title: Modulation of Sp1-dependent transcription by a cis-acting E2F element in dhfr promoter.
abstract: The dihydrofolate reductase (dhfr) promoter contains cis-acting elements for Sp1 and E2F. Here we examined the cooperative regulation of dhfr gene transcription by Sp1 and E2F in human osteosarcoma cells, U2OS. Trichostatin A, an inhibitor of histone deacetylases, markedly stimulated dhfr promoter activity, a response that was enhanced by the deletion of an E2F element. In contrast, deletion of the dhfr Sp1 binding sites completely abolished promoter stimulation by trichostatin A. Cotransfection assays showed that activation of dhfr transcription by expression of E2F1/DP1 requires the reiterated Sp1 elements, whereas activation by Sp1 was enhanced by the deletion of the E2F element. Expression of HDAC1 with Sp1 suppressed promoter activity and suppression was not alleviated by coexpression of E2F1/DP1. These results suggest that HDAC1 acts through Sp1 to repress dhfr promoter activity, and that the E2F element modulates the activity of Sp1 at the dhfr promoter through a cis-acting mechanism.
authors.affiliation: Kidney Institute, Keimyung University School of Medicine, 700-712, Daegu, Republic of Korea.
authors.forename: Kwan-Kyu
authors.initials: KK
authors.lastname: Park
authors.forename: Seok-Woo
authors.initials: SW
authors.lastname: Rue
authors.forename: In-Seon
authors.initials: IS
authors.lastname: Lee
authors.forename: Hyun-Chul
authors.initials: HC
authors.lastname: Kim
authors.forename: In-Kyu
authors.initials: IK
authors.lastname: Lee
authors.forename: Jong-Deok
authors.initials: JD
authors.lastname: Ahn
authors.forename: Hyun-Soo
authors.initials: HS
authors.lastname: Kim
authors.forename: Tae-Shick
authors.initials: TS
authors.lastname: Yu
authors.forename: Jong-Young
authors.initials: JY
authors.lastname: Kwak
authors.forename: Nicholas H
authors.initials: NH
authors.lastname: Heintz
authors.forename: Junji
authors.initials: J
authors.lastname: Magae
authors.forename: Young-Chae
authors.initials: YC
authors.lastname: Chang
mesh_terms: D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D018797:Cell Cycle Proteins; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; D004791:Enzyme Inhibitors / Q000494:pharmacology; D056572:Histone Deacetylase Inhibitors; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000187:drug effects; D012097:Repressor Proteins / Q000378:metabolism; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D013762:Tetrahydrofolate Dehydrogenase / Q000235:genetics*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured
chemical_list: D018797:Cell Cycle Proteins; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; D004791:Enzyme Inhibitors; D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D012097:Repressor Proteins; D016329:Sp1 Transcription Factor; D014157:Transcription Factors; C012589:trichostatin A; D013762:Tetrahydrofolate Dehydrogenase