Reduce Protein Aggregation Research Articles

Non-invasive infra-red therapy (1072 nm) reduces β-amyloid protein levels in the brain of an Alzheimer’s disease mouse model, TASTPM

BackgroundAlzheimer’s disease (AD) is the most prevalent neurodegenerative disease and common cause of dementias in the Western world. This study investigated the expression profile of heat-shock proteins (HSPs) involved in maintaining healthy neurons in the TASTPM AD mouse model, and whether chronic treatment with 1072nm infra-red (IR1072) modified the expression profiles of HSPs and amyloidopathy in female TASTPM mice. Methodology/principal findingsQuantitative immunoblotting and immunohistochemistry were used to examine the expression of proteins such as HSPs, phosphorylated tau (tau-P), amyloid precursor protein (APP), β-amyloid1–40 (Aβ), and Aβ1–42. TASTPM mice at 3, 7 and 12months were investigated as well as female TASTPM mice which had undergone a chronic, 5month, IR1072 treatment. During the first 12months of age, a critical period of AD progression, reduced HSP40 and HSP105 were observed. αB-crystallin, Aβ1–42 and tau-P increased over this period, particularly between 3 and 7months. Chronic IR1072 treatment of female TASTPM mice elicited significant increases in HSP60, 70 and 105 and phosphorylated-HSP27 (P-HSP27) (50–139%), together with a concomitant profound decrease in αB-crystallin, APP, tau-P, Aβ1–40 and Aβ1–42 (43–81%) protein levels at 7months of age. Furthermore, IR1072 treatment elicited a modest, but significant, reduction in Aβ1–42 plaques in the cerebral cortex. Conclusions/significant findingsIR1072 treatment provides a novel non-invasive and safe way to upregulate a panel of stress response proteins in the brain, known to both reduce protein aggregation and neuronal apoptosis. This approach recently entered clinical trials for AD in the USA, and may provide a novel disease modifying therapy for a range of neuropathologies.

Evolutionary Optimization of Protein Folding

Nature has shaped the make up of proteins since their appearance, 3.8 billion years ago. However, the fundamental drivers of structural change responsible for the extraordinary diversity of proteins have yet to be elucidated. Here we explore if protein evolution affects folding speed. We estimated folding times for the present-day catalog of protein domains directly from their size-modified contact order. These values were mapped onto an evolutionary timeline of domain appearance derived from a phylogenomic analysis of protein domains in 989 fully-sequenced genomes. Our results show a clear overall increase of folding speed during evolution, with known ultra-fast downhill folders appearing rather late in the timeline. Remarkably, folding optimization depends on secondary structure. While alpha-folds showed a tendency to fold faster throughout evolution, beta-folds exhibited a trend of folding time increase during the last 1.5 billion years that began during the “big bang” of domain combinations. As a consequence, these domain structures are on average slow folders today. Our results suggest that fast and efficient folding of domains shaped the universe of protein structure. This finding supports the hypothesis that optimization of the kinetic and thermodynamic accessibility of the native fold reduces protein aggregation propensities that hamper cellular functions.

Investigating the Interactions between Aβ and Amylin: Insight into the Link between Alzheimer's and Type II Diabetes

The self-assembly of peptides is associated with protein aggregation in numerous incurable diseases, including amyloid β (Aβ) in Alzheimer's disease (AD), α-synuclein in Parkinson's disease (PD), and amylin in type II diabetes (T2D). Experimental evidence led to the hypothesis that cross-amyloid interactions, e.g., interactions between Aβ and amylin also play a critical role in protein aggregation. Structure-based characterization of the interactions between two types of amyloids is fundamental to understanding the self-assembly mechanism that exists between them and may pave the way to elucidate the link between two diseases, e.g. T2D and AD. Combining computational tools with experimental data this lecture illustrates for the first time the interactions between Aβ and amylin oligomers. Identifying the specific “hot regions” bindings of amylin with Aβ demonstrates polymorphic Amylin-Aβ complexes. This study may provide insight into the link between diseases and may pave the way to the development of drugs that could ameliorate neurodegenerative diseases by interrupting the interaction between the relevant proteins and hence reducing protein aggregation. The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2011) under grant agreement 303741.

