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Pediococcus pentosaceus LAB6- and Lactiplantibacillus plantarum LAB12-Derived Cell Free Supernatant Inhibited RhoA Activation and Reduced Amyloid-Β In Vitro

Zaki RM, Ramasamy K, Ahmad Alwi NA, Mohd Yusoff R, Lim SM

Probiotics Antimicrob Proteins, 2024 Feb;16(1):62-75.
PMID: 36443559 DOI: 10.1007/s12602-022-10009-7

Alzheimer's disease (AD) is characterized by aggregation of amyloid beta (Aβ) plaque. RhoA may serve as a potential target for prevention against AD given its role in the amyloidogenic pathway. The recent emergence of the gut-brain axis has linked lactic acid bacteria (LAB) to neuroprotection against AD. This study assessed the importance of RhoA inhibition in mediating the neuroprotective potential of LAB. To this end, de Man, Rogosa and Sharpe (MRS) broth fermented by lactobacilli or pediococci were tested against SK-N-SH (a human neuroblastoma cell line) in the presence of RhoA activator II for 24 h after which the RhoA activity was measured using the G-LISA Kit. Fluorescence staining of f-actin stress fibres was performed to validate RhoA inhibition. SK-N-SH was transfected with plasmid expressing amyloid precursor protein (APP) gene. The Aβ concentration in transfected cells exposed to LAB-derived cell free supernatant (CFS) in the presence of RhoA activator II was measured using the ELISA kit. Furthermore, this study measured organic acids in LAB-derived CFS using the gas chromatography. It was found that LAB-derived CFS yielded strain-dependent inhibition of RhoA, with LAB6- and LAB12-derived CFS being the most potent Pediococcal- and Lactiplantibacillus-based RhoA inhibitor, respectively. Lesser stress fibres were formed under treatment with LAB-derived CFS. The LAB-derived CFS also significantly inhibited Aβ in SK-N-SH transfected with APP gene in the presence of RhoA activator II. The LAB-derived CFS was presented with increased lactic acid, acetic acid, butyric acid and propionic acid. The present findings warrant in-depth study using animal models.

Matched MeSH terms: Amyloid beta-Protein Precursor/genetics; Amyloid beta-Protein Precursor/metabolism
A case of early-onset familial Alzheimer's disease with both APP and novel PSEN2 mutations presenting with non-amnestic features

Chee KY, Yee OK, Gaillard F, Velakoulis D, Mohd Zain NR, Yogendren L, et al.

Aust N Z J Psychiatry, 2017 Dec;51(12):1252-1253.
PMID: 28762277 DOI: 10.1177/0004867417722642
Matched MeSH terms: Amyloid beta-Protein Precursor/genetics*
Mechanisms of action of amyloid-beta and its precursor protein in neuronal cell death

Leong YQ, Ng KY, Chye SM, Ling APK, Koh RY

Metab Brain Dis, 2020 01;35(1):11-30.
PMID: 31811496 DOI: 10.1007/s11011-019-00516-y

Extracellular senile plaques and intracellular neurofibrillary tangles are the neuropathological findings of the Alzheimer's disease (AD). Based on the amyloid cascade hypothesis, the main component of senile plaques, the amyloid-beta (Aβ) peptide, and its derivative called amyloid precursor protein (APP) both have been found to place their central roles in AD development for years. However, the recent therapeutics have yet to reverse or halt this disease. Previous evidence demonstrates that the accumulation of Aβ peptides and APP can exert neurotoxicity and ultimately neuronal cell death. Hence, we discuss the mechanisms of excessive production of Aβ peptides and APP serving as pathophysiologic stimuli for the initiation of various cell signalling pathways including apoptosis, necrosis, necroptosis and autophagy which lead to neuronal cell death. Conversely, the activation of such pathways could also result in the abnormal generation of APP and Aβ peptides. An elucidation of actions of APP and its metabolite, Aβ, could be vital in suggesting novel therapeutic opportunities.

