Fig. 5.

Co-operative facilitation of sarcosyl-insoluble aggregation with active GSK3β and 3-MA treatment. Cells were transiently transfected with each tau construct in the presence of constitutively active GSK3β or kinase-dead GSK3β. One day after transfection, the cells were treated with 3-MA for 24 hrs. Cell lysates were homogenized and then fractionated into RAB, RIRA, Sarkosyl-soluble, and Sarkosyl-insoluble fractions. After sarkosyl fractionation assay, each fraction was separated by SDS-PAGE and immunobloted with total tau antibody (5A6). Even in the absence of active GSK3β, partitioning into the sarkosyl-insoluble fraction was observed in T4C3, an aggregation-prone tau species, whereas not observed in T4 and T4-2EC. In the presence of active GSK3β, sarkosyl-insoluble aggregates were observed in all tau species and 3-MA treatment resulted in the increased amount of sarkosyl-insoluble aggregates.