Figure 4.

Induction of eIF2α phosphorylation through arsenite treatment enhances R345W fibulin-3-eGLuc2 secretion. A) TREx-293 cells were treated with 100 μM arsenite for up to 9 h, and cell lysates were probed for eIF2α-P and total eIF2α by Western blot analysis. Data are representative of 3 independent experiments. B) TREx-293 cells expressing WT or R345W fibulin-3-eGLuc2 were treated with increasing concentrations of arsenite (6.75-100 μM) for 9 h (n≥3±sd). C) Time course of the effect of arsenite (100 μM) on fibulin-3 secretion in TREx-293 cells expressing WT or R345W fibulin-3-eGLuc2 (n≥3±sd). D) TREx-293T cells expressing WT or R345W fibulin-3 eGLuc2 were transfected with CT-GADD34 or GFP and treated with 100 μM arsenite for 3 h. Lysates were analyzed by Western blot analysis as described above. Data are representative of 3 independent experiments. E) Expression of CT-GADD34 eliminates arsenite-enhanced R345W secretion. Transfected cells were treated with 25-100 μM arsenite for 9 h (n≥3±sd), as indicated. *P < 0.05, t test. GLuc luminescence assay was used to monitor fibulin-3 secretion (B, C, E).