Common Features of the Pericentromere and Nucleolus.

Colleen J Lawrimore,Kerry Bloom

doi:10.3390/genes10121029

Colleen J Lawrimore, Kerry Bloom

Open Access

https://doi.org/10.3390/genes10121029

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Journal: Genes	Publication Date: Dec 10, 2019
Citations: 21	License type: CC BY 4.0

Affiliation: University of North Carolina at Chapel Hill

Abstract

Both the pericentromere and the nucleolus have unique characteristics that distinguish them amongst the rest of genome. Looping of pericentromeric DNA, due to structural maintenance of chromosome (SMC) proteins condensin and cohesin, drives its ability to maintain tension during metaphase. Similar loops are formed via condensin and cohesin in nucleolar ribosomal DNA (rDNA). Condensin and cohesin are also concentrated in transfer RNA (tRNA) genes, genes which may be located within the pericentromere as well as tethered to the nucleolus. Replication fork stalling, as well as downstream consequences such as genomic recombination, are characteristic of both the pericentromere and rDNA. Furthermore, emerging evidence suggests that the pericentromere may function as a liquid–liquid phase separated domain, similar to the nucleolus. We therefore propose that the pericentromere and nucleolus, in part due to their enrichment of SMC proteins and others, contain similar domains that drive important cellular activities such as segregation, stability, and repair.

Highlights

During cell division, the centromere functions as an essential genetic locus for ensuring faithful chromosome segregation
The pericentromere is defined as the cohesin- and condensin-enriched region spanning
Deletion of Ulp2, an isopeptidase that removes small ubiquitin-like modifier (SUMO) from proteins, causes a decrease in pericentric condensin clustering [79], as well as a decrease in condensin localization to ribosomal DNA (rDNA) sites [80] in budding yeast. This result is consistent with decrease in tension at the pericentromere [79] and lack of sister chromatid cohesion [81], suggesting a role for sumoylation in these activities of pericentric condensin

Summary

Introduction

The centromere functions as an essential genetic locus for ensuring faithful chromosome segregation. The pericentromere is defined as the cohesin- and condensin-enriched region spanning. In regional centromeres, which are enriched in heterochromatic alpha satellite repeats, there are multiple sites of microtubule attachment. Despite these differences, the interkinetochore distance is conserved among eukaryotes [6], suggesting an important conservation of centromere mechanics. RDNA is localized to chromosome XII, consisting of 150 tandem repeats of ~ 9 kb each. The pericentromere and nucleolus have a number of similarities between their domains These include condensin/cohesin localization and proteins that regulate the formation of DNA loops. Transfer RNA (tRNA) genes, enriched in condensin and cohesin, are located within the pericentromere region and tethered to the nucleolus. We discuss in detail these commonalities between the pericentromere and the nucleolus

DNA Loops Are Enriched in the Pericentromere and Nucleolus

Replication Fork Stalling in Pericentromere and rDNA

Recombination Control in the Pericentromere and rDNA

Phase Separation in the Nucleolus and Pericentromere

Conclusions