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Amyloid β and Alzheimer’s Disease: Molecular Updates from Physiology to Pathology 3.0

A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Molecular Neurobiology".

Deadline for manuscript submissions: closed (15 October 2023) | Viewed by 5728

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Guest Editor
Italian National Research Council, Institute of Crystallography (IC), 95126 Catania, Italy
Interests: Alzheimer’s disease; molecular neurobiology; amyloid-β; primary cortical neurons; signal transduction; BDNF; insulin and insulin-like growth factor signaling in Alzheimer's disease; HSP60; Aβ and copper; small molecules and peptide inhibitors of Aβ aggregation
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Special Issue Information

Dear Colleagues,

This Special Issue is the continuation of our previous Special Issue "Amyloid β and Alzheimer’s Disease: Molecular Updates from Physiology to Pathology 2.0".

Alzheimer’s disease (AD) is still an incurable disease with an incidence that is expected to increase in the near future. In previous decades, the pathophysiology of AD has been extensively investigated. Several approaches have been employed to disclose the molecular mechanisms underlying the cellular dysfunctions typically observed in AD. From in vitro and in vivo findings, we have learned that Aβ oligomers (AβOs), rather than Aβ fibrils, are mainly responsible for the effects leading to neurodegeneration. They have shown a better correlation with the severity of the disease and, in line with this observation, were found to induce synaptic dysfunction in the early stage of the disease, promote oxidative stress, and interfere with the activation of important cellular receptors. However, besides these unquestionable roles of Aβ oligomers, the primary cause of Aβ over-production and aggregation is far from being completely clarified.

Moreover, after initial evidence that Aβ monomers are innocuous, an increasing amount of data have indicated that Aβ may have important physiological roles in neuronal activity. A more comprehensive understanding of Aβ functions, from physiology to the occurrence of AD pathological conditions, could contribute to the refinement of pharmacological interventions and the design of new drug candidates.

Most AD drugs have been projected to block Aβ production or aggregation. However, the targeting of all Aβ species, including monomers, might be the reason for the continuous failure of clinical trials. The recent encouraging results of antibodies which preferentially bind to toxic AβOs seem to support this view.

The aim of this Special Issue of IJMS is to collect, in a broader perspective, scientific papers as well as reviews of the current literature, that deal with amyloid beta peptide function in health and/or disease. All original works that look at the role of Aβ within and beyond the disease and contribute to the improvement of the molecular understanding of Alzheimer’s disease are welcome.

This special issue is supervised by Dr. Maria Laura Giuffrida and assisted by our Topical Advisory Panel Member Dr. Binsen Li (David Geffen School of Medicine at UCLA, Los Angeles, CA, USA).

Dr. Maria Laura Giuffrida
Guest Editor

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. International Journal of Molecular Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. There is an Article Processing Charge (APC) for publication in this open access journal. For details about the APC please see here. Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Alzheimer’s disease
  • Aβ monomers
  • Aβ oligomers
  • signal transduction
  • neuroprotection
  • anti- Aβ therapy

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Published Papers (3 papers)

