Expression of MCM10 and TopBP1 is regulated by cell proliferation and UV irradiation via the E2F transcription factor.
MCM10 and TopBP1 function in the initiation of DNA replication, by regulating the chromatin binding of the DNA polymerase alpha loading factor, CDC45. TopBP1 is also known as a DNA damage response protein. In this study, we showed that the transcription of human MCM10 and TopBP1 is activated by transcription factors E2F1-3, but not by factors E2F4-7. Analysis of various MCM10 and TopBP1 promoter constructs showed that an E2F-responsive sequence in the vicinity of the transcription initiation site is necessary for the E2F1-induced activation of MCM10 and TopBP1 gene transcription, which is further suppressed by pRb. The promoter activities of human MCM10 and TopBP1 were demonstrated to be growth dependent via the E2F-responsive sequence. Although E2F1 was stabilized by ultraviolet (UV) irradiation, the mRNA expression level of TopBP1 was suppressed in HCT116 human diploid colon cancer cells. We showed, by performing chromatin immunoprecipitation that, in response to UV irradiation but not doxorubicin treatment, E2F4 accumulated on the MCM10 and TopBP1 promoters. Our data suggest a model in which UV irradiation-induced DNA damage depends, at least in part, on the accumulation of the E2F4 transcription factor on the MCM10 and TopBP1 promoters, which results in suppression of DNA replication.
Yoshida
Kenichi
K
Division of Genetic Diagnosis, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan. yoshidak@ims.u-tokyo.ac.jp
Inoue
Ituro
I
D001483:Base Sequence; D015153:Blotting, Western; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D002455:Cell Division / Q000502:physiology*; D002460:Cell Line; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; D050704:E2F4 Transcription Factor; D005786:Gene Expression Regulation / Q000502:physiology* / Q000528:radiation effects*; D006801:Humans; D064110:Minichromosome Maintenance Proteins; D009687:Nuclear Proteins; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012045:Regulatory Sequences, Nucleic Acid; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D014466:Ultraviolet Rays
D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D017931:DNA Primers; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; D050704:E2F4 Transcription Factor; C493762:E2F4 protein, human; C489613:MCM10 protein, human; D009687:Nuclear Proteins; C110513:TOPBP1 protein, human; D014157:Transcription Factors; D064110:Minichromosome Maintenance Proteins