Nrf2-mediated neuroprotection in the MPTP mouse model of Parkinson's disease : Critical role for the astrocyte
24 Feb 2009-Proceedings of the National Academy of Sciences of the United States of America (National Academy of Sciences)-Vol. 106, Iss: 8, pp 2933-2938
TL;DR: Stark results indicate that Nrf2 expression restricted to astrocytes is sufficient to protect against MPTP andAstrocytic modulation of the NRF2-ARE pathway is a promising target for therapeutics aimed at reducing or preventing neuronal death in PD.
Abstract: Oxidative stress has been implicated in the etiology of Parkinson's disease (PD) and in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) animal model of PD. It is known that under conditions of oxidative stress, the transcription factor NF-E2-related factor (Nrf2) binds to antioxidant response element (ARE) to induce antioxidant and phase II detoxification enzymes. To investigate the role of Nrf2 in the process of MPTP-induced toxicity, mice expressing the human placental alkaline phosphatase (hPAP) gene driven by a promoter containing a core ARE sequence (ARE-hPAP) were used. ARE-hPAP mice were injected (30 mg/kg) once per day for 5 days and killed 7 days after the last MPTP injection. In response to this design, ARE-dependent gene expression was decreased in striatum whereas it was increased in substantia nigra. The same MPTP protocol was applied in Nrf2(+/+) and Nrf2(-/-) mice; Nrf2 deficiency increases MPTP sensitivity. Furthermore, we evaluated the potential for astrocytic Nrf2 overexpression to protect from MPTP toxicity. Transgenic mice with Nrf2 under control of the astrocyte-specific promoter for the glial fribillary acidic protein (GFAP-Nrf2) on both a Nrf2(+/+) and Nrf2(-/-) background were administered MPTP. In the latter case, only the astrocytes expressed Nrf2. Independent of background, MPTP-mediated toxicity was abolished in GFAP-Nrf2 mice. These striking results indicate that Nrf2 expression restricted to astrocytes is sufficient to protect against MPTP and astrocytic modulation of the Nrf2-ARE pathway is a promising target for therapeutics aimed at reducing or preventing neuronal death in PD.
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TL;DR: Astrocyte functions in healthy CNS, mechanisms and functions of reactive astrogliosis and glial scar formation, and ways in which reactive astrocytes may cause or contribute to specific CNS disorders and lesions are reviewed.
Abstract: Astrocytes are specialized glial cells that outnumber neurons by over fivefold. They contiguously tile the entire central nervous system (CNS) and exert many essential complex functions in the healthy CNS. Astrocytes respond to all forms of CNS insults through a process referred to as reactive astrogliosis, which has become a pathological hallmark of CNS structural lesions. Substantial progress has been made recently in determining functions and mechanisms of reactive astrogliosis and in identifying roles of astrocytes in CNS disorders and pathologies. A vast molecular arsenal at the disposal of reactive astrocytes is being defined. Transgenic mouse models are dissecting specific aspects of reactive astrocytosis and glial scar formation in vivo. Astrocyte involvement in specific clinicopathological entities is being defined. It is now clear that reactive astrogliosis is not a simple all-or-none phenomenon but is a finely gradated continuum of changes that occur in context-dependent manners regulated by specific signaling events. These changes range from reversible alterations in gene expression and cell hypertrophy with preservation of cellular domains and tissue structure, to long-lasting scar formation with rearrangement of tissue structure. Increasing evidence points towards the potential of reactive astrogliosis to play either primary or contributing roles in CNS disorders via loss of normal astrocyte functions or gain of abnormal effects. This article reviews (1) astrocyte functions in healthy CNS, (2) mechanisms and functions of reactive astrogliosis and glial scar formation, and (3) ways in which reactive astrocytes may cause or contribute to specific CNS disorders and lesions.
4,075 citations
Cites background from "Nrf2-mediated neuroprotection in th..."
...On the other hand, activation of the transcription factor Nrf2 selectively in astrocytes protects mice from MPTP-induced Parkinsonism by activating anti-oxidative response pathways [40]....
