• Biomolecules & Therapeutics
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• v.14 no.2
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• pp.106-109
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• 2006

Neprilysin (Nep) is known to be important to degrade $A{\beta}$ derived from amyloid precursor protein (APP) by cleavage with $\beta-and\;\gamma$-secretases. In order to determine whether a correspondence between $A{\beta}-42/{\gamma}-secretase$ activity and Nep levels exists in postnatal aging of transgenic mice expressing either neuron-specific enolase (NSE)-controlled human mutant presenilin-2 (hPS2m) or APPsw alone, the levels of Nep expression and $A{\beta}-42/{\gamma}-secretase$ activity were examined age of 5, 12, and 20 months, respectively. The levels of Nep expression in both types of transgenic brains were decreased relative to those of control mice in a aging-related manner, while the level of $A{\beta}-42/{\gamma}-secretase$ activity was reversibly increased. Thus, changes in $A{\beta}-42$ may all reflect variation in amounts of Nep enzyme.

• Journal of Microbiology and Biotechnology
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• v.27 no.11
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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.

• The Journal of Korean Medicine
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• v.27 no.2 s.66
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• pp.122-133
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• 2006

Objectives : The amyloid $\beta$-protein ($A\beta$) is the principal component of the senile plaques characteristic of Alzheimer's disease (AD) and elicits a toxic effect on neurons in vitro and in vivo. Many environmental factors including antioxidants and proteoglycans modify $A{\beta}toxicity$. In this study, we have investigated the protective effects of water- and organic solvent-extracts of Hemerocallis fulva root fractions pre-extracted with methanol on $A\beta$-induced oxidative cell death in cultured rat pheochromocytoma (PC12) cells. Methods : For this study, we used MTT reduction assay for detection of protective effects of water- and organic solvent-extracts of Hemerocallis fulva root fractions pre-extracted with methanol on $A{\beta}_{25-35}$-induced cytotoxicity to PC12 cells. We also used cell-based $\beta$-secretase assay system to investigate the inhibitory effect of water- and organic solvent-extracts of Hemerocallis fulva root on $\beta$-secretase activity. Results : We previously reported that methanol extracts of Hemerocallis fulva root strongly attenuated cytotoxicity induced by the three $A\beta$ fragments ($A{\beta}_{25-35},\;A{\beta}_{1-42}\;A{\beta}_{1-43}$) to both SK-N-MC and PC12 cells. In the present study, we found that butanol-, ethylacetate-, chloroform-, and water-extracts of Hemerocallis fulva root fractions pre-extracted with methanol had strong protective effects against $A{\beta}_{25-35}$-induced cytotoxicity to PC12 cells and inhibitory potency to $\beta$-secretase activity. Conclusion : These results suggest that butanol-, ethylacetate-, chloroform-, and water-extracts of Hemerocallis fulva root fractions pre-extracted with methanol may contain the protective component(s) against $A\beta$-induced cell death in PC12 cells as well as inhibitory component(s) to $\beta$-secretase activity.

• Korean Journal of Biological Psychiatry
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• v.8 no.1
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• pp.62-70
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• 2001

Alzheimer's disease(AD) is associated with a characteristic neuropathology. The major hallmarks of AD are senile plaques (SPs) and neurofibrillary tangles(NFTs). ${\beta}$-amyloid protein($A{\beta}$) is derived from the proteolysis of amyloid precursor protein(APP) and then converted to SPs. Mature SPs produce cytotoxicity through direct toxic effects and activation of microglia and complement. NFTs are composed of paired helical filaments(PHFs) including abnormally phosphorylated form of the microtubule-associated protein(MAP) tau and increased tau level in cerebrospinal fluid may be observed in most AD. The aggregation of $A{\beta}$ and tau formation are thought to be a final common pathway of AD. Acetylcholine, dopamine, serotonin, GABA and their receptors are associated with AD. Especially, decreased nicotinic acetylcholine receptors(nAChRs) in AD are reported. Genetic lesions associated with AD are mutations in the structural genes for the APP located on chromosome 21, presenilin(PSN)1 located on chromosome 14 and PSN2 located on chromosome 1. Also, trisomy 21, Apo-E gene located on chromosome 19, PMF locus, low density lipoprotein receptor-related protein and ${\alpha}$-macroglobulin increase risk of AD. In this article, we will review about the neurobiology of AD and some newly developed research areas.

