scholarly journals Up-regulation of APP endocytosis by neuronal aging drives amyloid dependent-synapse loss

2021 ◽  
Author(s):  
Tatiana Burrinha ◽  
Isak Martinsson ◽  
Ricardo Gomes ◽  
Ana Paula Terrasso ◽  
Gunnar K. Gouras ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Late Onset ◽  
Aged Mouse ◽  
App Processing ◽  
Synapse Loss ◽  
Aged Brain ◽  
Early Endosomes ◽  
Aβ Production

Neuronal aging increases the risk of late-onset Alzheimer's disease. During normal aging, synapses decline, and β-amyloid (Aβ) accumulates intraneuronally. However, little is known about the underlying cell biological mechanisms. We studied normal neuronal aging using normal aged brain and aged mouse primary neurons that accumulate lysosomal lipofuscin and show synapse loss. We identify the up-regulation of amyloid precursor protein (APP) endocytosis as a neuronal aging mechanism that potentiates APP processing and Aβ production in vitro and in vivo. The increased APP endocytosis may contribute to the observed early endosomes enlargement in the aged brain. Mechanistically, we show that clathrin-dependent APP endocytosis requires F-actin and that clathrin and endocytic F-actin increase with neuronal aging. Finally, Aβ production inhibition reverts synaptic decline in aged neurons while Aβ accumulation, promoted by endocytosis up-regulation in younger neurons, recapitulates aging-related synapse decline. Overall, we identify APP endocytosis up-regulation as a potential mechanism of neuronal aging and, thus, a novel target to prevent late-onset Alzheimer's disease.

scholarly journals Neuronal aging potentiates beta-amyloid generation via amyloid precursor protein endocytosis

2019 ◽  
Author(s):  
Tatiana Burrinha ◽  
Ricardo Gomes ◽  
Ana Paula Terrasso ◽  
Cláudia Guimas Almeida
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Amyloid Precursor Protein ◽  
Precursor Protein ◽  
App Processing ◽  
Early Endosomes ◽  
Primary Mouse ◽  
Β Amyloid ◽  
Aβ Production

AbstractAging increases the risk of Alzheimer’s disease (AD). During normal aging synapses decline and β-Amyloid (Aβ) accumulates. An Aβ defective clearance with aging is postulated as responsible for Aβ accumulation, although a role for increased Aβ production with aging can also lead to Aβ accumulation. To test this hypothesis, we established a long-term culture of primary mouse neurons that mimics neuronal aging (lysosomal lipofuscin accumulation and synapse decline). Intracellular endogenous Aβ42 accumulated in aged neurites due to increased amyloid-precursor protein (APP) processing. We show that APP processing is up-regulated by a specific age-dependent increase in APP endocytosis. Endocytosed APP accumulated in early endosomes that, in turn were found augmented in aged neurites. APP processing and early endosomes up-regulation was recapitulated in vivo. Finally, we found that inhibition of Aβ production reduced the decline in synapses in aged neurons. We propose that potentiation of APP endocytosis by neuronal aging increases Aβ production, which contributes to aging-dependent decline in synapses.SummaryHow aging increases the risk of Alzheimer’s disease is not clear. We show that normal neuronal aging increases the intracellular production of β-amyloid, due to an upregulation of the amyloid precursor protein endocytosis. Importantly, increased Aβ production contributes to the aging-dependent synapse loss.

