The embryonic linker histone H1 variant of Drosophila, dBigH1, regulates zygotic genome activation.
Histone H1 is an essential chromatin component. Metazoans usually contain multiple stage-specific H1s. In particular, specific variants replace somatic H1s during early embryogenesis. In this regard, Drosophila was an exception because a single dH1 was identified that, starting at cellularization, is detected throughout development in somatic cells. Here, we identify the embryonic H1 of Drosophila, dBigH1. dBigH1 is abundant before cellularization occurs, when somatic dH1 is absent and the zygotic genome is inactive. Upon cellularization, when the zygotic genome is progressively activated, dH1 replaces dBigH1 in the soma, but not in the primordial germ cells (PGCs) that have delayed zygotic genome activation (ZGA). In addition, a loss-of-function mutant shows premature ZGA in both the soma and PGCs. Mutant embryos die at cellularization, showing increased levels of active RNApol II and zygotic transcripts, along with DNA damage and mitotic defects. These results show an essential function of dBigH1 in ZGA regulation.
Institute of Molecular Biology of Barcelona, CSIC, 08028 Barcelona, Spain; Institute for Research in Biomedicine, IRB Barcelona, 08028 Barcelona, Spain.
Salvador
S
Pérez-Montero
Albert
A
Carbonell
Tomás
T
Morán
Alejandro
A
Vaquero
Fernando
F
Azorín
D000595:Amino Acid Sequence; D000818:Animals; D004249:DNA Damage; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000196:embryology / Q000235:genetics* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D049750:Genome, Insect; D005854:Germ Cells / Q000378:metabolism; D006657:Histones / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008938:Mitosis; D008969:Molecular Sequence Data; D009154:Mutation; D012319:RNA Polymerase II / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015053:Zygote / Q000378:metabolism*
D029721:Drosophila Proteins; D006657:Histones; D012333:RNA, Messenger; D012319:RNA Polymerase II