• Toxicological Research
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• v.17
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• pp.47-57
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• 2001

Alzheimer's disease (AD) is the most common cause of dementia in the elderly, and its pathology is characterized by the presence of numerous numbers of senile plaques and neurofibrillary tangles. Several genetic and transgenic studies have indicated that excess amount of $\beta$-amyloid protein (A$\beta$) is produced by mutations of $\beta$TEX>$\beta$-amyloid precursor protein and causes learning impairment. Moreover, $A\beta$ has a toxic effect on cultured nerve cells. To prepare AD model animals, we have examined continuous (2 weeks) infusion of $A\beta$ into the cerebral ventricle of rats. Continuous infusion of $A\beta$ induces learning impairment in water maze and passive avoidance tasks, and decreases choline acetyltransferase activity in the frontal cortex and hippocampus. Immunohistochemical analysis revealed diffuse depositions of $A\beta$ in the cerebral cortex and hippocampus around the ventricle. Furthermore, the nicotine-evoked release of acetylcholine and dopamine in the frontal cortex/hippocampus and striatum, respectively, is decreased in the $A\beta$-infused group. Perfusion of nicotine (50 $\mu\textrm{M}$) reduced the amplitude of electrically evoked population spikes in the CA1 pyramidal cells of the control group, but not in those of the $A\beta$-infused group, suggesting the impairment of nicotinic signaling in the $A\beta$-infused group. In fact, Kd, but not Bmax, values for ［$^3H$］ cytisine binding in the hippocampus significantly increased in the $A\beta$-infused rats. suggesting the decrease in affinity of nicotinic acetylcholine receptors. Long-term potentiation (LTP) induced by tetanic stimulations in CA1 pyramidal cells, which is thought to be an essential mechanism underlying learning and memory, was readily observed in the control group, whereas it was impaired in the $A\beta$-infused group. Taken together, these results suggest that $A\beta$ infusion impairs the signal transduction mechanisms via nicotinic acetylcholine receptors. This dysfunction may be responsible, at least in part, for the impairment of LTP induction and may lead to learning and memory impairment. We also found the reduction of glutathione- and Mn-superoxide dismutase-like immunoreactivity in the brains of $A\beta$-infused rats. Administration of antioxidants or nootropics alleviated learning and memory impairment induced by $A\beta$ infusion. We believe that investigation of currently available transgenic and non-transgenic animal models for AD will help to clarify the pathogenic mechanisms and allow assessment of new therapeutic strategies.

• Journal of Physiology & Pathology in Korean Medicine
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• v.28 no.3
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• pp.317-321
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• 2014

Amyloid-${\beta}$ protein ($A{\beta}$) is a pathological component of Alzheimer's disease (AD) by participating in the senile plaque formation in the patient's brain. Although the exact mechanism of $A{\beta}$ toxicity is not fully elucidated, it is considered to be closely related to its fibrillation process. For prevention of AD, recent studies have suggested various small molecules which inhibit $A{\beta}$ fibrillation. In this report, ${\beta}$-asarone found in acorus plant has been investigated as an anti-amyloid molecule. ${\beta}$-Asarone was demonstrated to prevent in vitro fibrillation of $A{\beta}$ by inducing the oligomer formation that obviously decreased cytotoxicity. Therefore, ${\beta}$-asarone could be suggested as an inhibitory agent of $A{\beta}$ fibrillation and toxicity, which would help us not only to understand underlying principle of amyloidogenesis mechanism but also to develop a controlling strategy toward AD.

• BMB Reports
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• v.52 no.7
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• pp.439-444
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• 2019

Although hypoxic/ischemic injury is thought to contribute to the incidence of Alzheimer's disease (AD), the molecular mechanism that determines the relationship between hypoxia-induced ${\beta}$-amyloid ($A{\beta}$) generation and development of AD is not yet known. We have now investigated the protective effects of N,4,5-trimethylthiazol-2-amine hydrochloride (KHG26702), a novel thiazole derivative, on oxygen-glucose deprivation (OGD)-reoxygenation (OGD-R)-induced $A{\beta}$ production in SH-SY5Y human neuroblastoma cells. Pretreatment of these cells with KHG26702 significantly attenuated OGD-R-induced production of reactive oxygen species and elevation of levels of malondialdehyde, prostaglandin $E_2$, interleukin 6 and glutathione, as well as superoxide dismutase activity. KHG26702 also reduced OGD-R-induced expression of the apoptotic protein caspase-3, the apoptosis regulator Bcl-2, and the autophagy protein becn-1. Finally, KHG26702 reduced OGD-R-induced $A{\beta}$ production and cleavage of amyloid precursor protein, by inhibiting secretase activity and suppressing the autophagic pathway. Although supporting data from in vivo studies are required, our results indicate that KHG26702 may prevent neuronal cell damage from OGD-R-induced toxicity.

