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. 2021 Mar 24;12(4):548–554. doi: 10.1021/acsmedchemlett.0c00350

Glucosamine and Its Analogues as Modulators of Amyloid-β Toxicity

Ana R Araújo †,‡,*, Vânia I B Castro †,‡, Rui L Reis †,‡, Ricardo A Pires †,‡,*
PMCID: PMC8040036  PMID: 33859794

Abstract

graphic file with name ml0c00350_0006.jpg

In Alzheimer’s disease (AD), amyloid-β (Aβ) oligomers are considered key mediators of synaptic dysfunction and cognitive impairment. These unstable intermediate Aβ species can interfere with different cellular organelles, leading to neuronal cell death, through the formation of Ca2+-permeable membrane pores, impairment in the levels of acetylcholine neurotransmitters, increased insulin resistance, promotion of pro-inflammatory cascades, among others. Based on a series of evidences that indicate the key role of glycosaminoglycans (GAGs) in amyloid plaque formation, we evaluated the capacity of four monosaccharides, i.e., glucosamine (GlcN), N-acetyl glucosamine (GlcNAc), glucosamine-6-sulfate (GlcN6S), and glucosamine-6-phosphate (GlcN6P), to reduce the Aβ-mediated pathological hallmarks. The tested monosaccharides, in particular, GlcN6S and GlcN6P, were able to interact with Aβ aggregates, reducing neuronal cell death, Aβ-mediated damage to the cellular membrane, acetylcholinesterase activity, insulin resistance, and pro-inflammation levels.

Keywords: Alzheimer’s disease, amyloid-beta peptide, glucosamine analogues, membrane dysfunction, insulin resistance

The aggregation of misfolded peptides/proteins is at the onset of different amyloid-based pathologies, including the most common neurodegenerative disorders, e.g., Alzheimer’s disease (AD) or Parkinson disease, but also metabolic ones, e.g., type-2 diabetes mellitus.1 In AD, there are two main pathological hallmarks, namely, the deposition of extracellular senile plaques composed of misfolded amyloid-β (Aβ) aggregates and the presence of intracellular neurofibrillary tangles of hyperphosphorylated Tau in the affected neurons.2 It has been under debate which is the primary one responsible for the onset of AD. While it has been reported that AD-mediated dementia only occurs in patients that present neurofibrillary tangles in the affected regions of the brain (i.e., medial temporal lobe and peripheral cortex),3 it has been also demonstrated that Aβ is present above a certain threshold in the biological environment before the deposition of hyperphosphorylated Tau and the beginning of dementia.4,5 These observations lead to the present notion that the increased Aβ deposition in the brain is at the onset of AD.

Aβ is generated and released to the extracellular space after the sequential cleavage of the transmembrane amyloid precursor protein (APP) by β-site amyloid precursor protein cleaving enzyme 1 (BACE1), followed by the γ-secretase complex. The generated Aβ monomers are highly prone to aggregate into cytotoxic supramolecular forms, putting them at the center of the disease progression.6,7 Initial studies reported that high molecular weight Aβ fibrils (adopting a parallel β-sheet conformation, as the ones in the senile plaques) were the main source of toxicity. However, more recently, it has been reported that it is the diffusible oligomers (usually adopting an antiparallel8 or a mixture of antiparallel8,9 and parallel10,11 β-sheet conformations) that are perturbing the cellular homeostasis and are highly toxic.12 Importantly, Aβ has been targeted by antibodies to tag them for elimination by the cellular machinery;13,14 however, until now, this strategy did not generate the expected outcomes.

Cytotoxic Aβ oligomers are usually generated during the aggregation pathway that ultimately leads to the formation of fibrils. However, the fibrils themselves are under a dynamic equilibrium between assembly and disassembly, where oligomers are transiently present. In order to reduce their presence, two main approaches have been suggested: (1) the remodeling of the oligomers into thermodynamically stable off-pathway noncytotoxic forms;15 or (2) the development of strategies that stabilize fibrils by blocking their disassembly into the cytotoxic Aβ oligomers.16

It is well-established that glycosaminoglycans (GAGs, e.g., heparan sulfate, chondroitin sulfate)17−20 can modulate the supramolecular assembly of Aβ, in particular, by stabilizing the nanofibers and protecting them against disassembly and proteolytic degradation.21 These interactions are described to occur mostly through electrostatic forces between the negatively charged saccharide units and the positively charged peptide domains.22 In addition, it is known that Aβ oligomers interact with the negatively charged membrane components (e.g., phospholipids and glycoproteins). Moreover, saccharide conjugates have been reported to ameliorate Aβ-mediated toxicity.23−26 It has been also shown that saccharide analogues modulate heparan sulfate synthesis, impacting in the production of Aβ of different lengths, i.e., 40–42.27