Matched MeSH terms: Amyloid beta-Protein Precursor/genetics; Amyloid beta-Protein Precursor/metabolism*
Evaluation of the Expression of Amyloid Precursor Protein and the Ratio of Secreted Amyloid Beta 42 to Amyloid Beta 40 in SH-SY5Y Cells Stably Transfected with Wild-Type, Single-Mutant and Double-Mutant Forms of the APP Gene for the Study of Alzheimer's Disease Pathology

Pahrudin Arrozi A, Shukri SNS, Wan Ngah WZ, Mohd Yusof YA, Ahmad Damanhuri MH, Makpol S

Appl Biochem Biotechnol, 2017 Nov;183(3):853-866.
PMID: 28417423 DOI: 10.1007/s12010-017-2468-6

Neuroblastoma cell lines such as SH-SY5Y are the most frequently utilized models in neurodegenerative research, and their use has advanced the understanding of the pathology of neurodegeneration over the past few decades. In Alzheimer's disease (AD), several pathogenic mutations have been described, all of which cause elevated levels of pathological hallmarks such as amyloid-beta (Aβ). Although the genetics of Alzheimer's disease is well known, familial AD only accounts for a small number of cases in the population, with the rest being sporadic AD, which contains no known mutations. Currently, most of the in vitro models used to study AD pathogenesis only examine the level of Aβ42 as a confirmation of successful model generation and only perform comparisons between wild-type APP and single mutants of the APP gene. Recent findings have shown that the Aβ42/40 ratio in cerebrospinal fluid (CSF) is a better diagnostic indicator for AD patients than is Aβ42 alone and that more extensive Aβ formation, such as accumulation of intraneuronal Aβ, Aβ plaques, soluble oligomeric Aβ (oAβ), and insoluble fibrillar Aβ (fAβ) occurs in TgCRND8 mice expressing a double-mutant form (Swedish and Indiana) of APP, later leading to greater progressive impairment of the brain. In this study, we generated SH-SY5Y cells stably transfected separately with wild-type APP, the Swedish mutation of APP, and the Swedish and Indiana mutations of APP and evaluated the APP expression as well as the Aβ42/40 ratio in those cells. The double-mutant form of APP (Swedish/Indiana) expressed markedly high levels of APP protein and showed a high Aβ2/40 ratio compared to wild-type and single-mutant cells.

Matched MeSH terms: Amyloid beta-Protein Precursor/genetics*
Fulltext Role of neurotoxicants in the pathogenesis of Alzheimer's disease: a mechanistic insight

Nisa FY, Rahman MA, Hossen MA, Khan MF, Khan MAN, Majid M, et al.

Ann Med, 2021 Dec;53(1):1476-1501.
PMID: 34433343 DOI: 10.1080/07853890.2021.1966088

Alzheimer's disease (AD) is the most conspicuous chronic neurodegenerative syndrome, which has become a significant challenge for the global healthcare system. Multiple studies have corroborated a clear association of neurotoxicants with AD pathogenicity, such as Amyloid beta (Aβ) proteins and neurofibrillary tangles (NFTs), signalling pathway modifications, cellular stress, cognitive dysfunctions, neuronal apoptosis, neuroinflammation, epigenetic modification, and so on. This review, therefore, aimed to address several essential mechanisms and signalling cascades, including Wnt (wingless and int.) signalling pathway, autophagy, mammalian target of rapamycin (mTOR), protein kinase C (PKC) signalling cascades, cellular redox status, energy metabolism, glutamatergic neurotransmissions, immune cell stimulations (e.g. microglia, astrocytes) as well as an amyloid precursor protein (APP), presenilin-1 (PSEN1), presenilin-2 (PSEN2) and other AD-related gene expressions that have been pretentious and modulated by the various neurotoxicants. This review concluded that neurotoxicants play a momentous role in developing AD through modulating various signalling cascades. Nevertheless, comprehension of this risk agent-induced neurotoxicity is far too little. More in-depth epidemiological and systematic investigations are needed to understand the potential mechanisms better to address these neurotoxicants and improve approaches to their risk exposure that aid in AD pathogenesis.Key messagesInevitable cascade mechanisms of how Alzheimer's Disease-related (AD-related) gene expressions are modulated by neurotoxicants have been discussed.Involvement of the neurotoxicants-induced pathways caused an extended risk of AD is explicited.Integration of cell culture, animals and population-based analysis on the clinical severity of AD is addressed.

