title: The TALE transcription factor homothorax functions to assemble heterochromatin during Drosophila embryogenesis.
abstract: We have previously identified Homothorax (Hth) as an important factor for the correct assembly of the pericentromeric heterochromatin during the first fast syncytial divisions of the Drosophila embryo. Here we have extended our studies to later stages of embryonic development. We were able to show that hth mutants exhibit a drastic overall reduction in the tri-methylation of H3 in Lys9, with no reduction of the previous di-methylation. One phenotypic outcome of such a reduction is a genome instability visualized by the many DNA breaks observed in the mutant nuclei. Moreover, loss of Hth leads to the opening of closed heterochromatic regions, including the rDNA genomic region. Our data show that the satellite repeats get transcribed in wild type embryos and that this transcription depends on the presence of Hth, which binds to them as well as to the rDNA region. This work indicates that there is an important role of transcription of non-coding RNAs for constitutive heterochromatin assembly in the Drosophila embryo, and suggests that Hth plays an important role in this process.
authors: Centro de Biología Molecular "Severo Ochoa" CSIC-UAM, C/ Nicolás Cabrera, 1 Universidad Autónoma de Madrid, Madrid, Spain.
authors: Miguel Angel
authors: MA
authors: Zaballos
authors: Centro de Biología Molecular "Severo Ochoa" CSIC-UAM, C/ Nicolás Cabrera, 1 Universidad Autónoma de Madrid, Madrid, Spain.
authors: Walter
authors: W
authors: Cantero
authors: Centro de Biología Molecular "Severo Ochoa" CSIC-UAM, C/ Nicolás Cabrera, 1 Universidad Autónoma de Madrid, Madrid, Spain.
authors: Natalia
authors: N
authors: Azpiazu
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002466:Cell Nucleolus / Q000378:metabolism; D053960:DNA Breaks; D004275:DNA, Ribosomal / Q000235:genetics; D004276:DNA, Satellite / Q000235:genetics; D003850:Deoxyribonuclease I / Q000378:metabolism; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000196:embryology* / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000378:metabolism*; D047108:Embryonic Development; D005260:Female; D006570:Heterochromatin / Q000378:metabolism*; D006657:Histones / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism*; D008239:Lysine / Q000378:metabolism; D008745:Methylation; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D012335:RNA, Ribosomal / Q000235:genetics; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D004275:DNA, Ribosomal; D004276:DNA, Satellite; D029721:Drosophila Proteins; D006570:Heterochromatin; D006657:Histones; D018398:Homeodomain Proteins; D012335:RNA, Ribosomal; D014157:Transcription Factors; C108704:hth protein, Drosophila; D003850:Deoxyribonuclease I; D008239:Lysine