scholarly journals Alzheimer's disease BIN1 coding variants increase intracellular Aβ by interfering with BACE1 recycling

2021 ◽  
Author(s):  
Catarina Perdigão ◽  
Mariana A Barata ◽  
Tatiana Burrinha ◽  
Claudia Guimas Almeida
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Beta Amyloid ◽  
Early Endosome ◽  
Dominant Negative Effect ◽  
Causal Mechanism ◽  
Wild Type ◽  
Endocytic Recycling ◽  
Early Endosomes ◽  
Coding Variants

Genetics identified BIN1 as the second most important risk locus associated with late-onset Alzheimer's disease after APOE4. Here we show the consequences of two coding variants in BIN1 (rs754834233 and rs138047593), both in terms of intracellular beta-amyloid accumulation (iAbeta) and early endosome enlargement, two interrelated early cytopathological Alzheimer's disease phenotypes, supporting their association with LOAD risk. We previously found that Bin1 deficiency potentiates beta-amyloid production by decreasing BACE1 recycling and enlarging early endosomes. Here, we demonstrate that the expression of the two LOAD mutant forms of Bin1 did not rescue the iAbeta accumulation and early endosome enlargement induced by Bin1 knockdown and recovered by wild-type Bin1. The LOAD coding variants reduced Bin1 interaction with BACE1 likely causing a dominant-negative effect since Bin1 mutants, but not wild-type Bin1, overexpression increased iAbeta42 due to defective BACE1 recycling and accumulation in early endosomes. Endocytic recycling of transferrin was similarly affected by Bin1 wild-type and mutants, indicating that Bin1 is a general regulator of endocytic recycling. These data show that the LOAD mutations in Bin1 lead to a loss of function, suggesting that endocytic recycling defects are an early causal mechanism of Alzheimer's disease.

scholarly journals The Alzheimer susceptibility gene BIN1 induces isoform-dependent neurotoxicity through early endosome defects

2022 ◽  
Vol 10 (1) ◽  
Author(s):  
Erwan Lambert ◽  
Orthis Saha ◽  
Bruna Soares Landeira ◽  
Ana Raquel Melo de Farias ◽  
Xavier Hermant ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Susceptibility Gene ◽  
Early Endosome ◽  
Systematic Search ◽  
Knock Out ◽  
Early Endosomes ◽  
Pathophysiological Role ◽  
Induced Neurons ◽  
Endosomal Vesicles

AbstractThe Bridging Integrator 1 (BIN1) gene is a major susceptibility gene for Alzheimer’s disease (AD). Deciphering its pathophysiological role is challenging due to its numerous isoforms. Here we observed in Drosophila that human BIN1 isoform1 (BIN1iso1) overexpression, contrary to human BIN1 isoform8 (BIN1iso8) and human BIN1 isoform9 (BIN1iso9), induced an accumulation of endosomal vesicles and neurodegeneration. Systematic search for endosome regulators able to prevent BIN1iso1-induced neurodegeneration indicated that a defect at the early endosome level is responsible for the neurodegeneration. In human induced neurons (hiNs) and cerebral organoids, BIN1 knock-out resulted in the narrowing of early endosomes. This phenotype was rescued by BIN1iso1 but not BIN1iso9 expression. Finally, BIN1iso1 overexpression also led to an increase in the size of early endosomes and neurodegeneration in hiNs. Altogether, our data demonstrate that the AD susceptibility gene BIN1, and especially BIN1iso1, contributes to early-endosome size deregulation, which is an early pathophysiological hallmark of AD pathology.

scholarly journals The Alzheimer's disease genetic risk factor BIN1 induces isoform-dependent neurotoxicity through early endosome defects