Effects of Group 3 LEA protein model peptides on desiccation-induced protein aggregation

Group 3 late embryogenesis abundant (G3LEA) proteins have amino acid sequences with characteristic 11-mer motifs and are known to reduce aggregation of proteins during dehydration. Previously, we clarified the structural and thermodynamic properties of the 11-mer repeating units in G3LEA proteins using synthetic peptides composed of two or four tandem repeats originating from an insect (Polypedilum vanderplanki), nematodes and plants. The purpose of the present study is to test the utility of such 22-mer peptides as protective reagents for aggregation-prone proteins. For lysozyme, desiccation-induced aggregation was abrogated by low molar ratios of a 22-mer peptide, PvLEA-22, derived from a P. vanderplanki G3LEA protein sequence. However, an unexpected behavior was noted for the milk protein, α-casein. On drying, the resultant aggregation was significantly suppressed in the presence of PvLEA-22 with its molar ratios>25 relative to α-casein. However, when the molar ratio was <10, aggregation occurred on addition of PvLEA-22 to aqueous solutions of α-casein. Other peptides derived from nematode, plant and randomized G3LEA protein sequences gave similar results. Such an anomalous solubility change in α-casein was shown to be due to a pH shift to ca. 4, a value nearly equal to the isoelectric point (pI) of α-casein, when any of the 22-mer peptides was mixed. These results demonstrate that synthetic peptides derived from G3LEA protein sequences can reduce protein aggregation caused both by desiccation and, at high molar ratios, also by pH effects, and therefore have potential as stabilization reagents.

Nanoscale Biofilm Modification-Method Concerning a Myoglobin/11-MUA Bilayers for Bioelectronic Device

We developed surface modification tools for the fabrication of a bioelectronic device which consists of a myoglobin monolayer self-assembled on an 11-MUA layer. To utilize a single protein as the active element, it was necessary to reduce protein aggregation on the protein layer in the nanobio electronic device, which was developed in our previous study and shown to display basic biomemory functions. Here, the reduction of myoglobin aggregation was accomplished by using 3-(3-cholamidopropyl) dimethylammonio-11-propanesulfonate (CHAPS) to fabricate a well-defined protein layer on the bioelectronic device. We investigated two different surface modification methods for making well oriented biofilm. The effects of CHAPS on the formation of a myoglobin layer self-assembled on an 11-MUA layer were examined by atomic force microscopy and Raman spectroscopy. The size of the myoglobin aggregates was reduced from 200-250 nm to 10-40 nm depending on treatment method. The sustaining redox property of the CHAPS treated myoglobin layer was examined using cyclic voltammetry. Using these techniques, we found that after surfactant CHAPS treatment, protein aggregation was dramatically reduced and the protein layer still maintained its inherent electrochemical properties.

Ibuprofen ameliorates protein aggregation and astrocytic gliosis, but not cognitive dysfunction, in a transgenic mouse expressing dementia with Lewy bodies-linked P123H β-synuclein

Epidemiological studies have shown that ibuprofen, a non-steroidal anti-inflammatory drug, reduces the risk for neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD). In this context, it has been shown that chronic treatment with ibuprofen improves cognitive dysfunction and histopathologic outcome in mouse models of AD. However, the therapeutic effects of ibuprofen in animal models of PD and related synucleinopathies such as dementia with Lewy bodies (DLB) have not been investigated. Therefore, the main objective of this study was to determine if ibuprofen ameliorates neuropathology and cognitive dysfunction in a transgenic (tg) mouse expressing DLB-linked P123H β-synuclein. P123H β-synuclein tg mice and their non-tg littermates aged 3 months were given ibuprofen in their diet (n=13). Controls did not receive ibuprofen (n=11). After 3 months, the mice were evaluated using a Morris water maze test, followed by neuropathological analyses. Compared to control P123H β-synuclein tg mice, P123H β-synuclein tg mice that received ibuprofen had significantly reduced protein aggregation and astrogliosis. However, ibuprofen treatment produced little improvement of the learning disability of P123H β-synuclein tg mice in the Morris water maze test. These results suggest that amelioration of neuropathologies by ibuprofen does not necessarily lead to improved cognitive function in synucleinopathies such as DLB.

