title: Antagonism versus cooperativity with TALE cofactors at the base of the functional diversification of Hox protein function.
abstract: Extradenticle (Exd) and Homothorax (Hth) function as positive transcriptional cofactors of Hox proteins, helping them to bind specifically their direct targets. The posterior Hox protein Abdominal-B (Abd-B) does not require Exd/Hth to bind DNA; and, during embryogenesis, Abd-B represses hth and exd transcription. Here we show that this repression is necessary for Abd-B function, as maintained Exd/Hth expression results in transformations similar to those observed in loss-of-function Abd-B mutants. We characterize the cis regulatory module directly regulated by Abd-B in the empty spiracles gene and show that the Exd/Hth complex interferes with Abd-B binding to this enhancer. Our results suggest that this novel Exd/Hth function does not require the complex to bind DNA and may be mediated by direct Exd/Hth binding to the Abd-B homeodomain. Thus, in some instances, the main positive cofactor complex for anterior Hox proteins can act as a negative factor for the posterior Hox protein Abd-B. This antagonistic interaction uncovers an alternative way in which MEIS and PBC cofactors can modulate Abd-B like posterior Hox genes during development.
authors: CABD, CSIC/JA/Universidad Pablo de Olavide, Seville, Spain.
authors: María Luisa
authors: ML
authors: Rivas
authors: Jose Manuel
authors: JM
authors: Espinosa-Vázquez
authors: Nagraj
authors: N
authors: Sambrani
authors: Stephen
authors: S
authors: Greig
authors: Samir
authors: S
authors: Merabet
authors: Yacine
authors: Y
authors: Graba
authors: James Castelli-Gair
authors: JC
authors: Hombría
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster / Q000235:genetics / Q000254:growth & development; D047108:Embryonic Development / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: C062393:Abd-B proteins, Drosophila; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D014157:Transcription Factors; C083405:exd protein, Drosophila; C108704:hth protein, Drosophila