Tau-YFP aggregates transfer between co-cultured cells. A,
cells were transfected separately with mCherry or Tau-YFP. The two cell
populations were either mixed immediately prior to analysis or co-cultured for
48 h. Co-cultured cells were treated with buffer, monomer, or aggregates,
followed by flow cytometry (10,000 cells sorted per condition). tx,
treatment. B, quantification of flow cytometry revealed that 0.15% of
cells score positive for mCherry and YFP (upper right quadrant of
cell plot) when cells were mixed immediately prior to counting. 0.3 and 0.25%
of cells are dual positive when cells are treated with buffer (B) or
monomer (M), versus 1% when treated with Tau aggregates
(A), indicating transfer of aggregated full-length Tau-YFP between
cells. *, p < 10-7 (unpaired Student's
t test, n = 4, 10,000 cells counted per experiment).
C, dual positive cells were collected, fixed, and mounted. Direct
visualization indicates a Tau-YFP inclusion (white arrowhead) within
an mCherry-expressing cell. Scale bar, 10 μm.