Thioridazine Induces Cardiotoxicity via Reactive Oxygen Species-Mediated hERG Channel Deficiency and L-Type Calcium Channel Activation

Figure 6

THIO accelerates the degradation of the hERG channel on the cell surface. (a) Time-dependent effects of incubating hERG-HEK293 cells with BFA (10 μM) in 0 or 3 μM THIO on hERG protein expression level. (b) Image densities of 155 kDa hERG bands were normalized to their values measured at . . (c–e) Impaired hERG proteins are degraded in both the lysosome and proteasome. hERG expression was detected after hERG-HEK293 cells were incubated with THIO or the proteasome/lysosome inhibitor for 24 h. Bafilomycin significantly restored the reduced 155 kDa hERG. MG132 and bafilomycin restored the reduced 135 kDa hERG. . (f) Immunoprecipitation results of hERG ubiquitination. Whole-cell lysates were immunoprecipitated with an anti-hERG antibody and immunoblotted using either an anti-ubiquitin or anti-hERG antibody. 3 μM THIO significantly increased the ubiquitination of hERG protein. . (g) Immunoprecipitation results of hERG protein after treatment with the lysosome inhibitor or proteasome inhibitor for 24 h. . vs. control and vs. THIO.

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