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20 pages, 3406 KiB  
Article
The Unfolded Protein Response in a Murine Model of Alzheimer’s Disease: Looking for Predictors
by Giulia Sita, Agnese Graziosi, Camilla Corrieri, Luca Ghelli, Sabrina Angelini, Pietro Cortelli, Patrizia Hrelia and Fabiana Morroni
Int. J. Mol. Sci. 2023, 24(22), 16200; https://doi.org/10.3390/ijms242216200 - 11 Nov 2023
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Abstract
Alzheimer’s disease (AD) represents the most frequent type of dementia worldwide, and aging is the most important risk factor for the sporadic form of the pathology. The endoplasmic reticulum (ER), the main cellular actor involved in proteostasis, appears significantly compromised in AD due [...] Read more.
Alzheimer’s disease (AD) represents the most frequent type of dementia worldwide, and aging is the most important risk factor for the sporadic form of the pathology. The endoplasmic reticulum (ER), the main cellular actor involved in proteostasis, appears significantly compromised in AD due to the accumulation of the β-amyloid (Aβ) protein and the phosphorylated Tau protein. Increasing protein misfolding activates a specific cellular response known as Unfolded Protein Response (UPR), which orchestrates the recovery of ER function. The aim of the present study was to investigate the role of UPR in a murine model of AD induced by intracerebroventricular (i.c.v.) injection of Aβ1–42 oligomers at 3 or 18 months. The oligomer injection in aged animals induced memory impairment, oxidative stress, and the depletion of glutathione reserve. Furthermore, the RNA sequencing and the bioinformatic analysis performed showed the enrichment of several pathways involved in neurodegeneration and protein regulations. The analysis highlighted the significant dysregulation of the protein kinase RNA-like ER kinase (PERK), inositol-requiring protein 1α (IRE1α) and activating transcription factor 6 (ATF-6). In turn, ER stress affected the PI3K/Akt/Gsk3β and MAPK/ERK pathways, highlighting Mapkapk5 as a potential marker, whose regulation could lead to the definition of new pharmacological and neuroprotective strategies to counteract AD. Full article
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25 pages, 10490 KiB  
Article
Artemisia annua Extract Improves the Cognitive Deficits and Reverses the Pathological Changes of Alzheimer’s Disease via Regulating YAP Signaling
by Wenshu Zhou, Bingxi Lei, Chao Yang, Marta Silva, Xingan Xing, Hua Yu, Jiahong Lu and Wenhua Zheng
Int. J. Mol. Sci. 2023, 24(6), 5259; https://doi.org/10.3390/ijms24065259 - 9 Mar 2023
Cited by 3 | Viewed by 2705
Abstract
Alzheimer’s disease (AD) is a chronic neurodegenerative disease characterized by the occurrence of cognitive deficits. With no effective treatments available, the search for new effective therapies has become a major focus of interest. In the present study, we describe the potential therapeutic effect [...] Read more.
Alzheimer’s disease (AD) is a chronic neurodegenerative disease characterized by the occurrence of cognitive deficits. With no effective treatments available, the search for new effective therapies has become a major focus of interest. In the present study, we describe the potential therapeutic effect of Artemisia annua (A. annua) extract on AD. Nine-month-old female 3xTg AD mice were treated with A. annua extract for three months via oral administration. Animals assigned to WT and model groups were administrated with an equal volume of water for the same period. Treated AD mice significantly improved the cognitive deficits and exhibited reduced Aβ accumulation, hyper-phosphorylation of tau, inflammatory factor release and apoptosis when compared with untreated AD mice. Moreover, A. annua extract promoted the survival and proliferation of neural progenitor cells (NPS) and increased the expression of synaptic proteins. Further assessment of the implicated mechanisms revealed that A. annua extract regulates the YAP signaling pathway in 3xTg AD mice. Further studies comprised the incubation of PC12 cells with Aβ1–42 at a concentration of 8 μM with or without different concentrations of A. annua extract for 24 h. Obtained ROS levels, mitochondrial membrane potential, caspase-3 activity, neuronal cell apoptosis and assessment of the signaling pathways involved was performed using western blot and immunofluorescence staining. The obtained results showed that A. annua extract significantly reversed the Aβ1–42-induced increase in ROS levels, caspase-3 activity and neuronal cell apoptosis in vitro. Moreover, either inhibition of the YAP signaling pathway, using a specific inhibitor or CRISPR cas9 knockout of YAP gene, reduced the neuroprotective effect of the A. annua extract. These findings suggest that A. annua extract may be a new multi-target anti-AD drug with potential use in the prevention and treatment of AD. Full article
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21 pages, 9048 KiB  
Article
Secondary Structure in Amyloids in Relation to Their Wild Type Forms
by Irena Roterman, Katarzyna Stapor and Leszek Konieczny
Int. J. Mol. Sci. 2023, 24(1), 154; https://doi.org/10.3390/ijms24010154 - 21 Dec 2022
Viewed by 1261
Abstract
The amyloid structures and their wild type forms, available in the PDB database, provide the basis for comparative analyses. Globular proteins are characterised by a 3D spatial structure, while a chain in any amyloid fibril has a 2D structure. Another difference lies in [...] Read more.
The amyloid structures and their wild type forms, available in the PDB database, provide the basis for comparative analyses. Globular proteins are characterised by a 3D spatial structure, while a chain in any amyloid fibril has a 2D structure. Another difference lies in the structuring of the hydrogen bond network. Amyloid forms theoretically engage all the NH and C=O groups of the peptide bonds in a chain with two hydrogen bonds each. In addition, the hydrogen bond network is highly ordered—as perpendicular to the plane of the chain. The β-structure segments provide the hydrogen bond system with an anti-parallel system. The folds appearing in the rectilinear propagation of the segment with the β-structure are caused by just by one of the residues in the sequence—residues with a Rα-helical or Lα-helical conformation. The antiparallel system of the hydrogen bonds in the β-structure sections at the site of the amino acid with a Rα- or Lα-helical conformation changes into a parallel system locally. This system also ensures that the involvement of the C=O and H-N groups in the construction of the interchain hydrogen bond, while maintaining a perpendicular orientation towards the plane of the chain. Conformational analysis at the level of the Phi and Psi angles indicates the presence of the conditions for the structures observed in the amyloids. The specificity of amyloid structures with the dominant conformation expressed as |Psi| = |Phi| reveals the system of organisation present in amyloid fibrils. The Phi, Psi angles, as present in this particular structure, transformed to form |Psi| = |Phi| appear to be ordered co-linearly. Therefore, the calculation of the correlation coefficient may express the distribution around this idealised localisation on the Ramachandran map. Additionally, when the outstanding points are eliminated, the part of amyloid chain can be classified as fulfilling the defined conditions. In addition, the presentation of the chain structure using geometric parameters, V-angle—the angle between the planes of the adjacent peptide bonds (angle versus the virtual axis Cα-Cα) and the radius of the curvature R, depending on the size of the angle V, allows for a quantitative assessment of changes during amyloid transformation. Full article
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