Genipin Attenuates Tau Phosphorylation and Aβ Levels in Cellular Models of Alzheimer's Disease

2021 ◽  
Author(s):  
Meiting Li ◽  
Nan Cai ◽  
Liang Gu ◽  
Lijun Yao ◽  
Decheng Bi ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Signaling Pathway ◽  
Molecular Mechanisms ◽  
Tau Phosphorylation ◽  
Brain Disorder ◽  
Cellular Models ◽  
Aβ Generation ◽  
Aβ Production

Abstract Alzheimer’s disease (AD) is a devastating brain disorder characterized by neurofibrillary tangles and amyloid plaques. Inhibiting Tau protein and amyloid-beta (Aβ) production or removing these molecules are considered potential therapeutic strategies for AD. Genipin is an aglycone and is isolated from the extract of Gardenia jasminoides Ellis fruit. In this study, the effect and molecular mechanisms of genipin on the inhibition of Tau aggregation and Aβ generation were investigated. The results showed that genipin bound to Tau and protected against heparin-induced Tau fibril formation. Moreover, genipin suppressed Tau phosphorylation probably by downregulating the expression of CDK5 and GSK-3β, and activated mTOR-dependent autophagy via the SIRT1/LKB1/AMPK signaling pathway in Tau-overexpressing cells. In addition, genipin decreased Aβ production by inhibiting BACE1 expression through the PERK/eIF2α signaling pathway in N2a/SweAPP cells. These data indicated that genipin could effectively lead to a significant reduction of phosphorylated Tau level and Aβ generation in vitro, suggesting that genipin might be developed into an effective therapeutic complement or a potential nutraceutical for preventing AD.

scholarly journals Gga3 deletion and a GGA3 rare variant associated with late onset Alzheimer’s disease trigger BACE1 accumulation in axonal swellings

2020 ◽  
Vol 12 (570) ◽  
pp. eaba1871
Author(s):  
Selene Lomoio ◽  
Rachel Willen ◽  
WonHee Kim ◽  
Kevin Z. Ho ◽  
Edward K. Robinson ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Rare Variant ◽  
Late Onset ◽  
Early Stage ◽  
Loss Of Function ◽  
Axonal Trafficking ◽  
Axonal Swellings

Axonal dystrophy, indicative of perturbed axonal transport, occurs early during Alzheimer’s disease (AD) pathogenesis. Little is known about the mechanisms underlying this initial sign of the pathology. This study proves that Golgi-localized γ-ear-containing ARF binding protein 3 (GGA3) loss of function, due to Gga3 genetic deletion or a GGA3 rare variant that cosegregates with late-onset AD, disrupts the axonal trafficking of the β-site APP-cleaving enzyme 1 (BACE1) resulting in its accumulation in axonal swellings in cultured neurons and in vivo. We show that BACE pharmacological inhibition ameliorates BACE1 axonal trafficking and diminishes axonal dystrophies in Gga3 null neurons in vitro and in vivo. These data indicate that axonal accumulation of BACE1 engendered by GGA3 loss of function results in local toxicity leading to axonopathy. Gga3 deletion exacerbates axonal dystrophies in a mouse model of AD before β-amyloid (Aβ) deposition. Our study strongly supports a role for GGA3 in AD pathogenesis, where GGA3 loss of function triggers BACE1 axonal accumulation independently of extracellular Aβ, and initiates a cascade of events leading to the axonal damage distinctive of the early stage of AD.

scholarly journals APOE4 exacerbates synapse loss and neurodegeneration in Alzheimer’s disease patient iPSC-derived cerebral organoids

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Jing Zhao ◽  
Yuan Fu ◽  
Yu Yamazaki ◽  
Yingxue Ren ◽  
Mary D. Davis ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Healthy Subject ◽  
Late Onset ◽  
Disease Patient ◽  
Underlying Mechanism ◽  
Synapse Loss ◽  
Induced Pluripotent ◽  
Human Ipsc ◽  
Normal Cognition

