FIGURE 4.

Immunofluorescence labeling of fibroblasts transfected with ER membrane-targeted constructs. A–H, perinuclear, Tau-immunoreactive deposits were observed in cells transfected with truncated Tau constructs SSTau(190–390) (A and B), SSTau(190–441) (C and D), or SSTau(296–390) (G and H). The deposits were also observed in cells following induction of co-expressed hTau40 (E and F). Aggregates of SSTau(296–390) were more dispersed into the cytoplasm than the longer construct and remained granular in appearance following saponin treatment (H). The Tau from the longer construct, SSTau(190–441), was competent in associating with microtubules (J). Perinuclear aggregates formed with SSTau(190–390) (K) are distributed throughout the cytoplasm following treatment of nocodazole (L), a treatment that both depolymerizes microtubules and disperses the perinuclear stacks of Golgi and ER elements throughout the cell. Cells were treated with butyrate (A–D and G–K), with butyrate and IPTG (E and F), or with butyrate plus nocodazole (10 μm for 1 h) (L). Cells were fixed with paraformaldehyde followed by extraction with Triton X-100 with the exception of cells that were extracted with saponin and then fixed in glutaraldehyde (H and J). All cells were labeled using mAb 7/51. Scale bars, 10 μm.