title: Human MMS21/NSE2 is a SUMO ligase required for DNA repair.
abstract: DNA repair is required for the genomic stability and well-being of an organism. In yeasts, a multisubunit complex consisting of SMC5, SMC6, MMS21/NSE2, and other non-SMC proteins is required for DNA repair through homologous recombination. The yeast MMS21 protein is a SUMO ligase. Here we show that the human homolog of MMS21 is also a SUMO ligase. hMMS21 stimulates sumoylation of hSMC6 and the DNA repair protein TRAX. Depletion of hMMS21 by RNA interference (RNAi) sensitizes HeLa cells toward DNA damage-induced apoptosis. Ectopic expression of wild-type hMMS21, but not its ligase-inactive mutant, rescues this hypersensitivity of hMMS21-RNAi cells. ATM/ATR are hyperactivated in hMMS21-RNAi cells upon DNA damage. Consistently, hMMS21-RNAi cells show an increased number of phospho-CHK2 foci. Finally, we show that hMMS21-RNAi cells show a decreased capacity to repair DNA lesions as measured by the comet assay. Our findings suggest that the human SMC5/6 complex and the SUMO ligase activity of hMMS21 are required for the prevention of DNA damage-induced apoptosis by facilitating DNA repair in human cells.
authors.affiliation: Department of Pharmacology, The University of Texas Southwestern Medical Center, Dallas, 75390-9041, USA.
authors.forename: Patrick Ryan
authors.initials: PR
authors.lastname: Potts
authors.forename: Hongtao
authors.initials: H
authors.lastname: Yu
mesh_terms: D000595:Amino Acid Sequence; D017209:Apoptosis; D018797:Cell Cycle Proteins / Q000502:physiology*; D019070:Cell Lineage; D002868:Chromosomal Proteins, Non-Histone; D020552:Comet Assay; D004247:DNA / Q000378:metabolism; D004249:DNA Damage; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005982:Glutathione Transferase / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D008025:Ligases / Q000235:genetics* / Q000502:physiology*; D008856:Microscopy, Fluorescence; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010957:Plasmids / Q000378:metabolism; D014176:Protein Biosynthesis; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D011995:Recombination, Genetic; D025842:SUMO-1 Protein / Q000378:metabolism*; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D012568:Schizosaccharomyces; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D044763:Ubiquitin-Conjugating Enzymes / Q000378:metabolism; D000098843:Ubiquitin-Conjugating Enzyme UBC9
chemical_list: D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; C500948:Mms21 protein, S cerevisiae; C432931:SMC5 protein, human; C432932:SMC6 protein, human; D025842:SUMO-1 Protein; D029701:Saccharomyces cerevisiae Proteins; C095563:TSN protein, human; C498305:TSNAX protein, human; D004247:DNA; D044763:Ubiquitin-Conjugating Enzymes; D005982:Glutathione Transferase; D008025:Ligases; C503501:NSMCE2 protein, human; D000098843:Ubiquitin-Conjugating Enzyme UBC9