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P2–057: Interactome analyses of mature gamma‐secretase complexes reveals distinct molecular environments of presenilin paralogs and preferential binding of signal peptide peptidase to PS2
Author(s) -
Boehm Christopher,
Won Jeon Amy Hye,
Chen Fusheng,
Fraser Paul,
Mount Howard,
St. GeorgeHyslop Peter,
SchmittUlms Gerold
Publication year - 2013
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.2013.05.700
Subject(s) - presenilin , interactome , biology , transmembrane protein , mutant , hek 293 cells , membrane protein , microbiology and biotechnology , biochemistry , gene , alzheimer's disease , receptor , membrane , medicine , disease , pathology
demonstrated PZP immunoreactivity in the brain, predominantly localized to microglial cells. We observed an increased amount of PZP immunoreactive microglial cells in the AD brain compared to healthy controls and in addition, PZP immunoreactive cells were found in close association with senile plaques. PZP is best known as a serum protein that is upregulated during pregnancy and is capable of covalently binding and immobilizing various ligands mostly related to protease inhibition. The increased abundance and close proximity of PZP to AD plaques suggests involvement of protease inhibition during plaque formation. In this study we aim to investigate the pathophysiological role of PZP in AD by analyzing brain derived PZP and its interaction partners. Methods: We will enrich senile plaques and PZP from human brain tissue using two techniques i.e. laser capture microdissection (LCM) and immunoprecipitation (IP). PZP will be quantified using nano liquid chromatography mass spectrometry (nLC-MS) based techniques and selective reaction monitoring (SRM). Ligand binding to PZP generates a shift in the molecular weight of such a complex. Peptides that are generated enzymatically by trypsin cleavage of a PZP-ligand complex generate information on how the ligand is bound covalently to PZP. In this manner we can identify PZP interaction partners and the biochemical process of binding. Results: IP method optimization was performed using serum from pregnant women that contained high levels of PZP. We successfully enriched PZP from this material and identified a number of interaction partners using our approach. Experiments on human AD and control brain lysates and on brain samples isolated by LCM are ongoing. Conclusions: Our data indicate that PZP is a potential early player in AD that might contribute to plaque formation. Increased serum PZP might be indicative of an early inflammatory, microglia mediated process in the brain aimed at clearing aggregating factors. Failure of this mechanism, e.g. altered ligand binding or clearance, may contribute to plaque formation.