Altered cell shape is linked to increased p34cdc2 gene expression in fibroblasts expressing a mutant E2F-1 transcription factor.
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.
Logan
T J
TJ
Department of Biochemistry and Molecular Pharmacology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
Jordan
K L
KL
Evans
D L
DL
Hall
D J
DJ
D016475:3T3 Cells; D000818:Animals; D016203:CDC2 Protein Kinase / Q000502:physiology*; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D048429:Cell Size; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; D005347:Fibroblasts / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D006133:Growth Substances / Q000502:physiology*; D051379:Mice; D056465:Retinoblastoma-Binding Protein 1; D016196:S Phase; D013329:Structure-Activity Relationship; D050680:Transcription Factor DP1; D014157:Transcription Factors / Q000502:physiology*; D014158:Transcription, Genetic; D015854:Up-Regulation
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; D006133:Growth Substances; D056465:Retinoblastoma-Binding Protein 1; D050680:Transcription Factor DP1; D014157:Transcription Factors; D016203:CDC2 Protein Kinase