engleski

Cleavage by BACE1 is upregulated in murine primary neurons of a rare neurodegenerative disorder Niemann-Pick type C

The β-site amyloid precursor protein cleavage enzyme 1 (BACE1), has been considered as a therapeutic target for the treatment of Alzheimer’s disease (AD) as it initiates the proteolytic cleavage of the β-amyloid precursor protein (APP) to generate toxic amyloid-β peptides that accumulate in AD patients’ brains. We have recently shown that BACE1-mediated proteolysis is enhanced in a rare, inherited lysosomal storage disorder Niemann-Pick type C (NPC) that shares several pathological features with AD. The analysis of NPC1-mouse brains revealed that enhanced cleavage by BACE1 in NPC involves APP and also additional, recently identified BACE1 substrates, seizure protein 6 (Sez6) and seizure 6-like protein (Sez6L), which are primarily cleaved by BACE1. The goal of this work was to characterize BACE1-mediated proteolysis in murine primary neurons of NPC1- vs. wt-mice and to test whether inhibition of BACE1 may have any beneficial effect(s) on the pathological features of NPC, including enlargement of early endosomes, tau hyperphosphorylation and cholesterol accumulation. Female and male NPC1+/- mice (BALB/cNctr-Npc1N/+, the Jackson Laboratory, USA) were mated and the primary neuronal cultures were generated from the isolated brains of P0 pups. NPC1-genotyping was performed in parallel. We showed that BACE1-mediated proteolysis of Sez6 and Sez6L is enhanced in NPC1- vs. wt-neurons and that BACE1 inhibition blocked formation of the BACE1- generated sSez6/sSez6L fragments. Furthermore, immunocytochemistry analysis revealed more punctuate staining of Sez6 and Sez6L in NPC1- vs. wt-neurons, suggesting their accumulation within endosomal vesicles. BACE1-inhibition reversed the punctuate staining of Sez6/Sez6L in NPC1-neurons to that as in wt-neuronal cultures. These findings confirm that NPC1-neurons show enhanced proteolysis by BACE1, indicating that BACE1 may be involved in the pathogenesis of NPC disease and that inhibiting BACE1may ameliorate pathological feature(s) of NPC.

NPC1 ; BACE1

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