Based on this evidence, herein, we evaluated if glucosamine (GlcN) and its analogues are able to modulate the toxicity of Aβ42. We selected four GlcN analogues, namely, GlcN with a positive charge, N-acetyl glucosamine (GlcNAc) with a neutral charge, and glucosamine-6-sulfate (GlcN6S) and glucosamine-6-phosphate (GlcN6P) with a negative charge (structures presented in Scheme 1). These monosaccharides were chosen in order to evaluate if the electrostatic forces were indeed the main drivers of their activity in the modulation of the Aβ42 supramolecular assembly and cytotoxicity. Under these conditions, we hypothesize that the negatively charged saccharides (available in the extracellular space) are able to compete with the cell membrane glycoproteins for Aβ42 binding and sequestration. Moreover, the sulfated GAGs are known to interact specifically with different proteins,28 and by comparison between the activity of GlcN6S and GlcN6P, we can assess if the presence of a sulfate moiety is able to provide additional benefits in the modulation of the Aβ42 aggregation, toxicity, membrane disruption, and insulin resistance, typically observed in the AD pathological scenario. It is relevant to note that there are a series of compounds able to modulate the supramolecular assembly of Aβ42, namely, trimethylamine glycerol or DMSO,29 short peptides (able to accelerate Aβ aggregation),30 natural compounds (e.g., EGCG13 or vescalagin31), and many more. In the case of natural compounds, their application is usually hampered due to their low capacity to be absorbed by the body or problems related with their fast elimination. In the case of the monosaccharides studied herein, most of them are found in the constitution of GAGs and are usually stable under physiological conditions.

Scheme 1. Chemical Structure of the GlcN and Its Analogues: (A) GlcN, (B) GlcNAc, (C) GlcN6S, and (D) GlcN6P.

Scheme 1

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We started by screening the Aβ42 aggregation kinetics for 10 days in the absence/presence of several concentrations (from 250 μM up to 50 mM) of each monosaccharide using the Thioflavin-T (ThT) assay (sensitive to parallel β-sheets). Aβ42 aggregation (in the absence of monosaccharides) followed a typical profile presenting the secondary nucleation and fibril elongation regions, i.e., exponential growth and plateau phase, respectively (Figure S11).32 A strong ThT signal is observed during the formation/elongation of the Aβ42 fibrils (composed of parallel β-sheets) in the presence of the monosaccharides, throughout the whole range of concentrations with the exception of the 50 mM. All of the monosaccharides seem to be able to enhance the secondary nucleation (i.e., formation of new fibers from oligomers nucleated on the surface of the existing ones), promoting a robust elongation of the Aβ42 aggregates.33 Since fibrils are stated to be less cytotoxic, we selected the 1 mM concentration of each monosaccharide to follow their ability to remodel Aβ42 supramolecular organization. We then used Western blot (WB) with the 6E10 antibody to evaluate the size of peptide aggregates produced during the assembly pathway (Figure 1A,B and Figures S16 and S17) for 1 and 5 days. The observed remodeling of the Aβ42 aggregates seems to affect the section of the peptide related with 6E10 epitope binding site (i.e., region 1–16). This is more evident in the case of GlcN6S and GlcN6P (from day 1 of incubation until 5 days) due to the overall decrease of detected Aβ42 structures. Importantly, the presence of GlcN6S generated a significant decrease in the amount of the cytotoxic Aβ42 oligomers (sizes of aggregates <15 kDa) since day 1.

Figure 1.

Figure 1

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Relative densitometric bar graphs of Aβ42 assembly (25 μM) quantified by WB after (A) 1 day or (B) 5 days of incubation, using the antibody 6E10. Loss of antiparallel β-sheets in the supramolecular organization of Aβ42 followed by circular dichroism during (C) 1 and (D) 5 days in the presence of 1 mM of each monosaccharide. Error bars = SD, ***p < 0.001, **p < 0.01, *p < 0.05 (all vs control of 25 μM Aβ42).

To complement these data, we used circular dichroism (CD) to assess the Aβ42 secondary structure upon contact with the monosaccharides (Figures S12–S15) during 5 days. A series of alterations in the CD spectra (both in terms of intensity and profile) promoted by all monosaccharides are clearly observed. Aβ42 oligomers, protofibrils, and mature fibrils are organized under different secondary structures maintained by parallel or antiparallel β-sheets, which are dependent on the twisting angles between β-strands. We then fitted all the CD spectra using the BestSel34 deconvoluting algorithm, allowing one to predict the types of structures present in an ensemble of Aβ42 supramolecular aggregates. Some reports show that antiparallel β-sheets are related to cytotoxic oligomers.8 In contrast, the Aβ parallel β-sheets are usually associated with the less toxic and more stable species, e.g., nanofibers detected in the extracellular senile plaques.7

Our results (Figure 1C,D) are consistent with the ability of the monosaccharides (in particular, of GlcN6S) to decrease the antiparallel β-sheets characteristic of the cytotoxic Aβ42 aggregates. This observation is sustained over time, as after 5 days of incubation the reduction of the antiparallel arrangement is maintained, being consistent with the results obtained from the ThT and WB.

The Aβ42 supramolecular organization in the presence/absence of the monosaccharides was also assessed by attenuated total reflectance Fourier transform infrared (ATR-FTIR) (Figure 2) and dynamic light scattering (DLS) (Figure S18A). Using the DLS analysis, the existence of polymorphism of the Aβ42 aggregates in the presence and absence of each monosaccharide is clear (with two distinct peaks for Aβ42). In addition, the Aβ42 FTIR spectra in the absence and presence of the monosaccharides immediately after preparation (Figure S18B) shows a higher prevalence of the parallel β-sheets and turns (at ∼1625 and ∼1695 cm–1—related with elongated sheets, elongated β-strand formation, as well as planar sheet arrangements) in the supramolecular structure of Aβ42. Importantly, a peak near ∼1625 cm–1 was linked to parallel β-sheets (and to fibrils), whereas a peak at ∼1690 cm–1 was assigned to antiparallel β-sheets (and toxic oligomers).35 As in the CD experiments, the ATR-FTIR data indicate the prevalence of the parallel β-sheets in the presence of GlcN6S/GlcN6P. In contrast, the spectra of Aβ42 in the presence of GlcN/GlcNAc are similar to the one obtained for Aβ42 alone (Figure S19).

