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P3‐165: Effect of aging on functional brain connectivity: Association with apolipoprotein E genotype
Author(s) -
Ponomareva Natalya V.,
Boikova Tatyana,
Kunijeva Svetlana,
Rogaev Evgeny
Publication year - 2010
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2010.05.1663
Subject(s) - apolipoprotein e , psychology , neuroscience , electroencephalography , allele , memory impairment , cognition , medicine , disease , biology , genetics , gene
Background: Six different N-terminal amyloid precursor protein (APP) fragments, with molecular weight w12 kDa, have previously been identified in human cerebrospinal fluid (CSF). In a pilot study, both the sum of their concentrations, measured by western blot, and the relative abundance pattern, measured by mass spectrometry, were different in Alzheimer’s disease (AD) patients compared to healthy controls. To test if these differences were also reflected in protease activities that possibly give rise to the w12 kDa fragments an enzymatic assay was developed and the activity in CSF was investigated for its potential as a biomarker for AD. Methods: The substrate in the protease activity assay was a custom made fluorochrome/quencher labeled peptide that covers the cleavage sites in APP (APP118-APP127) corresponding to the C-termini of the six w12 kDa APP fragments. The activity was measured in CSF from 55 AD patients and 17 controls. Results: There was a significant increase in the protease activity in CSF from AD patients compared to the controls (p 1⁄4 0.001). This is in line with previous results which indicate that the sum of the w12 kDa fragments are elevated in AD. Results from inhibition studies strongly suggests that the enzyme responsible for the cleavage of the substrate is an aspartic protease since a sub nM IC50 value was recorded for Pepstatin A while no inhibition was observed for the cysteine protease specific inhibitor E64 at concentrations up to100 nM. Conclusions: There exists an enzymatic activity in CSF capable of cleaving a peptide substrate that spans a portion, close to the N-terminal, of APP. In a pilot study the activity is increased in AD patients compared to controls suggesting that it can be used as a biomarker.