Regulation of cell growth-dependent expression of mammalian CDC6 gene by the cell cycle transcription factor E2F.
CDC6 of Saccharomyces cerevisiae regulates the DNA replication initiation through the origin recognition complex (ORC). Identification of a human homolog of the CDC6 gene (HsCdc6) suggests a universal role of the gene product in DNA replication. Expression of HsCdc6 is growth-regulated. We investigated the molecular basis of growth-regulated expression of mammalian Cdc6. The promoter activity of isolated HsCdc6 upstream region was activated at late G1 and G1/S boundary in the cell cycle of rat embryonic fibroblast REF52 cells by the addition of serum. The isolated promoter was activated by exogenous expression of E2F without serum stimulation. However a mutant promoter lacking the E2F recognition sites failed to respond to serum stimulation and exogenous expression of E2F. Expression of endogenous Cdc6 was induced by exogenous expression of E2F. Therefore, we concluded that the growth-regulated expression of mammalian Cdc6 was mediated by E2F. Moreover, we demonstrated that exogenous overexpression of either HsCdc6 or HsOrc1 failed to induce DNA synthesis unlike overexpression of E2F1, even though E2F1 induced both Cdc6 and Orc1, suggesting that E2F may regulate the expression of another gene(s), besides Cdc6 and Orc1, required for induction of cellular DNA synthesis in mammalian cells.
Human Gene Sciences Center, Graduate School of Dentistry, Tokyo Medical and Dental University, Japan.
K
K
Ohtani
A
A
Tsujimoto
M
M
Ikeda
M
M
Nakamura
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002352:Carrier Proteins; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000235:genetics*; D002455:Cell Division; D002460:Cell Line; D004247:DNA / Q000096:biosynthesis; D004268:DNA-Binding Proteins / Q000235:genetics; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; D005786:Gene Expression Regulation; D006801:Humans; D008322:Mammals; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics*; D051738:Origin Recognition Complex; D011401:Promoter Regions, Genetic; D051381:Rats; D056465:Retinoblastoma-Binding Protein 1; D050680:Transcription Factor DP1; D014157:Transcription Factors / Q000378:metabolism*
C103706:CDC6 protein, human; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; C493755:E2f1 protein, rat; D009687:Nuclear Proteins; C497223:ORC1 protein, human; D051738:Origin Recognition Complex; D056465:Retinoblastoma-Binding Protein 1; D050680:Transcription Factor DP1; D014157:Transcription Factors; D004247:DNA