title: Constitutive expression of the E2F1 transcription factor in fibroblasts alters G0 and S phase transit following serum stimulation.
abstract: The E2F1 transcription factor was constitutively expressed in NIH3T3 fibroblasts to determine its effect on the cell cycle. These E2F1 cell lines were not tightly synchronized in G0 phase of the cell cycle following serum starvation, as are normal fibroblasts. Instead, the cells are spread throughout G0 and G1 phase with a portion of the population initiating DNA synthesis. Upon serum stimulation, the remaining cells in G0/G1 begin to enter S phase immediately but with a reduced rate. Constitutive expression of E2F1 appears to primarily affect the G0 phase, since transit of proliferating E2F1 cell lines through G1 phase is the same as control cells. Consistent with a shortened G0 phase, the E2F1 cell lines have a significantly reduced cellular volume. Additionally, the first S phase after serum stimulation, but not subsequent S phases, is nearly doubled in the E2F1 cell lines compared with control cells. Cell lines expressing a deletion mutant of E2F1 (termed E2F1d87), known to significantly affect cell shape, have cell cycle and volume characteristics similar to the E2F1 expressing cells. However, all S phase durations are considerably lengthened and the cells demonstrate delayed growth after plating.
authors.affiliation: Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
authors.forename: T J
authors.initials: TJ
authors.lastname: Logan
authors.forename: K L
authors.initials: KL
authors.lastname: Jordan
authors.forename: D J
authors.initials: DJ
authors.lastname: Hall
mesh_terms: D016475:3T3 Cells; D000818:Animals; D002352:Carrier Proteins; D002453:Cell Cycle; D018797:Cell Cycle Proteins; D002455:Cell Division; D048429:Cell Size; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; D005434:Flow Cytometry; D007399:Interphase; D051379:Mice; D056465:Retinoblastoma-Binding Protein 1; D016196:S Phase; D013997:Time Factors; D050680:Transcription Factor DP1; D014157:Transcription Factors / Q000096:biosynthesis* / Q000502:physiology
chemical_list: C533431:Arid4a protein, mouse; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; C493754:E2f1 protein, mouse; D056465:Retinoblastoma-Binding Protein 1; D050680:Transcription Factor DP1; D014157:Transcription Factors