DOI: 10.1101/484568Dec 3, 2018Paper

Two Contrasting Classes of Nucleolus-Associated Domains in Mouse Fibroblast Heterochromatin

BioRxiv : the Preprint Server for Biology
Anastassiia VertiiPaul D Kaufman

Abstract

In interphase eukaryotic cells, almost all heterochromatin is located adjacent to the nucleolus or to the nuclear lamina, thus defining Nucleolus Associated Domains (NADs) and Lamina Associated Domains (LADs), respectively. Here, we determined the first genome-scale map of murine NADs in mouse embryonic fibroblasts (MEFs) via deep sequencing of chromatin associated with purified nucleoli. We developed a Bioconductor package called NADfinder and demonstrated that it identifies NADs more accurately than other peak-calling tools, due to its critical feature of chromosome-level local baseline correction. We detected two distinct classes of NADs. Type I NADs associate frequently with both the nucleolar periphery and with the nuclear lamina, and generally display characteristics of constitutive heterochromatin, including late DNA replication, enrichment of H3K9me3 and little gene expression. In contrast, Type II NADs associate with nucleoli but do not overlap with LADs. Type II NADs tend to replicate earlier, display greater gene expression, and are more often enriched in H3K27me3 than Type I NADs. The nucleolar associations of both classes of NADs were confirmed via DNA-FISH, which also detected Type I but not Type II probes enriche...Continue Reading

Related Concepts

Mental Association
Cell Differentiation Process
Cell Nucleolus
Chromatin
Chromosomes
Fibroblasts
Gene Expression
Genome
Interferon Type I
Laboratory mice

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