Protein Aggregation in Neurodegenerative Diseases: Insights from Computational Analyses

Biological aggregation is a process where bio-macromolecules such as proteins, lipids and nucleic acids essentially self-associate in an ordered fashion into functional complexes (that may be normal or pathological) and finally precipitate out due to formation of higher order conglomerates of low solubility. Neurodegenerative diseases are, in general, associated with the deposition of pathogenic aggregates composed of amyloid fibrils/plaques in tissues. Sequence analysis of proteins prone to aggregation has aided the evolution of accurate prediction algorithms now being used in designing aggregation-reducing mutations. Computational and experimental researches have proved that preventing aggregation does not necessarily prevent amyloidosis and vice-versa. Investigation of amyloid fibril formation with the help of these approaches shall lead to the understanding of the mechanism and prevention from various neurodegenerative diseases. We have observed in our past computational studies that there are certain “sequence breaker” amino acid residues which when placed in the aggregation-prone stretches, drastically affect the aggregation propensity and fibrillization activity. The sequence breaker concept is quite similar to that of the “gatekeeper residues” which have been explored earlier [1, 2]. On such grounds, we have studied α-synuclein, which is the pathogenic protein implicated in Parkinsons Disease (PD) as well as other neurodegenerative diseases, and identified a double mutant of A53T (familial PD-causing) mutant that increases its solubility, positively enhances its thermodynamic stability and nearly ends the aggregation propensity in the diseased state (which is a precursor to amyloidosis). Moreover, as protein aggregation is the key to control the symptoms of most neurodegenerative diseases, numerous small peptides (therapeutic drugs) as well as small molecules have been designed to target the aggregation-prone regions in individual experimental studies. This is also an important facet in biotherapeutics where constant efforts are being made to reduce protein aggregation. The focus of this article is to shed light on the recent technologies and developments in bioinformatics to investigate protein aggregation (with α-synuclein as a recurring example). Keywords: amyloid, fibrillization, aggregation propensity, mutants, neurodegenerative diseases, Parkinson's disease, protein aggregation, protein misfolding, synuclein, cytotoxicity, computational prediction

Hydroimidazolone Modification of the Conserved Arg12 in Small Heat Shock Proteins: Studies on the Structure and Chaperone Function Using Mutant Mimics

Methylglyoxal (MGO) is an α-dicarbonyl compound present ubiquitously in the human body. MGO reacts with arginine residues in proteins and forms adducts such as hydroimidazolone and argpyrimidine in vivo. Previously, we showed that MGO-mediated modification of αA-crystallin increased its chaperone function. We identified MGO-modified arginine residues in αA-crystallin and found that replacing such arginine residues with alanine residues mimicked the effects of MGO on the chaperone function. Arginine 12 (R12) is a conserved amino acid residue in Hsp27 as well as αA- and αB-crystallin. When treated with MGO at or near physiological concentrations (2–10 µM), R12 was modified to hydroimidazolone in all three small heat shock proteins. In this study, we determined the effect of arginine substitution with alanine at position 12 (R12A to mimic MGO modification) on the structure and chaperone function of these proteins. Among the three proteins, the R12A mutation improved the chaperone function of only αA-crystallin. This enhancement in the chaperone function was accompanied by subtle changes in the tertiary structure, which increased the thermodynamic stability of αA-crystallin. This mutation induced the exposure of additional client protein binding sites on αA-crystallin. Altogether, our data suggest that MGO-modification of the conserved R12 in αA-crystallin to hydroimidazolone may play an important role in reducing protein aggregation in the lens during aging and cataract formation.

Identification of cell culture conditions to control protein aggregation of IgG fusion proteins expressed in Chinese hamster ovary cells

The presence of aggregated forms of proteins can be problematic for therapeutics due to the potential for immunogenic and pharmacokinetic issues. Although downstream processing can remove the aggregated forms, inhibiting aggregate formation upstream during the cell culture stage could reduce the burden on downstream processing and potentially improve process yields. This study first examined the effects of environmental factors (temperature, pH, and dissolved oxygen) and medium components (bivalent copper ion, cysteine, and cystine) on the aggregation of two different recombinant fusion proteins expressed by Chinese hamster ovary (CHO) cells. Any strategy to reduce protein aggregation upstream during cell culture must also consider potential effects on critical upstream parameters such as cell growth, harvest titer, and protein sialylation levels. Manipulating the culture temperature shift and cystine concentration in the medium were both identified as effective and practical strategies for reducing protein aggregation in both CHO-cell expression systems. Furthermore, a combination of both strategies was more effective in reducing protein aggregation levels compared to either approach individually; and without any negative effects on harvest titer and protein sialylation. This study demonstrates a practical methodology for decreasing protein aggregation during upstream processing and emphasizes the importance of process understanding to ensure production of recombinant glycoprotein therapeutics with consistent product quality.