Abstract APOE4 is the strongest genetic risk factor associated with late-onset Alzheimer’s disease (AD). To address the underlying mechanism, we develop cerebral organoid models using induced pluripotent stem cells (iPSCs) with APOE ε3/ε3 or ε4/ε4 genotype from individuals with either normal cognition or AD dementia. Cerebral organoids from AD patients carrying APOE ε4/ε4 show greater apoptosis and decreased synaptic integrity. While AD patient-derived cerebral organoids have increased levels of Aβ and phosphorylated tau compared to healthy subject-derived cerebral organoids, APOE4 exacerbates tau pathology in both healthy subject-derived and AD patient-derived organoids. Transcriptomics analysis by RNA-sequencing reveals that cerebral organoids from AD patients are associated with an enhancement of stress granules and disrupted RNA metabolism. Importantly, isogenic conversion of APOE4 to APOE3 attenuates the APOE4-related phenotypes in cerebral organoids from AD patients. Together, our study using human iPSC-organoids recapitulates APOE4-related phenotypes and suggests APOE4-related degenerative pathways contributing to AD pathogenesis.

Patient-specific and in vitro models for the analysis of late-onset Alzheimer’s disease

2017 ◽  
Vol 27 ◽  
pp. S1033-S1034
Author(s):  
T. Ehrhardt ◽  
M. Jung ◽  
C. Hartmann ◽  
I. Giegling ◽  
D. Rujescu
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Late Onset ◽  
In Vitro Models ◽  
Patient Specific

scholarly journals Fibrillogenesis in Alzheimer's disease of amyloid β peptides and apolipoprotein E

1995 ◽  
Vol 306 (2) ◽  
pp. 599-604 ◽  
Author(s):  
E M Castano ◽  
F Prelli ◽  
T Wisniewski ◽  
A Golabek ◽  
R A Kumar ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Apolipoprotein E ◽  
Late Onset ◽  
Senile Plaques ◽  
Amyloid Β ◽  
Fibril Formation ◽  
Tau Proteins ◽  
Amyloid Formation

A central event in Alzheimer's disease is the conformational change from normally circulating soluble amyloid beta peptides (A beta) and tau proteins into amyloid fibrils, in the form of senile plaques and neurofibrillary tangles respectively. The apolipoprotein E (apoE) gene locus has recently been associated with late-onset Alzheimer's disease. It is not know whether apoE plays a direct role in the pathogenesis of the disease. In the present work we have investigated whether apoE can affect the known spontaneous in vitro formation of amyloid-like fibrils by synthetic A beta analogues using a thioflavine-T assay for fibril formation, electron microscopy and Congo Red staining. Our results show that, under the conditions used, apoE directly promotes amyloid fibril formation, increasing both the rate of fibrillogenesis and the total amount of amyloid formed. ApoE accelerated fibril formation of both wild-type A beta-(1-40) and A beta-(1-40A), an analogue created by the replacement of valine with alanine at residue 18, which alone produces few amyloid-like fibrils. However, apoE produced only a minimal effect on A beta-(1-40Q), found in the Dutch variant of Alzheimer's disease. When recombinant apoE isoforms were used, apoE4 was more efficient than apoE3 at enhancing amyloid formation. These in vitro observations support the hypothesis that apoE acts as a pathological chaperone, promoting the beta-pleated-sheet conformation of soluble A beta into amyloid fibres, and provide a possible explanation for the association of the apoE4 genetic isoform with Alzheimer's disease.

scholarly journals Postmortem Neocortical 3H-PiB Binding and Levels of Unmodified and Pyroglutamate Aβ in Down Syndrome and Sporadic Alzheimer’s Disease

2021 ◽  
Vol 13 ◽  
Author(s):  
Violetta N. Pivtoraiko ◽  
Tamara Racic ◽  
Eric E. Abrahamson ◽  
Victor L. Villemagne ◽  
Benjamin L. Handen ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Down Syndrome ◽  
Late Onset ◽  
Amyloid Β ◽  
Molecular Profile ◽  
Amyloid Angiopathy ◽  
Neuritic Plaques ◽  
Amyloid Deposits

