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author:("shimojo, Mika")
1.  Microglial Activation and Antioxidant Responses Induced by the Parkinson’s Disease Protein α-Synuclein 
Parkinson’s disease (PD) is the second most common age-related neurodegenerative disorder typified by tremor, rigidity, akinesia and postural instability due in part to the loss of dopamine within the nigrostriatal system. The pathologic features of this disorder include the loss of substantia nigra dopamine neurons and attendant striatal terminals, the presence of large protein-rich neuronal inclusions containing fibrillar α-synuclein and increased numbers of activated microglia. Evidence suggests that both misfolded α-synuclein and oxidative stress play an important role in the pathogenesis of sporadic PD. Here we review evidence that α-synuclein activates glia inducing inflammation and that Nrf2-directed phase-II antioxidant enzymes play an important role in PD. We also provide new evidence that the expression of antioxidant enzymes regulated in part by Nrf2 is increased in a mouse model of α-synuclein overexpression. We show that misfolded α-synuclein directly activates microglia inducing the production and release of the proinflammatory cytokine, TNF-α, and increasing antioxidant enzyme expression. Importantly, we demonstrate that the precise structure of α-synuclein is important for induction of this proinflammatory pathway. This complex α-synuclein-directed glial response highlights the importance of protein misfolding, oxidative stress and inflammation in PD and represents a potential locus for the development of novel therapeutics focused on induction of the Nrf2-directed antioxidant pathway and inhibition of protein misfolding.
doi:10.1007/s11481-012-9401-0
PMCID: PMC3582877  PMID: 23054368
Synucleinopathy; Microglia; Toll like receptors; Innate immunity; Nrf2; Antioxidant enzymes
2.  An Intrinsically Disordered Region of the Acetyltransferase p300 with Similarity to Prion-Like Domains Plays a Role in Aggregation 
PLoS ONE  2012;7(11):e48243.
Several human diseases including neurodegenerative disorders and cancer are associated with abnormal accumulation and aggregation of misfolded proteins. Proteins with high tendency to aggregate include the p53 gene product, TAU and alpha synuclein. The potential toxicity of aberrantly folded proteins is limited via their transport into intracellular sub-compartments, the aggresomes, where misfolded proteins are stored or cleared via autophagy. We have identified a region of the acetyltransferase p300 that is highly disordered and displays similarities with prion-like domains. We show that this region is encoded as an alternative spliced variant independently of the acetyltransferase domain, and provides an interaction interface for various misfolded proteins, promoting their aggregation. p300 enhances aggregation of TAU and of p53 and is a component of cellular aggregates in both tissue culture cells and in alpha-synuclein positive Lewy bodies of patients affected by Parkinson disease. Down-regulation of p300 impairs aggresome formation and enhances cytotoxicity induced by misfolded protein stress. These data unravel a novel activity of p300, offer new insights into the function of disordered domains and implicate p300 in pathological aggregation that occurs in neurodegeneration and cancer.
doi:10.1371/journal.pone.0048243
PMCID: PMC3486812  PMID: 23133622
3.  Microglial Activation and Antioxidant Responses Induced by the Parkinson’s Disease Protein α-Synuclein 
Parkinson’s disease (PD) is the second most common age-related neurodegenerative disorder typified by tremor, rigidity, akinesia and postural instability due in part to the loss of dopamine within the nigrostriatal system. The pathologic features of this disorder include the loss of substantia nigra dopamine neurons and attendant striatal terminals, the presence of large protein-rich neuronal inclusions containing fibrillar α-synuclein and increased numbers of activated microglia. Evidence suggests that both misfolded α-synuclein and oxidative stress play an important role in the pathogenesis of sporadic PD. Here we review evidence that α-synuclein activates glia inducing inflammation and that Nrf2-directed phase-II antioxidant enzymes play an important role in PD. We also provide new evidence that the expression of antioxidant enzymes regulated in part by Nrf2 is increased in a mouse model of α-synuclein overexpression. We show that misfolded α-synuclein directly activates microglia inducing the production and release of the proinflammatory cytokine, TNF-α, and increasing antioxidant enzyme expression. Importantly, we demonstrate that the precise structure of α-synuclein is important for induction of this proinflammatory pathway. This complex α-synuclein-directed glial response highlights the importance of protein misfolding, oxidative stress and inflammation in PD and represents a potential locus for the development of novel therapeutics focused on induction of the Nrf2-directed antioxidant pathway and inhibition of protein misfolding.
