title: Functional interaction of CCAAT/enhancer-binding-protein-α basic region mutants with E2F transcription factors and DNA.
abstract: The transcription factor CCAAT/enhancer-binding protein α (C/EBPα) regulates cell cycle arrest and terminal differentiation of neutrophils and adipocytes. Mutations in the basic leucine zipper domain (bZip) of C/EBPα are associated with acute myeloid leukemia. A widely used murine transforming C/EBPα basic region mutant (BRM2) entails two bZip point mutations (I294A/R297A). BRM2 has been discordantly described as defective for DNA binding or defective for interaction with E2F. We have separated the two BRM2 mutations to shed light on the intertwined reciprocity between C/EBPα-E2F-DNA interactions. Both, C/EBPα I294A and R297A retain transactivation capacity and interaction with E2F-DP. The C/EBPα R297A mutation destabilized DNA binding, whereas the C/EBPα I294A mutation enhanced binding to DNA. The C/EBPα R297A mutant, like BRM2, displayed enhanced interaction with E2F-DP but failed to repress E2F-dependent transactivation although both mutants were readily suppressed by E2F1 for transcription through C/EBP cis-regulatory sites. In contrast, the DNA binding enhanced C/EBPα I294A mutant displayed increased repression of E2F-DP mediated transactivation and resisted E2F-DP mediated repression. Thus, the efficient repression of E2F dependent S-phase genes and the activation of differentiation genes reside in the balanced DNA binding capacity of C/EBPα.
authors.affiliation: Tumorigenesis and Cell Differentiation, Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Kowenz-Leutz
authors.affiliation: Protein Sample Production Facility, Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Schuetz
authors.affiliation: Tumorigenesis and Cell Differentiation, Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany; Institute of Biology, Humboldt University of Berlin, Berlin, Germany.
authors.forename: Qingbin
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Tumorigenesis and Cell Differentiation, Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany.
authors.forename: Maria
authors.initials: M
authors.lastname: Knoblich
authors.affiliation: Protein Sample Production Facility, Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany; Chemistry and Biochemistry Institute, Freie Universität Berlin, Berlin, Germany.
authors.forename: Udo
authors.initials: U
authors.lastname: Heinemann
authors.affiliation: Tumorigenesis and Cell Differentiation, Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany; Institute of Biology, Humboldt University of Berlin, Berlin, Germany. Electronic address: aleutz@mdc-berlin.de.
authors.forename: Achim
authors.initials: A
authors.lastname: Leutz
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D022762:CCAAT-Enhancer-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism*; D050684:E2F Transcription Factors / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D054730:Protein Interaction Domains and Motifs / Q000235:genetics; D017433:Protein Structure, Secondary / Q000235:genetics; D017386:Sequence Homology, Amino Acid
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; C515848:CEBPA protein, human; C530718:CEBPA protein, mouse; D050684:E2F Transcription Factors; D050505:Mutant Proteins; D004247:DNA
keywords: CCAAT-enhancer-binding protein (C/EBP); Cell proliferation; Differentiation; E2F transcription factor