Dataset Information

CERT_L reduces C16 ceramide, amyloid-? levels, and inflammation in a model of Alzheimer's disease.

ABSTRACT:

Background

Dysregulation of ceramide and sphingomyelin levels have been suggested to contribute to the pathogenesis of Alzheimer's disease (AD). Ceramide transfer proteins (CERTs) are ceramide carriers which are crucial for ceramide and sphingomyelin balance in cells. Extracellular forms of CERTs co-localize with amyloid-? (A?) plaques in AD brains. To date, the significance of these observations for the pathophysiology of AD remains uncertain.

Methods

A plasmid expressing CERT_L, the long isoform of CERTs, was used to study the interaction of CERT_L with amyloid precursor protein (APP) by co-immunoprecipitation and immunofluorescence in HEK cells. The recombinant CERT_L protein was employed to study interaction of CERT_L with amyloid-? (A?), A? aggregation process in presence of CERT_L, and the resulting changes in A? toxicity in neuroblastoma cells. CERT_L was overexpressed in neurons by adeno-associated virus (AAV) in a mouse model of familial AD (5xFAD). Ten weeks after transduction, animals were challenged with behavior tests for memory, anxiety, and locomotion. At week 12, brains were investigated for sphingolipid levels by mass spectrometry, plaques, and neuroinflammation by immunohistochemistry, gene expression, and/or immunoassay.

Results

Here, we report that CERT_L binds to APP, modifies A? aggregation, and reduces A? neurotoxicity in vitro. Furthermore, we show that intracortical injection of AAV, mediating the expression of CERT_L, decreases levels of ceramide d18:1/16:0 and increases sphingomyelin levels in the brain of male 5xFAD mice. CERT_L in vivo over-expression has a mild effect on animal locomotion, decreases A? formation, and modulates microglia by decreasing their pro-inflammatory phenotype.

Conclusion

Our results demonstrate a crucial role of CERT_L in regulating ceramide levels in the brain, in amyloid plaque formation and neuroinflammation, thereby opening research avenues for therapeutic targets of AD and other neurodegenerative diseases.

SUBMITTER: Crivelli SM

PROVIDER: S-EPMC7890977 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

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Publications

CERT<sub>L</sub> reduces C16 ceramide, amyloid-β levels, and inflammation in a model of Alzheimer's disease.

Crivelli Simone M SM Luo Qian Q Stevens Jo A A JAA Giovagnoni Caterina C van Kruining Daan D Bode Gerard G den Hoedt Sandra S Hobo Barbara B Scheithauer Anna-Lena AL Walter Jochen J Mulder Monique T MT Exley Christopher C Mold Matthew M Mielke Michelle M MM De Vries Helga E HE Wouters Kristiaan K van den Hove Daniel L A DLA Berkes Dusan D Ledesma María Dolores MD Verhaagen Joost J Losen Mario M Bieberich Erhard E Martinez-Martinez Pilar P

Alzheimer's research & therapy 20210217 1

<h4>Background</h4>Dysregulation of ceramide and sphingomyelin levels have been suggested to contribute to the pathogenesis of Alzheimer's disease (AD). Ceramide transfer proteins (CERTs) are ceramide carriers which are crucial for ceramide and sphingomyelin balance in cells. Extracellular forms of CERTs co-localize with amyloid-β (Aβ) plaques in AD brains. To date, the significance of these observations for the pathophysiology of AD remains uncertain.<h4>Methods</h4>A plasmid expressing CERT<su ...[more]

PMID: 33597019

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Project description:It has been demonstrated that peroxisome proliferator-activated receptor γ (PPARγ) can regulate the transcription of its target gene, insulin-degrading enzyme (IDE), and thus enhance the expression of the IDE protein. The protein can degrade β amyloid (Aβ), a core pathological product of Alzheimer's disease (AD). PPARγ can also regulate the transcription of other target gene, β-amyloid cleavage enzyme 1 (BACE1), and thus inhibit the expression of the BACE1 protein. BACE1 can hydrolyze amyloid precursor protein (APP), the precursor of Aβ. In adipose tissue, PPARγ agonists can inhibit the phosphorylation of PPARγ by inhibiting cyclin-dependent kinase 5 (CDK5), which in turn affects the expression of target genes regulated by PPARγ. PPARγ agonists may also exert inhibitory effects on the phosphorylation of PPARγ in the brain, thereby affecting the expression of the aforementioned PPARγ target genes and reducing Aβ levels. The present study confirmed this hypothesis by showing that PPARγ agonist pioglitazone attenuated the neuronal apoptosis of primary rat hippocampal neurons induced by Aβ1-42, downregulated CDK5 expression, weakened the binding of CDK5 to PPARγ, reduced PPARγ phosphorylation, increased the expression of PPARγ and IDE, decreased the expression of BACE1, reduced APP production, and downregulated intraneuronal Aβ1-42 levels. These effects were inhibited by the PPARγ antagonist GW9662. After CDK5 silencing with CDK5 shRNA, the above effect of pioglitazone was not observed, except when upregulating the expression of PPARγ in Aβ1-42 treated neurons. In conclusion, this study demonstrated that pioglitazone could inhibit the phosphorylation of PPARγ in vitro by inhibiting CDK5 expression, which in turn affected the expression of PPARγ target genes Ide and Bace1, thereby promoting Aβ degradation and reducing Aβ production. This reduced Aβ levels in the brain, thereby exerting neuroprotective effects in an AD model.

Dataset Information

CERT_L reduces C16 ceramide, amyloid-? levels, and inflammation in a model of Alzheimer's disease.

Background

Methods

Results

Conclusion

Publications

CERT<sub>L</sub> reduces C16 ceramide, amyloid-β levels, and inflammation in a model of Alzheimer's disease.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Dataset Information

CERTL reduces C16 ceramide, amyloid-? levels, and inflammation in a model of Alzheimer's disease.

Background

Methods

Results

Conclusion

Publications

CERT<sub>L</sub> reduces C16 ceramide, amyloid-β levels, and inflammation in a model of Alzheimer's disease.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

CERT_L reduces C16 ceramide, amyloid-? levels, and inflammation in a model of Alzheimer's disease.