Matched MeSH terms: Amyloid beta-Protein Precursor/genetics
Mutations, associated with early-onset Alzheimer's disease, discovered in Asian countries

Bagyinszky E, Youn YC, An SS, Kim S

Clin Interv Aging, 2016;11:1467-1488.
PMID: 27799753

Alzheimer's disease (AD), the most common form of senile dementia, is a genetically complex disorder. In most Asian countries, the population and the number of AD patients are growing rapidly, and the genetics of AD has been extensively studied, except in Japan. However, recent studies have been started to investigate the genes and mutations associated with AD in Korea, the People's Republic of China, and Malaysia. This review describes all of the known mutations in three early-onset AD (EOAD) causative genes (APP, PSEN1, and PSEN2) that were discovered in Asian countries. Most of the EOAD-associated mutations have been detected in PSEN1, and several novel PSEN1 mutations were recently identified in patients from various parts of the world, including Asia. Until 2014, no PSEN2 mutations were found in Asian patients; however, emerging studies from Korea and the People's Republic of China discovered probably pathogenic PSEN2 mutations. Since several novel mutations were discovered in these three genes, we also discuss the predictions on their pathogenic nature. This review briefly summarizes genome-wide association studies of late-onset AD and the genes that might be associated with AD in Asian countries. Standard sequencing is a widely used method, but it has limitations in terms of time, cost, and efficacy. Next-generation sequencing strategies could facilitate genetic analysis and association studies. Genetic testing is important for the accurate diagnosis and for understanding disease-associated pathways and might also improve disease therapy and prevention.

Matched MeSH terms: Amyloid beta-Protein Precursor/genetics*
Fulltext APP, PSEN1, and PSEN2 Mutations in Asian Patients with Early-Onset Alzheimer Disease

Giau VV, Bagyinszky E, Youn YC, An SSA, Kim S

Int J Mol Sci, 2019 Sep 25;20(19).
PMID: 31557888 DOI: 10.3390/ijms20194757

The number of patients with Alzheimer's disease (AD) is rapidly increasing in Asia. Mutations in the amyloid protein precursor (APP), presenilin-1 (PSEN1), and presenilin-2 (PSEN2) genes can cause autosomal dominant forms of early-onset AD (EOAD). Although these genes have been extensively studied, variant classification remains a challenge, highlighting the need to colligate mutations across populations. In this study, we performed a genetic screening for mutations in the APP, PSEN1, and PSEN2 genes in 200 clinically diagnosed EOAD patients across four Asian countries, including Thailand, Malaysia, the Philippines, and Korea, between 2009 and 2018. Thirty-two (16%) patients presented pathogenic APP, PSEN1, or PSEN2 variants; eight (25%), 19 (59%), and five (16%) of the 32 patients presented APP, PSEN1, and PSEN2 variants, respectively. Among the 21 novel and known non-synonymous variants, five APP variants were found in Korean patients and one APP variant was identified in a Thai patient with EOAD. Nine, two, and one PSEN1 mutation was found in a Korean patient, Malaysian siblings, and a Thai patient, respectively. Unlike PSEN1 mutations, PSEN2 mutations were rare in patients with EOAD; only three variants were found in Korean patients with EOAD. Comparison of AD-causative point mutations in Asian countries; our findings explained only a small fraction of patients, leaving approximately 84% (p = 0.01) of autosomal dominant pedigrees genetically unexplained. We suggest that the use of high-throughput sequencing technologies for EOAD patients can potentially improve our understanding of the molecular mechanisms of AD.

Matched MeSH terms: Amyloid beta-Protein Precursor/genetics*; Amyloid beta-Protein Precursor/chemistry
Fulltext Modulation of Proteome Profile in AβPP/PS1 Mice Hippocampus, Medial Prefrontal Cortex, and Striatum by Palm Oil Derived Tocotrienol-Rich Fraction

Hamezah HS, Durani LW, Yanagisawa D, Ibrahim NF, Aizat WM, Makpol S, et al.

J Alzheimers Dis, 2019;72(1):229-246.
PMID: 31594216 DOI: 10.3233/JAD-181171

Tocotrienol-rich fraction (TRF) is a mixture of vitamin E analogs derived from palm oil. We previously demonstrated that supplementation with TRF improved cognitive function and modulated amyloid pathology in AβPP/PS1 mice brains. The current study was designed to examine proteomic profiles underlying the therapeutic effect of TRF in the brain. Proteomic analyses were performed on samples of hippocampus, medial prefrontal cortex (mPFC), and striatum using liquid chromatography coupled to Q Exactive HF Orbitrap mass spectrometry. From these analyses, we profiled a total of 5,847 proteins of which 155 proteins were differentially expressed between AβPP/PS1 and wild-type mice. TRF supplementation of these mice altered the expression of 255 proteins in the hippocampus, mPFC, and striatum. TRF also negatively modulated the expression of amyloid beta A4 protein and receptor-type tyrosine-protein phosphatase alpha protein in the hippocampus. The expression of proteins in metabolic pathways, oxidative phosphorylation, and those involved in Alzheimer's disease were altered in the brains of AβPP/PS1 mice that received TRF supplementation.

