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Giguère N, Pacelli C, Saumure C, Bourque MJ, Matheoud D, Levesque D, Slack RS, Park DS, Trudeau LÉ. Comparative analysis of Parkinson's disease-associated genes in mice reveals altered survival and bioenergetics of Parkin-deficient dopamine neurons. J Biol Chem 2018; 293:9580-9593. [PMID: 29700116 DOI: 10.1074/jbc.ra117.000499] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 04/23/2018] [Indexed: 11/06/2022] Open
Abstract
Many mutations in genes encoding proteins such as Parkin, PTEN-induced putative kinase 1 (PINK1), protein deglycase DJ-1 (DJ-1 or PARK7), leucine-rich repeat kinase 2 (LRRK2), and α-synuclein have been linked to familial forms of Parkinson's disease (PD). The consequences of these mutations, such as altered mitochondrial function and pathological protein aggregation, are starting to be better understood. However, little is known about the mechanisms explaining why alterations in such diverse cellular processes lead to the selective loss of dopamine (DA) neurons in the substantia nigra (SNc) in the brain of individuals with PD. Recent work has shown that one of the reasons for the high vulnerability of SNc DA neurons is their high basal rate of mitochondrial oxidative phosphorylation (OXPHOS), resulting from their highly complex axonal arborization. Here, we examined whether axonal growth and basal mitochondrial function are altered in SNc DA neurons from Parkin-, Pink1-, or DJ-1-KO mice. We provide evidence for increased basal OXPHOS in Parkin-KO DA neurons and for reduced survival of DA neurons that have a complex axonal arbor. The surviving smaller neurons exhibited reduced vulnerability to the DA neurotoxin and mitochondrial complex I inhibitor MPP+, and this reduction was associated with reduced expression of the DA transporter. Finally, we found that glial cells play a role in the reduced resilience of DA neurons in these mice and that WT Parkin overexpression rescues this phenotype. Our results provide critical insights into the complex relationship between mitochondrial function, axonal growth, and genetic risk factors for PD.
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Affiliation(s)
- Nicolas Giguère
- From the Departments of Pharmacology and Physiology and.,Neurosciences
| | - Consiglia Pacelli
- the Department of Clinical and Experimental Medicine, University of Foggia, Foggia 71122, Italy
| | - Caroline Saumure
- From the Departments of Pharmacology and Physiology and.,Neurosciences
| | | | - Diana Matheoud
- Neurosciences.,the Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Québec, Montreal H2X 0A9, Canada
| | - Daniel Levesque
- the Faculty of Pharmacy, Université de Montréal, Québec, Montreal H4T 1J4, Canada.,the Faculty of Pharmacy, Université de Montréal, Québec, Montreal H4T 1J4, Canada
| | - Ruth S Slack
- the Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario K1M 8M5, Canada
| | - David S Park
- the Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario K1M 8M5, Canada
| | - Louis-Éric Trudeau
- From the Departments of Pharmacology and Physiology and .,Neurosciences.,the Faculty of Pharmacy, Université de Montréal, Québec, Montreal H4T 1J4, Canada.,Central Nervous System Research Group (GRSNC), Faculty of Medicine, Université de Montréal, Québec, Montreal H4T 1J4, Canada
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Benskey MJ, Sellnow RC, Sandoval IM, Sortwell CE, Lipton JW, Manfredsson FP. Silencing Alpha Synuclein in Mature Nigral Neurons Results in Rapid Neuroinflammation and Subsequent Toxicity. Front Mol Neurosci 2018; 11:36. [PMID: 29497361 PMCID: PMC5819572 DOI: 10.3389/fnmol.2018.00036] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 01/26/2018] [Indexed: 12/19/2022] Open
Abstract
