| First Author | Dafnis I | Year | 2018 |
| Journal | Biochem J | Volume | 475 |
| Issue | 10 | Pages | 1839-1859 |
| PubMed ID | 29743204 | Mgi Jnum | J:263678 |
| Mgi Id | MGI:6163896 | Doi | 10.1042/BCJ20180068 |
| Citation | Dafnis I, et al. (2018) ApoE isoforms and carboxyl-terminal-truncated apoE4 forms affect neuronal BACE1 levels and Abeta production independently of their cholesterol efflux capacity. Biochem J 475(10):1839-1859 |
| abstractText | The beta-site amyloid precursor protein-cleaving enzyme 1 (BACE1) initiates the production of amyloid-beta peptide (Abeta), which is central to the pathogenesis of Alzheimer's disease (AD). Changes in brain cholesterol homeostasis have been suggested to affect Abeta metabolism. Cholesterol homeostasis is maintained in the brain by apolipoprotein E (apoE). The apoE4 isoform constitutes the major risk factor for AD. Here, we investigated the effect of apoE forms on Abeta generation and on BACE1 levels. We also examined the potential involvement in these processes of cholesterol transporters ABCG1 and ABCG4 or the lipoprotein receptor SR-BI, which are implicated in cholesterol efflux to apoE. It was found that reconstituted lipoprotein-associated apoE isoforms promoted the increase of Abeta production and oligomerization and of BACE1 levels in human neuroblastoma SK-N-SH cells, with an apoE4 >/= apoE3 > apoE2 potency rank order. Progressive carboxyl-terminal apoE4 deletions between residues 230-299 decreased the protein's ability to increase BACE1, while further truncations up to residue 166 prevented apoE4 from increasing BACE1 and Abeta levels in SK-N-SH and primary mouse neuronal cells. ABCG1, but not ABCG4 or SR-BI, moderately increased Abeta production and BACE1 levels in SK-N-SH cells. All apoE forms affected Abeta production/oligomerization and BACE1 levels in a pattern that did not follow that of their capacity to promote ABCG1, ABCG4 or SR-BI-mediated cholesterol efflux. Overall, our data indicate that apoE-containing lipoprotein particles can have a direct effect on BACE1 levels and Abeta secretion and possibly contribute to AD pathogenetic processes, independently of their capacity to promote cholesterol efflux. |
