Amyloid precursor protein glycosylation is altered in the brain of patients with Alzheimer's disease

The Potential Role of Artemisinins Against Neurodegenerative Diseases

Artemisinin (ART) and its derivatives, collectively referred to as artemisinins (ARTs), have been approved for the treatment of malaria for decades. ARTs are converted into dihydroartemisinin (DHA), the only active form, which is reductive in vivo. In this review, we provide a brief overview of the neuroprotective potential of ARTs and the underlying mechanisms on several of the most common neurodegenerative diseases, particularly considering their potential application in those associated with cognitive and motor impairments including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS). ARTs act as autophagy balancers to alleviate AD and PD. They inhibit neuroinflammatory responses by regulating phosphorylation of signal transduction proteins, such as AKT, PI3K, ERK, NF-[Formula: see text]B, p38 MAPK, I[Formula: see text]B[Formula: see text]. In addition, ARTs regulate GABAergic signaling in a dose-dependent manner. Although they competitively inhibit the binding of gephyrin to GABAergic receptors, low doses of ARTs enhance GABAergic signaling. ARTs can also inhibit ferroptosis, activate the Akt/Bcl-2, AMPK, or ERK/CREB pathways to reduce oxidative stress, and maintain mitochondrial homeostasis, protecting neurons from oxidative stress injury. More importantly, ARTs structurally combine with and suppress [Formula: see text]-Amyloid (A[Formula: see text]-induced neurotoxicity, reduce P-tau, and maintain O-GlcNAcylation/Phosphorylation balance, leading to relieved pathological changes in neurodegenerative diseases. Collectively, these natural properties endow ARTs with unique potential for application in neurodegenerative diseases.

The alteration and role of glycoconjugates in Alzheimer's disease

Alzheimer's disease (AD) is a prevalent neurodegenerative disorder characterized by abnormal protein deposition. With an alarming 30 million people affected worldwide, AD poses a significant public health concern. While inhibiting key enzymes such as β-site amyloid precursor protein-cleaving enzyme 1 and γ-secretase or enhancing amyloid-β clearance, has been considered the reasonable strategy for AD treatment, their efficacy has been compromised by ineffectiveness. Furthermore, our understanding of AD pathogenesis remains incomplete. Normal aging is associated with a decline in glucose uptake in the brain, a process exacerbated in patients with AD, leading to significant impairment of a critical post-translational modification: glycosylation. Glycosylation, a finely regulated mechanism of intracellular secondary protein processing, plays a pivotal role in regulating essential functions such as synaptogenesis, neurogenesis, axon guidance, as well as learning and memory within the central nervous system. Advanced glycomic analysis has unveiled that abnormal glycosylation of key AD-related proteins closely correlates with the onset and progression of the disease. In this context, we aimed to delve into the intricate role and underlying mechanisms of glycosylation in the etiopathology and pathogenesis of AD. By highlighting the potential of targeting glycosylation as a promising and alternative therapeutic avenue for managing AD, we strive to contribute to the advancement of treatment strategies for this debilitating condition.

Evaluation and targeting of amyloid precursor protein (APP)/amyloid beta (Aβ) axis in amyloidogenic and non-amyloidogenic pathways: A time outside the tunnel

In Alzheimer disease (AD), amyloid precursor protein (APP) and production of amyloid beta (Aβ) which is generated by amyloidogenic pathway is implicated in neurotoxicity and neuronal cell deaths. However, physiological Aβ level is essential to improves neuronal survival, attenuates neuronal apoptosis and has neuroprotective effect. In addition, physiological APP level has neurotrophic effect on the central nervous system (CNS). APP has a critical role in the brain growth and development via activation of long-term potentiation (LTP) and acceleration of neurite outgrowth. Moreover, APP is cleaved by α secretase to form a neuroprotective soluble APP alpha (sAPPα) in non-amyloidogenic pathway. Consequently, this mini-review purposes to highlight the possible beneficial role of APP and Aβ. In addition, this mini-review discussed the modulation of APP processing and Aβ production.

