SAF-A promotes origin licensing and replication fork progression to ensure robust DNA replication

Caitlin Connolly, Saori Takahashi, Hisashi Miura, Ichiro Hiratani, Nick Gilbert, Anne Donaldson, Shin-ichiro Hiraga* (Corresponding Author)

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)
8 Downloads (Pure)

Abstract

The organisation of chromatin is closely intertwined with biological activities of
chromosome domains, including transcription and DNA replication status. Scaffold attachment factor A (SAF-A), also known as Heteronuclear Ribonucleoprotein Protein U (HNRNPU), contributes to the formation of open chromatin structure. Here we demonstrate that SAF-A promotes the normal progression of DNA replication, and enables resumption of replication after inhibition. We report that cells depleted for SAF-A show reduced origin licensing in G1 phase, and consequently reduced origin activation frequency in S phase. Replication forks also progress less consistently in cells depleted for SAF-A, contributing to reduced DNA synthesis rate. Single-cell replication timing analysis revealed two distinct effects of SAF-A depletion: first, the boundaries between early- and late-replicating domains become more blurred; and second, SAF-A depletion causes replication timing changes that tend to bring regions of discordant domain compartmentalisation and replication timing into concordance. Associated with these defects, SAF-A-depleted cells show elevated g-H2AX formation and tend to enter quiescence. Overall we find that SAF-A
protein promotes robust DNA replication to ensure continuing cell proliferation.
Original languageEnglish
Article numberjcs.258991
Number of pages15
JournalJournal of Cell Science
Volume135
Issue number2
Early online date10 Dec 2021
DOIs
Publication statusPublished - 24 Jan 2022

Bibliographical note

Funding
CC was supported by a BBSRC EASTBIO Doctoral Training programme PhD
studentship. SH was supported by Daiwa Anglo-Japanese Foundation
812 (12928/13746). Work in the Hiraga-Donaldson lab supported by Cancer Research UK awards C1445/A19059 and DRCPGM\100013. NG is supported by Medical Research Council (MC_UU_00007/13)
Acknowledgements
Information for SAF-A expression was obtained at The Cancer Genome Atlas
TCGA) Research Network (https://www.cancer.gov/tcga). We thank Dr Ryu-suke
Nozawa for help in the early stage of the project, and Professor Julian Blow for
advice on the 3D licensing assay. Thanks to the staff of the Iain Fraser Cytometry
Centre, and Microscopy and Histology facility at the University of Aberdeen.

Keywords

  • DNA replication
  • Chromatin
  • Replication stress

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