Systemic Loss and Gain of Chromatin Architecture throughout Zebrafish Development

Publication date: 3 July 2018
Source:Cell Reports, Volume 24, Issue 1
Author(s): Lucas J.T. Kaaij, Robin H. van der Weide, René F. Ketting, Elzo de Wit
The spatial organization of chromosomes is critical in establishing gene expression programs. We generated in situ Hi-C maps throughout zebrafish development to gain insight into higher-order chromatin organization and dynamics. Zebrafish chromosomes segregate in active and inactive chromatin (A/B compartments), which are further organized into topologically associating domains (TADs). Zebrafish A/B compartments and TADs have genomic features similar to those of their mammalian counterparts, including evolutionary conservation and enrichment of CTCF binding sites at TAD borders. At the earliest time point, when there is no zygotic transcription, the genome is highly structured. After zygotic genome activation (ZGA), the genome loses structural features, which are re-established throughout early development. Despite the absence of structural features, we see clustering of super-enhancers in the 3D genome. Our results provide insight into vertebrate genome organization and demonstrate that the developing zebrafish embryo is a powerful model system to study the dynamics of nuclear organization.

Graphical abstract

Teaser

How do developing zebrafish embryos organize their genome? Kaaij et al. show that, early in development, when there is no transcription, the genome is highly structured; however, when the zygotic genome is activated, this organization is lost. Later in development, the genome again adopts a structured organization.


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