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Loss of PINK1 causes mitochondrial functional defects and increased sensitivity to oxidative stress.

ABSTRACT: Parkinson's disease (PD) is a common neurodegenerative disorder thought to be associated with mitochondrial dysfunction. Loss of function mutations in the putative mitochondrial protein PINK1 (PTEN-induced kinase 1) have been linked to familial forms of PD, but the relation of PINK1 to mammalian mitochondrial function remains unclear. Here, we report that germline deletion of the PINK1 gene in mice significantly impairs mitochondrial functions. Quantitative electron microscopic studies of the striatum in PINK1(-/-) mice at 3-4 and 24 months revealed no gross changes in the ultrastructure or the total number of mitochondria, although the number of larger mitochondria is selectively increased. Functional assays showed impaired mitochondrial respiration in the striatum but not in the cerebral cortex at 3-4 months of age, suggesting specificity of this defect for dopaminergic circuitry. Aconitase activity associated with the Krebs cycle is also reduced in the striatum of PINK1(-/-) mice. Interestingly, mitochondrial respiration activities in the cerebral cortex are decreased in PINK1(-/-) mice at 2 years compared with control mice, indicating that aging can exacerbate mitochondrial dysfunction in these mice. Furthermore, mitochondrial respiration defects can be induced in the cerebral cortex of PINK1(-/-) mice by cellular stress, such as exposure to H(2)O(2) or mild heat shock. Together, our findings demonstrate that mammalian PINK1 is important for mitochondrial function and provides critical protection against both intrinsic and environmental stress, suggesting a pathogenic mechanism by which loss of PINK1 may lead to nigrostriatal degeneration in PD.

SUBMITTER: Gautier CA

PROVIDER: S-EPMC2516271 | biostudies-literature | 2008 Aug

REPOSITORIES: biostudies-literature

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Loss of PINK1 causes mitochondrial functional defects and increased sensitivity to oxidative stress.

Gautier Clement A CA Kitada Tohru T Shen Jie J

Proceedings of the National Academy of Sciences of the United States of America 20080807 32

Parkinson's disease (PD) is a common neurodegenerative disorder thought to be associated with mitochondrial dysfunction. Loss of function mutations in the putative mitochondrial protein PINK1 (PTEN-induced kinase 1) have been linked to familial forms of PD, but the relation of PINK1 to mammalian mitochondrial function remains unclear. Here, we report that germline deletion of the PINK1 gene in mice significantly impairs mitochondrial functions. Quantitative electron microscopic studies of the st ...[more]

PMID: 18687901

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Project description:PTEN-induced kinase 1 (PINK1) is linked to recessive Parkinsonism (EOPD). Pink1 deletion results in impaired dopamine (DA) release and decreased mitochondrial respiration in the striatum of mice. To reveal additional mechanisms of Pink1-related dopaminergic dysfunction, we studied Ca²+ vulnerability of purified brain mitochondria, DA levels and metabolism and whether signaling pathways implicated in Parkinson's disease (PD) display altered activity in the nigrostriatal system of Pink1?/? mice.Purified brain mitochondria of Pink1?/? mice showed impaired Ca²+ storage capacity, resulting in increased Ca²+ induced mitochondrial permeability transition (mPT) that was rescued by cyclosporine A. A subpopulation of neurons in the substantia nigra of Pink1?/? mice accumulated phospho-c-Jun, showing that Jun N-terminal kinase (JNK) activity is increased. Pink1?/? mice 6 months and older displayed reduced DA levels associated with increased DA turnover. Moreover, Pink1?/? mice had increased levels of IL-1?, IL-12 and IL-10 in the striatum after peripheral challenge with lipopolysaccharide (LPS), and Pink1?/? embryonic fibroblasts showed decreased basal and inflammatory cytokine-induced nuclear factor kappa-? (NF-?B) activity. Quantitative transcriptional profiling in the striatum revealed that Pink1?/? mice differentially express genes that (i) are upregulated in animals with experimentally induced dopaminergic lesions, (ii) regulate innate immune responses and/or apoptosis and (iii) promote axonal regeneration and sprouting.Increased mitochondrial Ca²+ sensitivity and JNK activity are early defects in Pink1?/? mice that precede reduced DA levels and abnormal DA homeostasis and may contribute to neuronal dysfunction in familial PD. Differential gene expression in the nigrostriatal system of Pink1?/? mice supports early dopaminergic dysfunction and shows that Pink1 deletion causes aberrant expression of genes that regulate innate immune responses. While some differentially expressed genes may mitigate neurodegeneration, increased LPS-induced brain cytokine expression and impaired cytokine-induced NF-?B activation may predispose neurons of Pink1?/? mice to inflammation and injury-induced cell death.

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Loss of PINK1 causes mitochondrial functional defects and increased sensitivity to oxidative stress.

Publications

Loss of PINK1 causes mitochondrial functional defects and increased sensitivity to oxidative stress.

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