2021 ◽  
Author(s):  
Erwan Lambert ◽  
Orthis Saha ◽  
Bruna Soares Landeira ◽  
Ana Raquel Melo de Farias ◽  
Xavier Hermant ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Risk Factor ◽  
Genetic Risk ◽  
Early Endosome ◽  
Genetic Risk Factor ◽  
Endosome Trafficking ◽  
Early Endosomes ◽  
Induced Neurons ◽  
The Impact

The Bridging Integrator 1 (BIN1) gene is a major genetic risk factor for Alzheimer's disease (AD) but little is known about its physiological functions. In addition, deciphering its potential pathophysiological role is difficult due to its numerous isoforms expressed in different cerebral cell types. Here we took advantage of a drosophila model to assess in vivo the impact of different BIN1 isoforms on neuronal toxicity: the neuronal isoform 1 (BIN1iso1), the muscular isoform 8 (BIN1iso8) and the ubiquituous isoform 9 (BIN1iso9). We showed that contrary to BIN1iso8 and BIN1iso9, BIN1iso1 overexpression induced neurodegeneration and an accumulation of vesicles mainly labeled by endosome markers. Systematic search for endosome trafficking regulators that are able to rescue BIN1iso1-induced neurodegeneration indicated a defect in the early endosome trafficking machinery. In human induced neurons and cerebral organoids, BIN1 knock-out resulted in narrowing of the early endosomes. This phenotype was rescued by BIN1iso1 expression but not that of BIN1iso9. Finally, in accordance with our previous observation in flies, we also observed that BIN1iso1 overexpression led to an increase in size of the early endosomes in human induced neurons. Altogether, our data demonstrate that the AD genetic risk factor BIN1, and especially BIN1iso1, contributes to early-endosome size deregulation which is a very early pathophysiological feature observed in AD pathogenesis.

scholarly journals Apoptotic Activities of Wild-Type and Alzheimer's Disease-Related Mutant Presenilins in Drosophila melanogaster

1999 ◽  
Vol 146 (6) ◽  
pp. 1351-1364 ◽  
Author(s):  
Yihong Ye ◽  
Mark E. Fortini
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Drosophila Melanogaster ◽  
Genetic Model ◽  
Cell Types ◽  
Notch Receptor ◽  
Dominant Negative ◽  
Dominant Negative Effect ◽  
Loss Of Function ◽  
Wild Type

Mutant human presenilins cause early-onset familial Alzheimer's disease and render cells susceptible to apoptosis in cultured cell models. We show that loss of presenilin function in Drosophila melanogaster increases levels of apoptosis in developing tissues. Moreover, overexpression of presenilin causes apoptotic and neurogenic phenotypes resembling those of Presenilin loss-of-function mutants, suggesting that presenilin exerts a dominant negative effect when expressed at high levels. In Drosophila S2 cells, Psn overexpression leads to reduced Notch receptor synthesis affecting levels of the intact ∼300-kD precursor and its ∼120-kD processed COOH-terminal derivatives. Presenilin-induced apoptosis is cell autonomous and can be blocked by constitutive Notch activation, suggesting that the increased cell death is due to a developmental mechanism that eliminates improperly specified cell types. We describe a genetic model in which the apoptotic activities of wild-type and mutant presenilins can be assessed, and we find that Alzheimer's disease-linked mutant presenilins are less effective at inducing apoptosis than wild-type presenilin.

[18F]-florbetaben PET/CT Imaging in the Alzheimer’s Disease Mouse Model APPswe/PS1dE9

2018 ◽  
Vol 16 (1) ◽  
pp. 49-55 ◽  
Author(s):  
J. Stenzel ◽  
C. Rühlmann ◽  
T. Lindner ◽  
S. Polei ◽  
S. Teipel ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Mouse Model ◽  
New Drugs ◽  
Imaging Data ◽  
Wild Type ◽  
Preclinical Research ◽  
Standardized Uptake Values ◽  
Pet Ct

