Two E2F sites control growth-regulated and cell cycle-regulated transcription of the Htf9-a/RanBP1 gene through functionally distinct mechanisms.
The gene encoding Ran-binding protein 1 (RanBP1) is transcribed in a cell cycle-dependent manner. The RanBP1 promoter contains two binding sites for E2F factors, named E2F-c, located proximal to the transcription start, and E2F-b, falling in a more distal promoter region. We have now induced site-directed mutagenesis in both sites. We have found that the distal E2F-b site, together with a neighboring Sp1 element, actively controls up-regulation of transcription in S phase. The proximal E2F-c site plays no apparent role in cycling cells yet is required for transcriptional repression upon growth arrest. Protein binding studies suggest that each E2F site mediates specific interactions with individual E2F family members. In addition, transient expression assays with mutagenized promoter constructs indicate that the functional role of each site is also dependent on its position relative to other regulatory elements in the promoter context. Thus, the two E2F sites play opposite genetic functions and control RanBP1 transcription through distinct molecular mechanisms.
Di Fiore
B
B
Consiglio Nazionale delle Ricerche Centre of Evolutionary Genetics, c/o University La Sapienza, Via degli Apuli 4, 00185 Rome, Italy.
Guarguaglini
G
G
Palena
A
A
Kerkhoven
R M
RM
Bernards
R
R
Lavia
P
P
D016475:3T3 Cells; D000818:Animals; D002352:Carrier Proteins; D018797:Cell Cycle Proteins / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D050684:E2F Transcription Factors; D005656:Fungal Proteins / Q000235:genetics* / Q000502:physiology; D016193:G1 Phase; D019204:GTP-Binding Proteins / Q000235:genetics* / Q000502:physiology; D016350:Leucine Zippers; D051379:Mice; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins / Q000235:genetics* / Q000502:physiology; D011401:Promoter Regions, Genetic; D056465:Retinoblastoma-Binding Protein 1; D016196:S Phase; D013329:Structure-Activity Relationship; D050680:Transcription Factor DP1; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D020931:ran GTP-Binding Protein
C533431:Arid4a protein, mouse; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D005656:Fungal Proteins; D009687:Nuclear Proteins; D056465:Retinoblastoma-Binding Protein 1; D050680:Transcription Factor DP1; D014157:Transcription Factors; C091775:ran-binding protein 1; D019204:GTP-Binding Proteins; D020931:ran GTP-Binding Protein