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. 2013 Jan;20(1):77-85.
doi: 10.1038/cdd.2012.95. Epub 2012 Aug 3.

Optic atrophy 1 mediates mitochondria remodeling and dopaminergic neurodegeneration linked to complex I deficiency

D Ramonet  1 , C Perier, A Recasens, B Dehay, J Bové, V Costa, L Scorrano, M Vila
Affiliations

Optic atrophy 1 mediates mitochondria remodeling and dopaminergic neurodegeneration linked to complex I deficiency

D Ramonet et al. Cell Death Differ. 2013 Jan.

Abstract

Mitochondrial complex I dysfunction has long been associated with Parkinson's disease (PD). Recent evidence suggests that mitochondrial involvement in PD may extend beyond a sole respiratory deficit and also include perturbations in mitochondrial fusion/fission or ultrastructure. Whether and how alterations in mitochondrial dynamics may relate to the known complex I defects in PD is unclear. Optic atrophy 1 (OPA1), a dynamin-related GTPase of the inner mitochondrial membrane, participates in mitochondrial fusion and apoptotic mitochondrial cristae remodeling. Here we show that complex I inhibition by parkinsonian neurotoxins leads to an oxidative-dependent disruption of OPA1 oligomeric complexes that normally keep mitochondrial cristae junctions tight. As a consequence, affected mitochondria exhibit major structural abnormalities, including cristae disintegration, loss of matrix density and swelling. These changes are not accompanied by mitochondrial fission but a mobilization of cytochrome c from cristae to intermembrane space, thereby lowering the threshold for activation of mitochondria-dependent apoptosis by cell death agonists in compromised neurons. All these pathogenic changes, including mitochondrial structural remodeling and dopaminergic neurodegeneration, are abrogated by OPA1 overexpression, both in vitro and in vivo. Our results identify OPA1 as molecular link between complex I deficiency and alterations in mitochondrial dynamics machinery and point to OPA1 as a novel therapeutic target for complex I cytopathies, such as PD.

