Expression of alternative oxidase in Drosophila ameliorates diverse phenotypes due to cytochrome oxidase deficiency

Kemppainen, K. K. et al. (2013) Expression of alternative oxidase in Drosophila ameliorates diverse phenotypes due to cytochrome oxidase deficiency. Human Molecular Genetics, 23(8), pp. 2078-2093. (doi: 10.1093/hmg/ddt601) (PMID:24293544) (PMCID:PMC3959817)

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Mitochondrial dysfunction is a significant factor in human disease, ranging from systemic disorders of childhood to cardiomyopathy, ischaemia and neurodegeneration. Cytochrome oxidase, the terminal enzyme of the mitochondrial respiratory chain, is a frequent target. Lower eukaryotes possess alternative respiratory-chain enzymes that provide non-proton-translocating bypasses for respiratory complexes I (single-subunit reduced nicotinamide adenine dinucleotide dehydrogenases, e.g. Ndi1 from yeast) or III + IV [alternative oxidase (AOX)], under conditions of respiratory stress or overload. In previous studies, it was shown that transfer of yeast Ndi1 or Ciona intestinalis AOX to Drosophila was able to overcome the lethality produced by toxins or partial knockdown of complex I or IV. Here, we show that AOX can provide a complete or substantial rescue of a range of phenotypes induced by global or tissue-specific knockdown of different cIV subunits, including integral subunits required for catalysis, as well as peripheral subunits required for multimerization and assembly. AOX was also able to overcome the pupal lethality produced by muscle-specific knockdown of subunit CoVb, although the rescued flies were short lived and had a motility defect. cIV knockdown in neurons was not lethal during development but produced a rapidly progressing locomotor and seizure-sensitivity phenotype, which was substantially alleviated by AOX. Expression of Ndi1 exacerbated the neuronal phenotype produced by cIV knockdown. Ndi1 expressed in place of essential cI subunits produced a distinct residual phenotype of delayed development, bang sensitivity and male sterility. These findings confirm the potential utility of alternative respiratory chain enzymes as tools to combat mitochondrial disease, while indicating important limitations thereof.

Item Type:Articles
Additional Information:This work was supported by funding from the Academy of Finland Tampere University Hospital Medical Research Fund; the Sigrid Juselius Foundation and European Research Council (advanced grant 232738 to H.T.J., starting grant 260632 to A.S.). P.R. received support from AMMi (Association contre les Maladies Mitochondriales), from Action Rémy and ANR projects MitOxy and AifInter. Funding to pay the Open Access publication charges for this article was provided by University of Tampere.
Glasgow Author(s) Enlighten ID:Sanz Montero, Professor Alberto
Authors: Kemppainen, K. K., Rinne, J., Sriram, A., Lakanmaa, M., Zeb, A., Tuomela, T., Popplestone, A., Singh, S., Sanz, A., Rustin, P., and Jacobs, H. T.
College/School:College of Medical Veterinary and Life Sciences > Institute of Molecular Cell and Systems Biology
Journal Name:Human Molecular Genetics
Publisher:Oxford University Press
ISSN (Online):1460-2083

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