Background: Positron-emission-tomography (PET) using 18F labeled florbetaben allows noninvasive in vivo-assessment of amyloid-beta (Aβ), a pathological hallmark of Alzheimer’s disease (AD). In preclinical research, [<sup>18</sup>F]-florbetaben-PET has already been used to test the amyloid-lowering potential of new drugs, both in humans and in transgenic models of cerebral amyloidosis. The aim of this study was to characterize the spatial pattern of cerebral uptake of [<sup>18</sup>F]-florbetaben in the APPswe/ PS1dE9 mouse model of AD in comparison to histologically determined number and size of cerebral Aβ plaques. Methods: Both, APPswe/PS1dE9 and wild type mice at an age of 12 months were investigated by smallanimal PET/CT after intravenous injection of [<sup>18</sup>F]-florbetaben. High-resolution magnetic resonance imaging data were used for quantification of the PET data by volume of interest analysis. The standardized uptake values (SUVs) of [<sup>18</sup>F]-florbetaben in vivo as well as post mortem cerebral Aβ plaque load in cortex, hippocampus and cerebellum were analyzed. Results: Visual inspection and SUVs revealed an increased cerebral uptake of [<sup>18</sup>F]-florbetaben in APPswe/ PS1dE9 mice compared with wild type mice especially in the cortex, the hippocampus and the cerebellum. However, SUV ratios (SUVRs) relative to cerebellum revealed only significant differences in the hippocampus between the APPswe/PS1dE9 and wild type mice but not in cortex; this differential effect may reflect the lower plaque area in the cortex than in the hippocampus as found in the histological analysis. Conclusion: The findings suggest that histopathological characteristics of Aβ plaque size and spatial distribution can be depicted in vivo using [<sup>18</sup>F]-florbetaben in the APPswe/PS1dE9 mouse model.

scholarly journals A Super-Resolved View of the Alzheimer’s Disease-Related Amyloidogenic Pathway in Hippocampal Neurons

2021 ◽  
pp. 1-20
Author(s):  
Yang Yu ◽  
Yang Gao ◽  
Bengt Winblad ◽  
Lars Tjernberg ◽  
Sophia Schedin Weiss
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Hippocampal Neurons ◽  
Three Dimensional ◽  
Amyloid Β ◽  
Stimulated Emission ◽  
Amyloid Β Peptide ◽  
Primary Neurons ◽  
Amyloid Β Protein ◽  
Early Endosomes

Background: Processing of the amyloid-β protein precursor (AβPP) is neurophysiologically important due to the resulting fragments that regulate synapse biology, as well as potentially harmful due to generation of the 42 amino acid long amyloid β-peptide (Aβ 42), which is a key player in Alzheimer’s disease. Objective: Our aim was to clarify the subcellular locations of the amyloidogenic AβPP processing in primary neurons, including the intracellular pools of the immediate substrate, AβPP C-terminal fragment (APP-CTF) and the product (Aβ 42). To overcome the difficulties of resolving these compartments due to their small size, we used super-resolution microscopy. Methods: Mouse primary hippocampal neurons were immunolabelled and imaged by stimulated emission depletion (STED) microscopy, including three-dimensional, three-channel imaging and image analyses. Results: The first (β-secretase) and second (γ-secretase) cleavages of AβPP were localized to functionally and distally distinct compartments. The β-secretase cleavage was observed in early endosomes, where we were able to show that the liberated N- and C-terminal fragments were sorted into distinct vesicles budding from the early endosomes in soma. Lack of colocalization of Aβ 42 and APP-CTF in soma suggested that γ-secretase cleavage occurs in neurites. Indeed, APP-CTF was, in line with Aβ 42 in our previous study, enriched in the presynapse but absent from the postsynapse. In contrast, full-length AβPP was not detected in either the pre- or the postsynaptic side of the synapse. Furthermore, we observed that endogenously produced and endocytosed Aβ 42 were localized in different compartments. Conclusion: These findings provide critical super-resolved insight into amyloidogenic AβPP processing in primary neurons.

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