ABSTRACT
Neuronal apoptosis induced by amyloid ß-peptide (Aß) plays an important role in the pathophysiology of Alzheimer's disease (AD). However, the molecular mechanism underlying Aß-induced apoptosis remains undetermined. The disialoganglioside GD3 involves ceramide-, Fas- and TNF-α-mediated apoptosis in lymphoid cells and hepatocytes. Although the implication of GD3 has been suggested, the precise role of GD3 in Aß-induced apoptosis is still unclear. Here, we investigated the changes of GD3 metabolism and characterized the distribution and trafficking of GD3 during Aß-induced apoptosis using human brain-derived TE671 cells. Extracellular Aß-induced apoptosis in a mitochondrial-dependent manner. GD3 level was negligible in the basal condition. However, in response to extracellular Aß, both the expression of GD3 synthase mRNA and the intracellular GD3 level were dramatically increased. Neosynthesized GD3 rapidly accumulated in cell surface lipid microdomains, and was then translocated to mitochondria to execute the apoptosis. Disruption of membrane lipid microdomains with methyl-ß-cyclodextrin significantly prevented both GD3 accumulation in cell surface and Aß-induced apoptosis. Our data suggest that rapidly accumulated GD3 in plasma membrane lipid microdomains prior to mitochondrial translocation is one of the key events in Aß-induced apoptosis.