The Entamoeba histolytica methylated LINE-binding protein EhMLBP provides protection against heat shock

Adaptation to environmental stress is a key process that allows the unicellular parasite Entamoeba histolytica to survive in its human host. We previously characterized EhMLBP as an essential protein for the growth and the virulence of the parasite. EhMLBP binds to methylated repetitive DNA, and is one of the core proteins of the parasite's epigenetic machinery. Here, we show that EhMLBP and heat shock proteins have common properties. EhMLBP is induced by heat shock and its expression is regulated by a heat shock element binding site that is located in its 5' non-coding region. Following heat shock, the perinuclear localization of EhMLBP in control trophozoites is replaced by an even distribution within the nucleus alongside with an enhanced recruitment of EhMLBP to the reverse transcriptase of a long interspersed nucleotide element (LINE) DNA. Constitutive overexpression of EhMLBP protects trophozoites against heat shock and reduces protein aggregation. This protective function is lost in trophozoites that overexpress a mutated form of EhMLBP which is devoid of its heat shock domain. To the best of our knowledge, this is the first report of a methyl DNA-binding protein that plays a protective role against heat shock.

Purification of Hsp104, a Protein Disaggregase

Hsp104 is a hexameric AAA+ protein(1) from yeast, which couples ATP hydrolysis to protein disaggregation (Fig. 1). This activity imparts two key selective advantages. First, renaturation of disordered aggregates by Hsp104 empowers yeast survival after various protein-misfolding stresses, including heat shock. Second, remodeling of cross-beta amyloid fibrils by Hsp104 enables yeast to exploit myriad prions (infectious amyloids) as a reservoir of beneficial and heritable phenotypic variation. Remarkably, Hsp104 directly remodels preamyloid oligomers and amyloid fibrils, including those comprised of the yeast prion proteins Sup35 and Ure2). This amyloid-remodeling functionality is a specialized facet of yeast Hsp104. The E. coli orthologue, ClpB, fails to remodel preamyloid oligomers or amyloid fibrils. Hsp104 orthologues are found in all kingdoms of life except, perplexingly, animals. Indeed, whether animal cells possess any enzymatic system that couples protein disaggregation to renaturation (rather than degradation) remains unknown. Thus, we and others have proposed that Hsp104 might be developed as a therapeutic agent for various neurodegenerative diseases connected with the misfolding of specific proteins into toxic preamyloid oligomers and amyloid fibrils. There are no treatments that directly target the aggregated species associated with these diseases. Yet, Hsp104 dissolves toxic oligomers and amyloid fibrils composed of alpha-synuclein, which are connected with Parkinson's Disease as well as amyloid forms of PrP. Importantly, Hsp104 reduces protein aggregation and ameliorates neurodegeneration in rodent models of Parkinson's Disease and Huntington's disease. Ideally, to optimize therapy and minimize side effects, Hsp104 would be engineered and potentiated to selectively remodel specific aggregates central to the disease in question. However, the limited structural and mechanistic understanding of how Hsp104 disaggregates such a diverse repertoire of aggregated structures and unrelated proteins frustrates these endeavors. To understand the structure and mechanism of Hsp104, it is essential to study the pure protein and reconstitute its disaggregase activity with minimal components. Hsp104 is a 102 kDa protein with a pI of -5.3, which hexamerizes in the presence of ADP or ATP, or at high protein concentrations in the absence of nucleotide. Here, we describe an optimized protocol for the purification of highly active, stable Hsp104 from E. coli. The use of E. coli allows simplified large-scale production and our method can be performed quickly and reliably for numerous Hsp104 variants. Our protocol increases Hsp104 purity and simplifies His(6)-tag removal compared to a previous purification method from E. coli. Moreover, our protocol is more facile and convenient than two more recent protocols.

Acidic residue modifications restore chaperone activity of β-casein interacting with lysozyme

An important factor in medicine and related industries is the use of chaperones to reduce protein aggregation. Here we show that chaperone ability is induced in β-casein by modification of its acidic residues using Woodward's Reagent K (WRK). Lysozyme at pH 7.2 was used as a target protein to study β-casein chaperone activities. The mechanism for chaperone activity of the modified β-casein was determined using UV–vis absorbencies, fluorescence spectroscopy, differential scanning calorimetry and theoretical calculations. Our results indicated that the β-casein destabilizes the lysozyme and increases its aggregation rate. However, WRK-ring sulfonate anion modifications enhanced the hydrophobicity of β-casein resulting in its altered net negative charge upon interactions with lysozyme. The reversible stability of lysozyme increased in the presence of WRK-modified β-casein, and hence its aggregation rate decreased. These results demonstrate the enhanced chaperone activity of modified β-casein and its protective effects on lysozyme refolding.

