title: Association of bromodomain BET proteins with chromatin requires dimerization through the conserved motif B.
abstract: BET (bromodomain and extra terminal domain) family proteins are unique among bromodomain-containing proteins in that they not only associate with acetylated chromatin in interphase, but also remain attached to chromosomes during mitosis. Although the two tandem bromodomains are essential to display this behaviour, they do not suffice. In this work we report that a small conserved domain, motif B, is also required. A deletion mutant of this domain dissociates from mitotic chromosomes. However, inhibition of histone deacetylases alleviates dissociation. We also show that motif-B-dependent association with chromosomes is not restricted to mitosis. Interestingly, our results indicate that motif B constitutes a surface for homo- and hetero-dimerization between BET proteins. Finally, linked to the prominent role BET proteins play in cell proliferation, we report that ectopic expression of the family member Brd2 interferes with neuronal differentiation in P19 cells and in the vertebrate neural tube, probably because of preservation of adequate levels of cyclin A2 and cyclin D1. By contrast, a deletion mutant of motif B fails to perform in this way, highlighting the relevance of this domain for Brd2 function.
authors.affiliation: Stem Cells Department, Centro Andaluz de Biología Molecular y Medicina Regenerativa and Consejo Superior de Investigaciones Científicas, Av Americo Vespucio, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Garcia-Gutierrez
authors.forename: Maria
authors.initials: M
authors.lastname: Mundi
authors.forename: Mario
authors.initials: M
authors.lastname: Garcia-Dominguez
mesh_terms: D000107:Acetylation; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D018929:Cell Culture Techniques; D002453:Cell Cycle / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology; D002843:Chromatin / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone; D017124:Conserved Sequence; D019281:Dimerization; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors; D014162:Transfection; D000092468:Bromodomain Containing Proteins
chemical_list: D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D017346:Protein Serine-Threonine Kinases; D014157:Transcription Factors; C098415:BRD2 protein, human; D000092468:Bromodomain Containing Proteins; C490844:Brd2 protein, mouse