• Biomolecules & Therapeutics
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• 제31권3호
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• pp.285-297
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• 2023

Alzheimer's disease (AD) is a neurodegenerative disease with progressive memory loss and the cognitive decline. AD is mainly caused by abnormal accumulation of misfolded amyloid β (Aβ), which leads to neurodegeneration via a number of possible mechanisms such as down-regulation of brain-derived neurotrophic factor-tropomyosin-related kinase B (BDNF-TRKB) signaling pathway. 7,8-Dihydroxyflavone (7,8-DHF), a TRKB agonist, has demonstrated potential to enhance BDNF-TRKB pathway in various neurodegenerative diseases. To expand the capacity of flavones as TRKB agonists, two natural flavones quercetin and apigenin, were evaluated. With tryptophan fluorescence quenching assay, we illustrated the direct interaction between quercetin/apigenin and TRKB extracellular domain. Employing Aβ folding reporter SH-SY5Y cells, we showed that quercetin and apigenin reduced Aβ-aggregation, oxidative stress, caspase-1 and acetylcholinesterase activities, as well as improved the neurite outgrowth. Treatments with quercetin and apigenin increased TRKB Tyr516 and Tyr817 and downstream cAMP-response-element binding protein (CREB) Ser133 to activate transcription of BDNF and BCL2 apoptosis regulator (BCL2), as well as reduced the expression of pro-apoptotic BCL2 associated X protein (BAX). Knockdown of TRKB counteracted the improvement of neurite outgrowth by quercetin and apigenin. Our results demonstrate that quercetin and apigenin are to work likely as a direct agonist on TRKB for their neuroprotective action, strengthening the therapeutic potential of quercetin and apigenin in treating AD.

• BMB Reports
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• 제56권3호
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• pp.202-207
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• 2023

We investigated the neuroprotective effects of deca nano-graphene oxide (daNGO) against reactive oxygen species (ROS) and inflammation in the human neuroblastoma cell line SH-SY5Y and in the 6-hydroxydopamine (6-OHDA) induced Parkinsonian rat model. An MTT assay was performed to measure cell viability in vitro in the presence of 6-OHDA and/or daNGO. The intracellular ROS level was quantified using 2',7'-dichlorofluorescein diacetate. daNGO showed neuroprotective effects against 6-OHDA-induced toxicity and also displayed ROS scavenging properties. We then tested the protective effects of daNGO against 6-OHDA induced toxicity in a rat model. Stepping tests showed that the akinesia symptoms were improved in the daNGO group compared to the control group. Moreover, in an apomorphine-induced rotation test, the number of net contralateral rotations was decreased in the daNGO group compared to the control group. By immunofluorescent staining, the animals in the daNGO group had more tyrosine hydroxylase-positive cells than the controls. By anti-Iba1 staining, 6-OHDA induced microglial activation showed a significantly decrease in the daNGO group, indicating that the neuroprotective effects of graphene resulted from anti-inflammation. In conclusion, nano-graphene oxide has neuroprotective effects against the neurotoxin induced by 6-OHDA on dopaminergic neurons.

• Nutrition Research and Practice
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• 제14권5호
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• pp.438-452
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• 2020

BACKGROUND/OBJECTIVES: Brain senescence causes cognitive impairment and neurodegeneration. It has also been demonstrated that curcumin (Cur) and hesperetin (Hes), both antioxidant polyphenolic compounds, mediate anti-aging and neuroprotective effects. Therefore, the objective of this study was to investigate whether Cur, Hes, and/or their combination exert anti-aging effects in D-galactose (Dg)-induced aged neuronal cells and rats. MATERIALS/METHODS: SH-SY5Y cells differentiated in response to retinoic acid were treated with Cur (1 μM), Hes (1 μM), or a combination of both, followed by 300 mM Dg. Neuronal loss was subsequently evaluated by measuring average neurite length and analyzing expression of β-tubulin III, phosphorylated extracellular signal-regulated kinases, and neurofilament heavy polypeptide. Cellular senescence and related proteins, p16 and p21, were also investigated, including their regulation of antioxidant enzymes. In vivo, brain aging was induced by injecting 250 mg/kg body weight (b.w.) Dg. The effects of supplementing this model with 50 mg/kg b.w. Cur, 50 mg/kg b.w. Hes, or a combination of both for 3 months were subsequently evaluated. Brain aging was examined with a step-through passive avoidance test and apoptosis markers were analyzed in brain cortex tissues. RESULTS: Cur, Hes, and their combination improved neuron length and cellular senescence by decreasing the number of β-gal stained cells, down-regulated expression of p16 and p21, and up-regulated expression of antioxidant enzymes, including superoxide dismutase 1, glutathione peroxidase 1, and catalase. Administration of Cur, Hes, or their combination also tended to ameliorate cognitive impairment and suppress apoptosis in the cerebral cortex by down-regulating Bax and poly (ADP-ribose) polymerase expression and increasing Bcl-2 expression. CONCLUSIONS: Cur and Hes appear to attenuate Dg-induced brain aging via regulation of antioxidant enzymes and apoptosis. These results suggest that Cur and Hes may mediate neuroprotective effects in the aging process, and further study of these antioxidant polyphenolic compounds is warranted.

