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Over‐expression of the catalytic core of mitochondrial DNA (mtDNA) polymerase in the nervous system of Drosophila melanogaster reduces median life span by inducing mtDNA depletion
Author(s) -
MartínezAzorín Francisco,
Calleja Manuel,
HernándezSierra Rosana,
Farr Carol L.,
Kaguni Laurie S.,
Garesse Rafael
Publication year - 2008
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2007.05122.x
Subject(s) - drosophila melanogaster , mitochondrial dna , biology , genetics , mitochondrion , microbiology and biotechnology , gene
DNA polymerase γ (pol γ) is the sole DNA polymerase devoted to mitochondrial DNA (mtDNA) replication. We have characterized the molecular and physiological effects of over‐expression of the catalytic subunit of pol γ, pol γ‐α, in the nervous system of Drosophila melanogaster using the upstream activation sequence (UAS)/yeast transcriptional activator by binding to UAS (GAL4) system. Tissue‐specific over‐expression of pol γ‐α was confirmed by immunoblot analysis, whereas the very low levels of endogenous protein are undetectable in UAS or GAL4 control lines. The transgenic flies over‐expressing pol γ‐α in the nervous system showed a moderate increase in pupal lethality, and a significant decrease in the median life span of adult flies. Moreover, these flies displayed a decrease in the rate of synthesis of mtDNA, which is accompanied by a significant mtDNA depletion, and a corresponding decrease in the levels of mitochondrial transcription factor A (mtTFA). Biochemical analysis showed an oxidative phosphorylation (OXPHOS) defect in transgenic flies, which were more susceptible to oxidative stress. Although we did not detect apoptosis in the nervous system of adult transgenic flies, brains of larvae over‐expressing pol γ‐α showed evidence of increased cell death that correlates with the observed phenotypes. Our data establish an animal model that mimics some of the features of human mtDNA depletion syndromes.