Characterization of N-glycome profile in mouse brain tissue regions by MALDI-TOF/MS

Glycosylation is one of the most common types of post-translational modifications in mammals. It is well known that N-glycans play a key role in cell adhesion, differentiation, synapsis, and myelination during the development of the mammalian central nervous system (CNS). Neuropathological symptoms (such as epilepsy and Alzheimer's disease) are usually accompanied by N-glycosylation changes. In this study, we extracted N-glycan chains from eight regions of the mouse brain, and combined high-throughput, high-resolution matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS) with the Fmoc N-hydroxysuccinimide ester (Fmoc-OSU) derivatization method to improve the sensitivity of glycan detection to characterize the total N-glycans in the mouse brain. A total of 96 N-glycan moieties were detected. An exhaustive examination of the relative abundance of N-glycans, coupled with a comparative analysis of differences, has uncovered discernible variations of statistical significance, including high mannose, fucosylated, sialylated, and galactosylated N-glycans. According to our investigations, a thorough and regionally specific cartography of glycans within the brain can facilitate the investigation of glycan-mediated mechanisms related to both the developmental trajectory and functional output of the brain. Additionally, this approach may serve as a basis for identifying potential biomarkers that are relevant to various brain-associated pathologies.

New insight into protein glycosylation in the development of Alzheimer's disease

Alzheimer's disease (AD) is a chronic neurodegenerative disease that seriously endangers the physical and mental health of patients, however, there are still no effective drugs or methods to cure this disease up to now. Protein glycosylation is the most common modifications of the translated proteins in eukaryotic cells. Recently many researches disclosed that aberrant glycosylation happens in some important AD-related proteins, such as APP, Tau, Reelin and CRMP-2, etc, suggesting a close link between abnormal protein glycosylation and AD. Because of its complexity and diversity, glycosylation is thus considered a completely new entry point for understanding the precise cause of AD. This review comprehensively summarized the currently discovered changes in protein glycosylation patterns in AD, and especially introduced the latest progress on the mechanism of protein glycosylation affecting the progression of AD and the potential application of protein glycosylation in AD detection and treatment, thereby providing a wide range of opportunities for uncovering the pathogenesis of AD and promoting the translation of glycosylation research into future clinical applications.

Dessert or Poison? The Roles of Glycosylation in Alzheimer's, Parkinson's, Huntington's Disease, and Amyotrophic Lateral Sclerosis

Ministry of Education and Key Laboratory of Neurons and glial cells of the central nervous system (CNS) are modified by glycosylation and rely on glycosylation to achieve normal neural function. Neurodegenerative disease is a common disease of the elderly, affecting their healthy life span and quality of life, and no effective treatment is currently available. Recent research implies that various glycosylation traits are altered during neurodegenerative diseases, suggesting a potential implication of glycosylation in disease pathology. Herein, we summarized the current knowledge about glycosylation associated with Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and Amyotrophic lateral sclerosis (ALS) pathogenesis, focusing on their promising functional avenues. Moreover, we collected research aimed at highlighting the need for such studies to provide a wealth of disease-related glycosylation information that will help us better understand the pathophysiological mechanisms and hopefully specific glycosylation information to provide further diagnostic and therapeutic directions for neurodegenerative diseases.

Boronate Avidity Assisted by Dendrimer-like Polyhedral Oligomeric Silsesquioxanes for a Microfluidic Platform for Selective Enrichment of Ubiquitination and Glycosylation

A new strategy of improving boronate avidity with good accessibility of sites was suggested by utilizing a dendrimer-like structure of boron materials based on octavinyl-polyhedral oligomeric silsesquioxanes (Ov-POSS). 3-(Acrylamido)phenylboronic acid (AAPBA) was used as a functional monomer and ethylene glycol dimethacrylate (EDMA) and Ov-POSS as cross-linkers. The resulting Ov-POSS cross-linked boron monolith exhibited 27 times stronger affinity for glycoproteins than the Ov-POSS-free monolith. Importantly, the bonding strength of the poly(AAPBA-co-Ov-POSS-co-EDMA) monolith to the glycoproteins with multiple sugars, horseradish peroxidase (HRP) was 4 orders of magnitude higher than that of the single cis-diol-containing compound. The resulting monolith was used as a part of a microfluidic platform for online processing of the protein extracts from mouse liver, which integrated five functions, including protein grading, denaturation, enzymatic hydrolysis, and enrichment of glycopeptides and ubiquitin-modified peptides. The sample processing time can be reduced by nearly half compared to the offline method. Moreover, 86.7% of glycopeptides and 75% of glycoproteins were newly identified after treatment. All of the results indicated that the synergistic strategy of Ov-POSS cross-linking can significantly improve trace glycosylation's binding capacity and enrichment performance. The microfluidic platform developed may provide a promising technical tool for automated, high-efficiency, high-throughput analysis for post-translational modification proteomics.