Matched MeSH terms: Amyloid beta-Protein Precursor/genetics; Amyloid beta-Protein Precursor/metabolism
Fulltext Comparative Effects of Alpha- and Gamma-Tocopherol on Mitochondrial Functions in Alzheimer's Disease In Vitro Model

Pahrudin Arrozi A, Shukri SNS, Wan Ngah WZ, Mohd Yusof YA, Ahmad Damanhuri MH, Jaafar F, et al.

Sci Rep, 2020 06 02;10(1):8962.
PMID: 32488024 DOI: 10.1038/s41598-020-65570-4

Vitamin E acts as an antioxidant and reduces the level of reactive oxygen species (ROS) in Alzheimer's disease (AD). Alpha-tocopherol (ATF) is the most widely studied form of vitamin E besides gamma-tocopherol (GTF) which also shows beneficial effects in AD. The levels of amyloid-beta (Aβ) and amyloid precursor protein (APP) increased in the brains of AD patients, and mutations in the APP gene are known to enhance the production of Aβ. Mitochondrial function was shown to be affected by the increased level of Aβ and may induce cell death. Here, we aimed to compare the effects of ATF and GTF on their ability to reduce Aβ level, modulate mitochondrial function and reduce the apoptosis marker in SH-SY5Y cells stably transfected with the wild-type or mutant form of the APP gene. The Aβ level was measured by ELISA, the mitochondrial ROS and ATP level were quantified by fluorescence and luciferase assay respectively whereas the complex V enzyme activity was measured by spectrophotometry. The expressions of genes involved in the regulation of mitochondrial membrane permeability such as voltage dependent anion channel (VDAC1), adenine nucleotide translocase (ANT), and cyclophilin D (CYPD) were determined by quantitative real-time polymerase chain reaction (qRT-PCR), while the expressions of cyclophilin D (CypD), cytochrome c, Bcl2 associated X (BAX), B cell lymphoma-2 (Bcl-2), and pro-caspase-3 were determined by western blot. Our results showed that mitochondrial ROS level was elevated accompanied by decreased ATP level and complex V enzyme activity in SH-SY5Y cells expressing the mutant APP gene (p protein was significantly overexpressed in cells transfected with the wild-type (WT) and mutant APP gene (p protein, and the ratio of BAX/Bcl-2 were increased in the following order; SH-SY5Y-APP-WT

Matched MeSH terms: Amyloid beta-Protein Precursor/drug effects; Amyloid beta-Protein Precursor/metabolism
A novel rat model of Alzheimer's disease based on lentiviral-mediated expression of mutant APP

Parsi S, Pandamooz S, Heidari S, Naji M, Morfini G, Ahmadiani A, et al.

Neuroscience, 2015 Jan 22;284:99-106.
PMID: 25270904 DOI: 10.1016/j.neuroscience.2014.09.045

Alzheimer's disease (AD) is characterized by progressive and irreversible cognitive and memory impairment. The discovery of familial forms of AD (fAD) in association with specific gene mutations facilitated the generation of numerous rodent models. These models in turn proved valuable for the study of molecular mechanisms underlying AD pathogenesis, and facilitated translational research and preclinical drug development. This study aimed to introduce a new rat model of AD simulating some aspects of the sporadic cases of disease.

Matched MeSH terms: Amyloid beta-Protein Precursor/genetics*
Fulltext Tocotrienol-Rich Fraction of Palm Oil Improves Behavioral Impairments and Regulates Metabolic Pathways in AβPP/PS1 Mice

Durani LW, Hamezah HS, Ibrahim NF, Yanagisawa D, Nasaruddin ML, Mori M, et al.

J Alzheimers Dis, 2018;64(1):249-267.
PMID: 29889072 DOI: 10.3233/JAD-170880

We have recently shown that the tocotrienol-rich fraction (TRF) of palm oil, a mixture of vitamin E analogs, improves amyloid pathology in vitro and in vivo. However, precise mechanisms remain unknown. In this study, we examined the effects of long-term (10 months) TRF treatment on behavioral impairments and brain metabolites in (15 months old) AβPP/PS1 double transgenic (Tg) Alzheimer's disease (AD) mice. The open field test, Morris water maze, and novel object recognition tasks revealed improved exploratory activity, spatial learning, and recognition memory, respectively, in TRF-treated Tg mice. Brain metabolite profiling of wild-type and Tg mice treated with and without TRF was performed using ultrahigh performance liquid chromatography (UHPLC) coupled to high-resolution accurate mass (HRAM)-orbitrap tandem mass spectrometry (MS/MS). Metabolic pathway analysis found perturbed metabolic pathways that linked to AD. TRF treatment partly ameliorated metabolic perturbations in Tg mouse hippocampus. The mechanism of this pre-emptive activity may occur via modulation of metabolic pathways dependent on Aβ interaction or independent of Aβ interaction.

