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Sumoylation regulates EXO1 stability and processing of DNA damage


Bologna, Serena; Altmannova, Veronika; Valtorta, Emanuele; Koenig, Christiane; Liberali, Prisca; Gentili, Christian; Anrather, Dorothea; Ammerer, Gustav; Pelkmans, Lucas; Krejci, Lumir; Ferrari, Stefano (2015). Sumoylation regulates EXO1 stability and processing of DNA damage. Cell Cycle, 14(15):2439-2450.

Abstract

DNA double-strand break repair by the error-free pathway of homologous recombination (HR) requires the concerted action of several factors. Among these, EXO1 and DNA2/BLM are responsible for the extensive resection of DNA ends to produce 3'-overhangs, which are essential intermediates for downstream steps of HR. Here we show that EXO1 is a SUMO target and that sumoylation affects EXO1 ubiquitylation and protein stability. We identify an UBC9-PIAS1/PIAS4-dependent mechanism controlling human EXO1 sumoylation in vivo and demonstrate conservation of this mechanism in yeast by the Ubc9-Siz1/Siz2 using an in vitro reconstituted system. Furthermore, we show physical interaction between EXO1 and the de-sumoylating enzyme SENP6 both in vitro and in vivo, promoting EXO1 stability. Finally, we identify the major sites of sumoylation in EXO1 and show that ectopic expression of a sumoylation-deficient form of EXO1 rescues the DNA damage-induced chromosomal aberrations observed upon wt-EXO1 expression. Thus, our study identifies a novel layer of regulation of EXO1, making the pathways that regulate its function an ideal target for therapeutic intervention.

Abstract

DNA double-strand break repair by the error-free pathway of homologous recombination (HR) requires the concerted action of several factors. Among these, EXO1 and DNA2/BLM are responsible for the extensive resection of DNA ends to produce 3'-overhangs, which are essential intermediates for downstream steps of HR. Here we show that EXO1 is a SUMO target and that sumoylation affects EXO1 ubiquitylation and protein stability. We identify an UBC9-PIAS1/PIAS4-dependent mechanism controlling human EXO1 sumoylation in vivo and demonstrate conservation of this mechanism in yeast by the Ubc9-Siz1/Siz2 using an in vitro reconstituted system. Furthermore, we show physical interaction between EXO1 and the de-sumoylating enzyme SENP6 both in vitro and in vivo, promoting EXO1 stability. Finally, we identify the major sites of sumoylation in EXO1 and show that ectopic expression of a sumoylation-deficient form of EXO1 rescues the DNA damage-induced chromosomal aberrations observed upon wt-EXO1 expression. Thus, our study identifies a novel layer of regulation of EXO1, making the pathways that regulate its function an ideal target for therapeutic intervention.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Institute of Molecular Cancer Research
07 Faculty of Science > Institute of Molecular Cancer Research

07 Faculty of Science > Institute of Molecular Life Sciences
Dewey Decimal Classification:570 Life sciences; biology
610 Medicine & health
Language:English
Date:3 August 2015
Deposited On:27 Aug 2015 12:56
Last Modified:08 Dec 2017 13:55
Publisher:Landes Bioscience
ISSN:1551-4005
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1080/15384101.2015.1060381
PubMed ID:26083678

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