FIG. 10.

Effect of the antioxidant α-tocopherol on metallothionein synthesis and ubiquitination of CFTR. (A) Cadmium induces synthesis of metallothionein. Metallothionein proteins were detected in cell lysates from cells treated for 3 days with cadmium (50μM) ± α-tocopherol (200μM). The membranes were reprobed with β-actin antibody to show that the same amount of protein was loaded in each lane. CFTR protein was detected as described in the “Materials and Methods” section. Data are representative of at least three independent experiments. (B) Cadmium induces ubiquitination of CFTR. Calu-3 cells were treated with 50μM cadmium ± 200μM α-tocopherol. CFTR present in cell lysate was immunoprecipitated using a C-CFTR antibody and the blot was subjected to immunoblotting using a monoclonal antibody that recognizes ubiquitin. Data are representative of at least three independent experiments.