Matched MeSH terms: Amyloid beta-Protein Precursor/genetics; Amyloid beta-Protein Precursor/metabolism
Neuroprotective effects of Foeniculum vulgare seeds extract on lead-induced neurotoxicity in mice brain

Bhatti S, Ali Shah SA, Ahmed T, Zahid S

Drug Chem Toxicol, 2018 Oct;41(4):399-407.
PMID: 29742941 DOI: 10.1080/01480545.2018.1459669

The present study investigates the neuroprotective effects of Foeniculum vulgare seeds in a lead (Pb)-induced brain neurotoxicity mice model. The dried seeds extract of Foeniculum vulgare was prepared with different concentrations of organic solvents (ethanol, methanol, n-hexane). The in vitro antioxidant activity of Foeniculum vulgare seed extracts was assessed through DPPH assay and the chemical composition of the extracts was determined by high-resolution 1H NMR spectroscopy. The age-matched male Balb/c mice (divided into 9 groups) were administered with 0.1% Pb and 75% and 100% ethanol extracts of Foeniculum vulgare seeds at a dose of 200 mg/kg/day and 20 mg/kg/day. The maximum antioxidant activity was found for 75% ethanol extract, followed by 100% ethanol extract. Gene expression levels of oxidative stress markers (SOD1 and Prdx6) and the three isoforms of APP (APP common, 770 and 695), in the cortex and hippocampus of the treated and the control groups were measured. Significant increase in APP 770 expression level while a substantial decrease was observed for SOD1, Prdx6 and APP 695 expression in Pb-treated groups. Interestingly, the deranged expression levels were significantly normalized by the treatment with ethanol extracts of Foeniculum vulgare seeds (specifically at dose of 200 mg/kg/day). Furthermore, the Pb-induced morphological deterioration of cortical neurons was significantly improved by the ethanol extracts of Foeniculum vulgare seeds. In conclusion, the present findings highlight the promising therapeutic potential of Foeniculum vulgare to minimize neuronal toxicity by normalizing the expression levels of APP isoforms and oxidative stress markers.

Matched MeSH terms: Amyloid beta-Protein Precursor/genetics
Fucosterol exerts protection against amyloid β-induced neurotoxicity, reduces intracellular levels of amyloid β and enhances the mRNA expression of neuroglobin in amyloid β-induced SH-SY5Y cells

Gan SY, Wong LZ, Wong JW, Tan EL

Int J Biol Macromol, 2019 Jan;121:207-213.
PMID: 30300695 DOI: 10.1016/j.ijbiomac.2018.10.021

Alzheimer's disease (AD) is a neurodegenerative disease that leads to progressive loss of neurons which often results in deterioration of memory and cognitive function. The development of AD is highly associated with the formation of senile plaques and neurofibrillary tangles. Amyloid β (Aβ) induces neurotoxicity and contributes to the development of AD. Recent evidences also highlighted the importance of neuroglobin (Ngb) in ameliorating AD. This study assessed the ability of fucosterol, a phytosterol found in brown alga, in protecting SH-SY5Y cells against Aβ-induced neurotoxicity. Its effects on the mRNA levels of APP and Ngb as well as the intracellular Aβ levels were also determined in Aβ-induced SH-SY5Y cells. SH-SY5Y cells were exposed to fucosterol prior to Aβ treatment. The effect on apoptosis was determined using Annexin V FITC staining and mRNA expression was studied using RT-PCR. Flow cytometry confirmed the protective effects of fucosterol on SH-SY5Y cells against Aβ-induced apoptosis. Pretreatment with fucosterol increased the Ngb mRNA levels but reduced the levels of APP mRNA and intracellular Aβ in Aβ-induced SH-SY5Y cells. These observations demonstrated the protective properties of fucosterol against Aβ-induced neurotoxicity in neuronal cells.