Human studies and preclinical models of Parkinson’s disease implicate the involvement of both the innate and adaptive immune systems in disease progression. Further, pro-inflammatory markers are highly enriched near neurons containing pathological forms of alpha synuclein (α-syn), and α-syn overexpression recapitulates neuroinflammatory changes in models of Parkinson’s disease. These data suggest that α-syn may initiate a pathological inflammatory response, however the mechanism by which α-syn initiates neuroinflammation is poorly understood. Silencing endogenous α-syn results in a similar pattern of nigral degeneration observed following α-syn overexpression. Here we aimed to test the hypothesis that loss of α-syn function within nigrostriatal neurons results in neuronal dysfunction, which subsequently stimulates neuroinflammation. Adeno-associated virus (AAV) expressing an short hairpin RNA (shRNA) targeting endogenous α-syn was unilaterally injected into the substantia nigra pars compacta (SNc) of adult rats, after which nigrostriatal pathology and indices of neuroinflammation were examined at 7, 10, 14 and 21 days post-surgery. Removing endogenous α-syn from nigrostriatal neurons resulted in a rapid up-regulation of the major histocompatibility complex class 1 (MHC-1) within transduced nigral neurons. Nigral MHC-1 expression occurred prior to any overt cell death and coincided with the recruitment of reactive microglia and T-cells to affected neurons. Following the induction of neuroinflammation, α-syn knockdown resulted in a 50% loss of nigrostriatal neurons in the SNc and a corresponding loss of nigrostriatal terminals and dopamine (DA) concentrations within the striatum. Expression of a control shRNA did not elicit any pathological changes. Silencing α-syn within glutamatergic neurons of the cerebellum did not elicit inflammation or cell death, suggesting that toxicity initiated by α-syn silencing is specific to DA neurons. These data provide evidence that loss of α-syn function within nigrostriatal neurons initiates a neuronal-mediated neuroinflammatory cascade, involving both the innate and adaptive immune systems, which ultimately results in the death of affected neurons.
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Affiliation(s)
- Matthew J Benskey
- Department of Translational Science and Molecular Medicine, College of Human Medicine, Michigan State University, Grand Rapids, MI, United States
| | - Rhyomi C Sellnow
- Department of Translational Science and Molecular Medicine, College of Human Medicine, Michigan State University, Grand Rapids, MI, United States
| | - Ivette M Sandoval
- Department of Translational Science and Molecular Medicine, College of Human Medicine, Michigan State University, Grand Rapids, MI, United States.,Mercy Health Saint Mary's, Grand Rapids, MI, United States
| | - Caryl E Sortwell
- Department of Translational Science and Molecular Medicine, College of Human Medicine, Michigan State University, Grand Rapids, MI, United States.,Mercy Health Saint Mary's, Grand Rapids, MI, United States
| | - Jack W Lipton
- Department of Translational Science and Molecular Medicine, College of Human Medicine, Michigan State University, Grand Rapids, MI, United States.,Mercy Health Saint Mary's, Grand Rapids, MI, United States
| | - Fredric P Manfredsson
- Department of Translational Science and Molecular Medicine, College of Human Medicine, Michigan State University, Grand Rapids, MI, United States.,Mercy Health Saint Mary's, Grand Rapids, MI, United States
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Patterson JR, Kim EJ, Goudreau JL, Lookingland KJ. FosB and ΔFosB expression in brain regions containing differentially susceptible dopamine neurons following acute neurotoxicant exposure. Brain Res 2016; 1649:53-66. [PMID: 27566062 DOI: 10.1016/j.brainres.2016.08.030] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 08/20/2016] [Accepted: 08/22/2016] [Indexed: 11/29/2022]
Abstract
