• Bulletin of the Korean Chemical Society
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• v.26 no.8
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• pp.1255-1259
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• 2005

Lewy bodies (LBs) are neuronal inclusions that are closely related to Parkinson's disease (PD). The filamentous component of LB from patients with PD contains biochemically altered $\alpha$-synuclein. We have investigated the effect of the oxidized products of catecholamines on the modification of $\alpha$-synuclein. When $\alpha$-synuclein was incubated with the oxidized 3,4-dihydroxyphenylalanine (L-DOPA) or dopamine, the protein was induced to be aggregated. The oxidized catecholamine-mediated $\alpha$-synuclein aggregation was enhanced by copper ion. Radical scavengers, azide and N-acetyl cysteine significantly prevented the oxidized catecholamine-mediated $\alpha$-synuclein aggregation. The results suggest that free radical may play a role in $\alpha$-synuclein aggregation. Exposure of $\alpha$-synuclein to the oxidized products of catecholamines led to the formation of dityrosine. Antioxidant dipeptides carnosine, homocarnosine and anserine significantly protected $\alpha$-synuclein from the aggregation induced by the oxidized products of catecholamines.

• Archives of Pharmacal Research
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• v.27 no.8
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• pp.850-856
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• 2004

Intraneuronal deposition containing $\alpha$-synuclein is implicated in the pathogenesis of synuclein-opathies including Parkinsons disease (PD). Although it has been demonstrated that cytoplas-mic inclusions of wild type $\alpha$-synuclein are observed in the brain of PD patients and that $\alpha$-synuclein mutations such as A30P and A53T accelerate aggregate formation, the exact mech-anism by which $\alpha$-synuclein forms insoluble aggregates is still controversial. In the present study, to understand the possible involvement of tissue transglutaminase (tTG) in aggregate formation of $\alpha$-synuclein, SH-SY5Y cell lines stably expressing wild type or mutant (A30P or A53T) $\alpha$-synuclein were created and aggregate formation of $\alpha$-synuclein was observed upon activation of tTG. The data demonstrated that $\alpha$-synuclein negligibly interacted with tTG and that activation of tTG did not result in the aggregate formation of $\alpha$-synuclein in SH-SY5Y cells overexpressing either wild type or mutant $\alpha$-synuclein. In addition, $\alpha$-synuclein was not modi-fied by activated tTG in situ. These data suggest that tTG is unlikely to be a contributing factor to the formation of aggregates of $\alpha$-synuclein in a stable cell model.

• Fisheries and Aquatic Sciences
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• v.25 no.3
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• pp.117-139
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• 2022

Synucleinopathies such as Parkinson's disease (PD) are incurable neurodegenerative conditions characterised by the abnormal aggregation of α-synuclein protein in neuronal cells. In PD, fibrillary synuclein aggregation forms Lewy bodies and Lewy neurites in the substantia nigra and cortex on the brain. Dementia with Lewy bodies and multiple system atrophy are also associated with α-synuclein protein abnormalities. α-synuclein is one of three synuclein proteins, and while its precise function is still unknown, one hypothesis posits that α-synuclein propagates from the enteric nervous system through the vagus nerve and into the brain, resulting in synucleinopathy. Studies on synucleinopathies should thus encompass not only the central nervous system but must necessarily include the gut and microbiome. The zebrafish (Danio rerio) is a well-established model for human neuronal pathologies and have been used in studies ranging from genetic models of hereditary disorders to neurotoxin-induced neurodegeneration as well as gut-brain-axis studies. There is significant genetic homology between zebrafish and mammalian vertebrates which is what makes the zebrafish so amenable to modelling human conditions but in the case of synucleinopathies, the zebrafish notably does not possess an α-synuclein homolog. Synuclein orthologs are present in the zebrafish however, and transgenic zebrafish that carry human α-synuclein have been generated. In addition, the zebrafish is a highly advantageous model and ideal replacement for reducing the use of mammalian models. This review discusses the application of the zebrafish as a model for synucleinopathies in efforts to further understand synuclein function and explore therapeutic strategies.