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TL;DR: The authors' data provide clues as to how neurons and astrocytes differ in their ability to dynamically regulate glycolytic flux and lactate generation attributable to unique splicing of PKM2, the gene encoding the glycoleytic enzyme pyruvate kinase.
Abstract: The major cell classes of the brain differ in their developmental processes, metabolism, signaling, and function To better understand the functions and interactions of the cell types that comprise these classes, we acutely purified representative populations of neurons, astrocytes, oligodendrocyte precursor cells, newly formed oligodendrocytes, myelinating oligodendrocytes, microglia, endothelial cells, and pericytes from mouse cerebral cortex We generated a transcriptome database for these eight cell types by RNA sequencing and used a sensitive algorithm to detect alternative splicing events in each cell type Bioinformatic analyses identified thousands of new cell type-enriched genes and splicing isoforms that will provide novel markers for cell identification, tools for genetic manipulation, and insights into the biology of the brain For example, our data provide clues as to how neurons and astrocytes differ in their ability to dynamically regulate glycolytic flux and lactate generation attributable to unique splicing of PKM2, the gene encoding the glycolytic enzyme pyruvate kinase This dataset will provide a powerful new resource for understanding the development and function of the brain To ensure the widespread distribution of these datasets, we have created a user-friendly website (http://webstanfordedu/group/barres_lab/brain_rnaseqhtml) that provides a platform for analyzing and comparing transciption and alternative splicing profiles for various cell classes in the brain
3,891 citations
Cites background from "Nrf2-mediated neuroprotection in th..."
...…spectrum disorders, epilepsy, Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, amyotrophic lateral sclerosis, and stroke (Matute et al., 2005; Tian et al., 2005; Nagai et al., 2007; Chen et al., 2009; Li et al., 2011; Lioy et al., 2011; Molofsky et al., 2012; Zamanian et al., 2012)....
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...Accumulating evidence has demonstrated that glia are involved in a variety of neurological diseases, including schizophrenia, autism spectrum disorders, epilepsy, Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, amyotrophic lateral sclerosis, and stroke (Matute et al., 2005; Tian et al., 2005; Nagai et al., 2007; Chen et al., 2009; Li et al., 2011; Lioy et al., 2011; Molofsky et al., 2012; Zamanian et al., 2012)....
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TL;DR: The nuclear factor erythroid 2-related factor 2 (Nrf2) is an emerging regulator of cellular resistance to oxidants that controls the basal and induced expression of an array of antioxidant response element-dependent genes to regulate the physiological and pathophysiological outcomes of oxidant exposure.
Abstract: Organismal life encounters reactive oxidants from internal metabolism and environmental toxicant exposure. Reactive oxygen and nitrogen species cause oxidative stress and are traditionally viewed as being harmful. On the other hand, controlled production of oxidants in normal cells serves useful purposes to regulate signaling pathways. Reactive oxidants are counterbalanced by complex antioxidant defense systems regulated by a web of pathways to ensure that the response to oxidants is adequate for the body's needs. A recurrent theme in oxidant signaling and antioxidant defense is reactive cysteine thiol–based redox signaling. The nuclear factor erythroid 2–related factor 2 (Nrf2) is an emerging regulator of cellular resistance to oxidants. Nrf2 controls the basal and induced expression of an array of antioxidant response element–dependent genes to regulate the physiological and pathophysiological outcomes of oxidant exposure. This review discusses the impact of Nrf2 on oxidative stress and toxicity and how...
2,987 citations
Cites background from "Nrf2-mediated neuroprotection in th..."
...Nrf2 KO mice were significantly more sensitive to MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine)induced PD-like lesions in mice, which are alleviated by overexpression of Nrf2 in astrocytes (170)....
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TL;DR: The switching on and off of Nrf2 protects cells against free radical damage, prevents apoptosis, and promotes cell survival, and is a mechanism of critical importance for cellular protection and cell survival.
1,336 citations
TL;DR: The ability of dimethylfumarate to activate nuclear factor (erythroid-derived 2)-related factor 2 may offer a novel cytoprotective modality that further augments the natural antioxidant responses in multiple sclerosis tissue and is not yet targeted by other multiple sclerosis therapies.
