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XB-ART-56693
iScience June 28, 2019; 16 485-498.

The Spatiotemporal Control of Zygotic Genome Activation.

Gentsch GE , Owens NDL , Smith JC .


Abstract
One of the earliest and most significant events in embryonic development is zygotic genome activation (ZGA). In several species, bulk transcription begins at the midblastula transition (MBT) when, after a certain number of cleavages, the embryo attains a particular nuclear-to-cytoplasmic (N/C) ratio, maternal repressors become sufficiently diluted, and the cell cycle slows down. Here we resolve the frog ZGA in time and space by profiling RNA polymerase II (RNAPII) engagement and its transcriptional readout. We detect a gradual increase in both the quantity and the length of RNAPII elongation before the MBT, revealing that >1,000 zygotic genes disregard the N/C timer for their activation and that the sizes of newly transcribed genes are not necessarily constrained by cell cycle duration. We also find that Wnt, Nodal, and BMP signaling together generate most of the spatiotemporal dynamics of regional ZGA, directing the formation of orthogonal body axes and proportionate germ layers.

PubMed ID: 31229896
PMC ID: PMC6593175
Article link: iScience
Grant support: [+]

Genes referenced: ctnnb1 eomes fgf20 nodal3.1 nodal5 sia2 smad1 smad2 tbxt tbxt.2 ventx1.1 zeb2 znf470
GO keywords: RNA polymerase II activity [+]
Morpholinos: ctnnb1 MO2 eomes MO1 pou5f3.2 MO7 pou5f3.3 MO8 sox3 MO5 tbxt MO2 tbxt MO3 tbxt.2 MO3 tbxt.2 MO4 vegt MO10 vegt MO3

GEO Series: GSE122551: Xenbase,  NCBI

Article Images: [+] show captions
References [+] :
Agius, Endodermal Nodal-related signals and mesoderm induction in Xenopus. 2000, Pubmed, Xenbase