Max Planck Institute of Immunobiology and Epigenetics, 79108, Freiburg im Breisgau, Germany.
University of Freiburg, Faculty of Biology, 79108, Freiburg im Breisgau, Germany.
Nat Commun. 2021 Dec 1;12(1):7002. doi: 10.1038/s41467-021-27125-7.
During embryogenesis, the genome shifts from transcriptionally quiescent to extensively active in a process known as Zygotic Genome Activation (ZGA). In Drosophila, the pioneer factor Zelda is known to be essential for the progression of development; still, it regulates the activation of only a small subset of genes at ZGA. However, thousands of genes do not require Zelda, suggesting that other mechanisms exist. By conducting GRO-seq, HiC and ChIP-seq in Drosophila embryos, we demonstrate that up to 65% of zygotically activated genes are enriched for the histone variant H2A.Z. H2A.Z enrichment precedes ZGA and RNA Polymerase II loading onto chromatin. In vivo knockdown of maternally contributed Domino, a histone chaperone and ATPase, reduces H2A.Z deposition at transcription start sites, causes global downregulation of housekeeping genes at ZGA, and compromises the establishment of the 3D chromatin structure. We infer that H2A.Z is essential for the de novo establishment of transcriptional programs during ZGA via chromatin reorganization.
在胚胎发生过程中,基因组从转录静止状态转变为广泛活跃状态,这一过程被称为合子基因组激活(ZGA)。在果蝇中,先驱因子 Zelda 被认为是发育进程所必需的;然而,它仅能调控一小部分基因在 ZGA 中的激活。然而,数千个基因并不需要 Zelda,这表明存在其他机制。通过在果蝇胚胎中进行 GRO-seq、HiC 和 ChIP-seq,我们证明了多达 65%的合子激活基因富含组蛋白变体 H2A.Z。H2A.Z 富集先于 ZGA 和 RNA 聚合酶 II 加载到染色质上。体内敲低母源贡献的 Domino,一种组蛋白伴侣和 ATP 酶,会减少转录起始位点处的 H2A.Z 沉积,导致 ZGA 时管家基因的全面下调,并损害 3D 染色质结构的建立。我们推断,H2A.Z 通过染色质重排对于 ZGA 期间新转录程序的建立是必需的。