APOE in the bullseye of neurodegenerative diseases: impact of the APOE genotype in Alzheimer's disease pathology and brain diseases

ApoE is the major lipid and cholesterol carrier in the CNS. There are three major human polymorphisms, apoE2, apoE3, and apoE4, and the genetic expression of APOE4 is one of the most influential risk factors for the development of late-onset Alzheimer's disease (AD). Neuroinflammation has become the third hallmark of AD, together with Amyloid-β plaques and neurofibrillary tangles of hyperphosphorylated aggregated tau protein. This review aims to broadly and extensively describe the differential aspects concerning apoE. Starting from the evolution of apoE to how APOE's single-nucleotide polymorphisms affect its structure, function, and involvement during health and disease. This review reflects on how APOE's polymorphisms impact critical aspects of AD pathology, such as the neuroinflammatory response, particularly the effect of APOE on astrocytic and microglial function and microglial dynamics, synaptic function, amyloid-β load, tau pathology, autophagy, and cell-cell communication. We discuss influential factors affecting AD pathology combined with the APOE genotype, such as sex, age, diet, physical exercise, current therapies and clinical trials in the AD field. The impact of the APOE genotype in other neurodegenerative diseases characterized by overt inflammation, e.g., alpha- synucleinopathies and Parkinson's disease, traumatic brain injury, stroke, amyotrophic lateral sclerosis, and multiple sclerosis, is also addressed. Therefore, this review gathers the most relevant findings related to the APOE genotype up to date and its implications on AD and CNS pathologies to provide a deeper understanding of the knowledge in the APOE field.

Proceedings of workshop: "Neuroglycoproteins in health and disease", INNOGLY cost action

The Cost Action "Innovation with glycans: new frontiers from synthesis to new biological targets" (INNOGLY) hosted the Workshop "Neuroglycoproteins in health and disease", in Alicante, Spain, on March 2022. This event brought together an european group of scientists that presented novel insights into changes in glycosylation in diseases of the central nervous system and cancer, as well as new techniques to study protein glycosylation. Herein we provide the abstracts of all the presentations.

A Study on the Pathogenesis of Vascular Cognitive Impairment and Dementia: The Chronic Cerebral Hypoperfusion Hypothesis

The pathogenic mechanisms underlying vascular cognitive impairment and dementia (VCID) remain controversial due to the heterogeneity of vascular causes and complexity of disease neuropathology. However, one common feature shared among all these vascular causes is cerebral blood flow (CBF) dysregulation, and chronic cerebral hypoperfusion (CCH) is the universal consequence of CBF dysregulation, which subsequently results in an insufficient blood supply to the brain, ultimately contributing to VCID. The purpose of this comprehensive review is to emphasize the important contributions of CCH to VCID and illustrate the current findings about the mechanisms involved in CCH-induced VCID pathological changes. Specifically, evidence is mainly provided to support the molecular mechanisms, including Aβ accumulation, inflammation, oxidative stress, blood-brain barrier (BBB) disruption, trophic uncoupling and white matter lesions (WMLs). Notably, there are close interactions among these multiple mechanisms, and further research is necessary to elucidate the hitherto unsolved questions regarding these interactions. An enhanced understanding of the pathological features in preclinical models could provide a theoretical basis, ultimately achieving the shift from treatment to prevention.

A Method for Bridging Population-Specific Genotypes to Detect Gene Modules Associated with Alzheimer's Disease

BACKGROUND

Genome-wide association studies have successfully identified variants associated with multiple conditions. However, generalizing discoveries across diverse populations remains challenging due to large variations in genetic composition. Methods that perform gene expression imputation have attempted to address the transferability of gene discoveries across populations, but with limited success.

METHODS

Here, we introduce a pipeline that combines gene expression imputation with gene module discovery, including a dense gene module search and a gene set variation analysis, to address the transferability issue. Our method feeds association probabilities of imputed gene expression with a selected phenotype into tissue-specific gene-module discovery over protein interaction networks to create higher-level gene modules.

RESULTS

We demonstrate our method's utility in three case-control studies of Alzheimer's disease (AD) for three different race/ethnic populations (Whites, African descent and Hispanics). We discovered 182 AD-associated genes from gene modules shared between these populations, highlighting new gene modules associated with AD.

