TY - JOUR

T1 - Novel DNA mismatch-repair activity involving YB-1 in human mitochondria

AU - de Souza-Pinto, Nadja C

AU - Mason, Penelope A

AU - Hashiguchi, Kazunari

AU - Weissman, Lior

AU - Tian, Jingyan

AU - Guay, David

AU - Lebel, Michel

AU - Stevnsner, Tinna V

AU - Rasmussen, Lene Juel

AU - Bohr, Vilhelm A

N1 - Keywords: Cell Nucleus; Chloramphenicol Resistance; DNA Mismatch Repair; DNA, Mitochondrial; DNA-Binding Proteins; Electrophoretic Mobility Shift Assay; Hela Cells; Humans; Mitochondria; Nuclear Proteins; Oxygen Consumption; Subcellular Fractions

PY - 2009

Y1 - 2009

N2 - Maintenance of the mitochondrial genome (mtDNA) is essential for proper cellular function. The accumulation of damage and mutations in the mtDNA leads to diseases, cancer, and aging. Mammalian mitochondria have proficient base excision repair, but the existence of other DNA repair pathways is still unclear. Deficiencies in DNA mismatch repair (MMR), which corrects base mismatches and small loops, are associated with DNA microsatellite instability, accumulation of mutations, and cancer. MMR proteins have been identified in yeast and coral mitochondria; however, MMR proteins and function have not yet been detected in human mitochondria. Here we show that human mitochondria have a robust mismatch-repair activity, which is distinct from nuclear MMR. Key nuclear MMR factors were not detected in mitochondria, and similar mismatch-binding activity was observed in mitochondrial extracts from cells lacking MSH2, suggesting distinctive pathways for nuclear and mitochondrial MMR. We identified the repair factor YB-1 as a key candidate for a mitochondrial mismatch-binding protein. This protein localizes to mitochondria in human cells, and contributes significantly to the mismatch-binding and mismatch-repair activity detected in HeLa mitochondrial extracts, which are significantly decreased when the intracellular levels of YB-1 are diminished. Moreover, YB-1 depletion in cells increases mitochondrial DNA mutagenesis. Our results show that human mitochondria contain a functional MMR repair pathway in which YB-1 participates, likely in the mismatch-binding and recognition steps.

AB - Maintenance of the mitochondrial genome (mtDNA) is essential for proper cellular function. The accumulation of damage and mutations in the mtDNA leads to diseases, cancer, and aging. Mammalian mitochondria have proficient base excision repair, but the existence of other DNA repair pathways is still unclear. Deficiencies in DNA mismatch repair (MMR), which corrects base mismatches and small loops, are associated with DNA microsatellite instability, accumulation of mutations, and cancer. MMR proteins have been identified in yeast and coral mitochondria; however, MMR proteins and function have not yet been detected in human mitochondria. Here we show that human mitochondria have a robust mismatch-repair activity, which is distinct from nuclear MMR. Key nuclear MMR factors were not detected in mitochondria, and similar mismatch-binding activity was observed in mitochondrial extracts from cells lacking MSH2, suggesting distinctive pathways for nuclear and mitochondrial MMR. We identified the repair factor YB-1 as a key candidate for a mitochondrial mismatch-binding protein. This protein localizes to mitochondria in human cells, and contributes significantly to the mismatch-binding and mismatch-repair activity detected in HeLa mitochondrial extracts, which are significantly decreased when the intracellular levels of YB-1 are diminished. Moreover, YB-1 depletion in cells increases mitochondrial DNA mutagenesis. Our results show that human mitochondria contain a functional MMR repair pathway in which YB-1 participates, likely in the mismatch-binding and recognition steps.

U2 - 10.1016/j.dnarep.2009.01.021

DO - 10.1016/j.dnarep.2009.01.021

M3 - Journal article

C2 - 19272840

VL - 8

SP - 704

EP - 719

JO - DNA Repair

JF - DNA Repair

SN - 1568-7864

IS - 6

ER -