Matched MeSH terms: Amyloid beta-Protein Precursor/genetics
Fulltext Pharmaceutical Potential of Casein-Derived Tripeptide Met-Lys-Pro: Improvement in Cognitive Impairments and Suppression of Inflammation in APP/PS1 Mice

Matsuzaki Tada A, Hamezah HS, Pahrudin Arrozi A, Abu Bakar ZH, Yanagisawa D, Tooyama I

J Alzheimers Dis, 2022;89(3):835-848.
PMID: 35964178 DOI: 10.3233/JAD-220192

BACKGROUND: Tripeptide Met-Lys-Pro (MKP), a component of casein hydrolysates, has effective angiotensin-converting enzyme (ACE) inhibitory activity. Brain angiotensin II enzyme activates the NADPH oxidase complex via angiotensin II receptor type 1 (AT1) and enhances oxidative stress injury. ACE inhibitors improved cognitive function in Alzheimer's disease (AD) mouse models and previous clinical trials. Thus, although undetermined, MKP may be effective against pathological amyloid-β (Aβ) accumulation-induced cognitive impairment.
OBJECTIVE: The current study aimed to investigate the potential of MKP as a pharmaceutical against AD by examining MKP's effect on cognitive function and molecular changes in the brain using double transgenic (APP/PS1) mice.
METHODS: Experimental procedures were conducted in APP/PS1 mice (n = 38) with a C57BL/6 background. A novel object recognition test was used to evaluate recognition memory. ELISA was used to measure insoluble Aβ40, Aβ42, and TNF-α levels in brain tissue. Immunohistochemical analysis allowed the assessment of glial cell activation in MKP-treated APP/PS1 mice.
RESULTS: The novel object recognition test revealed that MKP-treated APP/PS1 mice showed significant improvement in recognition memory. ELISA of brain tissue showed that MKP significantly reduced insoluble Aβ40, Aβ42, and TNF-α levels. Immunohistochemical analysis indicated the suppression of the marker for microglia and reactive astrocytes in MKP-treated APP/PS1 mice.
CONCLUSION: Based on these results, we consider that MKP could ameliorate pathological Aβ accumulation-induced cognitive impairment in APP/PS1 mice. Furthermore, our findings suggest that MKP potentially contributes to preventing cognitive decline in AD.

Matched MeSH terms: Amyloid beta-Protein Precursor/genetics
Fulltext Pulsatile stretch as a novel modulator of amyloid precursor protein processing and associated inflammatory markers in human cerebral endothelial cells

Gangoda SVS, Avadhanam B, Jufri NF, Sohn EH, Butlin M, Gupta V, et al.

Sci Rep, 2018 01 26;8(1):1689.
PMID: 29374229 DOI: 10.1038/s41598-018-20117-6

Amyloid β (Aβ) deposition is a hallmark of Alzheimer's disease (AD). Vascular modifications, including altered brain endothelial cell function and structural viability of the blood-brain barrier due to vascular pulsatility, are implicated in AD pathology. Pulsatility of phenomena in the cerebral vasculature are often not considered in in vitro models of the blood-brain barrier. We demonstrate, for the first time, that pulsatile stretch of brain vascular endothelial cells modulates amyloid precursor protein (APP) expression and the APP processing enzyme, β-secretase 1, eventuating increased-Aβ generation and secretion. Concurrent modulation of intercellular adhesion molecule 1 and endothelial nitric oxide synthase (eNOS) signaling (expression and phosphorylation of eNOS) in response to pulsatile stretch indicates parallel activation of endothelial inflammatory pathways. These findings mechanistically support vascular pulsatility contributing towards cerebral Aβ levels.

Matched MeSH terms: Amyloid beta-Protein Precursor/analysis*
Fulltext Computational analysis of functional SNPs in Alzheimer's disease-associated endocytosis genes