• Bulletin of the Korean Chemical Society
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• v.33 no.9
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• pp.3071-3075
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• 2012

Human ${\alpha}$-synuclein is the major component of the protein aggregates known as Lewy bodies or Lewy neurites, which define the intracellular lesions of Parkinson's disease. Despite extensive efforts, the physiological function of ${\alpha}$-synuclein has not yet been elucidated in detail. As an approach to defining its function, proteins that interacted with ${\alpha}$-synuclein were screened in phage display assays. The SNARE protein vesicle t-SNARE-interacting protein homologous 1B (VTI1B) was identified as an interacting partner. A selective interaction between ${\alpha}$-synuclein and VTI1B was confirmed by coimmunoprecipitation and GST pull-down assays. VTI1B and ${\alpha}$-synuclein were colocalized in N2a neuronal cells, and overexpression of ${\alpha}$-synuclein changed the subcellular localization of VTI1B to be more dispersed throughout the cytosol. Considering the role played by VTI1B, ${\alpha}$-synuclein is likely to modulate vesicle trafficking by interacting with a SNARE complex.

• Laboraroty Animal Research
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• v.33 no.3
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• pp.244-250
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• 2017

${\alpha}$-Synuclein is abundantly expressed in neuronal tissue, plays an essential role in the pathogenesis of neurodegenerative disorders, and exerts a neuroprotective effect against oxidative stress. Cerebral ischemia causes severe neurological disorders and neuronal dysfunction. In this study, we examined ${\alpha}$-synuclein expression in middle cerebral artery occlusion (MCAO)-induced cerebral ischemic injury and neuronal cells damaged by glutamate treatment. MCAO surgical operation was performed on male Sprague-Dawley rats, and brain samples were isolated 24 hours after MCAO. We confirmed neurological behavior deficit, infarction area, and histopathological changes following MCAO injury. A proteomic approach and Western blot analysis demonstrated a decrease in ${\alpha}$-synuclein in the cerebral cortices after MCAO injury. Moreover, glutamate treatment induced neuronal cell death and decreased ${\alpha}$-synuclein expression in a hippocampal-derived cell line in a dose-dependent manner. It is known that ${\alpha}$-synuclein regulates neuronal survival, and low levels of ${\alpha}$-synuclein expression result in cytotoxicity. Thus, these results suggest that cerebral ischemic injury leads to a reduction in ${\alpha}$-synuclein and consequently causes serious brain damage.

• BMB Reports
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• v.56 no.2
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• pp.126-131
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• 2023

The abnormal accumulation and aggregation of the misfolded α-synuclein protein is the neuropathological hallmark of all α-synucleinopathies, including Parkinson's disease. The secreted proteins known as netrins (netrin-1, netrin-3, and netrin-4) are related to laminin and have a role in the molecular pathway for axon guidance and cell survival. Interestingly, only netrin-1 is significantly expressed in the substantia nigra (SN) of healthy adult brains and its expression inversely correlates with that of α-synuclein, which prompted us to look into the role of α-synuclein and netrin-1 molecular interaction in the future of dopaminergic neurons. Here, we showed that netrin-1 and α-synuclein directly interacted in pre-formed fibrils (PFFs) generation test, real time binding assay, and co-immunoprecipitation with neurotoxin treated cell lysates. Netrin-1 deficiency appeared to activate the dopaminergic neuronal cell death signal pathway via α-synuclein aggregation and hyperphosphorylation of α-synuclein S129. Taken together, netrin-1 can be a promising therapeutic molecule in Parkinson's disease.

• Biomolecules & Therapeutics
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• v.29 no.1
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• pp.83-89
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• 2021

Multiple system atrophy (MSA) is a neurodegenerative disease characterized by presence of α-synuclein-positive inclusions in the cytoplasm of oligodendrocytes. These glial cytoplasmic inclusions (GCIs) are considered an integral part of the pathogenesis of MSA, leading to demyelination and neuronal demise. What is most puzzling in the research fields of GCIs is the origin of α-synuclein aggregates in GCIs, since adult oligodendrocytes do not express high levels of α-synuclein. The most recent leading hypothesis is that GCIs form via transfer and accumulation of α-synuclein from neurons to oligodendrocytes. However, studies regarding this subject are limited due to the absence of proper human cell models, to demonstrate the entry and accumulation of neuronal α-synuclein in human oligodendrocytes. Here, we generated mature human oligodendrocytes that can take up neuronderived α-synuclein and form GCI-like inclusions. Mature human oligodendrocytes are derived from neural stem cells via "oligosphere" formation and then into oligodendrocytes, treating the cells with the proper differentiation factors at each step. In the final cell preparations, oligodendrocytes consist of the majority population, while some astrocytes and unidentified stem cell-like cells were present as well. When these cells were exposed to α-synuclein proteins secreted from neuron-like human neuroblastoma cells, oligodendrocytes developed perinuclear inclusion bodies with α-synuclein immunoreactivity, resembling GCIs, while the stem cell-like cells showed α-synuclein-positive, scattered puncta in the cytoplasm. In conclusion, we have established a human oligodendrocyte model for the study of GCI formation, and the characterization and use of this model might pave the way for understanding the pathogenesis of MSA.