Figure 2.

Figure 2

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ATR-FTIR spectra of the Aβ42 in the presence/absence of 1 mM of GlcN6S and GlcN6P, after 5 days of incubation.

All of the monosaccharides, but, in particular, GlcN6S and GlcN6P, interact with Aβ42, remodeling its supramolecular structure. However, instead of reducing the presence of aggregates, it induced their formation but under morphologies that are distinct from the ones usually described for the Aβ42 oligomers. In order to evaluate if these alterations were concomitant with reduction of Aβ42 toxicity, we evaluated the impact of the presence of the monosaccharides in the Aβ42-mediated cell death using the neuroblastoma cell line (SH-SY5Y). An initial screening of all the monosaccharides under cell culture conditions, in the absence of Aβ42, showed no major cytotoxicity for the 1 mM concentration (Figure S21A). Upon addition of Aβ42, all the monosaccharides, but, in particular, GlcN6S/GlcN6P, were able to rescue cell viability during 5 h, 24 h, and 5 days of incubation (Figures S21 and S22).

As mentioned before, several studies have revealed that one of the outcomes of the presence of Aβ42 in the pericellular space is the disruption of the cell membrane, leading to the influx of Ca2+ from the extracellular medium into the cytosol. This event is at the origin of a more complex cascade of biochemical changes that lead to an increased oxidative stress and neuronal cell death.36 We then evaluated if the presence of the monosaccharides is able to alter the Ca2+ influx caused by the presence of Aβ42. We used Fluo3-AM (Figures 3A and S24) and Calcein-AM (Figure S25) as fluorescent Ca2+ probes (i.e., increased fluorescence upon binding to the free Ca2+ present in the cytosol).37,38 The results obtained with both probes were comparable: i.e. in the presence of Aβ42 and GlcN6S the Fluo3-AM fluorescence reduces ∼41 and ∼60% for Calcein-AM (both to similar levels as the control, i.e., cells cultured in the absence of both Aβ42 and GlcN6S). In general, the presence of GlcN6S and GlcN6P protected the cell membrane from disruption and from the generation of additional Ca2+ pores, maintaining the ionic balance in the intracellular environment. This observation is consistent with the vital role of the negative charge of the monosaccharides to promote their interaction with Aβ42, diminishing its capacity to perturb the homeostasis of the lipid bilayer of the cell membrane.

Figure 3.

Figure 3

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(A) Representative fluorescence images of SH-SY5Y cells cultured for 24 h in the presence of Aβ42 (25 μM) and each monosaccharide (1 mM) showing the levels of intracellular free Ca2+ measured using Fluo3-AM. Scale bar = 100 μm (insets = 50 μm). (B) Graphical representation showing the Ca2+ imbalance caused by Aβ42 through their interaction with the lipid raft.

There are other biochemical alterations that are commonly observed in AD. One example is an enhanced activity of acetylcholinesterase (AChE), an enzyme that regulates the level of the acetylcholine neurotransmitter (related with memory, motivation, and movement) in the synaptic cleft.36 AChE cleaves acetylcholine, affecting the communication between neurons.39 It is usually overexpressed in AD, leading to the use of inhibitors as part of the available clinical treatments. We were able to replicate this increase in AChE activity of SH-SY5Y cells in the presence of Aβ42 (Figure S26, V vs Aβ42). We then tested if the presence of the monosaccharides was able to re-establish the basal level of AChE activity. Upon 1 day of incubation, GlcN6S significantly reduced the AChE activity to levels closer to the ones detected in the absence of Aβ42. Moreover, the acetylcholine receptor location and function can be altered by changes in the cell membrane, as it is highly dependent on Ca2+ channels and may form a complex with Aβ42 oligomers interfering in the protein kinase B (AKT) signaling pathway (related with glucose metabolism, apoptosis, or cell proliferation).39,40 These results indicate that there might be other pathological events, such as insulin resistance and deficiency in insulin signaling, that might be attenuated by the presence of GlcN6S. Therefore, to test this hypothesis, we analyzed the insulin signaling in SH-SY5Y cells, namely, the phosphorylation of AKT into pAKT1 (S473) and insulin receptor substrate 1 (IRS1) into pIRS1 (S612).41

As detailed in Figure 4D, insulin signaling involves its recognition by the insulin receptor (IR). Insulin binds to the α-subunit of the IR, and the β-subunit becomes activated and autophosphorylates on its tyrosine residues, leading to the phosphorylation and activation of IRS1.42

Figure 4.

Figure 4

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Ability of each monosaccharide to modulate the expression of (A) pIRS1, (B) pAKT1, and (C) Annexin 1 (ANXA1) by SH-SY5Y cells cultured for 1 h in the absence/presence of Aβ42. Proteins were resolved by SDS-PAGE and visualized by WB; **p < 0.01 and *p < 0.05 (vs V); ##p < 0.01 and #p < 0.05 (vs 25 μM Aβ42). (D) Schematic representation of the insulin signaling pathway affected by Aβ42.

