Therapeutic expression of hairpins targeting apolipoprotein B100 induces phenotypic and transcriptome changes in murine liver.

Constitutive expression of short hairpin RNAs (shRNAs) may cause cellular toxicity in vivo and using microRNA (miRNA) scaffolds can circumvent this problem. Previously, we have shown that embedding small interfering RNA sequences targeting apolipoprotein B100 (ApoB) in shRNA (shApoB) or miRNA (miApoB) scaffolds resulted in differential processing and long-term efficacy in vivo. Here we show that adeno-associated virus (AAV)-shApoB- or AAV-miApoB-mediated ApoB knockdown induced differential liver morphology and transcriptome expression changes. Our analyses indicate that ApoB knockdown with both shApoB and miApoB resulted in alterations of genes involved in lipid metabolism. In addition, in AAV-shApoB-injected animals, genes involved in immune system activation or cell growth and death were affected, which was associated with increased hepatocyte proliferation. Subsequently, in AAV-miApoB-injected animals, changes of genes involved in oxidoreductase activity, oxidative phosphorylation and nucleic bases biosynthetic processes were observed. Our results demonstrate that long-term knockdown of ApoB in vivo by shApoB or miApoB induces several transcriptome changes in murine liver. The increased hepatocyte profileration by AAV-shRNA may have severe long-term effects indicating that AAV-mediated RNA interference therapy using artificial miRNA may be a safer approach for familial hypercholesterolemia therapy.