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TOPBP1 recruits TOP2A to ultra-fine anaphase bridges to aid in their resolution.


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Authors

Broderick, Ronan 
Nieminuszczy, Jadwiga 
Blackford, Andrew N 
Winczura, Alicja 
Niedzwiedz, Wojciech 

Abstract

During mitosis, sister chromatids must be faithfully segregated to ensure that daughter cells receive one copy of each chromosome. However, following replication they often remain entangled. Topoisomerase IIα (TOP2A) has been proposed to resolve such entanglements, but the mechanisms governing TOP2A recruitment to these structures remain poorly understood. Here, we identify TOPBP1 as a novel interactor of TOP2A, and reveal that it is required for TOP2A recruitment to ultra-fine anaphase bridges (UFBs) in mitosis. The C-terminal region of TOPBP1 interacts with TOP2A, and TOPBP1 recruitment to UFBs requires its BRCT domain 5. Depletion of TOPBP1 leads to accumulation of UFBs, the majority of which arise from centromeric loci. Accordingly, expression of a TOPBP1 mutant that is defective in TOP2A binding phenocopies TOP2A depletion. These findings provide new mechanistic insights into how TOP2A promotes resolution of UFBs during mitosis, and highlights a pivotal role for TOPBP1 in this process.

Description

Keywords

Anaphase, Antigens, Neoplasm, Carrier Proteins, Cell Cycle Proteins, Cell Line, Tumor, Centromere, Chromatids, Chromosomes, DNA, DNA Topoisomerases, Type II, DNA-Binding Proteins, Gene Expression Regulation, Gene Expression Regulation, Neoplastic, Green Fluorescent Proteins, HEK293 Cells, HeLa Cells, Humans, Microscopy, Fluorescence, Mitosis, Mutation, Nuclear Proteins, Poly-ADP-Ribose Binding Proteins, Protein Binding, Protein Structure, Tertiary

Journal Title

Nat Commun

Conference Name

Journal ISSN

2041-1723
2041-1723

Volume Title

6

Publisher

Springer Science and Business Media LLC
Sponsorship
Cancer Research Uk (None)
We thank Drs G. Stewart and F. Esashi for cell lines, Professor T.D. Halazonetis, Dr G.J. Gorbsky and Dr G. Stewart for plasmids and antibodies. We also thank Dr C. Lagerholm (Wolfson Imaging Centre, Oxford) and Dr D. Waithe (CBRG, Oxford) for their help with microscopy and image analysis, and the Mass Spectrometry Laboratory (IBB PAS) for their work on analyses of GFP–TOP2A immunoprecipitation experiments. We also thank Professor I. Hickson for helpful comments on the manuscript. This work was funded by a Worldwide Cancer Research International Fellowship (to W.N.), a WIMM/Medical Research Council Senior Non-Clinical Fellowship (to W.N.), a Polish Ministry of Science and Higher Education fellowship (to J.N.) and Polish National Science Center grant N N303 571539 (to J.N.).