title: CUX1 and E2F1 regulate coordinated expression of the mitotic complex genes Ect2, MgcRacGAP, and MKLP1 in S phase.
abstract: Rho GTPases are critical for mitosis progression and completion of cytokinesis. During mitosis, the GDP/GTP cycle of Rho GTPases is regulated by the exchange factor Ect2 and the GTPase activating protein MgcRacGAP which associates with the kinesin MKLP1 in the centralspindlin complex. We report here that expression of Ect2, MgcRacGAP, and MKLP1 is tightly regulated during cell cycle progression. These three genes share similar cell cycle-related signatures within their promoter regions: (i) cell cycle gene homology region (CHR) sites located at -20 to +40 nucleotides of their transcription start sites that are required for repression in G(1), (ii) E2F binding elements, and (iii) tandem repeats of target sequences for the CUX1 transcription factor. CUX1 and E2F1 bind these three promoters upon S-phase entry, as demonstrated by chromatin immunoprecipitation, and regulate transcription of these genes, as established using promoter-luciferase reporter constructs and expression of activated or dominant negative transcription factors. Overexpression of either E2F1 or CUX1 increased the levels of the endogenous proteins whereas small interfering RNA knockdown of E2F1 or use of a dominant negative E2F1 reduced their expression levels. Thus, CUX1, E2F, and CHR elements provide the transcriptional controls that coordinate induction of Ect2, MgcRacGAP, and MKLP1 in S phase, leading to peak expression of these interacting proteins in G(2)/M, at the time they are required to regulate cytokinesis.
authors.affiliation: INSERM U749, Faculté de Pharmacie Paris XI, 92296 Châtenay-Malabry, France.
authors.forename: Laetitia
authors.initials: L
authors.lastname: Seguin
authors.forename: Caroline
authors.initials: C
authors.lastname: Liot
authors.forename: Rym
authors.initials: R
authors.lastname: Mzali
authors.forename: Ryoko
authors.initials: R
authors.lastname: Harada
authors.forename: Aurelie
authors.initials: A
authors.lastname: Siret
authors.forename: Alain
authors.initials: A
authors.lastname: Nepveu
authors.forename: Jacques
authors.initials: J
authors.lastname: Bertoglio
mesh_terms: D047369:Chromatin Immunoprecipitation; D004252:DNA Mutational Analysis; D050687:E2F1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D016193:G1 Phase / Q000502:physiology; D020690:GTPase-Activating Proteins / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007376:Interleukin-2 / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000235:genetics* / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D016196:S Phase / Q000502:physiology*; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors; D024363:Transcription Initiation Site
chemical_list: C080632:CUX1 protein, human; D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; C489850:ECT2 protein, human; D020690:GTPase-Activating Proteins; D018398:Homeodomain Proteins; D007376:Interleukin-2; C092935:KIF23 protein, human; D008869:Microtubule-Associated Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; D012097:Repressor Proteins; D014157:Transcription Factors; C115995:mgcRacGAP