| Popis: |
Recent evidence has emphasized soluble species of amyloid-β (Aβ) and tau as pathogenic effectors in AD. Despite the fact that Aβ, tau and α-synuclein (αSyn) can promote each other’s aggregation, the potential contribution of soluble αSyn to Alzheimer’s disease (AD) pathogenesis is unknown. Here, we found a ~2-fold increase over controls in soluble αSyn levels in AD brains in the absence of LB cytopathology. Importantly, soluble αSyn levels were a quantitatively stronger correlate of cognitive impairment than soluble Aβ and tau levels. To examine a putative role for αSyn in modulating cognitive function, we used the Barnes circular maze to assess spatial reference memory in transgenic mice overexpressing human wild-type αSyn. The results revealed that a ~3-fold elevation of αSyn in vivo induced memory deficits similar to those observed in AD mouse models. The neurobiological changes associated with this elevation of soluble αSyn included decreases in selected synaptic vesicle proteins and an alteration of the protein composition of synaptic vesicles. Finally, a synergism between Aβ/APP and human tau appears to be responsible for the abnormal elevation of soluble αSyn in transgenic mice. Altogether, our data reveal an unexpected role for soluble, intraneuronal αSyn in AD pathophysiology. |
