Protein Phosphatase 4 Promotes Hepatocyte Lipoapoptosis by Regulating RAC1/MLK3/JNK Pathway

Figure 6

PP4 regulated lipoapoptosis through regulating the activity of RAC1. HepG2 cells were pretreated with control LV and RAC1 shRNA LV for 24 h followed by palmitate treatment or AD-PP4 transfection. The levels of RAC1, PUMA, Bim, PP4, and c-caspase 3 and phosphorylation levels of JNK and MLK3 were measured by western blot analysis in palmitate treatment cells (a) and AD-PP4-transfected cells (c). Relative protein levels were quantified by densitometry and normalized (b, d). RAC1 activity was determined by binding to GST-PAK PBD and subsequent immunoblot analysis in AD-PP4- (e, f) and PP4 siRNA- (g, h) transfected cells. HepG2 cells were transfected with control AD or AD-PP4 for 24 h. The interaction between PP4 and RAC1 was confirmed using coimmunoprecipitation with an anti-PP4 antibody (i) and RAC1 antibody (j). Data are expressed as , and statistical significance for protein levels was determined by Student’s -test or one-way ANOVA (, ).

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