Under normal metabolism, the IR is phosphorylated in the tyrosine residues. In contrast, phosphorylation of serine residues hampers normal signal transduction, promoting insulin resistance.43 Therefore, the resistance pathway can be followed by tracking the phosphorylation of IRS1 at specific serine residues, e.g., S612.44 Moreover, phosphorylation of AKT is related with the translocation of the glucose transporter GLUT4 to the cell membrane, which occurs later in the insulin signaling cascade. In this case, a reduction of pAKT leads to the inhibition of the phosphorylation of AS160, which is required for the insulin-stimulated translocation of GLUT4 to the cell surface.41

Overall, under insulin resistance, pIRS (S612) is augmented and pAKT is reduced. We then used these markers to assess if the monosaccharides were able to modulate the Aβ42-mediated insulin resistance.45 The cell culture conditions used for the experiments included the presence of 10% of fetal bovine serum (FBS). FBS is reported to contain ∼10 μU/mL of insulin, leading to the activation of IRS1, without any additional insulin stimulus, as we observed. Anyway, we tested the addition of four concentrations of insulin in SH-SY5Y cell culture, during 1 h (Figure S27). Afterward, we monitored the insulin pathway under standard culture conditions (i.e., no additional insulin stimulus) and also with the supplementation of insulin (at 5 nM). Under standard culture conditions, the presence of Aβ42 (25 μM) alone increases the expression of pIRS1 at S612 (after 1 h of cell culture). The addition of each monosaccharide reduced its expression levels to close to the ones observed in the control experiment. However, GlcNAc, GlcN6S, and GlcN6P were clearly more efficient (Figure 4A). Of note, the supplementation of GlcN in animal intravenous studies shows that GlcN-mediated hexosamine biosynthesis increases in insulin-sensitive tissues, a metabolic pathway that has been implicated in the development of insulin resistance and impairment of glucose metabolism (typical features of type-2 diabetes).46 This is consistent with the inability of GlcN to reduce insulin resistance under our experimental conditions. We also evaluated the levels of insulin signaling by assessing the phosphorylation of AKT1 at S473 (pAKT1). In this case, we observed an increased expression of pAKT1 in the presence of GlcN6S and GlcN6P, indicating a trend to reach normal glucose metabolism (Figure 4B). In general, the expression of both pIRS1 (S612) and pAKT1, in the presence of GlcN6S and GlcN6P, supports the partial recovery of the homeostasis of insulin signaling. Of note, and as observed for the evaluation of the stability of the lipid bilayer, only the negatively charged monosaccharides were able to provide an overall recovery of the insulin signaling, confirming that their charge is critical to reduce the Aβ42-mediated dysfunctions.

Finally, most of the previously described AD-related pathological hallmarks are associated with inflammation. We then assessed the expression of Annexin 1 (ANXA1), as it is reported to be involved in the inflammatory response.47 ANXA1 is also a Ca2+-dependent phospholipid-binding protein, and at low Ca2+ concentrations, the ANXA1 N-terminal domain is embedded within the Ca2+ pore. The increment of Ca2+ concentrations (imbalance) causes the overexpression of ANXA1 in the extracellular space and may mediate multiple inflammatory responses of the cellular machinery.48 Initial ANXA1 overexpression was detected in the presence of Aβ42 alone (Figure 4C), which is in line with an increment of Aβ42-mediated inflammation. GlcN6S and GlcN6P restored ANXA1 expression to normal levels, indicating a reduction of the inflammatory pathway.

The results obtained by the quantification of pIRS1 (S612), pAKT1, and ANXA1 show that GlcN6S and GlcN6P are able to re-establish the normal insulin signaling. Additionally, the most important stimulus for insulin production is a postprandial increase of blood glucose level. Insulin is then released into the bloodstream and binds to the insulin receptors present in the cells from the peripheral tissues promoting (at the end of the pathway) the translocation of GLUT4 to the cell membrane and the subsequent transportation of glucose into the cell.49 We then stimulated cells with 5 nM of insulin (Figures S28 and S29) that recovered cells from the Aβ42-mediated damage (i.e., lower pIRS1 and ANXA1), which was enhanced by the presence of GlcN6S and GlcN6P.

Overall, we evaluated the capacity of four monosaccharides in their ability to re-establish the homeostasis of a series of AD hallmarks, namely, remodeling of the Aβ42 aggregates into noncytotoxic forms, reduction of membrane dysfunction, leveling of the AChE enzymatic activity, re-establishment of basal levels of insulin signaling, and reduction of inflammation. We found that GlcN6S and GlcN6P were able to promote the recovery from all of these AD-related dysfunctions. These results are probably related to their negative charge, which reduces their ability to be internalized by the cells (due to negative charge of the cell membrane), allowing them to interact electrostatically with Aβ42. Some of our observations have been previously reported for the GAG chondroitin sulfate at concentrations of 0.5 or 1.8 mg/mL, which are much higher than the ones herein used (i.e., 1 mM is equivalent to between 0.18 and 0.26 mg/mL, depending on the monosaccharide).20 It has been also shown that GlcNAc glycosylation of APP protects the AD brain.50 Importantly, Aβ42 is not glycosylated: our results indicate that nonconjugated GlcNAc does not seem to ameliorate Aβ42-mediated AD hallmarks. In addition, other small compounds, such as NIC5-15, can also modulate the AD hallmarks, but it does not act directly in the assembly of Aβ42, but by modulating APP and γ-secretase activities.51 In contrast, the monosaccharides herein tested are able to directly remodel the Aβ42 secondary structure.

