Nicotinamide attenuates the decrease in dendritic spine density in hippocampal primary neurons from 5xFAD mice, an Alzheimer’s disease animal model

Kim, Hyun-Ju; Kim, Bora; Cho, Joo Youn

doi:10.1186/s13041-020-0565-x

“…We performed Golgi staining to determine whether the RyR2 E4872Q +/− mutation affects the spine density and morphology of 5xFAD +/− CA1 pyramidal neurons. Consistent with previous studies ( de Pins et al, 2019 ; Kim et al, 2020 ; Yang et al, 2018 ), the density of overall protrusions and specifically the density of mushroom and branched spines were reduced significantly in 5xFAD +/− CA1 pyramidal neurons compared with WT cells ( Figure S7M ). The E4872Q +/− mutation (limiting RyR2 open time) prevented the loss of overall protrusions and branched spines, but not the loss of mushroom spines, of 5xFAD +/− /EQ +/− CA1 pyramidal cells ( Figure S7M ).…”

Section: Resultssupporting

confidence: 92%

Limiting RyR2 Open Time Prevents Alzheimer’s Disease-Related Neuronal Hyperactivity and Memory Loss but Not β-Amyloid Accumulation

Yao

¹

,

Sun

²

,

Institóris

³

et al. 2020

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SUMMARY Neuronal hyperactivity is an early primary dysfunction in Alzheimer’s disease (AD) in humans and animal models, but effective neuronal hyperactivity-directed anti-AD therapeutic agents are lacking. Here we define a previously unknown mode of ryanodine receptor 2 (RyR2) control of neuronal hyperactivity and AD progression. We show that a single RyR2 point mutation, E4872Q, which reduces RyR2 open time, prevents hyperexcitability, hyperactivity, memory impairment, neuronal cell death, and dendritic spine loss in a severe early-onset AD mouse model (5xFAD). The RyR2-E4872Q mutation upregulates hippocampal CA1-pyramidal cell A-type K + current, a well-known neuronal excitability control that is downregulated in AD. Pharmacologically limiting RyR2 open time with the R -carvedilol enantiomer (but not racemic carvedilol) prevents and rescues neuronal hyperactivity, memory impairment, and neuron loss even in late stages of AD. These AD-related deficits are prevented even with continued β-amyloid accumulation. Thus, limiting RyR2 open time may be a hyperactivity-directed, non-β-amyloid-targeted anti-AD strategy.

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“…However, primary neurons cultured from 5xFAD mice, which can serve as an amyloid model in vitro [55][56][57], displayed increased cell death when exposed to 5M of cell-derived hexameric A. Importantly, Together, our results support that the identified cell-derived hexameric A assembly has nucleating and seeding properties in the amyloid pathology.…”

Section: Table1 Inverse Correlation Between Monomeric and Hexameric Asupporting

confidence: 65%

“…Cytotoxic assay on primary neurons derived from transgenic 5xFAD mice was performed. It was previously reported that cultured neurons from AD transgenic animal models can reflect AD phenotypes in vitro [55][56][57]. We observed a significant increase in the proportion of cell death when neurons were treated with 5M of cell-derived hexameric A.…”

Section: Table1 Inverse Correlation Between Monomeric and Hexameric Amentioning

confidence: 49%

Mechanism of cellular production and in vivo seeding effects of hexameric β-amyloid assemblies

Vrancx

¹

,

Vadukul

²

,

Contino

³

et al. 2020

Preprint

0

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BackgroundThe β-amyloid peptide (Aβ) plays a key role in Alzheimer’s disease. After its production by catabolism of the amyloid precursor protein (APP) through the action of presenilin 1 (PS1)- or presenilin 2 (PS2)-dependent γ-secretases, monomeric Aβ can assemble in oligomers. In a pathological context, this eventually leads to the formation of fibrils, which deposit in senile plaques. Many studies suggest that Aβ toxicity is related to its soluble oligomeric intermediates. Among these, our interest focuses on hexameric Aβ, which acts as a nucleus for Aβ self-assembly.MethodsBiochemical analyses were used to identify hexameric Aβ in a wide range of models; cell lines, cerebrospinal fluid from cognitively impaired patients and transgenic mice exhibiting human Aβ pathology (5xFAD). We isolated this assembly and assessed both its effect on primary neuron viability in vitro, and its contribution to amyloid deposition in vivo following intracerebral injection. In both cases, we used wild-type mice (C57BL/6) to mimic an environment where hexameric Aβ is present alone and 5xFAD mice to incubate hexameric Aβ in a context where human Aβ species are pre-existing. Using CRISPR-Cas9, we produced stable knockdown human cell lines for either PS1 or PS2 to elucidate their contribution to the formation of hexameric Aβ.ResultsIn WT mice, we found that neither in vitro or in vivo exposure to hexameric Aβ was sufficient to induce cytotoxic effects or amyloid deposition. In 5xFAD mice, we observed a significant increase in neuronal death in vitro following exposure to 5μM hexameric Aβ, as well as a 1.47-fold aggravation of amyloid deposition in vivo. At the cellular level, we found hexameric Aβ in extracellular vesicles and observed a strong decrease in its excretion when PS2 was knocked down by 60%.ConclusionsOur results indicate the absence of cytotoxic effects of cell-derived hexameric Aβ by itself, but its capacity to aggravate amyloid deposition by seeding other Aβ species. We propose an important role for PS2 in the formation of this particular assembly in vesicular entities, in line with previous reports linking the restricted location of PS2 in acidic compartments to the production of more aggregation-prone Aβ.