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Figures

Figure 1
Figure 1
OPA1-dependent mitochondrial ultrastructural abnormalities, but not fission, following complex I inhibition. (a) Representative transmission electron microscopy images of the mitochondria in control and OPA1-overexpressing SH-SY5Y neuroblastoma cells treated with saline or MPP+. The percentage of normal (class I) and remodeled (class II) mitochondria was determined by analyzing a total of 293 mitochondria uniformly selected at random among the different genotype/treatment groups. (b) Representative images of mito-DsRed2-labeled mitochondria in control and OPA1-overexpressing SH-SY5Y neuroblastoma cells treated with saline or MPP+. Mitochondrial length was measured by morphometry and categorized as elongated (>3 μm), intermediate (0.5–3 μm) or fragmented (<0.5 μm). A total of 1433 mito-DsRed2-labeled mitochondria were analyzed uniformly selected at random among the different genotype/treatment groups. MPP+, 5 mM for 24 h. Scale bars, 0.2 μm in (a), 10 μm in (b)
Figure 2
Figure 2
Oxidative-mediated OPA1 desoligomerization following complex I inhibition. (a) Isolated nonsynaptosomal mouse brain mitochondria treated with different doses of MPP+ or osmotically swollen for 15 min were incubated with 1 mM (EDC) for 30 min followed by centrifugation. Proteins in the pellet were separated by SDS-PAGE and immunoblotted using anti-OPA1 antibodies. The asterisk indicates OPA1 oligomer; arrowheads indicate non-oligomeric OPA1. Histograms represent average quantification of OPA1 oligomers±S.E.M. from at least three independent experiments. (b) Isolated nonsynaptosomal mouse brain mitochondria were treated, processed and quantified as in a, in the presence or absence of tempol (500 μM for 15 min). In (a and b), *P<0.05, compared with untreated mitochondria; in b, #P<0.05, compared with MPP+-treated, tempol-free mitochondria
Figure 3
Figure 3
OPA1-dependent mobilization of cytochrome c following complex I inhibition. (a) Mitochondrial ascorbate/TMPD-driven respiration ratio in isolated nonsynaptosomal mouse brain mitochondria treated with MPP+ (500 μM for 5 min) preincubated with either recombinant OPA1 or reticulocyte lysate without OPA1 (control) for 25 min. (b and c) Isolated nonsynaptosomal mouse brain mitochondria were treated with a combination of MPP+ (100 μM) and recombinant Bax (100 nM) for 15 min, in the presence of either recombinant OPA1 or reticulocyte lysate without OPA1 (control). After centrifugation, the amount of cytochrome c in supernatant (b) and pellet (c) was determined by immunoblot. Histograms represent average±S.E.M. from at least three independent experiments. *P<0.05, compared with untreated mitochondria; #P<0.05, compared with MPP+-treated control mitochondria
Figure 4
Figure 4
OPA1 overexpression attenuates cytochrome c release and cell death linked to complex I inhibition. (a) Representative images of cytochrome c subcellular distribution (in green; red corresponds to mito-DsRed2-labeled mitochondria) in control (empty vector) and OPA1-overexpressing SH-SY5Y neuroblastoma cells treated with saline or MPP+. (b) Pearson's colocalization coefficients (Rp) between cytochrome c and mito-DsRed2-labeled mitochondria in the different experimental groups. At least three representative fields containing an average of 45 cells/field were analyzed per group. (c) Cell death determined by flow cytometry after propidium iodide staining in control (empty vector) and OPA1-overexpressing SH-SY5Y cells treated with saline or MPP+. Histograms represent average±S.E.M. from at least three independent experiments. MPP+, 5 mM for 24 h; *P<0.05, compared with untreated cells; #P<0.05, compared with MPP+-treated control (empty vector) cells. Scale bar, 10 μm
Figure 5
Figure 5
OPA1 overexpression attenuates dopaminergic nigrostriatal denervation in MPTP-intoxicated mice. (a) OPA1 immunoblot levels (L-OPA1, ∼100 kDa; S-OPA1, ∼80 kDa) by SDS-PAGE in ventral midbrain samples from mice treated with either saline or MPTP (30 mg/kg per day for 5 consecutive days) and killed 24 h (1 day) after the last saline or MPTP injection. (b) Schematic representation of the experimental design used for AAV-OPA1 injections in MPTP-treated mice (top). OPA1 immunoblot levels in mouse ventral midbrain samples ipsilateral and contralateral to AAV-OPA1 injections (bottom). (c) Representative photomicrographs of TH-immunostained SNpc (brown; thionin in purple) and striatum (Str, inset) from saline- and MPTP-treated mice, overexpressing GFP or OPA1, at day 21 post MPTP (top). Stereological cell counts of SNpc TH-immunoreactive neurons (left) and optical densitometry of striatal TH immunoreactivity (right) in the different experimental groups of animals at day 21 post MPTP (bottom). Histograms represent average±S.E.M. (n=5–8 animals per group); *P<0.05 compared with saline-injected mice; #P<0.05 compared with MPTP-treated GFP-expressing mice; Scale bar, 500 mM
Figure 6
Figure 6
Schematic representation of the proposed mechanism of OPA1-dependent mobilization of cytochrome c linked to complex I inhibition (see text for details). CI, complex I; Cyt. c, cytochrome c
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References

    1. Dauer W, Przedborski S. Parkinson's disease: mechanisms and models. Neuron. 2003;39:889–909. - PubMed
    1. Vila M, Jackson-Lewis V, Vukosavic S, Djaldetti R, Liberatore G, Offen D, et al. Bax ablation prevents dopaminergic neurodegeneration in the 1-methyl- 4-phenyl-1,2,3,6-tetrahydropyridine mouse model of Parkinson's disease. Proc Natl Acad Sci USA. 2001;98:2837–2842. - PMC - PubMed
    1. Vila M, Przedborski S. Targeting programmed cell death in neurodegenerative diseases. Nat Rev Neurosci. 2003;4:365–375. - PubMed
    1. Perier C, Tieu K, Guegan C, Caspersen C, Jackson-Lewis V, Carelli V, et al. Complex I deficiency primes Bax-dependent neuronal apoptosis through mitochondrial oxidative damage. Proc Natl Acad Sci USA. 2005;102:19126–19131. - PMC - PubMed
    1. Perier C, Bove J, Wu DC, Dehay B, Choi DK, Jackson-Lewis V, et al. Two molecular pathways initiate mitochondria-dependent dopaminergic neurodegeneration in experimental Parkinson's disease. Proc Natl Acad Sci USA. 2007;104:8161–8166. - PMC - PubMed

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