• Korean Journal of Pharmacognosy
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• v.46 no.1
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• pp.72-77
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• 2015

One of the most common forms of dementia, Alzheimer's disease (AD) is a progressive neurodegenerative disorder symptomatically characterized by impairment in memory and cognitive abilities. AD is characterized pathologically by the presence of intracellular neurofibrillary tangles and deposition of ${\beta}$-amyloid ($A{\beta}$) peptides, believed to be neurotoxic and now is also considered to have a role on the mechanism of memory dysfunction. In this study, we tested that MeOH extract of Impatiens balsamina L. (IBM) affects on the processing of APP from the APPswe over-expressing Neuro2a cell line. We found that IBM increased over 2 folds of the $sAPP{\alpha}$ secretion level, a main metabolite of ${\alpha}$-secretase. We shown that IBM reduced the secretion level of $A{\beta}42$ and $A{\beta}40$ without cytotoxicity. BACE (${\beta}$-site APP cleaving enzyme) FRET assay shown that BACE activity was specifically decreased in the presence of IBM. We suggest that Impatiens balsamina L. may be an useful source to develop a herbal medicine of BACE inhibitor for Alzheimer's disease.

• Biomolecules & Therapeutics
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• v.29 no.3
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• pp.290-294
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• 2021

Extracellular beta amyloid (Aβ) plaques are the neuropathological hallmarks of Alzheimer's disease (AD). Accordingly, reducing Aβ levels is considered a promising strategy for AD prevention. 3'-O-acetyl-24-epi-7,8-didehydrocimigenol-3-O-β-D-xylopryranoside significantly decreased the Aβ production and this effect was accompanied with reduced sAPPβ production known as a soluble ectodomain APP fragment through β-secretases in HeLa cells overexpressing amyloid precursor proteins (APPs). This compound also increased the level of sAPPα, which is a proteolytic fragment of APP by α-secretases. In addition, 3'-O-acetyl-24-epi-7,8-didehydrocimigenol-3-O-β-D-xylopryranoside decreased the protein level of β-secretases, but the protein levels of A disintegrin and metalloproteinase (ADAM) family, especially ADAM10 and ADAM17, are increased. Thus, 3'-O-acetyl-24-epi-7,8-didehydrocimigenol-3-O-β-D-xylopryranoside could be useful in the development of AD treatment in the aspect of amyloid pathology.

• Journal of Oriental Neuropsychiatry
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• v.18 no.1
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• pp.63-78
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• 2007

Objective : This experiment was designed to investigate the effect of Thalictrum foetidum(TFD) on the Alzheimer's disease. Method : The effects of TFD on amyloid precursor proteins(APP), acetylcholinesterase(AChE), glial fibrillary acidic protein(GFAP) mRNA of PC-12 cell treated by amyloid ${\beta}$ $protein(A{\beta})$ and $IL-1{\beta}$, IL-6, $TNF-{\alpha}$ mRNA of THP-l cell treated by lipopolysaccharide(LPS), AChE activity of PC-12 cell lysate treated by $A{\beta}$ and behavior of the memory deficit mice induced by scopolamine, and glucose, AChE in serum of the memory deficit mice induced by scopolamine were investigated, respectively. Results : The results were summarized as follows ; 1. TFD suppressed APP, AChE, GFAP mRNA in PC-12 cell treated by $A{\beta}$. 2. TFD suppressed $IL-1{\beta}$, IL-6, $TNF-{\alpha}$ mRNA in THP-l cell treated by LPS 3.. TFD suppressed AChE activity in cell lysate of PC-12 cell treated by $A{\beta}$. 4. TFD increased glucose and decreased AChE significantly in the serum of the memory deficit mice induced by scopolamine. 5. TFD group showed significantly inhibitory effect on the scopolamine-induced impairment of learning and memory in the experiment of Morris water maze. Conclusion : According to the above results, it is suggested that TFD might be usefully applied for prevention and treatment of Alzheimer's disease.