Expression of tau reduces secretion of Aβ without altering the amyloid precursor protein content in CHOsw cells

Insoluble deposits of tau and amyloid precursor protein (APP) peptides Aβ characterize Alzheimer’s disease. We studied the role of tau in the metabolism of APP in cells stably expressing APP Swedish mutation (CHOsw). Transient expression of tau in CHOsw cells caused morphological changes, bundling of microtubules and perinuclear aggregation of Golgi-derived vesicles. It also reduced the secretion of Aβ1–40 and Aβ1–42 without altering the APP steady state levels. This was accompanied by a reduction in the γ-secretase and an increase in the insulin degrading enzyme activities. Our results suggest that tau may play an inhibitory role in the amyloidogenic activity of APP.