Sir2 is induced by oxidative stress in a yeast model of Huntington disease and its activation reduces protein aggregation

Huntington disease (HD) is a neurodegenerative disorder caused by expansion of CAG trinucleotide repeats, leading to an elongated polyglutamine sequence (polyQ) in the huntingtin protein. Misfolding of mutant polyQ proteins with expanded tracts results in aggregation, causing cytotoxicity. Oxidative stress in HD has been documented in humans as important to disease progression. Using yeast cells as a model of HD, we report that when grown at high glucose concentration, cells expressing mutant polyQ do not show apparent oxidative stress. At higher cell densities, when glucose becomes limiting and cells are metabolically shifting from fermentation to respiration, protein oxidation and catalase activity increases in relation to the length of the polyQ tract. Oxidative stress, either endogenous as a result of mutant polyQ expression or exogenously generated, increases Sir2 levels. Δ sir2 cells expressing expanded polyQ lengths show signs of oxidative stress even at the early exponential phase. In a wild-type background, isonicotinamide, a Sir2 activator, decreases mutant polyQ aggregation and the stress generated by expanded polyQ. Taken together, these results describe mutant polyQ proteins as being more toxic in respiring cells, causing oxidative stress and an increase in Sir2 levels. Activation of Sir2 would play a protective role against this toxicity.

Effect of sodium tetrathionate on amyloid fibril: Insight into the role of disulfide bond in amyloid progression

Tissue deposition of fibrillar protein aggregates called amyloid is the root cause of several degenerative diseases. Thus identification of compounds which can prevent or reduce protein aggregation can serve as a potential therapeutic target. In the present study we have shown inhibitory effect of sodium tetrathionate toward Hen egg white lysozyme (HEWL) amyloidogenesis at pH 2.0. Our study reveals that without sulfonation, sodium tetrathionate prevents amyloid fibril progression. Moreover, it shows that formation of disulfide bonds rather than exposure of hydrophobic surface in protein plays a critical role in initiating fibrillation process. Inhibitory effect of reducing agent β-mercaptoethanol toward fibrillation process also confirms the involvement of disulfide bond in initiating HEWL amyloidogenesis. These results provide important information toward understanding key interactions that guide amyloidogenesis, which may facilitate development of potential therapeutics.

Glucocorticoid receptor‐mediated reduction of IgG‐fusion protein aggregation in Chinese hamster ovary cells

Formation of high molecular weight (HMW) species is a common issue encountered during manufacture of protein therapeutics. With advanced purification techniques, efficient removal of protein aggregates is no longer a challenging task, but it is important to minimize protein aggregation level at the culture stage to reduce the downstream burden and improve overall process yield. In this regard, our recent effort on medium optimization has led us to unexpectedly discover that glucocorticoids can significantly reduce the formation of HMW species in IgG-fusion protein produced by CHO cells. First, the effectiveness of dexamethasone can be seen at nanomolar concentrations, which allows this glucocorticoid analog to be a cost-efficient chemical for reducing protein aggregation in cell cultures. Second, this reduction is mediated through glucocorticoid receptors (GR) as it is antagonized by GR antagonist RU486. Third, GR activation upregulates expression of glutathione reductase but not protein disulfide-isomerase, which may help with providing a balanced redox condition in the cells. Last, the beneficial effect of dexamethasone is not limited to one cell line, and it can be repeated in a different cell line, indicating that glucocorticoids are also applicable to other DG44 cell lines for reducing protein aggregation.

Thermal-Assisted Refolding: Dilution Folding Initiated at High Temperature

Protein refolding from unfolded state is usually carried out at low temperature to reduce protein aggregation and proteolytic degradation. This review briefly introduces a unique method for the protein refolding via high temperature, typically at above melting temperature of the protein.

Multiple Evolutionary Mechanisms Reduce Protein Aggregation~!2009-04-21~!2009-07-09~!2010-01-02~!

