title: Sumoylation regulates EXO1 stability and processing of DNA damage.
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.
authors.affiliation: a Institute of Molecular Cancer Research; University of Zurich ; Zurich , Switzerland.
authors.forename: Serena
authors.initials: S
authors.lastname: Bologna
authors.forename: Veronika
authors.initials: V
authors.lastname: Altmannova
authors.forename: Emanuele
authors.initials: E
authors.lastname: Valtorta
authors.forename: Christiane
authors.initials: C
authors.lastname: Koenig
authors.forename: Prisca
authors.initials: P
authors.lastname: Liberali
authors.forename: Christian
authors.initials: C
authors.lastname: Gentili
authors.forename: Dorothea
authors.initials: D
authors.lastname: Anrather
authors.forename: Gustav
authors.initials: G
authors.lastname: Ammerer
authors.forename: Lucas
authors.initials: L
authors.lastname: Pelkmans
authors.forename: Lumir
authors.initials: L
authors.lastname: Krejci
authors.forename: Stefano
authors.initials: S
authors.lastname: Ferrari
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D002166:Camptothecin / Q000494:pharmacology; D002460:Cell Line; D003546:Cysteine Endopeptidases / Q000378:metabolism; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair / Q000235:genetics*; D045643:DNA Repair Enzymes / Q000235:genetics / Q000378:metabolism*; D005090:Exodeoxyribonucleases / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000235:genetics; D057809:HEK293 Cells; D006801:Humans; D000075223:Poly-ADP-Ribose Binding Proteins; D050828:Protein Inhibitors of Activated STAT / Q000235:genetics / Q000378:metabolism; D055550:Protein Stability; D025842:SUMO-1 Protein / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D025841:Small Ubiquitin-Related Modifier Proteins / Q000235:genetics / Q000378:metabolism; D058207:Sumoylation / Q000502:physiology*; D044763:Ubiquitin-Conjugating Enzymes / Q000235:genetics / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism; D054875:Ubiquitination; D000098843:Ubiquitin-Conjugating Enzyme UBC9
chemical_list: D000972:Antineoplastic Agents, Phytogenic; C106529:PIAS1 protein, human; C485891:PIAS4 protein, human; D000075223:Poly-ADP-Ribose Binding Proteins; D050828:Protein Inhibitors of Activated STAT; D025842:SUMO-1 Protein; C495501:SUMO1 protein, human; C117909:SUMO2 protein, human; D029701:Saccharomyces cerevisiae Proteins; C436836:Siz2 protein, S cerevisiae; D025841:Small Ubiquitin-Related Modifier Proteins; D044763:Ubiquitin-Conjugating Enzymes; D044767:Ubiquitin-Protein Ligases; C114331:EXO1 protein, human; D005090:Exodeoxyribonucleases; D003546:Cysteine Endopeptidases; C408873:SENP6 protein, human; C436837:Siz1 protein, S cerevisiae; D000098843:Ubiquitin-Conjugating Enzyme UBC9; D045643:DNA Repair Enzymes; D002166:Camptothecin
keywords: DNA resection; chromosome aberrations; exonuclease-1; sumoylation; ubiquitylation