Dataset Information

Diversity of Amyloid-beta Proteoforms in the Alzheimer's Disease Brain

ABSTRACT: Amyloid-beta (Aβ) plays a key role in the pathogenesis of Alzheimer’s disease (AD), but little is known about the proteoforms present in human AD brain. We used high-resolution mass spectrometry to analyze intact, undigested Aβ from purified soluble aggregates and insoluble material in brains of 6 cases with severe dementia and pathologically confirmed AD. The soluble aggregates are especially relevant because they are believed to be the most toxic form of Aβ. We found a diversity of Aβ peptides, with 26 unique proteoforms including various N- and C-terminal truncations. N- and C-terminal truncations comprised 73% and 30%, respectively, of the number of Aβ proteoforms detected. The Aβ proteoforms segregated between the soluble and more insoluble aggregates with N-terminal truncations predominating in the insoluble material and C- terminal truncations segregating into the soluble aggregates. In contrast, canonical Aβ comprised the minority of the number of identified proteoforms (15.3%) and did not distinguish between the soluble and more insoluble aggregates. The relative abundance of many truncated Aβ proteoforms did not correlate with post-mortem interval, suggesting they are not artefacts. This heterogeneity of Aβ proteoforms deepens our understanding of AD and offers many new avenues for investigation into pathological mechanisms of the disease, with implications for therapeutic development.

INSTRUMENT(S): Orbitrap Fusion

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Brain, Regional Part Of Nervous System

DISEASE(S): Alzheimer's Disease

SUBMITTER: Norelle Wildburger

LAB HEAD: David L. Brody

PROVIDER: PXD006552 | Pride | 2017-08-28

REPOSITORIES: Pride

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Dataset's files

Source:

			Action	DRS
	Pt1_F_100K_tech-rep1.mgf	Mgf
	Pt1_F_100K_tech-rep1.pride.mgf.gz	Mgf
	Pt1_F_100K_tech-rep1.raw	Raw
	Pt1_F_100K_tech-rep2.mgf	Mgf
	Pt1_F_100K_tech-rep2.pride.mgf.gz	Mgf

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Publications

Diversity of Amyloid-beta Proteoforms in the Alzheimer's Disease Brain.

Wildburger Norelle C NC Esparza Thomas J TJ LeDuc Richard D RD Fellers Ryan T RT Thomas Paul M PM Cairns Nigel J NJ Kelleher Neil L NL Bateman Randall J RJ Brody David L DL

Scientific reports 20170825 1

Amyloid-beta (Aβ) plays a key role in the pathogenesis of Alzheimer's disease (AD), but little is known about the proteoforms present in AD brain. We used high-resolution mass spectrometry to analyze intact Aβ from soluble aggregates and insoluble material in brains of six cases with severe dementia and pathologically confirmed AD. The soluble aggregates are especially relevant because they are believed to be the most toxic form of Aβ. We found a diversity of Aβ peptides, with 26 unique proteofo ...[more]

PMID: 28842697

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Project description:Alzheimer’s disease (AD) is the most common cause of late-life dementia characterized by progressive neurodegeneration and brain deposition of amyloid-β (Aβ) and phosphorylated tau. The APOE ε2 encoding apolipoprotein E (APOE2) is a protective allele against AD among the three genotypes (APOE ε2, ε3, ε4), while APOE4 is the strongest genetic factor substantially increasing AD risk. APOE regulates brain lipid homeostasis and maintaining synaptic plasticity and neuronal function, where APOE2 has a superior function compared to APOE3 and APOE4. Gene therapy that increases APOE2 levels in the brain is, therefore, a promising therapeutic strategy for AD treatment. We previously reported that PEGylated liposomes conjugated with transferrin and a cell-penetrating peptide Penetratin sufficiently deliver chitosan-APOE2 cDNA plasmid complex into the brain of wild-type mice. Here, we investigated how brain-targeting liposome-based APOE2 gene delivery influences Aβ)-related pathologies in amyloid model AppNL-G-F knockin mice at 12-month-old. We found a trend of reductions of insoluble Aβ levels in the mouse cortices 1 month after APOE2 gene therapy. Furthermore, in the AppNL-G-F knockin mice that received the APOE2 gene therapy, brain transcriptome analysis through RNA-sequencing identified the upregulation of genes/pathways related to neuronal development. This was supported by increases of Dlg4 and Syp mRNAs coding synaptic proteins in the experimental group. On the other hand, we found that APOE2 gene delivery increased soluble Aβ levels, including oligomers, as well as exacerbated neurite dystrophy and decreased synaptophysin. Together, our results suggest that brain-targeting liposome-based APOE2 gene therapy is potentially beneficial for synaptic formation at the transcriptional level. Forced APOE2 expressions, however, may exacerbate Aβ toxicity by increasing the dissociation of Aβ oligomers from aggregates in the presence of considerable amyloid burden.