Tey HJ, Ng CH

PeerJ, 2019;7:e7667.
PMID: 31592138 DOI: 10.7717/peerj.7667

Background: From genome wide association studies on Alzheimer's disease (AD), it has been shown that many single nucleotide polymorphisms (SNPs) of genes of different pathways affect the disease risk. One of the pathways is endocytosis, and variants in these genes may affect their functions in amyloid precursor protein (APP) trafficking, amyloid-beta (Aβ) production as well as its clearance in the brain. This study uses computational methods to predict the effect of novel SNPs, including untranslated region (UTR) variants, splice site variants, synonymous SNPs (sSNPs) and non-synonymous SNPs (nsSNPs) in three endocytosis genes associated with AD, namely PICALM, SYNJ1 and SH3KBP1.
Materials and Methods: All the variants' information was retrieved from the Ensembl genome database, and then different variation prediction analyses were performed. UTRScan was used to predict UTR variants while MaxEntScan was used to predict splice site variants. Meta-analysis by PredictSNP2 was used to predict sSNPs. Parallel prediction analyses by five different software packages including SIFT, PolyPhen-2, Mutation Assessor, I-Mutant2.0 and SNPs&GO were used to predict the effects of nsSNPs. The level of evolutionary conservation of deleterious nsSNPs was further analyzed using ConSurf server. Mutant protein structures of deleterious nsSNPs were modelled and refined using SPARKS-X and ModRefiner for structural comparison.
Results: A total of 56 deleterious variants were identified in this study, including 12 UTR variants, 18 splice site variants, eight sSNPs and 18 nsSNPs. Among these 56 deleterious variants, seven variants were also identified in the Alzheimer's Disease Sequencing Project (ADSP), Alzheimer's Disease Neuroimaging Initiative (ADNI) and Mount Sinai Brain Bank (MSBB) studies.
Discussion: The 56 deleterious variants were predicted to affect the regulation of gene expression, or have functional impacts on these three endocytosis genes and their gene products. The deleterious variants in these genes are expected to affect their cellular function in endocytosis and may be implicated in the pathogenesis of AD as well. The biological consequences of these deleterious variants and their potential impacts on the disease risks could be further validated experimentally and may be useful for gene-disease association study.

Matched MeSH terms: Amyloid beta-Protein Precursor
Fulltext Effects of Amyloid Precursor Protein Overexpression on NF-κB, Rho-GTPase and Pro-Apoptosis Bcl-2 Pathways in Neuronal Cells

Chan HH, Leong YQ, Voon SM, Pan ML, Leong CO, Lim CL, et al.

Rep Biochem Mol Biol, 2021 Jan;9(4):417-425.
PMID: 33969135 DOI: 10.52547/rbmb.9.4.417

Background: Alzheimer's disease (AD) is a neurodegenerative disorder that causes cognitive dysfunction. Previous studies have suggested that amyloid plaques, mainly comprising of amyloid-beta peptides, play a pivotal role in AD pathophysiology. This study focuses on the evaluation of the effects of amyloid precursor protein (APP) overexpression on NF-κB, Rho-GTPase and Bcl-2 mediated pro-apoptotic pathways in neuronal cells.
Methods: A lentiviral transduction system was used to generate SH-SY5Y cells overexpressing APP. Immunoblotting was conducted to determine expression levels of NF-κB, Rho-GTPase, and Bcl-2 family proteins in the APP overexpressed cells.
Results: In the NF-κB signaling pathway, APP-overexpressing SH-SY5Y cells showed that there was a reduction of p-NF-κB (p< 0.05) and IKKα. Subsequently, there was upregulation of protein expression of NF-Κb, IKKβ and IκBα. On the other hand, protein expression of RhoC (p< 0.05) and Rac1/2/3 was upregulated as compared to the control group. Meanwhile, a decrease in RhoA, Cdc42 (p< 0.05) and p-Rac1/cdc42 protein levels was observed in the APP-overexpressed group. Lastly, in the pro-apoptotic pathway, the expression of Bcl-2, Bid, Bok and Puma (p< 0.05) was up regulated in the APP-overexpressed group. Downregulation of Bad and Bim expression was observed in the APP-overexpressed as compared to the control group, and Bax expression remained unchanged in the APP-overexpressed group.
Conclusion: APP overexpression regulated signaling in the NF-κB, Rho-GTPase and Bcl-2 family pathways in neuronal cells, suggesting that these are involved in promoting neuronal survival and modulating synaptic plasticity in AD. However, further studies are essential to elucidate the APP-mediated mechanism of action.

