PCSK9 induces degradation of LRP-1.

<p><b>A</b>) PCSK9 transfection. HEK293 cells were transfected with PCSK9-V5 or empty control pIRES-V5 vector prior to being lysed in 1x RIPA. LDLR and LRP-1 levels were examined by Western blot in these cells, as well as in HepG2 cells stably expressing PCSK9-shRNA. PCSK9 levels were assessed using mAb-V5 in HEK293 cells and an anti-PCSK9 antibody in HepG2 cells. The levels of LDLR and LRP-1 were estimated relative to β-actin. Data are representative of at least three independent experiments. <b>B</b>) PCSK9 media swap. Conditioned serum-free media collected from HEK293 cells transfected with PCSK9-V5 or empty control pIRES-V5 vector was collected and applied to naive HEK293 or HepG2 cells. The effect of exogenous PCSK9 on LDLR and LRP-1 was assessed by Western blotting with anti-hLDLR and LRP-1 antibodies respectively. Cell-associated PCSK9 was measured using mAb-V5. The relative intensities of LDLR and LRP-1 were normalized to β-actin using NIH ImageJ software. Data are representative of at least three independent experiments.