doi:10.1007/s11481-012-9401-0
PMCID: PMC3582877  PMID: 23054368
Synucleinopathy; Microglia; Toll like receptors; Innate immunity; Nrf2; Antioxidant enzymes
4.  Therapeutic versus neuroinflammatory effects of passive immunization is dependent on Aβ/amyloid burden in a transgenic mouse model of Alzheimer's disease 
Background
Passive immunization with antibodies directed to Aβ decreases brain Aβ/amyloid burden and preserves memory in transgenic mouse models of Alzheimer's disease (AD). This therapeutic strategy is under intense scrutiny in clinical studies, but its application is limited by neuroinflammatory side effects (autoimmune encephalitis and vasogenic edema).
Methods
We intravenously administered the monoclonal Aβ protofibril antibody PFA1 to aged (22 month) male and female 3 × tg AD mice with intermediate or advanced AD-like neuropathologies, respectively, and measured brain and serum Aβ and CNS cytokine levels. We also examined 17 month old 3 × tg AD female mice with intermediate pathology to determine the effect of amyloid burden on responses to passive immunization.
Results
The 22 month old male mice immunized with PFA1 had decreased brain Aβ, increased serum Aβ, and no change in CNS cytokine levels. In contrast, 22 month old immunized female mice revealed no change in brain Aβ, decreased serum Aβ, and increased CNS cytokine levels. Identical experiments in younger (17 month old) female 3 × tg AD mice with intermediate AD-like neuropathologies revealed a trend towards decreased brain Aβ and increased serum Aβ accompanied by a decrease in CNS MCP-1.
Conclusions
These data suggest that passive immunization with PFA1 in 3 × tg AD mice with intermediate disease burden, regardless of sex, is effective in mediating potentially therapeutic effects such as lowering brain Aβ. In contrast, passive immunization of mice with a more advanced amyloid burden may result in potentially adverse effects (encephalitis and vasogenic edema) mediated by certain proinflammatory cytokines.
doi:10.1186/1742-2094-7-57
PMCID: PMC2955708  PMID: 20920207
5.  Progressive Behavioral Deficits in DJ-1 Deficient Mice are Associated with Normal Nigrostriatal Function 
Neurobiology of disease  2007;29(3):505-514.
Loss-of-function mutations in the DJ-1 gene account for an autosomal recessive form of Parkinson’s disease (PD). To investigate the physiological functions of DJ-1 in vivo, we generated DJ-1 knockout (DJ-1-/-) mice. Younger (< 1year) DJ-1 -/- mice were hypoactive and had mild gait abnormalities. Older DJ-1-/-, however, showed decreased bodyweight and grip strength, and more severe gait irregularities compared to wild-type littermates. The basal level of extracellular dopamine, evoked dopamine release and dopamine receptor D2 sensitivity appeared normal in the striatum of DJ-1-/- mice, which was consistent with similar results between DJ-1-/- and controls in behavioral paradigms specific for the dopaminergic system. An examination of spinal cord, nerve and muscle tissues failed to identify any pathological changes that were consistent with the noted motor deficits. Taken together, our findings suggest that loss of DJ-1 leads to progressive behavioral changes without significant alterations in nigrostriatal dopaminergic and spinal motor systems.
