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Published August 2009 | Published + Supplemental Material
Journal Article Open

Human Dna2 is a nuclear and mitochondrial DNA maintenance protein


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.

Additional Information

© 2009 American Society for Microbiology. Received 2 December 2008; returned for modification 5 January 2009; accepted 20 May 2009. We thank B. Van Houten for the mtDNA damage protocol, Emily Cheng for the MitoTracker reagent and helpful comments, S. Goffart for the detailed protocol and advice on mtDNA analysis by 2DNAGE, Elise Oster for technical assistance with the DNA damage assay, Avi Silver for DNA preparations, and members of the Stewart and Spelbrink laboratories for useful comments. We also thank Jason Weber for critical reading of the manuscript. This work was supported by the Cancer Biology Pathway, the Siteman Cancer Center at Barnes-Jewish Hospital, and the Washington University School of Medicine in St. Louis (J.P.D.); the Children's Discovery Institute (S.A.S.); Academy of Finland grants 110463 and 108380 (P.M.); USPHS GM087666 and the Ellison Foundation (J.L.C.); Academy of Finland grants 110689 and 103213 and CoE funding (J.N.S.); the Sigrid Juselius Foundation (J.N.S.); and the Tampere University Hospital Medical Research Fund (9G072 and 9H079 to J.N.S.).

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Supplemental Material - 1834leg.doc

Supplemental Material - Duxin_Sup_Figure_1.tif


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August 20, 2023
October 18, 2023