CONCLUSIONS

Our innovative framework has the potential to identify robust discoveries across populations based on gene modules, as demonstrated in AD.

The relationship of early- and late-onset Alzheimer’s disease genes with COVID-19

Individuals with Alzheimer’s disease and other neurodegenerative diseases have been exposed to excess risk by the COVID-19 pandemic. COVID-19’s main manifestations include high body temperature, dry cough, and exhaustion. Nevertheless, some affected individuals may have an atypical presentation at diagnosis but suffer neurological signs and symptoms as the first disease manifestation. These findings collectively show the neurotropic nature of SARS-CoV-2 virus and its ability to involve the central nervous system. In addition, Alzheimer’s disease and COVID-19 has a number of common risk factors and comorbid conditions including age, sex, hypertension, diabetes, and the expression of APOE ε4. Until now, a plethora of studies have examined the COVID-19 disease but only a few studies has yet examined the relationship of COVID-19 and Alzheimer’s disease as risk factors of each other. This review emphasizes the recently published evidence on the role of the genes of early- or late-onset Alzheimer’s disease in the susceptibility of individuals currently suffering or recovered from COVID-19 to Alzheimer’s disease or in the susceptibility of individuals at risk of or with Alzheimer’s disease to COVID-19 or increased COVID-19 severity and mortality. Furthermore, the present review also draws attention to other uninvestigated early- and late-onset Alzheimer’s disease genes to elucidate the relationship between this multifactorial disease and COVID-19.

Mucin-Type O-Glycosylation Proximal to β-Secretase Cleavage Site Affects APP Processing and Aggregation Fate

The amyloid-β precursor protein (APP) undergoes proteolysis by β- and γ-secretases to form amyloid-β peptides (Aβ), which is a hallmark of Alzheimer's disease (AD). Recent findings suggest a possible role of O-glycosylation on APP's proteolytic processing and subsequent fate for AD-related pathology. We have previously reported that Tyr681-O-glycosylation and the Swedish mutation accelerate cleavage of APP model glycopeptides by β-secretase (amyloidogenic pathway) more than α-secretase (non-amyloidogenic pathway). Therefore, to further our studies, we have synthesized additional native and Swedish-mutated (glyco)peptides with O-GalNAc moiety on Thr663 and/or Ser667 to explore the role of glycosylation on conformation, secretase activity, and aggregation kinetics of Aβ40. Our results show that conformation is strongly dependent on external conditions such as buffer ions and solvent polarity as well as internal modifications of (glyco)peptides such as length, O-glycosylation, and Swedish mutation. Furthermore, the level of β-secretase activity significantly increases for the glycopeptides containing the Swedish mutation compared to their nonglycosylated and native counterparts. Lastly, the glycopeptides impact the kinetics of Aβ40 aggregation by significantly increasing the lag phase and delaying aggregation onset, however, this effect is less pronounced for its Swedish-mutated counterparts. In conclusion, our results confirm that the Swedish mutation and/or O-glycosylation can render APP model glycopeptides more susceptible to cleavage by β-secretase. In addition, this study sheds new light on the possible role of glycosylation and/or glycan density on the rate of Aβ40 aggregation.

The dynamic brain N-glycome

The attachment of carbohydrates to other macromolecules, such as proteins or lipids, is an important regulatory mechanism termed glycosylation. One subtype of protein glycosylation is asparagine-linked glycosylation (N-glycosylation) which plays a key role in the development and normal functioning of the vertebrate brain. To better understand the role of N-glycans in neurobiology, it's imperative we analyse not only the functional roles of individual structures, but also the collective impact of large-scale changes in the brain N-glycome. The systematic study of the brain N-glycome is still in its infancy and data are relatively scarce. Nevertheless, the prevailing view has been that the neuroglycome is inherently restricted with limited capacity for variation. The development of improved methods for N-glycomics analysis of brain tissue has facilitated comprehensive characterisation of the complete brain N-glycome under various experimental conditions on a larger scale. Consequently, accumulating data suggest that it's more dynamic than previously recognised and that, within a general framework, it has a given capacity to change in response to both intrinsic and extrinsic stimuli. Here, we provide an overview of the many factors that can alter the brain N-glycome, including neurodevelopment, ageing, diet, stress, neuroinflammation, injury, and disease. Given this emerging evidence, we propose that the neuroglycome has a hitherto underappreciated plasticity and we discuss the therapeutic implications of this regarding the possible reversal of pathological changes via interventions. We also briefly review the merits and limitations of N-glycomics as an analytical method before reflecting on some of the outstanding questions in the field.

