Abstract
Human cells lacking RIF1 are highly sensitive to replication inhibitors, but the reasons for this sensitivity have been enigmatic. Here, we show that RIF1 must be present both during replication stress and in the ensuing recovery period to promote cell survival. Of two isoforms produced by alternative splicing, we find that RIF1-Long alone can protect cells against replication inhibition, but RIF1-Short is incapable of mediating protection. Consistent with this isoform-specific role, RIF1-Long is required to promote the formation of the 53BP1 nuclear bodies that protect unrepaired damage sites in the G1 phase following replication stress. Overall, our observations show that RIF1 is needed at several cell cycle stages after replication insult, with the RIF1-Long isoform playing a specific role during the ensuing G1 phase in damage site protection.
Highlights
The RIF1 protein has emerged as a central regulator of chromosome maintenance, acting in doublestrand break repair and DNA replication control (Chapman et al, 2013; Escribano-Dıaz et al, 2013; Hiraga et al, 2017)
We confirmed in a colony formation assay (CFA) that HEK293 cells depleted for RIF1 are sensitive to the DNA polymerase inhibitor Aphidicolin (Figure 1A,B)
To further test for separability of the effect of RIF1 in replication stress survival from its known roles in replication control, we investigated whether Phosphatase 1 (PP1) interaction is essential for RIF1-Long isoform cDNA (RIF1-L) to protect against Aphidicolin treatment
Summary
The RIF1 protein has emerged as a central regulator of chromosome maintenance, acting in doublestrand break repair and DNA replication control (Chapman et al, 2013; Escribano-Dıaz et al, 2013; Hiraga et al, 2017). During double-strand break repair, RIF1 is recruited by 53BP1, dependent upon phosphorylation of 53BP1 by ATM (Chapman et al, 2013; Escribano-Dıaz et al, 2013; Di Virgilio et al, 2013). RIF1-deficient cells are acutely sensitive to replication stress, appearing to be more sensitive to replication inhibitors than to double-strand break-inducing agents (Buonomo et al, 2009), suggesting that protection from stress is a critical RIF1 function
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
