Modeling pathogenic mutations of human twinkle in Drosophila suggests an apoptosis role in response to mitochondrial defects.

TitleModeling pathogenic mutations of human twinkle in Drosophila suggests an apoptosis role in response to mitochondrial defects.
Publication TypeJournal Article
Year of Publication2012
AuthorsSanchez-Martinez, A, Calleja, M, Peralta, S, Matsushima, Y, Hernandez-Sierra, R, Whitworth, AJ, Kaguni, LS, Garesse, R
JournalPLoS One
Volume7
Issue8
Paginatione43954
Date Published2012
ISSN1932-6203
KeywordsAmino Acid Sequence, Animals, Apoptosis, Cell Proliferation, Disease Models, Animal, DNA Helicases, Drosophila melanogaster, Humans, Longevity, Male, Mice, Mitochondria, Mitochondrial Diseases, Mitochondrial Proteins, Mutation, Ophthalmoplegia, Oxidative Phosphorylation
Abstract

The human gene C10orf2 encodes the mitochondrial replicative DNA helicase Twinkle, mutations of which are responsible for a significant fraction of cases of autosomal dominant progressive external ophthalmoplegia (adPEO), a human mitochondrial disease caused by defects in intergenomic communication. We report the analysis of orthologous mutations in the Drosophila melanogaster mitochondrial DNA (mtDNA) helicase gene, d-mtDNA helicase. Increased expression of wild type d-mtDNA helicase using the UAS-GAL4 system leads to an increase in mtDNA copy number throughout adult life without any noteworthy phenotype, whereas overexpression of d-mtDNA helicase containing the K388A mutation in the helicase active site results in a severe depletion of mtDNA and a lethal phenotype. Overexpression of two d-mtDNA helicase variants equivalent to two human adPEO mutations shows differential effects. The A442P mutation exhibits a dominant negative effect similar to that of the active site mutant. In contrast, overexpression of d-mtDNA helicase containing the W441C mutation results in a slight decrease in mtDNA copy number during the third instar larval stage, and a moderate decrease in life span in the adult population. Overexpression of d-mtDNA helicase containing either the K388A or A442P mutations causes a mitochondrial oxidative phosphorylation (OXPHOS) defect that significantly reduces cell proliferation. The mitochondrial impairment caused by these mutations promotes apoptosis, arguing that mitochondria regulate programmed cell death in Drosophila. Our study of d-mtDNA helicase overexpression provides a tractable Drosophila model for understanding the cellular and molecular effects of human adPEO mutations.

DOI10.1371/journal.pone.0043954
Alternate JournalPLoS ONE
Citation Key10.1371/journal.pone.0043954
PubMed ID22952820
PubMed Central IDPMC3429445
Grant List089698 / / Wellcome Trust / United Kingdom
GM45295 / GM / NIGMS NIH HHS / United States
R01 GM045295 / GM / NIGMS NIH HHS / United States