We believe that GlcN6S and GlcN6P present potential as single AD drug leads or as bioactive moieties to be integrated into nanocarriers targeting the control of the onset and progression of AD. Nevertheless, a mixture of molecules can also be explored in order to test if synergistic effects are observed.52 Our results can also pave the way to the testing of negatively charged monosaccharides for their capacity to ameliorate the hallmarks of other amyloid-based neurodegenerative disorders, through the leveling of their ensuing pathological biochemical cascades.

Acknowledgments

We acknowledge the financial support from the EC (FORECAST–668983). A.R.A. acknowledges the “Programa Operacional Regional do Norte”, “Fundo Social Europeu”, and Norte2020 PATH for her Ph.D. grant (NORTE-08-5369-FSE-000044).

Glossary

Abbreviations

GAGs

glycosaminoglycans

GlcN

glucosamine

GlcNAc

N-acetyl glucosamine

GlcN6S

glucosamine-6-sulfate

GlcN6P

glucosamine-6-phosphate

Aβ

amyloid-β

TREM2

triggering receptor expressed on myeloid cells 2

PLCG2

phospholipase C-gamma 2

ABCA

ATP-binding cassette cholesterol transporter

apoE

apolipoprotein E

G-protein

guanine nucleotide-binding proteins

IR

insulin receptor

AChE

acetylcholinesterase

AKT

protein kinase B

IRS1

insulin receptor substrate 1

ANXA1

annexin 1

Supporting Information Available

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsmedchemlett.0c00350.

  • Materials and methods and results from in vitro protein aggregation, e.g., remodeling of the Aβ42 secondary structure in the presence/absence of each monosaccharide; SH-SY5Y cell studies assessing Aβ42-mediated dysfunction, in the presence and absence of each monosaccharide (PDF)

Author Contributions

The manuscript was written through contributions of all authors.

The authors declare no competing financial interest.

Supplementary Material

ml0c00350_si_001.pdf (1.9MB, pdf)

