F1 transcription factor in fibroblasts alters G0 and S phase transit following serum stimulation

Logan, Thomas J.; Jordan, Kelly L.; Hall, D.

doi:10.1139/o96-003

Cited by 4 publications

(4 citation statements)

References 27 publications

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“…From this, it is evident that "growing" cells are more evenly distributed throughout the cell cycle while the serum-starved cells are primarily arrested in the G1 phase. As reported earlier (Logan et al, 1994(Logan et al, , 1996, during serum starvation, an increased number of the E2F1-expressing cells pass into S phase yet do not enter G2/M phase (Logan et al, 1996, and Figure 6B).…”

Section: Two-hybrid Screen Identifies Two Novel Proteins Thatsupporting

confidence: 84%

“…Constitutive expression of E2F1 in NIH3T3 fibroblasts causes increased entry of the cells into S phase during serum starvation conditions, yet they are unable to complete S phase (Logan et al, 1994;Johnson et al, 1993;Krek et al, 1994). The primary cell cycle phase affected by constitutive expression of E2F1 appears to be G0, since this phase is dramatically shortened in serum-starved fibroblasts, while G1 phase is unaffected (Logan et al, 1996).…”

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“…The cells demonstrate a rounded morphology during culture in 10% calf serum, such that normal cytoskeletal structures as microfilaments, micrutubules, and vinculin containing focal contacts are not detectable (Logan et al, 1994). In addition, the cells have a lengthened S phase (Logan et al, 1995(Logan et al, , 1996 and are more sensitive to S phase specific toxins (Logan et al, 1995). The E2F1d87 mutant lacks the cyclin A/cdk2 binding domain (Krek et al, 1994, Jordan and Hall unpublished observations).…”

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Isolation of Two Novel cDNAs Whose Products Associate with the Amino Terminus of the E2F1 Transcription Factor

et al. 1996

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The amino terminus of the E2F1 transcription factor is a protein-protein interaction domain since it associates with cyclin A/cdk2. Here, the two-hybrid yeast screen was used to clone genes whose products associate with the amino terminus of E2F1. The amino-terminal 121 amino acids of E2F1 were fused to the Lex A binding domain while a partial length cDNA library from the embryo of a 12 day old mouse was fused to the VP16 activation domain. Following coexpression of these fusions in yeast, two novel genes were cloned that code for proteins that associate with E2F1. In an in vitro assay, these E2F1 Binding Proteins (EBP1 and EBP2) associate with residues 1-121 of E2F1 or with the full-length protein; however, they do not associate with its carboxy terminus (residues 88-437). When EBP1 or EBP2 were expressed in COS cells along with E2F1 and the target promoter DNA polymerase alpha, repression of transcription was observed. However, no repression of DNA polymerase alpha was seen if the cells expressed a nonassociating mutant E2F1 (residues 88-437), along with EBP1 or EBP2. Finally, expression of the EBP2 gene is up-regulated in growing NIH3T3 fibroblasts, relative to serum-starved cells. However, this up-regulation of EBP2 expression is not seen in fibroblasts constitutively expressing E2F1.

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Section: Two-hybrid Screen Identifies Two Novel Proteins Thatsupporting

confidence: 84%

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confidence: 99%

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confidence: 99%

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Isolation of Two Novel cDNAs Whose Products Associate with the Amino Terminus of the E2F1 Transcription Factor

et al. 1996

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“…Dissociation of E2F‐1 from DNA, through the action of cyclin A/cdk2, appears to be a required event for transit through S‐phase. For example, expression of mutants of E2F‐1 lacking the cyclin A/cdk2 binding domain in cells results in a lengthened S‐phase [Krek et al, 1995; Logan et al, 1995, 1996; Stubbs et al, 1999].…”

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The E2F‐1 transcription factor is negatively regulated by its interaction with the MDMX protein

Strachan

Jordan‐Sciutto

Rallapalli

et al. 2002

J of Cellular Biochemistry

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Several proteins with important roles in oncogenesis have been shown to regulate the function of the E2F-1 transcription factor, which is known to activate the expression of genes required for proliferation and apoptosis. Here we identify the MDMX oncoprotein as an E2F-1-binding factor, from a yeast-two hybrid screen using a portion of the E2F-1 protein as "bait." We demonstrate that the region within MDMX needed for the E2F-1:MDMX interaction is located in the central part of the protein, C-terminal of the p53-binding domain. The region within E2F-1 needed for this association is adjacent to the DNA binding domain. Further, when expressed in vivo or in vitro the MDMX protein migrates as two isoforms on SDS-PAGE, the faster migrating isoform having the stronger affinity for the E2F-1 proteins. It appears that this interaction reduces the ability of E2F-1 to bind DNA. Expression of MDMX along with E2F-1 and Dp-1 in Saos2 cells reduces the ability of E2F-1 to bind to its consensus DNA sequence, without altering E2F-1 protein levels. These data indicate that the MDMX protein is capable of associating with E2F-1 and negatively regulating its DNA binding ability.

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Altered cell shape is linked to increased p34cdc2 gene expression in fibroblasts expressing a mutant E2F-1 transcription factor

et al. 1997

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The E2F1 transcription factor or an amino terminal deletion mutant termed E2F1d87 was constitutively expressed in NIH3T3 fibroblasts. Cells expressing wild-type E2F1 display a morphology indistinguishable from that of normal fibroblasts. However, the E2F1d87-expressing cells exhibited a distinct rounding during culture in media containing 10% calf serum. The morphology change was most pronounced during S phase, which was considerably lengthened in the E2F1d87-expressing cells. Consistent with this rounded shape, the E2F1d87-expressing cells have significantly increased levels of both p34cdc2 mRNA and protein. Also observed was an increase in active p34cdc2 in immunoprecipitates from extracts of the E2F1d87 cell line, as assayed by histone H1 kinase assay. The upregulation of p34cdc2 expression occurs at the transcriptional level and requires ectopic E2F1d87 along with serum growth factor stimulation, since culture of these cells in low serum media results in a flattened shape and a drop in p34cdc2 expression compared to that of the control cells.

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Constitutive expression of the E2F1 transcription factor in fibroblasts alters G0 and S phase transit following serum stimulation

Cited by 4 publications

References 27 publications

Isolation of Two Novel cDNAs Whose Products Associate with the Amino Terminus of the E2F1 Transcription Factor

Isolation of Two Novel cDNAs Whose Products Associate with the Amino Terminus of the E2F1 Transcription Factor

The E2F‐1 transcription factor is negatively regulated by its interaction with the MDMX protein

Altered cell shape is linked to increased p34cdc2 gene expression in fibroblasts expressing a mutant E2F-1 transcription factor

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