Lanabecestat

Alzheimer's disease (AD) is a neurodegenerative disease affecting older adults. AD pathogenesis involves the production of the highly neurotoxic amyloid-β peptide 1-42 (Aβ_1-42) from β-site amyloid precursor protein cleaving enzyme 1 (BACE1). The phosphorylation of BACE1 at Thr252 increases its enzymatic activity. This study examined the phosphorylation of BACE1 from human and rat BACE1 in silico through phosphorylation predictors. Besides, we explored how phosphorylation at various sites affected the BACE1 structure and its affinity with amyloid precursor protein (APP) and six BACE1 inhibitors. Additionally, we evaluated the phosphorylation of Thr252-BACE1 by glycogen synthase kinase 3 β (GSK3β) in vitro. The phosphorylation predictors showed that Thr252, Ser59, Tyr76, Ser71, and Ser83 could be phosphorylated. Also, Ser127 in rat BACE1 can be phosphorylated, but human BACE1 has a Gly at this position. Molecular dynamics simulations showed that Ser127 plays an important role in the open and closed BACE1 conformational structures. Docking studies and the molecular mechanics generalized Born surface area (MMGBSA) approach showed that human BACE1 phosphorylated at Thr252 and rat BACE1 phosphorylated at Ser71 have the best binding and free energy with APP, forming hydrogen bonds with Asp672. Importantly, inhibitors have a higher affinity for the phosphorylated rat BACE1 than for its human counterpart, which could explain their failure during clinical trials. Finally, in vitro experiments showed that GSK3β could phosphorylate BACE1. In conclusion, BACE1 phosphorylation influences the BACE1 conformation and its recognition of ligands and substrates. Thus, these features should be carefully considered in the design of BACE1 inhibitors.

Amyloid precursor protein (APP) is a brain-rich, single pass transmembrane protein that is proteolytically processed into multiple products, including amyloid-beta (Aβ), a major driver of Alzheimer disease (AD). Although both overexpression of APP and exogenously delivered Aβ lead to changes in sleep, whether APP processing plays an endogenous role in regulating sleep is unknown. Here, we demonstrate that APP processing into Aβ40 and Aβ42 is conserved in zebrafish and then describe sleep/wake phenotypes in loss-of-function appa and appb mutants. Larvae with mutations in appa had reduced waking activity, whereas larvae that lacked appb had shortened sleep bout durations at night. Treatment with the γ-secretase inhibitor DAPT also shortened night sleep bouts, whereas the BACE-1 inhibitor lanabecestat lengthened sleep bouts. Intraventricular injection of P3 also shortened night sleep bouts, suggesting that the proper balance of Appb proteolytic processing is required for normal sleep maintenance in zebrafish.