References

  1. Masters C. L.; Bateman R.; Blennow K.; Rowe C. C.; Sperling R. A.; Cummings J. L. Alzheimer’s disease. Nat. Rev. Dis. Primers 2015, 1, 15056. 10.1038/nrdp.2015.56. [DOI] [PubMed] [Google Scholar]
  2. Spires-Jones T. L.; Hyman B. T. The Intersection of Amyloid Beta and Tau at Synapses in Alzheimer’s Disease. Neuron 2014, 82, 756–771. 10.1016/j.neuron.2014.05.004. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Busche M. A.; Hyman B. T. Synergy between amyloid-β and tau in Alzheimer’s disease. Nat. Neurosci. 2020, 23, 1183–1193. 10.1038/s41593-020-0687-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Reimand J.; Collij L.; Scheltens P.; Bouwman F.; Ossenkoppele R.. Amyloid-beta CSF/PET discordance vs tau load 5 years later: It takes two to tangle. medRxiv 2020 10.1101/2020.01.29.20019539. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Pontecorvo M. J.; Devous M. D. Sr.; Navitsky M.; Lu M.; Salloway S.; Schaerf F. W.; Jennings D.; Arora A. K.; McGeehan A.; Lim N. C.; Xiong H.; Joshi A. D.; Siderowf A.; Mintun M. A.; Relationships between flortaucipir PET tau binding and amyloid burden, clinical diagnosis, age and cognition. Brain 2017, 140, 748–763. 10.1093/brain/aww334. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Aguzzi A.; O’Connor T. Protein aggregation diseases: pathogenicity and therapeutic perspectives. Nat. Rev. Drug Discovery 2010, 9, 237–248. 10.1038/nrd3050. [DOI] [PubMed] [Google Scholar]
  7. Knowles T. P.; Vendruscolo M.; Dobson C. M. The amyloid state and its association with protein misfolding diseases. Nat. Rev. Mol. Cell Biol. 2014, 15, 384–396. 10.1038/nrm3810. [DOI] [PubMed] [Google Scholar]
  8. Cerf E.; Sarroukh R.; Tamamizu-Kato S.; Breydo L.; Derclaye S.; Dufrene Y. F.; Narayanaswami V.; Goormaghtigh E.; Ruysschaert J. M.; Raussens V. Antiparallel beta-sheet: a signature structure of the oligomeric amyloid beta-peptide. Biochem. J. 2009, 421, 415–423. 10.1042/BJ20090379. [DOI] [PubMed] [Google Scholar]
  9. Gao Y.; Guo C.; Watzlawik J. O.; Randolph P. S.; Lee E. J.; Huang D.; Stagg S. M.; Zhou H.-X.; Rosenberry T. L.; Paravastu A. K. Out-of-Register Parallel β-Sheets and Antiparallel β-Sheets Coexist in 150-kDa Oligomers Formed by Amyloid-β(1–42). J. Mol. Biol. 2020, 432, 4388–4407. 10.1016/j.jmb.2020.05.018. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Chimon S.; Shaibat M. A.; Jones C. R.; Calero D. C.; Aizezi B.; Ishii Y. Evidence of fibril-like β-sheet structures in a neurotoxic amyloid intermediate of Alzheimer’s β-amyloid. Nat. Struct. Mol. Biol. 2007, 14, 1157–1164. 10.1038/nsmb1345. [DOI] [PubMed] [Google Scholar]
  11. Benzinger T. L.; Gregory D. M.; Burkoth T. S.; Miller-Auer H.; Lynn D. G.; Botto R. E.; Meredith S. C. Propagating structure of Alzheimer’s β-amyloid (10–35) is parallel β-sheet with residues in exact register. Proc. Natl. Acad. Sci. U. S. A. 1998, 95, 13407–13412. 10.1073/pnas.95.23.13407. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Verma M.; Vats A.; Taneja V. Toxic species in amyloid disorders: Oligomers or mature fibrils. Ann. Indian Acad. Neurol 2015, 18, 138–145. 10.4103/0972-2327.144284. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Panza F.; Lozupone M.; Seripa D.; Imbimbo B. P. Amyloid-beta immunotherapy for alzheimer disease: Is it now a long shot?. Ann. Neurol. 2019, 85, 303–315. 10.1002/ana.25410. [DOI] [PubMed] [Google Scholar]
  14. Rajasekhar K.; Chakrabarti M.; Govindaraju T. Function and toxicity of amyloid beta and recent therapeutic interventions targeting amyloid beta in Alzheimer’s disease. Chem. Commun. 2015, 51, 13434–13450. 10.1039/C5CC05264E. [DOI] [PubMed] [Google Scholar]
  15. Sandberg A.; Luheshi L. M.; Sollvander S.; Pereira de Barros T.; Macao B.; Knowles T. P.; Biverstal H.; Lendel C.; Ekholm-Petterson F.; Dubnovitsky A.; Lannfelt L.; Dobson C. M.; Hard T. Stabilization of neurotoxic Alzheimer amyloid-beta oligomers by protein engineering. Proc. Natl. Acad. Sci. U. S. A. 2010, 107, 15595–15600. 10.1073/pnas.1001740107. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Cohen S. I. A.; Cukalevski R.; Michaels T. C. T.; Saric A.; Tornquist M.; Vendruscolo M.; Dobson C. M.; Buell A. K.; Knowles T. P. J.; Linse S. Distinct thermodynamic signatures of oligomer generation in the aggregation of the amyloid-beta peptide. Nat. Chem. 2018, 10, 523–531. 10.1038/s41557-018-0023-x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Fraser P. E.; Darabie A. A.; McLaurin J. A. Amyloid-beta interactions with chondroitin sulfate-derived monosaccharides and disaccharides. implications for drug development. J. Biol. Chem. 2001, 276, 6412–6419. 10.1074/jbc.M008128200. [DOI] [PubMed] [Google Scholar]