Matched MeSH terms: Amyloid beta-Protein Precursor
Therapeutic potential of combined viral transduction and CRISPR/Cas9 gene editing in treating neurodegenerative diseases

Kuruvilla J, Sasmita AO, Ling APK

Neurol Sci, 2018 Nov;39(11):1827-1835.
PMID: 30076486 DOI: 10.1007/s10072-018-3521-0

BACKGROUND AND PURPOSE: The central nervous system (CNS) faces unique difficulties in attaining permanent therapy for neurodegenerative disorder (ND). Genomic level forms of therapy have garnered interest in the recent decade, with the novel CRISPR/Cas9 gene editing tool continuing to be explored due to its efficiency, safety, and adaptability to varying conditions. With the aid of viral vectors as transport vectors, the gene editing tool has produced promising in vitro and in vivo findings in study models. Thus, this review focuses on the recent advancements and update of CRISPR/Cas9 to combat neurodegenerative diseases.
METHODS: Articles detailing potential applications of CRISPR/Cas9 in neurodegenerative settings were retrieved from PubMed and Google Scholar with the keywords "CRISPR," "gene editing," and "neurodegenerative diseases." Relevant information was collected and critically reviewed.
RESULTS: The utility of CRISPR/Cas9 coupled with viral transduction ranges from the disruption of amyloid precursor protein (APP) production at a genomic level in Alzheimer's disease (AD) to the deletion of varying exon portions of the Dmd gene in Duchenne muscular dystrophy (DMD) which would increase dystrophin expression. This usage of CRISPR/Cas9 also extends to experimentally ameliorate the neurodegenerative effects caused by viral infections.
CONCLUSION: The CRISPR/Cas9 gene editing tool is a powerful arsenal in the field of gene therapy and molecular medicine; hence, more research should be called to focus on the ample potential this tool has to offer in the field of neurodegenerative diseases.

Matched MeSH terms: Amyloid beta-Protein Precursor
Beyond the Obvious: Smoking and Respiratory Infection Implications on Alzheimer's Disease

Wadhwa R, Paudel KR, Mehta M, Shukla SD, Sunkara K, Prasher P, et al.

CNS Neurol Disord Drug Targets, 2020;19(9):698-708.
PMID: 33109069 DOI: 10.2174/1871527319999200817112427

Tobacco smoke is not only a leading cause for chronic obstructive pulmonary disease, cardiovascular disorders, and lung and oral cancers, but also causes neurological disorders such as Alzheimer 's disease. Tobacco smoke consists of more than 4500 toxic chemicals, which form free radicals and can cross blood-brain barrier resulting in oxidative stress, an extracellular amyloid plaque from the aggregation of amyloid β (Aβ) peptide deposition in the brain. Further, respiratory infections such as Chlamydia pneumoniae, respiratory syncytial virus have also been involved in the induction and development of the disease. The necessary information collated on this review has been gathered from various literature published from 1995 to 2019. The review article sheds light on the role of smoking and respiratory infections in causing oxidative stress and neuroinflammation, resulting in Alzheimer's disease (AD). This review will be of interest to scientists and researchers from biological and medical science disciplines, including microbiology, pharmaceutical sciences and the translational researchers, etc. The increasing understanding of the relationship between chronic lung disease and neurological disease is two-fold. First, this would help to identify the risk factors and possible therapeutic interventions to reduce the development and progression of both diseases. Second, this would help to reduce the probable risk of development of AD in the population prone to chronic lung diseases.

Matched MeSH terms: Amyloid beta-Protein Precursor
Tocotrienol-Rich Fraction Modulates Amyloid Pathology and Improves Cognitive Function in AβPP/PS1 Mice

Ibrahim NF, Yanagisawa D, Durani LW, Hamezah HS, Damanhuri HA, Wan Ngah WZ, et al.

J Alzheimers Dis, 2017;55(2):597-612.
PMID: 27716672

Alzheimer's disease (AD) is the most common cause of dementia. The cardinal neuropathological characteristic of AD is the accumulation of amyloid-β (Aβ) into extracellular plaques that ultimately disrupt neuronal function and lead to neurodegeneration. One possible therapeutic strategy therefore is to prevent Aβ aggregation. Previous studies have suggested that vitamin E analogs slow AD progression in humans. In the present study, we investigated the effects of the tocotrienol-rich fraction (TRF), a mixture of vitamin E analogs from palm oil, on amyloid pathology in vitro and in vivo. TRF treatment dose-dependently inhibited the formation of Aβ fibrils and Aβ oligomers in vitro. Moreover, daily TRF supplementation to AβPPswe/PS1dE9 double transgenic mice for 10 months attenuated Aβ immunoreactive depositions and thioflavin-S-positive fibrillar type plaques in the brain, and eventually improved cognitive function in the novel object recognition test compared with control AβPPswe/PS1dE9 mice. The present result indicates that TRF reduced amyloid pathology and improved cognitive functions, and suggests that TRF is a potential therapeutic agent for AD.

Matched MeSH terms: Amyloid beta-Protein Precursor/genetics

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