APP for injury repair

The cleavage of the amyloid precursor protein (APP) by γ-secretase releases the Aβ peptide, which forms plaques that are associated with Alzheimer's. Because APP is induced by injury, boxers and head trauma sufferers are prone to developing Alzheimer's. But new findings suggest that, without APP, the initial injuries might be lethal. Maarten Leyssen, Bassem Hassan, and colleagues (VIB and the University of Leuven, Belgium) find that APP helps mature axons grow and branch.

The function of APP has been elusive, as mice and flies lacking APP develop relatively normally. So to look for postdevelopmental functions, Hassan's group induced neuronal APP expression in adult flies. The result was a strong arborization of mature axons.Recalling that APP is induced by injury, Leyssen devised a strategy to produce head wounds...