  18. Jha S.; Patil S. M.; Gibson J.; Nelson C. E.; Alder N. N.; Alexandrescu A. T. Mechanism of Amylin Fibrillization Enhancement by Heparin. J. Biol. Chem. 2011, 286, 22894–22904. 10.1074/jbc.M110.215814. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Rajasekhar K.; Govindaraju T. Current progress, challenges and future prospects of diagnostic and therapeutic interventions in Alzheimer’s disease. RSC Adv. 2018, 8, 23780–23804. 10.1039/C8RA03620A. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Fernandez-Busquets X.; Ponce J.; Bravo R.; Arimon M.; Martianez T.; Gella A.; Cladera J.; Durany N. Modulation of amyloid beta peptide(1–42) cytotoxicity and aggregation in vitro by glucose and chondroitin sulfate. Curr. Alzheimer Res. 2010, 7, 428–438. 10.2174/156720510791383787. [DOI] [PubMed] [Google Scholar]
  21. Iannuzzi C.; Irace G.; Sirangelo I. The effect of glycosaminoglycans (GAGs) on amyloid aggregation and toxicity. Molecules 2015, 20, 2510–2528. 10.3390/molecules20022510. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Meisl G.; Yang X.; Dobson C. M.; Linse S.; Knowles T. P. Modulation of electrostatic interactions to reveal a reaction network unifying the aggregation behaviour of the Ab42 peptide and its variants. Chemical science 2017, 8, 4352–4362. 10.1039/C7SC00215G. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Pan R.-Y.; Ma J.; Kong X.-X.; Wang X.-F.; Li S.-S.; Qi X.-L.; Yan Y.-H.; Cheng J.; Liu Q.; Jin W.; Tan C.-H.; Yuan Z. Sodium rutin ameliorates Alzheimer’s disease–like pathology by enhancing microglial amyloid-β clearance. Sci. Adv. 2019, 5, eaau6328 10.1126/sciadv.aau6328. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Paul A.; Li W.-H.; Viswanathan G. K.; Arad E.; Mohapatra S.; Li G.; Jelinek R.; Gazit E.; Li Y.-M.; Segal D. Tryptophan–glucosamine conjugates modulate tau-derived PHF6 aggregation at low concentrations. Chem. Commun. 2019, 55, 14621–14624. 10.1039/C9CC06868F. [DOI] [PubMed] [Google Scholar]
  25. Li G.; Yang W.-Y.; Li W.-H.; Luo Y.-Y.; Lim Y.-J.; Li Y.; Paul A.; Segal D.; Hong L.; Li Y.-M. Rational design of a cocktail of inhibitors against Aβ aggregation. Chem. - Eur. J. 2020, 26 (16), 3499–3503. 10.1002/chem.201905621. [DOI] [PubMed] [Google Scholar]
  26. Rigacci S.; Guidotti V.; Bucciantini M.; Nichino D.; Relini A.; Berti A.; Stefani M. Aβ (1–42) aggregates into non-toxic amyloid assemblies in the presence of the natural polyphenol oleuropein aglycon. Curr. Alzheimer Res. 2011, 8, 841–852. 10.2174/156720511798192682. [DOI] [PubMed] [Google Scholar]
  27. Kisilevsky R.; Szarek W. A.; Ancsin J.; Vohra R.; Li Z.; Marone S. Novel glycosaminoglycan precursors as antiamyloid agents. J. Mol. Neurosci. 2004, 24, 167–172. 10.1385/JMN:24:1:167. [DOI] [PubMed] [Google Scholar]
  28. Gandhi N. S.; Mancera R. L. The structure of glycosaminoglycans and their interactions with proteins. Chem. Biol. Drug Des. 2008, 72, 455–482. 10.1111/j.1747-0285.2008.00741.x. [DOI] [PubMed] [Google Scholar]
  29. Bieschke J.; Herbst M.; Wiglenda T.; Friedrich R. P; Boeddrich A.; Schiele F.; Kleckers D.; Lopez del Amo J. M.; Gruning B. A; Wang Q.; Schmidt M. R; Lurz R.; Anwyl R.; Schnoegl S.; Fandrich M.; Frank R. F; Reif B.; Gunther S.; Walsh D. M; Wanker E. E Small-molecule conversion of toxic oligomers to nontoxic β-sheet–rich amyloid fibrils. Nat. Chem. Biol. 2012, 8, 93–101. 10.1038/nchembio.719. [DOI] [PubMed] [Google Scholar]
  30. Soudy R.; Patel A.; Fu W.; Kaur K.; MacTavish D.; Westaway D.; Davey R.; Zajac J.; Jhamandas J. Cyclic AC253, a novel amylin receptor antagonist, improves cognitive deficits in a mouse model of Alzheimer’s disease. Alzheimers Dement (N Y) 2017, 3, 44–56. 10.1016/j.trci.2016.11.005. [DOI] [PMC free article] [PubMed] [Google Scholar]
  31. Araujo A. R.; Camero S.; Taboada P.; Reis R. L.; Pires R. A. Vescalagin and castalagin reduce the toxicity of amyloid-beta42 oligomers through the remodelling of its secondary structure. Chem. Commun. (Cambridge, U. K.) 2020, 56, 3187–3190. 10.1039/D0CC00192A. [DOI] [PubMed] [Google Scholar]
  32. Cohen S. I.; Linse S.; Luheshi L. M.; Hellstrand E.; White D. A.; Rajah L.; Otzen D. E.; Vendruscolo M.; Dobson C. M.; Knowles T. P. Proliferation of amyloid-beta42 aggregates occurs through a secondary nucleation mechanism. Proc. Natl. Acad. Sci. U. S. A. 2013, 110, 9758–9763. 10.1073/pnas.1218402110. [DOI] [PMC free article] [PubMed] [Google Scholar]
  33. Törnquist M.; Michaels T. C. T.; Sanagavarapu K.; Yang X.; Meisl G.; Cohen S. I. A.; Knowles T. P. J.; Linse S. Secondary nucleation in amyloid formation. Chem. Commun. 2018, 54, 8667–8684. 10.1039/C8CC02204F. [DOI] [PubMed] [Google Scholar]
  34. Micsonai A.; Wien F.; Kernya L.; Lee Y. H.; Goto Y.; Refregiers M.; Kardos J. Accurate secondary structure prediction and fold recognition for circular dichroism spectroscopy. Proc. Natl. Acad. Sci. U. S. A. 2015, 112, E3095–3103. 10.1073/pnas.1500851112. [DOI] [PMC free article] [PubMed] [Google Scholar]
