title: Human Dna2 is a nuclear and mitochondrial DNA maintenance protein.
abstract: Dna2 is a highly conserved helicase/nuclease that in yeast participates in Okazaki fragment processing, DNA repair, and telomere maintenance. Here, we investigated the biological function of human Dna2 (hDna2). Immunofluorescence and biochemical fractionation studies demonstrated that hDna2 was present in both the nucleus and the mitochondria. Analysis of mitochondrial hDna2 revealed that it colocalized with a subfraction of DNA-containing mitochondrial nucleoids in unperturbed cells. Upon the expression of disease-associated mutant forms of the mitochondrial Twinkle helicase which induce DNA replication pausing/stalling, hDna2 accumulated within nucleoids. RNA interference-mediated depletion of hDna2 led to a modest decrease in mitochondrial DNA replication intermediates and inefficient repair of damaged mitochondrial DNA. Importantly, hDna2 depletion also resulted in the appearance of aneuploid cells and the formation of internuclear chromatin bridges, indicating that nuclear hDna2 plays a role in genomic DNA stability. Together, our data indicate that hDna2 is similar to its yeast counterpart and is a new addition to the growing list of proteins that participate in both nuclear and mitochondrial DNA maintenance.
authors.affiliation: Department of Cell Biology and Physiology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
authors.forename: Julien P
authors.initials: JP
authors.lastname: Duxin
authors.forename: Benjamin
authors.initials: B
authors.lastname: Dao
authors.forename: Peter
authors.initials: P
authors.lastname: Martinsson
authors.forename: Nina
authors.initials: N
authors.lastname: Rajala
authors.forename: Lionel
authors.initials: L
authors.lastname: Guittat
authors.forename: Judith L
authors.initials: JL
authors.lastname: Campbell
authors.forename: Johannes N
authors.initials: JN
authors.lastname: Spelbrink
authors.forename: Sheila A
authors.initials: SA
authors.lastname: Stewart
mesh_terms: D015153:Blotting, Western; D002460:Cell Line; D002467:Cell Nucleus / Q000235:genetics* / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004249:DNA Damage; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism*; D004260:DNA Repair; D004261:DNA Replication / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000235:genetics*; D005455:Fluorescent Antibody Technique; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D018613:Microscopy, Confocal; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins; D009154:Mutation; D034622:RNA Interference
chemical_list: D004272:DNA, Mitochondrial; D024101:Mitochondrial Proteins; D004265:DNA Helicases; C509908:DNA2 protein, human; C431576:TWNK protein, human