Fig. 2
Tau concentration on the nuclear envelope and droplet-like tau inclusions. a, b Tau condensation occurred by pathogenic tau seeding. 4RD-YFP tau reporter cells were seeded as per Fig. 1 and imaged (a). Plot profiling analysis of tau signal intensities were conducted along the arrows with a length of 60 μm (b). a.u., arbitrary units. Scale bar, 20 μm and 10 μm in the boxed images. c Fluorescence recovery after photobleaching (FRAP) analysis for tau inclusions on the nuclear envelope and droplet fusions in ES1 cells. Nuclear envelope tau signals were photobleached (yellow arrowheads) at the indicated time point and then time-lapse images were obtained every 30 s for 30 min. Droplet-shaped tau inclusions fused together and became larger inclusions (red arrowheads). Scale bar, 10 μm. d Different focal plane images of the boxed areas in (c) at indicated time points. Z1 to Z6 are depths of field from bottom to top with 1-μm intervals. Arrowheads indicate tau inclusions fused into one bigger droplet. e Droplet fusions in the seeded cells were monitored by time-lapse imaging for 12 h (10 min/frame for 72 frames) and the increases in cross-sectional area (μm2) were measured every 3 h. Scale bar, 10 μm