Knockdown of Amyloid Precursor Protein: Biological Consequences and Clinical Opportunities

Amyloid precursor protein (APP) and its cleavage fragment Amyloid-β (Aβ) have fundamental roles in Alzheimer's disease (AD). Genetic alterations that either increase the overall dosage of APP or alter its processing to favour the generation of longer, more aggregation prone Aβ species, are directly causative of the disease. People living with one copy of APP are asymptomatic and reducing APP has been shown to lower the relative production of aggregation-prone Aβ species in vitro. For these reasons, reducing APP expression is an attractive approach for AD treatment and prevention. In this review, we will describe the structure and the known functions of APP and go on to discuss the biological consequences of APP knockdown and knockout in model systems. We highlight progress in therapeutic strategies to reverse AD pathology via reducing APP expression. We conclude that new technologies that reduce the dosage of APP expression may allow disease modification and slow clinical progression, delaying or even preventing onset.

Emerging roles of N-linked glycosylation in brain physiology and disorders

N-linked glycosylation is a complex, co- and post-translational series of events that connects metabolism to signaling in almost all cells. Metabolic assembly of N-linked glycans spans multiple cellular compartments, and early N-linked glycan biosynthesis is a central mediator of protein folding and the unfolded protein response (UPR). In the brain, N-linked glycosylated proteins participate in a myriad of processes, from electrical gradients to neurotransmission. However, it is less clear how perturbations in N-linked glycosylation impact and even potentially drive aspects of neurological disorders. In this review, we discuss our current understanding of the metabolic origins of N-linked glycans in the brain, their role in modulating neuronal function, and how aberrant N-linked glycosylation can drive neurological disorders.

Amyloid Aggregation of Streptococcus mutans Cnm Influences Its Collagen-Binding Activity

The cnm gene, coding for the glycosylated collagen- and laminin-binding surface adhesin Cnm, is found in the genomes of approximately 20% of Streptococcus mutans clinical isolates and is associated with systemic infections and increased caries risk. Other surface-associated collagen-binding proteins of S. mutans, such as P1 and WapA, have been demonstrated to form an amyloid quaternary structure with functional implications within biofilms. In silico analysis predicted that the β-sheet-rich N-terminal collagen-binding domain (CBD) of Cnm has a propensity for amyloid aggregation, whereas the threonine-rich C-terminal domain was predicted to be disorganized. In this study, thioflavin-T fluorescence and electron microscopy were used to show that Cnm forms amyloids in either its native glycosylated or recombinant nonglycosylated form and that the CBD of Cnm is the main amyloidogenic unit of Cnm. We then performed a series of in vitro, ex vivo, and in vivo assays to characterize the amylogenic properties of Cnm. In addition, Congo red birefringence indicated that Cnm is a major amyloidogenic protein of S. mutans biofilms. Competitive binding assays using collagen-coated microtiter plates and dental roots, a substrate rich in collagen, revealed that Cnm monomers inhibit S. mutans binding to collagenous substrates, whereas Cnm amyloid aggregates lose this property. Thus, while Cnm contributes to recognition and initial binding of S. mutans to collagen-rich surfaces, amyloid formation by Cnm might act as a negative regulatory mechanism to modulate collagen-binding activity within S. mutans biofilms and warrants further investigation. IMPORTANCE Streptococcus mutans is a keystone pathogen that promotes caries by acidifying the dental biofilm milieu. The collagen- and laminin-binding glycoprotein Cnm is a virulence factor of S. mutans. Expression of Cnm by S. mutans is hypothesized to contribute to niche expansion, allowing colonization of multiple sites in the body, including collagen-rich surfaces such as dentin and heart valves. Here, we suggest that Cnm function might be modulated by its aggregation status. As a monomer, its primary function is to promote attachment to collagenous substrates via its collagen-binding domain (CBD). However, in later stages of biofilm maturation, the same CBD of Cnm could self-assemble into amyloid fibrils, losing the ability to bind to collagen and likely becoming a component of the biofilm matrix. Our findings shed light on the role of functional amyloids in S. mutans pathobiology and ecology.

What Can N-glycomics and N-glycoproteomics of Cerebrospinal Fluid Tell Us about Alzheimer Disease?