Individuals with Down syndrome (DS) have a genetic predisposition for amyloid-β (Aβ) overproduction and earlier onset of Aβ deposits compared to patients with sporadic late-onset Alzheimer’s disease (AD). Positron emission tomography (PET) with Pittsburgh Compound-B (PiB) detects fibrillar Aβ pathology in living people with DS and AD, but its relationship with heterogeneous Aβ forms aggregated within amyloid deposits is not well understood. We performed quantitative in vitro3H-PiB binding assays and enzyme-linked immunosorbent assays of fibrillar (insoluble) unmodified Aβ40 and Aβ42 forms and N-terminus truncated and pyroglutamate-modified AβNpE3-40 and AβNpE3-42 forms in postmortem frontal cortex and precuneus samples from 18 DS cases aged 43–63 years and 17 late-onset AD cases aged 62–99 years. Both diagnostic groups had frequent neocortical neuritic plaques, while the DS group had more severe vascular amyloid pathology (cerebral amyloid angiopathy, CAA). Compared to the AD group, the DS group had higher levels of Aβ40 and AβNpE3-40, while the two groups did not differ by Aβ42 and AβNpE3-42 levels. This resulted in lower ratios of Aβ42/Aβ40 and AβNpE3-42/AβNpE3-40 in the DS group compared to the AD group. Correlations of Aβ42/Aβ40 and AβNpE3-42/AβNpE3-40 ratios with CAA severity were strong in DS cases and weak in AD cases. Pyroglutamate-modified Aβ levels were lower than unmodified Aβ levels in both diagnostic groups, but within group proportions of both pyroglutamate-modified Aβ forms relative to both unmodified Aβ forms were lower in the DS group but not in the AD group. The two diagnostic groups did not differ by 3H-PiB binding levels. These results demonstrate that compared to late-onset AD cases, adult DS individuals with similar severity of neocortical neuritic plaques and greater CAA pathology have a preponderance of both pyroglutamate-modified AβNpE3-40 and unmodified Aβ40 forms. Despite the distinct molecular profile of Aβ forms and greater vascular amyloidosis in DS cases, cortical 3H-PiB binding does not distinguish between diagnostic groups that are at an advanced level of amyloid plaque pathology. This underscores the need for the development of CAA-selective PET radiopharmaceuticals to detect and track the progression of cerebral vascular amyloid deposits in relation to Aβ plaques in individuals with DS.

scholarly journals Beta secretase 1-dependent amyloid precursor protein processing promotes excessive vascular sprouting through NOTCH3 signaling

2019 ◽  
Author(s):  
Claire S. Durrant ◽  
Karsten Ruscher ◽  
Olivia Sheppard ◽  
Michael P. Coleman ◽  
Ilknur Özen
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Amyloid Precursor Protein ◽  
Amyloid Beta ◽  
Precursor Protein ◽  
Vascular Pathology ◽  
Amyloid Precursor Protein Processing ◽  
App Processing ◽  
Bace1 Inhibition

AbstractAmyloid beta peptides (Aβ) proteins play a key role in vascular pathology in Alzheimer’s Disease (AD) including impairment of the blood brain barrier and aberrant angiogenesis. Although previous work has demonstrated a pro-angiogenic role of Aβ, the exact mechanisms by which amyloid precursor protein (APP) processing and endothelial angiogenic signalling cascades interact in AD remain a largely unsolved problem. Here, we report that increased endothelial sprouting in human-APP transgenic mouse (TgCRND8) tissue is dependent on β-secretase (BACE1) processing of APP. Higher levels of Aβ processing in TgCRND8 tissue coincides with decreased NOTCH3/JAG1 signalling, over-production of endothelial filopodia and increased numbers of vascular pericytes. Using a novel in vitro approach to study sprouting angiogenesis in TgCRND8 organotypic brain slice cultures (OBSCs), we find that BACE1 inhibition normalises excessive endothelial filopodia formation and restores NOTCH3 signalling. These data present the first evidence for the potential of BACE1 inhibition as an effective therapeutic target for aberrant angiogenesis in AD.SignificanceIn this study, we show that targeting amyloid beta processing provides an opportunity to selectively target tip cell filopodia-driven angiogenesis and develop therapeutic targets for vascular dysfunction related to aberrant angiogenesis in AD. Our data provide the first evidence for a safe level of BACE1 inhibition that can normalize excess angiogenesis in AD, without inducing vascular deficits in healthy tissue. Our findings may pave the way for the development of new angiogenesis dependent therapeutic strategies in Alzheimer’s Disease.