• Journal of Microbiology and Biotechnology
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• 제27권11호
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• pp.2044-2051
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• 2017

The main pathological hallmark of Alzheimer's disease is the deposition of amyloid-beta ($A{\beta}$) peptides in the brain. $A{\beta}$ has been widely used to mimic several aspects of Alzheimer's disease. However, several characteristics of amyloid-induced Alzheimer's disease pathology are not well established, especially in mice. The present study aimed to develop a new Alzheimer's disease model by investigating how $A{\beta}$ can be effectively aggregated using prokaryotes and eukaryotes. To express the $A{\beta}42$ complex in HEK293 cells, we cloned the $A{\beta}42$ region in a tandem repeat and incorporated the resulting construct into a eukaryotic expression vector. Following transfection into HEK293 cells via lipofection, cell viability assay and western blotting analysis revealed that exogenous $A{\beta}42$ can induce cell death and apoptosis. In addition, recombinant His-tagged $A{\beta}42$ was successfully expressed in Escherichia coli BL21 (DE3) and not only readily formed $A{\beta}$ complexes, but also inhibited the proliferation of SH-SY5Y cells and E. coli. For in vivo testing, recombinant His-tagged $A{\beta}42$ solution ($3{\mu}g/{\mu}l$ in $1{\times}PBS$ containing $1mM\;Ni^{2+}$) was injected stereotaxically into the left and right lateral ventricles of the brains of C57BL/6J mice (n = 8). Control mice were injected with $1{\times}PBS$ containing $1mM\;Ni^{2+}$ following the same procedure. Ten days after the sample injection, the Morris water maze test confirmed that exogenous $A{\beta}$ caused an increase in memory loss. These findings demonstrated that $Ni^{2+}$ is capable of complexing the 50-kDa amyloid and that intracerebroventricular injection of $A{\beta}42$ can lead to cognitive impairment, thereby providing improved Alzheimer's disease models.

• 한국축산식품학회지
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• 제33권2호
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• pp.258-267
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• 2013

각 돈피추출물의 수율과 단백질함량은 고분자 PS 처리구에서 높은 함량을 나타내었으며, 특히 단백질 함량은 저분자 LPS 처리구에 비해 유의적으로 높았고, 약 10배 정도의 높은 단백질 함량을 나타내었다(p<0.05). 항산화활성 측정결과 처리 농도가 증가할수록 높은 항산화 활성을 나타내었으며(p<0.05), 특히 고분자 PS 처리구에 비해 저분자 LPS 처리구에서 유의적으로 높은 효과를 나타내었다. ORAC 활성은 LPS 농도 1 mg/mL일 때, $141.39{\mu}M$ TE/g의 높은 활성을 나타내었다. 각 돈피추출물을 신경모세포종 SH-SY5Y 세포에 고농도로 처리한 결과 세포에 독성을 나타내지 않았다. 신경세포에 과산화수소를 처리하여 유발시킨 산화적 스트레스에 대한 PS와 LPS의 신경세포 보호효과를 확인한 결과, 모든 처리구에서 농도 의존적으로 세포 보호효과를 나타내었다. 특히 저분자인 LPS 처리구 농도 $100{\mu}g/mL$일 때, 86.45%의 세포생존율을 보였으며 $H_2O_2$ 대비 29.98%의 신경세포보호효과를 나타내었다. 독성 단백질인 $A{\beta}_{1-42}$를 처리하여 신경세포 보호효과를 확인한 결과, 고분자 PS 처리구보다는 저분자인 LPS 처리구 농도 $100{\mu}g/mL$일 때, 82.01%의 생존율을 보였으며 $A{\beta}_{1-42}$ 대비 14.38%의 신경세포보호효과를 나타내었다(p<0.05). AChE 저해효과를 확인해 본 결과, 고분자 PS 처리구에서는 거의 효과가 나타나지 않았으나, 저분자인 LPS 처리구에서는 농도 의존적으로 증가하는 경향을 나타내었으며, 농도 100 mg/mL일 때 33.62%의 높은 저해 효과를 나타내었다. 따라서 본 연구결과 돈피에서 분리한 3 kDa 이하의 저분자 효소분해물인 LPS는 높은 항산화 활성을 나타내었고, $H_2O_2$와 $A{\beta}_{1-42}$로 유발시킨 산화스트레스에 대한 신경세포 보호효과 및 AChE 저해 효과를 나타내어 향후 항산화 활성 및 신경세포보호를 위한 축산식품 소재로 이용 가능성이 있을 것으로 판단된다.