Multiple Evolutionary Mechanisms Reduce Protein Aggregation~!2009-04-21~!2009-07-09~!2010-01-02~!

Multiple Evolutionary Mechanisms Reduce Protein Aggregation

The folding of polypeptides into stable globular protein structures requires protein sequences with a relatively high hydrophobicity and secondary structure propensity. These biophysical properties, however, also favor protein aggregation via the formation of intermolecular beta-sheets and, as a result, globular structure and aggregation are inextricable properties of protein polypeptides. Aggregates that are enriched in beta-sheet structures have been found in diseased tissues in association with at least twenty different human disorders and the effect of aggregation on protein function include simple loss-of-function but also often a gain of toxicity. Given both the ubiquity and the potentially lethal consequences of protein aggregation, negative selective pressure strongly minimizes aggregation. Various evolutionary strategies keep aggregation in check, including (1) the optimisation of the thermodynamic stability of the protein, which precludes aggregation by burial of the aggregation prone regions in solvent inaccessible regions of the structure, (2) segregation between folding nuclei and aggregation nuclei within a protein sequence, (3) the placement of so-called gatekeeper residues at the flanks of aggregating segments, that reduce the aggregation rate of (partially) unfolded proteins, and (4) molecular chaperones that target aggregation nucleating sequences directly, thereby further suppressing aggregation in a cellular environment. In this review we describe the intrinsic features built into protein sequence and structure that protect against aggregation.

Critical role of transglutaminase and other stress proteins during neurodegenerative processes

Proteolytic stress, resulting from the intracellular accumulation of misfolded or aggregated proteins, which exceed the capacity of the ubiquitin-proteasome system to degrade them, plays a relevant role in neurodegenerative disorders, such as Alzheimer's disease, Parkinson's disease, and Huntington's chorea. Most of toxic protein aggregates are characterised by the presence of isopeptide bonds (cross-links) catalysed by transglutaminase activity; further, several disease-specific proteins-tau, amyloid-beta, alpha-synuclein, huntingtin-are in vitro and/or in vivo substrates of transglutaminase 2. These findings suggest an important role for transglutaminase 2-mediated cross-linking reactions in neurodegeneration. Therefore, the use of transglutaminase activity inhibitors could ameliorate neuronal cell death. New therapeutic perspectives also arise from the possibility to prevent or reduce protein aggregation by enhancing the activation of heat shock proteins, which have been shown to be potent suppressors of neurodegeneration in cell cultures/animal models. Interestingly, some heat shock proteins have been shown to be in vitro or in vivo cross-linked by transglutaminase 2. These observations seem to suggest that transglutaminase activity could be involved in the stabilization of intracellular protein aggregates by interfering with proteasomal degradation of misfolded proteins. Further studies are needed to validate leading hypotheses and to open new prospects for developing therapeutic tools.

Inhibition of α-mannosidase attenuates endoplasmic reticulum stress-induced neuronal cell death

N-glycosylation is crucial for proper folding of most of the proteins in the endoplasmic reticulum (ER). The N-glycans in the ER are mainly constructed of mannose. In this study, we examined whether inhibition of mannose trimming in the ER affects the susceptibility of PC-12 cells to ER stress. Pretreatment with 100 μM α-mannosidase inhibitor 1-deoxymannojirimycin (DMJ) in PC-12 cells significantly attenuated the cytotoxicity by ER stressors tunicamycin (TM), thapsigargin (TG), and amyloid β1-42 (Aβ1-42), and reduced caspase-3 activation by TM and TG. Pretreatment with DMJ also protected primary cultured mouse cortical neurons from Aβ1-42 toxicity. With regard to the effect of DMJ pretreatment on ER stress signaling in PC-12 cells, DMJ attenuated TM- and TG-induced CHOP expression and TG stimulated JNK phosphorylation, which is associated with ER stress dependent cell death. Next, we examined the effect of mannose oligosaccharides, which have similar structures to N-glycans in the ER, on amyloidogenesis of Aβ1-42 that causes ER stress dependent neuronal cell death. Mannopentaose (M5) and Man 9GlcNAc 2 (M9) oligosaccharides significantly inhibited the amyloidogenesis of Aβ1-42. Our data suggests that inhibition of N-glycan processing in the ER attenuates ER stress-induced cell death by increasing high-mannose type oligosaccharides that reduce protein aggregation, such as amyloidogenesis.