Abstract: Inflammation and oxidative stress are thought to promote tissue damage in multiple sclerosis. Thus, novel therapeutics enhancing cellular resistance to free radicals could prove useful for multiple sclerosis treatment. BG00012 is an oral formulation of dimethylfumarate. In a phase II multiple sclerosis trial, BG00012 demonstrated beneficial effects on relapse rate and magnetic resonance imaging markers indicative of inflammation as well as axonal destruction. First we have studied effects of dimethylfumarate on the disease course, central nervous system, tissue integrity and the molecular mechanism of action in an animal model of chronic multiple sclerosis: myelin oligodendrocyte glycoprotein induced experimental autoimmune encephalomyelitis in C57BL/6 mice. In the chronic phase of experimental autoimmune encephalomyelitis, preventive or therapeutic application of dimethylfumarate ameliorated the disease course and improved preservation of myelin, axons and neurons. In vitro, the application of fumarates increased murine neuronal survival and protected human or rodent astrocytes against oxidative stress. Application of dimethylfumarate led to stabilization of the transcription factor nuclear factor (erythroid-derived 2)-related factor 2, activation of nuclear factor (erythroid-derived 2)-related factor 2-dependent transcriptional activity and accumulation of NADP(H) quinoline oxidoreductase-1 as a prototypical target gene. Furthermore, the immediate metabolite of dimethylfumarate, monomethylfumarate, leads to direct modification of the inhibitor of nuclear factor (erythroid-derived 2)-related factor 2, Kelch-like ECH-associated protein 1, at cysteine residue 151. In turn, increased levels of nuclear factor (erythroid-derived 2)-related factor 2 and reduced protein nitrosylation were detected in the central nervous sytem of dimethylfumarate-treated mice. Nuclear factor (erythroid-derived 2)-related factor 2 was also upregulated in the spinal cord of autopsy specimens from untreated patients with multiple sclerosis. In dimethylfumarate-treated mice suffering from experimental autoimmune encephalomyelitis, increased immunoreactivity for nuclear factor (erythroid-derived 2)-related factor 2 was detected by confocal microscopy in neurons of the motor cortex and the brainstem as well as in oligodendrocytes and astrocytes. In mice deficient for nuclear factor (erythroid-derived 2)-related factor 2 on the same genetic background, the dimethylfumarate mediated beneficial effects on clinical course, axon preservation and astrocyte activation were almost completely abolished thus proving the functional relevance of this transcription factor for the neuroprotective mechanism of action. We conclude that the ability of dimethylfumarate to activate nuclear factor (erythroid-derived 2)-related factor 2 may offer a novel cytoprotective modality that further augments the natural antioxidant responses in multiple sclerosis tissue and is not yet targeted by other multiple sclerosis therapies.
936 citations
Cites background from "Nrf2-mediated neuroprotection in th..."
...…and analyses of neurodegenerative models for motoneuron disorders and Parkinson’s disease or cerebral ischaemia disclosed that Nrf2-mediated neuroprotection may not only be directly mediated, but critically involves effects via astrocytes (Kraft et al., 2004; Shih et al., 2005b; Chen et al., 2009)....
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...Ex vivo studies and analyses of neurodegenerative models for motoneuron disorders and Parkinson’s disease or cerebral ischaemia disclosed that Nrf2-mediated neuroprotection may not only be directly mediated, but critically involves effects via astrocytes (Kraft et al., 2004; Shih et al., 2005b; Chen et al., 2009)....
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References
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4,872 citations
TL;DR: The detected large numbers of HLA-DR-positive reactive microglia (macrophages) in the substantia nigra of all cases studied with Parkinson's disease and parkinsonism and suggest a frequent coexistence of DAT- and Parkinson-type pathology in elderly patients.
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2,526 citations
TL;DR: Strategies aimed at restoring complex I activity, reducing oxidative stress and α-synuclein aggregation, and enhancing protein degradation may hold particular promise as powerful neuroprotective agents in the treatment of PD.
