Quantitative Proteomics Identifies Surfactant-Resistant α-Synuclein in Cerebral Cortex of Parkinsonism-Dementia Complex of Guam but Not Alzheimer's Disease or Progressive Supranuclear Palsy

Abstract

Parkinsonism-dementia complex (PDC) remains a significant health burden to the Chamorro population. We tested the hypothesis that quantitative proteomics might provide fresh insight into this enigmatic illness by analyzing proteins resistant to surfactant extraction from patients with Alzheimer's disease (AD) or PDC and their matched controls using isobaric tags for relative and absolute quantification. In addition to the expected increase in abnormal frontal cortical A␤ peptides, tau, ubiquitin, and apolipoprotein E in AD, and tau in PDC, we identified ␣-synuclein (SNCA) as a major abnormal protein in PDC but not AD. We confirmed our isobaric tags for relative and absolute quantification findings by enzyme-linked immunosorbent assay in frontal and temporal cortices. We extended our assays to include a limited number of cases of progressive supranuclear palsy (PSP) and dementia with Lewy bodies; we observed increased abnormal tau but not SNCA in PSP, and abnormal SNCA in dementia with Lewy bodies that was quantitatively similar to PDC. Finally, soluble A␤ oligomers were selectively increased in AD but not PDC or PSP. These results show that frontal and temporal cortex in PDC is distinguished from AD and PSP by its accumulation of abnormal SNCA and suggest that PDC be considered a synucleinopathy as well as a tauopathy. (Am J

Cerebral Cortical Aβ42and PHF-τ in 325 Consecutive Brain Autopsies Stratified by Diagnosis, Location, andAPOE

“…Histelide has a unique set of combined advantages: like studies of frozen tissue it produces robustly quantitative, molecularly specific data as an ELISA, and like studies of fixed tissue, it can generate high quality immunohistochemical localization, in this case signal limited to cerebral cortical GM (3). For the present study, further advantages are that we measured Aβ 42 and PHF-τ in situ rather than from incomplete extractions of these very poorly soluble proteins (23). We were able to analyze the entire ACT autopsy cohort and were not limited to the subset of cases with frozen tissue, which has the potential to introduce case selection bias (14).…”

Pallidal neuronal apolipoprotein E in pantothenate kinase-associated neurodegeneration recapitulates ischemic injury to the globus pallidus

“…To prepare detergent-insoluble extracts of tissue, ten volume sice-cold 100 mM Tris, (pH 7.4)/10% sucrose “buffer A” containing protease and phosphatase inhibitors was added per gram tissue samples as previously described (Yang et al ., 2007) The tissue was sonicated with a probe sonicator for 30 s and then separated by ultracentrifugation at 450,000 × g for 20 min at 4°C. Supernatants were removed, and three subsequent serial extractions of the insoluble pellets were performed with the same volume of buffer A with 1% Triton X-100 followed by ultracentrifugation at each step.…”

Different Patterns of Cerebral Injury in Dementia With or Without Diabetes

“…Tissue was extracted exactly as previously described 13,26. Full thickness grey matter was dissected from underlying white matter and solubilized in buffer (10 mM Tris, 1mM EGTA, 1mM DTT, 10% sucrose, pH7.5) plus triton, 1% sedimented; supernatant fluid was used to measure detergent-soluble proteins.…”