title: Overexpression of DNA ligase III in mitochondria protects cells against oxidative stress and improves mitochondrial DNA base excision repair.
abstract: Base excision repair (BER) is the most prominent DNA repair pathway in human mitochondria. BER also results in a temporary generation of AP-sites, single-strand breaks and nucleotide gaps. Thus, incomplete BER can result in the generation of DNA repair intermediates that can disrupt mitochondrial DNA replication and transcription and generate mutations. We carried out BER analysis in highly purified mitochondrial extracts from human cell lines U2OS and HeLa, and mouse brain using a circular DNA substrate containing a lesion at a specific position. We found that DNA ligation is significantly slower than the preceding mitochondrial BER steps. Overexpression of DNA ligase III in mitochondria improved the rate of overall BER, increased cell survival after menadione induced oxidative stress and reduced autophagy following the inhibition of the mitochondrial electron transport chain complex I by rotenone. Our results suggest that the amount of DNA ligase III in mitochondria may be critical for cell survival following prolonged oxidative stress, and demonstrate a functional link between mitochondrial DNA damage and repair, cell survival upon oxidative stress, and removal of dysfunctional mitochondria by autophagy.
authors.affiliation: Center for Healthy Aging, SUND, University of Copenhagen, Denmark.
authors.forename: Mansour
authors.initials: M
authors.lastname: Akbari
authors.affiliation: Center for Healthy Aging, SUND, University of Copenhagen, Denmark.
authors.forename: Guido
authors.initials: G
authors.lastname: Keijzers
authors.affiliation: Center for Healthy Aging, SUND, University of Copenhagen, Denmark.
authors.forename: Scott
authors.initials: S
authors.lastname: Maynard
authors.affiliation: Laboratory of Molecular Gerontology, National Institute on Aging, 251 Bayview Boulevard, Baltimore, USA.
authors.forename: Morten
authors.initials: M
authors.lastname: Scheibye-Knudsen
authors.affiliation: Center for Healthy Aging, SUND, University of Copenhagen, Denmark.
authors.forename: Claus
authors.initials: C
authors.lastname: Desler
authors.affiliation: Center for Healthy Aging, SUND, University of Copenhagen, Denmark.
authors.forename: Ian D
authors.initials: ID
authors.lastname: Hickson
authors.affiliation: Laboratory of Molecular Gerontology, National Institute on Aging, 251 Bayview Boulevard, Baltimore, USA; Center for Healthy Aging, SUND, University of Copenhagen, Denmark. Electronic address: vbohr@nih.gov.
authors.forename: Vilhelm A
authors.initials: VA
authors.lastname: Bohr
mesh_terms: D000818:Animals; D001343:Autophagy / Q000187:drug effects; D001921:Brain / Q000378:metabolism*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000235:genetics / Q000378:metabolism*; D004260:DNA Repair; D004272:DNA, Mitochondrial / Q000378:metabolism*; D042967:Electron Transport Complex I / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects*; D000075223:Poly-ADP-Ribose Binding Proteins; D012402:Rotenone / Q000494:pharmacology; D024483:Vitamin K 3 / Q000494:pharmacology; D029867:Xenopus Proteins
chemical_list: D004272:DNA, Mitochondrial; D000075223:Poly-ADP-Ribose Binding Proteins; D029867:Xenopus Proteins; D012402:Rotenone; D024483:Vitamin K 3; D011088:DNA Ligases; D000072481:DNA Ligase ATP; C000618816:DNA ligase III alpha protein, Xenopus; C000618817:LIG3 protein, human; C000618818:Lig3 protein, mouse; D042967:Electron Transport Complex I
keywords: Autophagy; Cell survival; Mitochondrial DNA repair intermediates; Oxidative stress