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“…In line with the observation that cell-derived hexameric Aβ does not appear cytotoxic by itself, and considering its suggested role as a nucleus for Aβ self-assembly, we studied whether the harmful potential of Aβ hexamers could be unraveled when pre-existing Aβ species are present. Cytotoxic assay on primary neurons derived from transgenic 5xFAD mice was performed, as it t was previously reported that cultured neurons from AD transgenic animal models can re ect AD phenotypes in vitro [55][56][57]. We observed a signi cant increase in the proportion of cell death when neurons were treated with 5µM of cell-derived hexameric Aβ.…”

Section: Discussionmentioning

confidence: 81%

“…This suggests that the identi ed assembly is not cytotoxic by itself, at least in these experimental conditions. However, primary neurons cultured from 5xFAD mice, which can serve as an amyloid model in vitro [55][56][57], displayed increased cell death when exposed to 5µM of cell-derived hexameric Aβ. Importantly, this indicates that Aβ hexamers may have the ability to cause toxic effects only when there is pre-existing Aβ in the neuronal environment.…”

Section: Cell-derived Hexameric Aβ Causes Cell Viability Impairment Omentioning

confidence: 99%

Mechanism of Cellular Production and in Vivo Seeding Effects of Hexameric β-Amyloid Assemblies

Vrancx

¹

,

Vadukul

²

,

Contino

³

et al. 2021

Preprint

0

View full text Add to dashboard Cite

BackgroundThe β-amyloid peptide (Aβ) plays a key role in Alzheimer’s disease. After its production by catabolism of the amyloid precursor protein (APP) through the action of presenilin 1 (PS1)- or presenilin 2 (PS2)-dependent γ-secretases, monomeric Aβ can assemble in oligomers. In a pathological context, this eventually leads to the formation of fibrils, which deposit in senile plaques. Many studies suggest that Aβ toxicity is related to its soluble oligomeric intermediates. Among these, our interest focuses on hexameric Aβ, which acts as a nucleus for Aβ self-assembly.MethodsBiochemical analyses were used to identify hexameric Aβ in a wide range of models; cell lines, cerebrospinal fluid from cognitively impaired patients and transgenic mice exhibiting human Aβ pathology (5xFAD). We isolated this assembly and assessed both its effect on primary neuron viability in vitro, and its contribution to amyloid deposition in vivo following intracerebral injection. In both cases, we used wild-type mice (C57BL/6) to mimic an environment where hexameric Aβ is present alone and 5xFAD mice to incubate hexameric Aβ in a context where human Aβ species are pre-existing. Using CRISPR-Cas9, we produced stable knockdown human cell lines for either PS1 or PS2 to elucidate their contribution to the formation of hexameric Aβ.ResultsIn WT mice, we found that neither in vitro or in vivo exposure to hexameric Aβ was sufficient to induce cytotoxic effects or amyloid deposition. In 5xFAD mice, we observed a significant increase in neuronal death in vitro following exposure to 5μM hexameric Aβ, as well as a 1.47-fold aggravation of amyloid deposition in vivo. At the cellular level, we found hexameric Aβ in extracellular vesicles and observed a strong decrease in its excretion when PS2 was knocked down by 60%.ConclusionsOur results indicate the absence of cytotoxic effects of cell-derived hexameric Aβ by itself, but its capacity to aggravate amyloid deposition by seeding other Aβ species. We propose an important role for PS2 in the formation of this particular assembly in vesicular entities, in line with previous reports linking the restricted location of PS2 in acidic compartments to the production of more aggregation-prone Aβ.

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Nicotinamide attenuates the decrease in dendritic spine density in hippocampal primary neurons from 5xFAD mice, an Alzheimer’s disease animal model

Cited by 21 publications

References 45 publications

Limiting RyR2 Open Time Prevents Alzheimer’s Disease-Related Neuronal Hyperactivity and Memory Loss but Not β-Amyloid Accumulation

Limiting RyR2 Open Time Prevents Alzheimer’s Disease-Related Neuronal Hyperactivity and Memory Loss but Not β-Amyloid Accumulation

Mechanism of cellular production and in vivo seeding effects of hexameric β-amyloid assemblies

Mechanism of Cellular Production and in Vivo Seeding Effects of Hexameric β-Amyloid Assemblies

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