Abstract: Parkinson's disease (PD) is a complex disorder with many different causes, yet they may intersect in common pathways, raising the possibility that neuroprotective agents may have broad applicability in the treatment of PD. Current evidence suggests that mitochondrial complex I inhibition may be the central cause of sporadic PD and that derangements in complex I cause α-synuclein aggregation, which contributes to the demise of dopamine neurons. Accumulation and aggregation of α-synuclein may further contribute to the death of dopamine neurons through impairments in protein handling and detoxification. Dysfunction of parkin (a ubiquitin E3 ligase) and DJ-1 could contribute to these deficits. Strategies aimed at restoring complex I activity, reducing oxidative stress and α-synuclein aggregation, and enhancing protein degradation may hold particular promise as powerful neuroprotective agents in the treatment of PD.
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"Nrf2-mediated neuroprotection in th..." refers methods in this paper
...-Galactosidase was excised from hGFAP- gal sequence by using NotI and replaced with mNrf2 (NotI–NotI fragment) from pEF-Nrf2 [received from Jawed Alam, Alton Ochsner Medical Foundation, New Orleans, LA (5)]....
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TL;DR: The results may indicate that an increased level of lipid peroxidation continues to occur in the parkinsonian nigra up to the time of death, perhaps because of continued exposure to excess free radicals derived from some endogenous or exogenous neurotoxic species.
Abstract: Polyunsaturated fatty acid (PUFA) levels (an index of the amount of substrate available for lipid peroxidation) were measured in several brain regions from patients who died with Parkinson's disease and age-matched control human postmortem brains. PUFA levels were reduced in parkinsonian substantia nigra compared to other brain regions and to control tissue. However, basal malondialdehyde (MDA; an intermediate in the lipid peroxidation process) levels were increased in parkinsonian nigra compared with other parkinsonian brain regions and control tissue. Expressing basal MDA levels in terms of PUFA content, the difference between parkinsonian and control substantia nigra was even more pronounced. Stimulating MDA production by incubating tissue with FeSO4 plus ascorbic acid, FeSO4 plus H2O2, or air alone produced lower MDA levels in the parkinsonian substantia nigra, probably reflecting the lower PUFA content. These results may indicate that an increased level of lipid peroxidation continues to occur in the parkinsonian nigra up to the time of death, perhaps because of continued exposure to excess free radicals derived from some endogenous or exogenous neurotoxic species.
1,373 citations
TL;DR: Quantitative analysis of neuromelanin-pigmented neurons in control and parkinsonian midbrains demonstrates that the dopamine-containing cell groups of the normal human midbrain differ markedly from each other in the percentage of neurmelan in-pIGmented neurons they contain, and suggests a selective vulnerability of the neuromelsin- pigmented subpopulation of dopamine- containing mesencephalic neurons in Parkinson's disease.
Abstract: In idiopathic Parkinson's disease massive cell death occurs in the dopamine-containing substantia nigra1,24. A link between the vulnerability of nigral neurons and the prominent pigmentation of the substantia nigra, though long suspected, has not been proved2. This possibility is supported by evidence that N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and its metabolite MPP+, the latter of which causes destruction of nigral neurons, bind to neuromelanin3,4. We have directly tested this hypothesis by a quantitative analysis of neuromelanin-pigmented neurons in control and parkinsonian midbrains. The findings demonstrate first that the dopamine-containing cell groups of the normal human midbrain differ markedly from each other in the percentage of neuromelanin-pigmented neurons they contain. Second, the estimated cell loss in these cell groups in Parkinson's disease is directly correlated (r = 0.97, P = 0.0057) with the percentage of neuromelanin-pigmented neurons normally present in them. Third, within each cell group in the Parkinson's brains, there is greater relative sparing of non-pigmented than of neuromelanin-pigmented neurons. This evidence suggests a selective vulnerability of the neuromelanin-pigmented subpopulation of dopamine-containing mesencephalic neurons in Parkinson's disease.
1,233 citations
"Nrf2-mediated neuroprotection in th..." refers background in this paper
...Dopaminergic neuron loss results in reduced striatal dopamine (DA) and the hallmark clinical features of PD (3)....
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