Parkinson disease (PD) is characterized by progressive neuronal degeneration, in particular nigrostriatal dopamine (NSDA) neurons and consequent deficits in movement. In mice and non-human primates, NSDA neurons preferentially degenerate following exposure to the neurotoxicant 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Tuberoinfundibular (TI) DA neurons, in contrast, appear to be unaffected in PD and recover following acute MPTP exposure-induced injury (Behrouz et al., 2007; Benskey et al., 2012). The recovery of the TIDA neurons is dependent on de novo protein synthesis and positively correlated with an increase in parkin mRNA and protein expression (Benskey et al., 2012, 2015). Inhibition of parkin upregulation renders TIDA neurons susceptible to degeneration following MPTP exposure. In addition to parkin, other potentially protective proteins are likely to be differentially regulated in TIDA and NSDA neurons following neurotoxicant exposure. The regulation of potential transcription factors for parkin and other neuroprotective pathway genes are of interest since they may provide novel targets for PD disease modifying therapies. As such, we sought to determine if there are time-dependent differences in the expression of AP-1 transcription factors c-Fos, c-Jun, FosB, ΔFosB and JunD in TIDA and NSDA neurons of mice following acute MPTP exposure. We observed that both FosB and ΔFosB expression increase in brain regions containing TIDA, but not NSDA neurons. Furthermore, the nuclear and long-term expression of ΔFosB is consistent with its role as a transcription factor that may influence parkin transcription, which may underlie the unique ability of TIDA neurons to recovery from an injury that leads NSDA neurons to degeneration.
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Affiliation(s)
| | - Elizabeth J Kim
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, USA
| | - John L Goudreau
- Genetics Program, Michigan State University, East Lansing, MI, USA; Department of Neurology and Ophthalmology, Michigan State University, East Lansing, MI, USA; Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, USA; Neuroscience Program, Michigan State University, East Lansing, MI, USA; College of Osteopathic Medicine, Michigan State University, East Lansing, MI, USA
| | - Keith J Lookingland
- Genetics Program, Michigan State University, East Lansing, MI, USA; Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, USA; Neuroscience Program, Michigan State University, East Lansing, MI, USA; College of Osteopathic Medicine, Michigan State University, East Lansing, MI, USA.
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Parkin represses 6-hydroxydopamine-induced apoptosis via stabilizing scaffold protein p62 in PC12 cells. Acta Pharmacol Sin 2015; 36:1300-7. [PMID: 26364802 DOI: 10.1038/aps.2015.54] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 05/15/2015] [Indexed: 12/25/2022] Open
Abstract
AIM Parkin has been shown to exert protective effects against 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in different models of Parkinson disease. In the present study we investigated the molecular mechanisms underlying the neuroprotective action of parkin in vitro. METHODS HEK293, HeLa and PC12 cells were transfected with parkin, parkin mutants, p62 or si-p62. Protein expression and ubiquitination were assessed using immunoblot analysis. Immunoprecipitation assay was performed to identify the interaction between parkin and scaffold protein p62. PC12 and SH-SY5Y cells were treated with 6-OHDA (200 μmol/L), and cell apoptosis was detected using PI and Hoechst staining. RESULTS In HEK293 cells co-transfected with parkin and p62, parkin was co-immunoprecipitated with p62, and parkin overexpression increased p62 protein levels. In parkin-deficient HeLa cells, transfection with wild-type pakin, but not with ligase activity-deficient pakin mutants, significantly increased p62 levels, suggesting that parkin stabilized p62 through its E3 ligase activity. Transfection with parkin or p62 significantly repressed ERK1/2 phosphorylation in HeLa cells, but transfection with parkin did not repress ERK1/2 phosphorylation in p62-knockdown HeLa cells, suggesting that p62 was involved in parkin-induced inhibition on ERK1/2 phosphorylation. Overexpression of parkin or p62 significantly repressed 6-OHDA-induced ERK1/2 phosphorylation in PC12 cells, and parkin overexpression inhibited 6-OHDA-induced apoptosis in PC12 and SH-SY5Y cells. CONCLUSION Parkin protects PC12 cells against 6-OHDA-induced apoptosis via ubiquitinating and stabilizing scaffold protein p62, and repressing ERK1/2 activation.
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