The Embryonic Linker Histone H1 Variant of Drosophila, dBigH1, Regulates Zygotic Genome Activation

• Published in: Developmental cell 2013-09, Vol.26 (6), p.578-590
• Main Authors: Pérez-Montero, Salvador, Carbonell, Albert, Morán, Tomás, Vaquero, Alejandro, Azorín, Fernando
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; DNA Damage; Drosophila; Drosophila melanogaster - embryology; Drosophila melanogaster - genetics; Drosophila melanogaster - metabolism; Drosophila Proteins - chemistry; Drosophila Proteins - genetics; Drosophila Proteins - metabolism; Gene Expression Regulation, Developmental; Genome, Insect; Germ Cells - metabolism; Histones - chemistry; Histones - genetics; Histones - metabolism; Metazoa; Mitosis; Molecular Sequence Data; Mutation; RNA Polymerase II - genetics; RNA Polymerase II - metabolism; RNA, Messenger - genetics; RNA, Messenger - metabolism; Zygote - metabolism
• ISSN: 1534-5807; 1878-1551
• DOI: 10.1016/j.devcel.2013.08.011

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. •CG3509 encodes the embryonic H1 of Drosophila, dBigH1•dBigH1 is replaced by somatic dH1 at cellularization in somatic cells•dBigH1 is retained in the germline cells through development•dBigH1 regulates zygotic genome activation in the soma and the germline Pérez-Montero et al. identify the Drosophila embryonic H1, dBigH1, and show that it regulates zygotic genome activation (ZGA) in somatic and primordial germ cells (PGCs). dBigH1 loss results in premature ZGA in both tissues. During ZGA, somatic H1 replaces dBigH1 in the soma, but not in PGCs, where ZGA is delayed.