Proteomics-large-scale studies of proteins-has over the last decade gained an enormous interest for studies aimed at revealing proteins and pathways involved in disease. To fully understand biological and pathological processes it is crucial to also include post-translational modifications in the "omics". To this end, glycomics (identification and quantification of glycans enzymatically or chemically released from proteins) and glycoproteomics (identification and quantification of peptides/proteins with the glycans still attached) is gaining interest. The study of protein glycosylation requires a workflow that involves an array of sample preparation and analysis steps that needs to be carefully considered. Herein, we briefly touch upon important steps such as sample preparation and preconcentration, glycan release, glycan derivatization and quantification and advances in mass spectrometry that today are the work-horse for glycomics and glycoproteomics studies. Several proteins related to Alzheimer disease pathogenesis have altered protein glycosylation, and recent glycomics studies have shown differences in cerebrospinal fluid as well as in brain tissue in Alzheimer disease as compared to controls. In this review, we discuss these techniques and how they have been used to shed light on Alzheimer disease and to find glycan biomarkers in cerebrospinal fluid.

The significance of sialylation on the pathogenesis of Alzheimer's disease

Sialylation, one of the most common and complex modes of glycosylation, corresponds with the development of the infant brain and nervous system. The most prevalent neurodegenerative disease is Alzheimer's disease (AD), which is mainly characterized by cognitive decline and behavioral disorders. However, the relationship between sialylation and AD occurrence is poorly understood. In this article, we reviewed the role of sialylation on the occurrence and development of AD, then discussed the value of sialylation modification for AD diagnosis and treatment.

Unexpected beta-amyloid production by middle doses of resveratrol through stabilization of APP protein and AMPK-mediated inhibition of trypsin-like proteasome activity in a cell model of Alzheimer's disease

Resveratrol is a drug candidate used for Alzheimer's disease (AD) and shows beneficial effects in various toxicity and production models, although recent clinical trial data did not show satisfactory results. Here we demonstrated the potential side effects of resveratrol in AD. We demonstrated resveratrol concentration- and time-dependent Aβ production using Aβ secreted cellular model and analyzed resveratrol-related molecular signaling. In Swedish mutant of APP (APPsw) stably expressing cells, treatment with a middle dose of resveratrol for 24 h unexpectedly increased Aβ production, but higher concentrations or shorter treatment durations did not. Resveratrol-mediated Aβ production was caused by an increase in APP protein levels associated with proteasome-dependent regulation of APP stability. Inhibition of AMPK, cAMP production, and epac1 attenuated Aβ production and APP increase by resveratrol, which blocked the inhibition of trypsin-like proteasomal activity. In addition, high-dose resveratrol decreased Aβ secretion and β-secretase activity at any treatment duration. Our data suggest that an appropriate dose of resveratrol can paradoxically increase Aβ production via stabilization of APP protein in an AMPK-proteasome signaling-dependent manner, which provides mechanistic insights into prior unsatisfactory clinical outcomes and the future clinical use of resveratrol.

Mitochondria-associated membranes (MAMs): a potential therapeutic target for treating Alzheimer's disease

Alzheimer's disease (AD), a progressive neurodegenerative disorder, is a leading global health concern for individuals and society. However, the potential mechanisms underlying the pathogenesis of AD have not yet been elucidated. Currently, the most widely acknowledged hypothesis is amyloid cascade owing to the brain characteristics of AD patients, including great quantities of extracellular β-amyloid (Aβ) plaques and intracellular neurofibrillary tangles (NFTs). Nevertheless, the amyloid cascade hypothesis cannot address certain pathologies that precede Aβ deposition and NFTs formation in AD, such as aberrant calcium homeostasis, abnormal lipid metabolism, mitochondrial dysfunction and autophagy. Notably, these earlier pathologies are closely associated with mitochondria-associated membranes (MAMs), the physical structures connecting the endoplasmic reticulum (ER) and mitochondria, which mediate the communication between these two organelles. It is plausible that MAMs might be involved in a critical step in the cascade of earlier events, ultimately inducing neurodegeneration in AD. In this review, we focus on the role of MAMs in the regulation of AD pathologies and the potential molecular mechanisms related to MAM-mediated pathological changes in AD. An enhanced recognition of the preclinical pathogenesis in AD could provide new therapeutic strategies, shifting the modality from treatment to prevention.