  35. Sarroukh R.; Goormaghtigh E.; Ruysschaert J.-M.; Raussens V. ATR-FTIR: A “rejuvenated” tool to investigate amyloid proteins. Biochim. Biophys. Acta, Biomembr. 2013, 1828, 2328–2338. 10.1016/j.bbamem.2013.04.012. [DOI] [PubMed] [Google Scholar]
  36. Fabiani C.; Antollini S. S. Alzheimer’s Disease as a Membrane Disorder: Spatial Cross-Talk Among Beta-Amyloid Peptides, Nicotinic Acetylcholine Receptors and Lipid Rafts. Front. Cell. Neurosci. 2019, 13, 309. 10.3389/fncel.2019.00309. [DOI] [PMC free article] [PubMed] [Google Scholar]
  37. Evangelisti E.; Cascella R.; Becatti M.; Marrazza G.; Dobson C. M.; Chiti F.; Stefani M.; Cecchi C. Binding affinity of amyloid oligomers to cellular membranes is a generic indicator of cellular dysfunction in protein misfolding diseases. Sci. Rep. 2016, 6, 32721. 10.1038/srep32721. [DOI] [PMC free article] [PubMed] [Google Scholar]
  38. Patel H.; Tscheka C.; Heerklotz H. Characterizing vesicle leakage by fluorescence lifetime measurements. Soft Matter 2009, 5, 2849–2851. 10.1039/b908524f. [DOI] [Google Scholar]
  39. Ma K. G.; Qian Y. H. Alpha 7 nicotinic acetylcholine receptor and its effects on Alzheimer’s disease. Neuropeptides 2019, 73, 96–106. 10.1016/j.npep.2018.12.003. [DOI] [PubMed] [Google Scholar]
  40. Fabiani C.; Antollini S. S. Alzheimer’s Disease as a Membrane Disorder: Spatial Cross-Talk Among Beta-Amyloid Peptides, Nicotinic Acetylcholine Receptors and Lipid Rafts. Front. Cell. Neurosci. 2019, 13, 309. 10.3389/fncel.2019.00309. [DOI] [PMC free article] [PubMed] [Google Scholar]
  41. Świderska E.; Strycharz J.; Wróblewski A.; Szemraj J.; Drzewoski J.; Śliwińska A.. Role of PI3K/AKT Pathway in Insulin-Mediated Glucose Uptake. Blood Glucose Levels; IntechOpen, 2020; pp 155–160. [Google Scholar]
  42. Olivares-Reyes J. A.; Arellano-Plancarte A.; Castillo-Hernandez J. R. Angiotensin II and the development of insulin resistance: implications for diabetes. Mol. Cell. Endocrinol. 2009, 302, 128–139. 10.1016/j.mce.2008.12.011. [DOI] [PubMed] [Google Scholar]
  43. Arnold S. E.; Arvanitakis Z.; Macauley-Rambach S. L.; Koenig A. M.; Wang H. Y.; Ahima R. S.; Craft S.; Gandy S.; Buettner C.; Stoeckel L. E.; Holtzman D. M.; Nathan D. M. Brain insulin resistance in type 2 diabetes and Alzheimer disease: concepts and conundrums. Nat. Rev. Neurol. 2018, 14, 168–181. 10.1038/nrneurol.2017.185. [DOI] [PMC free article] [PubMed] [Google Scholar]
  44. Copps K. D.; White M. F. Regulation of insulin sensitivity by serine/threonine phosphorylation of insulin receptor substrate proteins IRS1 and IRS2. Diabetologia 2012, 55, 2565–2582. 10.1007/s00125-012-2644-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
  45. Najem D.; Bamji-Mirza M.; Yang Z.; Zhang W. Aβ-Induced Insulin Resistance and the Effects of Insulin on the Cholesterol Synthesis Pathway and Aβ Secretion in Neural Cells. Neurosci. Bull. 2016, 32, 227–238. 10.1007/s12264-016-0034-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
  46. Marshall S.; Bacote V.; Traxinger R. Discovery of a metabolic pathway mediating glucose-induced desensitization of the glucose transport system. Role of hexosamine biosynthesis in the induction of insulin resistance. J. Biol. Chem. 1991, 266, 4706–4712. 10.1016/S0021-9258(19)67706-9. [DOI] [PubMed] [Google Scholar]
  47. Perretti M.; D’acquisto F. Annexin A1 and glucocorticoids as effectors of the resolution of inflammation. Nat. Rev. Immunol. 2009, 9, 62–70. 10.1038/nri2470. [DOI] [PubMed] [Google Scholar]
  48. Zhao B.; Wang J.; Liu L.; Li X.; Liu S.; Xia Q.; Shi J. Annexin A1 translocates to nucleus and promotes the expression of pro-inflammatory cytokines in a PKC-dependent manner after OGD/R. Sci. Rep. 2016, 6, 27028–27028. 10.1038/srep27028. [DOI] [PMC free article] [PubMed] [Google Scholar]
  49. Di Camillo B.; Carlon A.; Eduati F.; Toffolo G. M. A rule-based model of insulin signalling pathway. BMC Syst. Biol. 2016, 10, 38. 10.1186/s12918-016-0281-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
  50. Zhu Y. P.; Shan X. Y.; Yuzwa S. A.; Vocadlo D. J. The Emerging Link between O-GlcNAc and Alzheimer Disease. J. Biol. Chem. 2014, 289, 34472–34481. 10.1074/jbc.R114.601351. [DOI] [PMC free article] [PubMed] [Google Scholar]
  51. McLaurin J.; Kierstead M. E; Brown M. E; Hawkes C. A; Lambermon M. H L; Phinney A. L; Darabie A. A; Cousins J. E; French J. E; Lan M. F; Chen F.; Wong S. S N; Mount H. T J; Fraser P. E; Westaway D.; George-Hyslop P. S. Cyclohexanehexol inhibitors of Abeta aggregation prevent and reverse Alzheimer phenotype in a mouse model. Nat. Med. 2006, 12, 801–808. 10.1038/nm1423. [DOI] [PubMed] [Google Scholar]
  52. Zhang H. Y. One-compound-multiple-targets strategy to combat Alzheimer’s disease. FEBS Lett. 2005, 579, 5260–5264. 10.1016/j.febslet.2005.09.006. [DOI] [PubMed] [Google Scholar]

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