Alzheimer’s therapy targeting the β-secretase enzyme BACE1: Benefits and potential limitations from the perspective of animal model studies

• BACE1 knockout mice provide a useful model to test therapeutic β-secretase inhibition.
• BACE1−/− mice show adverse phenotypes in line with a growing list of BACE1 substrates.
• Inhibitors, immunization and siRNAs specific for BACE1 activities are tested in vivo.
• Benefits of BACE1 inhibition in APP mice decrease with disease progression.
• Combination approaches may be useful for boosting efficacies of BACE1 inhibition.

Accumulating evidence points to the amyloid-β (Aβ) peptide as the culprit in the pathogenesis of Alzheimer’s disease (AD). β-Site amyloid precursor protein (APP)-cleaving enzyme 1 (BACE1) is a protease that is responsible for initiating Aβ production. Although precise mechanisms that trigger Aβ accumulation remain unclear, BACE1 inhibition undoubtedly represents an important intervention that may prevent and/or cure AD. Remarkably, animal model studies with knockouts, virus-delivered small interfering RNAs, immunization and bioavailable small-molecule agents that specifically inhibit BACE1 activity strongly support the idea for the therapeutic BACE1 inhibition. Meanwhile, a growing number of BACE1 substrates besides APP uncover new physiological roles of this protease, raising some concern regarding the safety of BACE1 inhibition. Here, I review recent progress in preclinical studies that have evaluated the efficacies and potential limitations of genetic/pharmacological inhibition of BACE1, with special focus on AD-associated phenotypes including synaptic dysfunction, neuron loss and memory deficits in animal models.