Figure 7.

Cytoplasmic Bsr RNAs associate with arsenite-induced stress granules. (A) REFs were transiently transfected with a GFP-G3BP expression plasmid, and stress granules were induced by arsenite treatment (0.5 mM for 30 min). Top, a representative cell is shown (left), the cytoplasm of which contains eight dot-like signals. The two boxes (termed 1 and 2) indicate the position of the enlarged fields (right). The contrasts have been enhanced to highlight Bsr dots (white arrows). Bottom, several large SGs that contain multiple spliced Bsr RNAs are shown. SGs are visualized by GFP-G3BP (green), and spliced Bsr RNAs are detected by a Cy3-labeled probe (red). (B) Cytoplasmic Bsr RNAs are not detected in P-bodies. A representative arsenite-treated REF is shown (left) with three boxes (termed a, b, and c) indicating the position of the enlarged fields (right) showing spliced Bsr RNA containing-SGs juxtaposed to PBs. PBs and SGs are visualized by DCP1-GFP (green) and poly(A) RNA signals with a Cy5-labeled poly(dT) probe (blue), respectively, whereas spliced Bsr RNAs are detected by a Cy3-labeled probe (red). The outline of the nucleus is indicated according to DAPI staining. For unknown reasons, nuclear Bsr staining and poly(A+) staining are altered in some arsenite-treated cells. Bars, 5 μm.