• Animal cells and systems
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• v.10 no.3
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• pp.115-120
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• 2006

Parkinson's disease (PD) is a neurodegenerative disease caused by selective degeneration of dopaminergic neurons in the substantia nigra. Mutations in ${\alpha}$-synuclein have been causally linked to the pathogenesis of hereditary PD. In addition, it is a major component of Lewy body found in the brains of sporadic cases as well. In the present study, we examined whether overexpression of wild type or PD-related mutant ${\alpha}$-synuclein induces unfolded protein response (UPR) and triggers the known signaling pathway of the resulting endoplasmic reticulum (ER) stress in SH-SY5Y cells. Overexpression of wild type, A30P, and A53T ${\alpha}$-synuclein all induced XBP-1 mRNA splicing, one of the late stage UPR events. However, activation of ER membrane kinases and upregulation of ER or cytoplsmic chaperones were not detected when ${\alpha}$-synuclein was overexpressed. However, basal level of cytoplsmic calcium was elevated in ${\alpha}$-synuclein-expressing cells. Our observation suggests that overexpression of ${\alpha}$-synuclein induces UPR independent of the known ER membrane kinase-mediated signaling pathway and induces ER stress by disturbing calcium homeostasis.

• Laboraroty Animal Research
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• v.34 no.4
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• pp.195-202
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• 2018

Hyperglycemia is one of the major risk factors for stroke. Hyperglycemia can lead to a more extensive infarct volume, aggravate neuronal damage after cerebral ischemia. ${\alpha}$-Synuclein is especially abundant in neuronal tissue, where it underlies the etiopathology of several neurodegenerative diseases. This study investigated whether hyperglycemic conditions regulate the expression of ${\alpha}$-synuclein in middle cerebral artery occlusion (MCAO)-induced cerebral ischemic injury. Male Sprague-Dawley rats were treated with streptozotocin (40 mg/kg) via intraperitoneal injection to induce hyperglycemic conditions. MCAO were performed four weeks after streptozotocin injection to induce focal cerebral ischemia, and cerebral cortex tissues were obtained 24 hours after MCAO. We confirmed that MCAO induced neurological functional deficits and cerebral infarction, and these changes were more extensive in diabetic animals compared to non-diabetic animals. Moreover, we identified a decrease in ${\alpha}$-synuclein after MCAO injury. Diabetic animals showed a more serious decrease in ${\alpha}$-synuclein than non-diabetic animals. Western blot and reverse-transcription PCR analyses confirmed more extensive decreases in ${\alpha}$-synuclein expression in MCAO-injured animals with diabetic condition than these of non-diabetic animals. It is accepted that ${\alpha}$-synuclein modulates neuronal cell death and exerts a neuroprotective effect. Thus, the results of this study suggest that hyperglycemic conditions cause more serious brain damage in ischemic brain injuries by decreasing ${\alpha}$-synuclein expression.

• Biomolecules & Therapeutics
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• v.21 no.3
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• pp.222-228
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• 2013

Although the role of ${\alpha}$-synuclein aggregation on Parkinson's disease is relatively well known, the physiological role and the regulatory mechanism governing the expression of ${\alpha}$-synuclein are unclear yet. We recently reported that ${\alpha}$-synuclein is expressed and secreted from cultured astrocytes. In this study, we investigated the effect of valproic acid (VPA), which has been suggested to provide neuroprotection by increasing ${\alpha}$-synuclein in neuron, on ${\alpha}$-synuclein expression in rat primary astrocytes. VPA concentration-dependently increased the protein expression level of ${\alpha}$-synuclein in cultured rat primary astrocytes with concomitant increase in mRNA expression level. Likewise, the level of secreted ${\alpha}$-synuclein was also increased by VPA. VPA increased the phosphorylation of Erk1/2 and JNK and pretreatment of a JNK inhibitor SP600125 prevented the VPA-induced increase in ${\alpha}$-synuclein. Whether the increased ${\alpha}$-synuclein in astrocytes is involved in the reported neuroprotective effects of VPA awaits further investigation.