Prevention of atherosclerosis and hepatic steatosis by combined, liver-specific deletion of GPR146 and ANGPTL3

Background and Aims: GWAS identified GPR146 as a novel lipid gene. Subsequent studies in mice validated Gpr146 deletion reduces circulating lipids and is atheroprotective, independent of LDL-R. Whereas, Mendelian randomisation studies highlight that GPR146is causally linked with plasma levels of ALT, AST, and CRP. Several lines of evidence point to a role for ANGPTL3 mediating the effects of GPR146. Methods: We used somatic gene editing to generate liver-specific deletions of Gpr146, Angptl3, and Gpr146/Angptl3. The experimental groups were fed with a regular chow and 60% kcal HFD, independently. Plasma levels of total cholesterol (TC), triglycerides (TG), ALT and AST and hepatic lipids were measured. Hepatic and aortic histology, RNAseq, qRT-PCR, western blotting and targeted proteomics were used to characterise the mouse model. Results: Somatic gene editing showed 85% reductions in the targeted genes at the mRNA and protein levels. Compared to chow-fed controls, plasma TG was reduced by 28%, 58% and 75%, whereas plasma TC was reduced by 21%, 37% and 58% and hepatic lipid levels were reduced by 21%, 26%, and 46% in Gpr146, Angptl3 and Gpr146/Angptl3deleted mice, respectively. Body and liver weights of the experimental groups remained unchanged. Conclusions: This study shows that function of Gpr146 is independent of Angptl3, and combined deletion of both genes has a favourable outcome by reducing circulating and hepatic lipids in an additive manner. These findings indicate the therapeutic potential of targeting Gpr146 and Angptl3to protect against atherosclerosis and fatty liver disease.