scholarly journals CNI-1493 inhibits Aβ production, plaque formation, and cognitive deterioration in an animal model of Alzheimer's disease

2008 ◽  
Vol 205 (7) ◽  
pp. 1593-1599 ◽  
Author(s):  
Michael Bacher ◽  
Richard Dodel ◽  
Bayan Aljabari ◽  
Kathy Keyvani ◽  
Philippe Marambaud ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Memory Performance ◽  
Amyloid Β ◽  
Amyloid Plaque ◽  
Amyloid Β Protein ◽  
Aβ Oligomers ◽  
App Processing ◽  
Model Of Alzheimer’S Disease

Alzheimer's disease (AD) is characterized by neuronal atrophy caused by soluble amyloid β protein (Aβ) peptide “oligomers” and a microglial-mediated inflammatory response elicited by extensive amyloid deposition in the brain. We show that CNI-1493, a tetravalent guanylhydrazone with established antiinflammatory properties, interferes with Aβ assembly and protects neuronal cells from the toxic effect of soluble Aβ oligomers. Administration of CNI-1493 to TgCRND8 mice overexpressing human amyloid precursor protein (APP) for a treatment period of 8 wk significantly reduced Aβ deposition. CNI-1493 treatment resulted in 70% reduction of amyloid plaque area in the cortex and 87% reduction in the hippocampus of these animals. Administration of CNI-1493 significantly improved memory performance in a cognition task compared with vehicle-treated mice. In vitro analysis of CNI-1493 on APP processing in an APP-overexpressing cell line revealed a significant dose-dependent decrease of total Aβ accumulation. This study indicates that the antiinflammatory agent CNI-1493 can ameliorate the pathophysiology and cognitive defects in a murine model of AD.

scholarly journals Therapeutic Potential of Dental Pulp Stem Cell Secretome for Alzheimer’s Disease Treatment: An In Vitro Study

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Nermeen El-Moataz Bellah Ahmed ◽  
Masashi Murakami ◽  
Yujiro Hirose ◽  
Misako Nakashima
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Stem Cells ◽  
Stem Cell ◽  
Dental Pulp ◽  
Therapeutic Potential ◽  
Late Onset ◽  
In Vitro Study ◽  
Promising Source

The secretome obtained from stem cell cultures contains an array of neurotrophic factors and cytokines that might have the potential to treat neurodegenerative conditions. Alzheimer’s disease (AD) is one of the most common human late onset and sporadic neurodegenerative disorders. Here, we investigated the therapeutic potential of secretome derived from dental pulp stem cells (DPSCs) to reduce cytotoxicity and apoptosis caused by amyloid beta (Aβ) peptide. We determined whether DPSCs can secrete the Aβ-degrading enzyme, neprilysin (NEP), and evaluated the effects of NEP expression in vitro by quantitating Aβ-degrading activity. The results showed that DPSC secretome contains higher concentrations of VEGF, Fractalkine, RANTES, MCP-1, and GM-CSF compared to those of bone marrow and adipose stem cells. Moreover, treatment with DPSC secretome significantly decreased the cytotoxicity of Aβpeptide by increasing cell viability compared to nontreated cells. In addition, DPSC secretome stimulated the endogenous survival factor Bcl-2 and decreased the apoptotic regulator Bax. Furthermore, neprilysin enzyme was detected in DPSC secretome and succeeded in degradingAβ1–42in vitro in 12 hours. In conclusion, our study demonstrates that DPSCs may serve as a promising source for secretome-based treatment of Alzheimer’s disease.

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