β-site amyloid precursor protein cleaving enzyme 1 (BACE1) cleaves β-amyloid precursor protein (APP) and initiates the production of amyloid-β peptides (Aβ), which is thought to trigger Alzheimer's disease (AD). Recent reports demonstrate that BACE1 levels are elevated in brains of AD mouse models as well as in postmortem AD brain tissue, implying a role for aberrant BACE1 activity in AD pathogenesis. However, cellular mechanisms by which the level and activity of BACE1 are controlled are not yet clear. We took a proteomics approach to search for cellular modulators of BACE1 activity. BACE1-harboring protein complexes in SH-SY5Y human neuroblastoma cells were subject to in vivo crosslinking and tandem affinity purification (TAP) followed by mass spectrometry. One of the BACE1-interacting proteins identified is Sorting Nexin 6 (SNX6), a member of the Phox homology (PX) domain-containing trafficking protein family, whose function is implicated in protein trafficking. We show that SNX6 is expressed in neurons of mammalian brains. We also find that reducing SNX6 by RNA interference increases BACE1-mediated APP cleavage, resulting in the increase of Aβ production. Conversely, overexpression of SNX6 decreases BACE1-mediated APP cleavage, leading to a reduction in Aβ. SNX6 mainly localizes to the endosomal compartments, while a subset of SNX6 co-localizes with BACE1 in the trans-Golgi network (TGN). Subcellular fractionation reveals that SNX6 regulates cellular BACE1 levels by modulating BACE1 levels in the TGN. Using BACE1 antibody uptake assays, we show that reducing SNX6 enhances the retrograde transport of BACE1 from cell surface to the TGN. In sum, SNX6 functions as a negative regulator of BACE1-mediated cleavage of APP and Aβ production, illustrating a novel pathway for BACE1 regulation in AD. SNX6 may also represent a novel therapeutic target for the treatment of Alzheimer's disease.
|School Location:||United States -- New York|
|Source:||DAI-B 69/01, Dissertation Abstracts International|
|Keywords:||Alzheimer's disease, Amyloid precursor protein, BACE1, Beta-secretase, Sorting nexin|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be