• Molecules and Cells
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• 제42권6호
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• pp.480-494
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• 2019

Aggregates of disease-causing proteins dysregulate cellular functions, thereby causing neuronal cell loss in diverse neurodegenerative diseases. Although many in vitro or in vivo studies of protein aggregate inhibitors have been performed, a therapeutic strategy to control aggregate toxicity has not been earnestly pursued, partly due to the limitations of available aggregate models. In this study, we established a tetracycline (Tet)-inducible nuclear aggregate (${\beta}23$) expression model to screen potential lead compounds inhibiting ${\beta}23$-induced toxicity. High-throughput screening identified several natural compounds as nuclear ${\beta}23$ inhibitors, including peucedanocoumarin III (PCIII). Interestingly, PCIII accelerates disaggregation and proteasomal clearance of both nuclear and cytosolic ${\beta}23$ aggregates and protects SH-SY5Y cells from toxicity induced by ${\beta}23$ expression. Of translational relevance, PCIII disassembled fibrils and enhanced clearance of cytosolic and nuclear protein aggregates in cellular models of huntingtin and ${\alpha}$-synuclein aggregation. Moreover, cellular toxicity was diminished with PCIII treatment for polyglutamine (PolyQ)-huntingtin expression and ${\alpha}$-synuclein expression in conjunction with 6-hydroxydopamine (6-OHDA) treatment. Importantly, PCIII not only inhibited ${\alpha}$-synuclein aggregation but also disaggregated preformed ${\alpha}$-synuclein fibrils in vitro. Taken together, our results suggest that a Tet-Off ${\beta}23$ cell model could serve as a robust platform for screening effective lead compounds inhibiting nuclear or cytosolic protein aggregates. Brain-permeable PCIII or its derivatives could be beneficial for eliminating established protein aggregates.

• The Korean Journal of Physiology and Pharmacology
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• 제21권6호
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• pp.625-632
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• 2017

Familial Parkinson's disease (PD) has been linked to point mutations and duplication of the ${\alpha}$-synuclein (${\alpha}$-syn) gene. Mutant ${\alpha}$-syn expression increases the vulnerability of neurons to exogenous insults. In this study, we developed a new PD model in the transgenic mice expressing mutant hemizygous (hemi) or homozygous (homo) A53T ${\alpha}$-synuclein (${\alpha}$-syn Tg) and their wildtype (WT) littermates by treatment with sub-toxic (10 mg/kg, i.p., daily for 5 days) or toxic (30 mg/kg, i.p., daily for 5 days) dose of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Tyrosine hydroxylase and Bcl-2 levels were reduced in the ${\alpha}$-syn Tg but not WT mice by sub-toxic MPTP injection. In the adhesive removal test, time to remove paper was significantly increased only in the homo ${\alpha}$-syn Tg mice. In the challenging beam test, the hemi and homo ${\alpha}$-syn Tg mice spent significantly longer time to traverse as compared to that of WT group. In order to find out responsible proteins related with vulnerability of mutant ${\alpha}$-syn expressed neurons, DJ-1 and ubiquitin enzyme expressions were examined. In the SN, DJ-1 and ubiquitin conjugating enzyme, UBE2N, levels were significantly decreased in the ${\alpha}$-syn Tg mice. Moreover, A53T ${\alpha}$-syn overexpression decreased DJ-1 expression in SH-SY5Y cells. These findings suggest that the vulnerability to oxidative injury such as MPTP of A53T ${\alpha}$-syn mice can be explained by downregulation of DJ-1.

• 한국식품영양과학회지
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• 제45권7호
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• pp.966-972
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• 2016

본 연구에서는 해조류 추출물 20종의 치매 예방 및 개선 소재로서의 가치를 검토하기 위해 총폴리페놀 함량, ABTS radical 소거능, acetylcholinesterase(AChE) 저해 활성, ${\beta}$-secretase 효소 억제 활성 및 신경세포 보호 효과를 비교하였다. 해조류 추출물의 총폴리페놀 함량과 ABTS radical 소거능을 측정한 결과 감태 추출물의 총폴리페놀 함량이 가장 높았으며, 검둥감태와 감태 추출물이 높은 ABTS radical 소거능을 나타내었다. AChE 저해 활성을 검토한 결과 감태, 검둥감태, 바위수염이 30% 이상의 높은 저해 활성을 보였고 그중 감태가 가장 높은 억제율을 나타내었다. 또한, ${\beta}$-secretase 효소 억제 활성은 검둥감태, 감태, 왜모자반 추출물에서 관찰되었다. $H_2O_2$에 의해 유도된 신경세포 독성에 대한 보호 효과는 감태, 검둥감태, 왜모자반 추출물 $100{\mu}g/mL$ 농도에서 관찰되었다. 이상의 결과로 미루어 보았을 때 감태 추출물이 치매 예방 및 개선제로서의 활용 가능성이 가장 뛰어난 것으로 생각되며, 추가로 생리활성 물질 구명 및 작용기전 입증을 위한 후속 연구가 진행되어야 할 것으로 생각한다.