Regulation of SUMO2 target proteins by the proteasome in human cells exposed to replication stress.
In human cells, SUMO2 is predominantly conjugated to target proteins in response to cellular stress. Previous studies suggested that proteins conjugated to SUMO2, but not to SUMO1, could be regulated by the ubiquitin-mediated proteasome system. Hence, we set out to understand the role of the proteasome in determining the fate of proteins conjugated to SUMO2 when cells are treated with DNA replication stress conditions. We conducted a quantitative proteomic analysis in a U2OS cell line stably expressing SUMO2(Q87R) tagged with StrepHA in the presence or absence of epoxomicin (EPOX), a proteasome inhibitor. We identified subgroups of putative SUMO2 targets that were either degraded or stabilized by EPOX upon SUMO2 conjugation in response to replication stress. Interestingly, the subgroup of proteins degraded upon SUMO2 conjugation was enriched in proteins playing roles in DNA damage repair and replication, while the proteins stabilized upon SUMOylation were mainly involved in chromatin maintenance. In addition, we identified 43 SUMOylation sites in target proteins, of which 17 are located in the proximity of phosphorylated residues. Considering that DNA replication stress is a major source of genome instability, which is suggested to drive tumorigenesis and possibly aging, our data will facilitate future functional studies in the fields of DNA metabolism and cancer biology.
†Center for Chromosome Stability, and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Panum Institute, Blegdamsvej 3b, DK-2200 Copenhagen, Denmark.
Sara
S
Bursomanno
‡Ubiquitin Proteolysis Group, TDI Mass Spectrometry Laboratory, Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Headington, OX3 7FZ Oxford, UK.
Joanna F
JF
McGouran
‡Ubiquitin Proteolysis Group, TDI Mass Spectrometry Laboratory, Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Headington, OX3 7FZ Oxford, UK.
Benedikt M
BM
Kessler
†Center for Chromosome Stability, and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Panum Institute, Blegdamsvej 3b, DK-2200 Copenhagen, Denmark.
Ian D
ID
Hickson
†Center for Chromosome Stability, and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Panum Institute, Blegdamsvej 3b, DK-2200 Copenhagen, Denmark.
Ying
Y
Liu
D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002468:Cell Physiological Phenomena / Q000502:physiology*; D003001:Cloning, Molecular; D004261:DNA Replication / Q000502:physiology*; D005434:Flow Cytometry; D006801:Humans; D013058:Mass Spectrometry; D008856:Microscopy, Fluorescence; D009842:Oligopeptides / Q000494:pharmacology; D046988:Proteasome Endopeptidase Complex / Q000187:drug effects / Q000502:physiology*; D059748:Proteolysis / Q000187:drug effects; D040901:Proteomics / Q000379:methods*; D025841:Small Ubiquitin-Related Modifier Proteins / Q000378:metabolism*; D013312:Stress, Physiological / Q000502:physiology*
D018797:Cell Cycle Proteins; D009842:Oligopeptides; C117909:SUMO2 protein, human; D025841:Small Ubiquitin-Related Modifier Proteins; D046988:Proteasome Endopeptidase Complex; C078846:epoxomicin
DNA replication stress; SUMOylation consensus sites; epoxomicin; mass spectrometry; proteolysis