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. 2021 Feb 11;12:593862. doi: 10.3389/fphys.2021.593862

FIGURE 2.

FIGURE 2

Impact of PCSK9 knockdown on LRP1 expression and CTRP9-induced mitochondrial biogenesis. (A) H9C2 cardiomyoblasts were transfected with siRNA directed against rat PCSK9 or mock siRNA for 48 h. Afterward PCSK9 mRNA, LRP1 mRNA, and LRP1 protein expression were analyzed. mRNA expression of PCSK9 and LRP1 as determined by real-time PCR and densitometry of protein data and representative Western blots for LRP1 and GAPDH are shown. (B) Adult rat cardiomyocytes were incubated with siRNA directed against rat PCSK9 or mock siRNA for 48 h and afterward analyzed for PCSK9 mRNA and LRP1 mRNA or protein expression by real-time PCR or Western blotting. GAPDH served as a loading control. (C) H9C2 cardiomyoblasts were transfected with siRNA directed against rat PCSK9 or mock siRNA for 48 h and thereafter treated with CTRP9 (4 μg/ml) for the indicated times. Activation of AMPK was analyzed after 20 min stimulation with CTRP9 and mtDNA content and citrate synthase activity after 24 h stimulation with CTRP9 as described in Figure 1. All data are mean ± SEM, 4 independent experiments, n = 8–16 per group, *p < 0.05; **p < 0.01.