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P4‐025: DOES LEUCINE‐RICH REPEAT KINASE 2 MEDIATE ALPHA‐SYNUCLEIN SEEDING VIA ITS ROLE IN ENDOCYTOSIS?
Author(s) -
Delbroek Lore,
Kolen Kristof,
Arranz Amaia,
Daneels Guy,
Mandemakers Wim,
Calafate Sara,
Moechars Diederik
Publication year - 2014
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.2014.05.1539
Subject(s) - lrrk2 , endocytosis , alpha synuclein , microbiology and biotechnology , biology , phosphorylation , kinase , knockout mouse , parkinson's disease , biochemistry , mutation , cell , receptor , medicine , gene , disease
recent findings proposing cell surface heparan sulfate proteoglycans (HSPGs) as a unifying uptake mechanism for Ab, tau and a-synuclein, we aimed to investigate whether ApoE interferes with cellular a-synuclein uptake. Methods: Wild-type and heparan sulfate (HS)-deficient CHO cells were exposed to various concentrations of hilyte-488 labeled alphasynuclein in the presence or absence of heparin and recombinant or astrocyte-secreted ApoE in vitro. To investigate whether Ab competes with a-synuclein for cellular uptake, we further co-treated cells with a-synuclein and increasing concentrations of Ab1-42. Cells were harvested using trypsin and a-synuclein uptake was monitored using FACS. Results: a-synuclein uptake was reduced approximately 10-fold in HS-deficient cells compared to wild-type control cells. Heparin also efficiently reduced a-synuclein uptake in both wild-type and HS-deficient cells. Recombinant ApoE2 and ApoE4, but not ApoE3, reduced a-synuclein uptake in both cell lines; however, astrocyte-secreted ApoE reduced a-synuclein uptake only in wild-type CHO cells. Ab did not compete with a-synuclein for cellular uptake at a-synuclein/Ab molecular ratios 1:0.5, 1:1, 1:2 and 1:4. Conclusions:We confirm HS as an important mediator of a-synuclein uptake and propose an ApoE isoform-dependent effect on a-synuclein uptake that is further modulated by ApoE post-translational modification and/or lipidation. We also propose that the HSPG-subclasses mediating Ab and a-synuclein uptake differ as when combined they did not compete for cellular uptake. Our results pave way for future studies aimed at dissecting the cellular mechanisms linking ApoE to not only amyloid pathology but also synucleinopathy.