Deregulated expression of E2F-1 induces cyclin A- and E-associated kinase activities independently from cell cycle position.
The transcription factor E2F activates genes required for S phase, such as cyclin E and cyclin A. We show that, contrary to long term effects of E2F-1 overexpression, short ectopic overexpression of this transcription factor in logarithmically growing cells does neither affect the cell cycle distribution nor the cell size, but heavily induces cyclin E and A expression as well as cyclin E- and A-dependent kinase activities. We further separated logarithmically growing E2F-1-overexpressing cells according to their different cell cycle phases by centrifugal elutriation. These experiments revealed that deregulated E2F-1 expression triggers high levels of cyclin E and A expression and kinase activities in small early G1 cells, normally not exhibiting these activities. These effects on the regulation of cyclin E- and A-associated kinases are not accompanied by any detectable alteration in the rate of progression through the cell cycle, suggesting that these changes are independent of any mitogenic properties of E2F-1.
Soucek
T
T
Obstetrics and Gynecology, University of Vienna, Department of Prenatal Diagnosis and Therapy, Austria.
Pusch
O
O
Hengstschläger-Ottnad
E
E
Adams
P D
PD
Hengstschläger
M
M
D000818:Animals; D002352:Carrier Proteins; D002453:Cell Cycle; D018797:Cell Cycle Proteins; D002460:Cell Line; D018844:Cyclin-Dependent Kinases / Q000378:metabolism*; D016213:Cyclins / Q000235:genetics*; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; D005786:Gene Expression Regulation; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D056465:Retinoblastoma-Binding Protein 1; D050680:Transcription Factor DP1; D014157:Transcription Factors / Q000235:genetics*
D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D016213:Cyclins; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; C493755:E2f1 protein, rat; D012333:RNA, Messenger; D056465:Retinoblastoma-Binding Protein 1; D050680:Transcription Factor DP1; D014157:Transcription Factors; D018844:Cyclin-Dependent Kinases