title: G1/S-regulated E2F-containing protein complexes bind to the mouse thymidine kinase gene promoter.
abstract: By performing DNase I footprint analysis, we had identified three distinct protein binding sequences (MT1, MT2, and MT3) located on the mouse thymidine kinase (TK) upstream promoter (Dou, Q.-P., Fridovich-Keil, J. L., and Pardee, A.B. (1991) Proc. Natl. Acad. Sci. U.S.A. 88, 1157-1161). Here we report that MT2 includes an E2F-like binding site (GTTCGCGGGCAAA), as shown by the following evidence. (i) MT2 bound specifically to an affinity-purified fusion human E2F protein. (ii) Both MT2 and an authentic E2F site (TTTCGCGCGCTTT) bound specifically to similar or identical nuclear protein complexes. (iii) Formation of both these DNA-protein complexes were cell cycle-dependent: a G0/G1 phase-specific complex (E2F.G0/G1) was replaced by an S phase-specific complex(es) (E2F.S), whereas "free" E2F increased after the G1/S transition. (iv) Pulse inhibition of protein synthesis with cycloheximide interchanged these complexes with similar kinetics. (v) When MT2-shifted E2F.G0/G1, E2F.S, and free E2F were eluted and analyzed by Western blot assay using a specific antiserum to human E2F-1, two forms of murine E2F (62 and 66 kDa) were observed from all three complexes. The compositions of these MT2-bound complexes were also investigated. Studies using specific antibodies revealed that p107, a retinoblastoma-like protein, was present in both E2F-G0/G1 and E2F.S, whereas cyclin E.cyclin A.cdk2 were only present in E2F.S complex(es). These data suggest that removal of the p107-containing E2F.G0/G1 complex, a candidate repressor, from the MT2 site in late G1 may be essential for S phase-dependent transcription of the mouse TK gene.
authors.affiliation: Division of Cell Growth and Regulation, Dana-Farber Cancer Institute, Boston, Massachusetts.
authors.forename: Q P
authors.initials: QP
authors.lastname: Dou
authors.forename: S
authors.initials: S
authors.lastname: Zhao
authors.forename: A H
authors.initials: AH
authors.lastname: Levin
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: K
authors.initials: K
authors.lastname: Helin
authors.forename: A B
authors.initials: AB
authors.lastname: Pardee
mesh_terms: D000818:Animals; D001483:Base Sequence; D001667:Binding, Competitive; D002352:Carrier Proteins; D002453:Cell Cycle; D018797:Cell Cycle Proteins; D016384:Consensus Sequence; D016213:Cyclins / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; D015971:Gene Expression Regulation, Enzymologic; D046911:Macromolecular Substances; D051379:Mice; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics; D011993:Recombinant Fusion Proteins; D056465:Retinoblastoma-Binding Protein 1; D013937:Thymidine Kinase / Q000235:genetics*; D050680:Transcription Factor DP1; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: C533431:Arid4a protein, mouse; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D016213:Cyclins; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; C493754:E2f1 protein, mouse; D046911:Macromolecular Substances; D009687:Nuclear Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D056465:Retinoblastoma-Binding Protein 1; D050680:Transcription Factor DP1; D014157:Transcription Factors; D013937:Thymidine Kinase