RESUMEN
The most common neurodegenerative disorder afflicting the aging human population is Alzheimer's disease (AD). A major hallmark of AD is dementia from a loss of neuronal function, attributed to the presence and accumulation of ß-amyloid (Aß) peptide into senile plaques. Preceding senile plaque formation, abnormalities in axons can be observed as changes in morphologies and intracellular trafficking. Recently, it has been recognized that Aß also accumulates within neurons and this intraneuronal Aß accumulation has been reported to be critical in the disruption of synapses and cognitive function. Here, we report on the internalization of a fluorescently labeled Aß peptide into cultured chick retinal neurons. The pattern of Aß distribution during the time course of incubation is reminiscent of the endocytic pathway. Furthermore, the distribution of the internalized Aß peptide converges with that of myosin Vb and both relocalize from the axon to cell body. These observations are consistent with the hypothesis that AD proceeds as a result of an imbalance between Aß production and Aß clearance, suggesting a role for myosin Vb in this process.