FIGURE 4.

Impact of exogenous PCSK9 on LDL uptake and LDL-R or LRP1 protein expression. (A) HepG2 cells were treated with an adenovirus expressing murine wild-type PCSK9 or a gain-of-function (GOF) variant of PCSK9 (D377Y). Cell lysates and supernatants of HepG2 cells were collected 48 h after infection and analyzed by Western Blotting. (B) H9C2 cells were treated with murine wild-type PCSK9 at the indicated concentration for 24 h and LDL uptake normalized per DNA content as a measure of cell number was analyzed afterward. (C) H9C2 cells were treated with murine wild-type PCSK9 or GOF PCSK9 (each 0.5 μg/ml) for 24 h and LDL uptake was analyzed afterward. (D) H9C2 cells were treated with murine wild-type PCSK9 or GOF PCSK9 (each 0.5 μg/ml) for 24 h and afterward the membrane and cytosolic fraction were isolated from these cells. Representative Western blots for LDL-R, LRP1 or CD36 and densitometry of the according protein data are shown. Na-K-ATPase served as a loading control. (E) Adult rat cardiomyocytes were treated and analyzed as described in (D). (F) Neonatal rat cardiomyocytes were treated and analyzed as described in (D). All data are mean ± SEM, 4 independent experiments, n = 8–24 per group, *p < 0.05, **p < 0.01.