Targeted quantitative analysis of synaptic proteins in Alzheimer's disease brain

Chang, Rachel Yoon Kyung, Etheridge, Naomi, Dodd, Peter R. and Nouwens, Amanda S. (2014) Targeted quantitative analysis of synaptic proteins in Alzheimer's disease brain. Neurochemistry International, 75 66-75. doi:10.1016/j.neuint.2014.05.011

Author Chang, Rachel Yoon Kyung
Etheridge, Naomi
Dodd, Peter R.
Nouwens, Amanda S.
Title Targeted quantitative analysis of synaptic proteins in Alzheimer's disease brain
Journal name Neurochemistry International   Check publisher's open access policy
ISSN 0197-0186
Publication date 2014-08-01
Sub-type Article (original research)
DOI 10.1016/j.neuint.2014.05.011
Volume 75
Start page 66
End page 75
Total pages 10
Place of publication Camden, London, United Kingdom
Publisher Elsevier
Language eng
Formatted abstract
• We targeted synaptic proteins in AD cases & controls by label-free multiple reaction monitoring.
• PRDX1 & DRP1 protein levels significantly higher in AD hippocampus cf AD motor cortex.
• PRDX1, CKB and aldolase C significantly lower in non-AD hippocampus cf non-AD motor cortex.
• Linear and highly reproducible assays were achieved using an internal standard protein.

Brain tissue from Alzheimer’s disease (AD) patients shows significant loss of synapses in selected regions. Synaptic degeneration is the best predictor for loss of cognitive functions ante mortem. The molecular mechanisms underlying this degeneration remain unknown. Our previous two-dimensional gel-electrophoresis proteomics study found that 26 synaptic proteins are differentially expressed in Alzheimer’s brain. It is difficult to quantify global protein expression using this technique because (a) several proteins can migrate together and (b) isoforms of the same protein can migrate to different places. The present study estimated global synaptic protein levels by label-free multiple reaction monitoring. Multiple reaction monitoring is a powerful and sensitive mass spectrometry technique that specifically targets multiple protein of interests. The severely AD-affected hippocampus was compared with motor cortex, a relatively spared region. We targeted ten proteins in autopsy brain based on the earlier study. Analytes separated by high performance liquid-chromatography were monitored on a hybrid triple quadrupole linear ion trap mass spectrometer in multiple reaction monitoring mode. With the use of an internal standard protein, linear and highly reproducible (CV < 9%) label-free assays were achieved. Data were contrasted with the gel-based study to highlight differences and similarities. Significantly higher expression levels of peroxiredoxin-1 (may provide antioxidant protection) and dihydropyrimidinase-related protein-1 (associated with cytoskeletal remodeling) were found in AD hippocampus. Significantly lower levels of peroxiredoxin-1 and the energy-related enzymes creatine kinase B and fructose-bisphosphate aldolase C were found in non-AD hippocampus. Our previously reported difference in synaptotagmin expression is probably isoform-specific. These findings suggest potential roles of key proteins in synaptic loss in AD, and/or a protective mechanism in non-AD brain tissue.
Keyword Degeneration
Multiple reaction monitoring
Creatine kinase
Oxidative stress
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2015 Collection
School of Chemistry and Molecular Biosciences
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Created: Fri, 06 Jun 2014, 20:45:10 EST by Mrs Louise Nimwegen on behalf of School of Chemistry & Molecular Biosciences