doi:10.1016/j.nbd.2007.11.011
PMCID: PMC2271119  PMID: 18187333
DJ-1; knockout mouse; Parkinson’s disease; dopamine; striatum; spinal cord; muscle; motor behavior
6.  Amyotrophic Lateral Sclerosis 2-Deficiency Leads to Neuronal Degeneration in Amyotrophic Lateral Sclerosis through Altered AMPA Receptor Trafficking 
Amyotrophic lateral sclerosis (ALS), the most common adult-onset motor neuron disease is caused by a selective loss of motor neurons. One form of juvenile onset autosomal recessive ALS (ALS2) has been linked to the loss of function of the ALS2 gene. The pathogenic mechanism of ALS2-deficiency, however, remains unclear. To further understand the function of alsin that is encoded by the full-length ALS2 gene, we screened proteins interacting with alsin. Here, we report that alsin interacted with glutamate receptor interacting protein 1 (GRIP1) both in vitro and in vivo, and colocalized with GRIP1 in neurons. In support of the physiological interaction between alsin and GRIP1, the subcellular distribution of GRIP1 was altered in ALS2-/- spinal motor neurons, which correlates with a significant reduction of AMPA-type glutamate receptor subunit 2 (GluR2) at the synaptic/cell surface of ALS2-/- neurons. The decrease of calcium-impermeable GluR2-containing AMPA receptors at the cell/synaptic surface rendered ALS2-/- neurons more susceptible to glutamate receptor-mediated neurotoxicity. Our findings reveal a novel function of alsin in AMPA receptor trafficking and provide a novel pathogenic link between ALS2-deficiency and motor neuron degeneration, suggesting a protective role of alsin in maintaining the survival of motor neurons.
doi:10.1523/JNEUROSCI.2084-06.2006
PMCID: PMC2556290  PMID: 17093100
ALS2; knock-out mouse; motor neuron; GRIP1; AMPA receptor; excitotoxicity
7.  Influence of Duration of Focal Cerebral Ischemia and Neuronal Nitric Oxide Synthase on Translocation of Apoptosis-Inducing Factor to the Nucleus 
Neuroscience  2006;144(1):56-65.
Translocation of apoptosis-inducing factor (AIF) from the mitochondria to the nucleus can play a major role in neuronal death elicited by oxidant stress. The time course of nuclear translocation of AIF after experimental stroke may vary with the severity of injury and may be accelerated by oxidant stress associated with reperfusion and nitric oxide (NO) production. Western immunoblots of AIF on nuclear fractions of ischemic hemisphere of male mice showed no significant increase with 1 hour of middle cerebral artery occlusion and no reperfusion, whereas increases were detectable after 6 and 24 hours of permanent ischemia. However, as little as 20 minutes of reperfusion after 1 hour of middle cerebral artery occlusion resulted in an increase in nuclear AIF coincident with an increase in poly(ADP-ribose) polymer (PAR) formation. Further nuclear AIF accumulation was seen at 6 and 24 hours of reperfusion. In contrast, 20 minutes of reperfusion after 2 hours of occlusion did not increase nuclear AIF. In this case, nuclear AIF became detectable at 6 and 24 hours of reperfusion. With brief occlusion of 30 minute duration, nuclear AIF remained undetectable at both 20 minutes and 6 hours and became evident only after 24 hours of reperfusion. Inhibition of neuronal NO synthase attenuated formation of PAR and nuclear AIF accumulation. Gene deletion of neuronal NO synthase also attenuated nuclear AIF accumulation. Therefore, reperfusion accelerates AIF translocation to the nucleus when focal ischemia is of moderate duration (1 hour), but is markedly delayed after brief ischemia (30 minutes). Nuclear translocation of AIF eventually occurs with prolonged focal ischemia with or without reperfusion. Neuronally-derived NO is a major factor contributing to nuclear AIF accumulation after stroke.
doi:10.1016/j.neuroscience.2006.08.065
PMCID: PMC1876769  PMID: 17049179
apoptosis; middle cerebral artery; mouse; poly(ADP-ribose); reperfusion; stroke

Results 1-7 (7)