Figure 2. GPR146 Deficiency Reduces Hepatic SREBP2 Activities and VLDL Secretion Rate.

(A-D) Changes of plasma TG (A and C) and TC (B and D) after Poloxamer-407 injection in Gpr146 whole body knockout mice (Gpr146^+/+ vs Gpr146^−/−, n=12–14 mice per group, by Student’s t-test) and liver-specific knockout mice (Alb-Cre- vs Alb-Cre+, n=8 mice per group, by Student’s t-test) fed chow.

(E) Plasma TC levels of 16-hour fasted male and female Gpr146 liver-specific knockout (Alb-Cre+) and control littermates (Alb-Cre-) fed chow (n= 11–15 mice per group, by Student’s t-test).

(F) Depletion of GPR146 via CRISPR/Cas9 leads to reduced APOB100 secretion in Huh7 human hepatoma cells (n=4 replicates per genotype per experiment, representative of 3 independent experiments, by Student’s t-test).

(G) Recombinantly overexpressed GPR146, compared with GFP control, results in increased APOB100 secretion (n=3 replicates per genotype per experiment, representative of 2 independent experiments, by one-way ANOVA).

(H) Top ranking REACTOME pathway gene sets discovered from gene set enrichment analysis (GSEA) of genes that are differentially expressed in liver of male Gpr146^+/+ mice and Gpr146^−/− littermates (n=3 mice per group) upon 6-hour refeeding after a 16-hour fast.

(I) Heat map of cholesterol biosynthesis (REACTOME Pathway Database)-related genes in livers of male Gpr146^+/+ and Gpr146^−/− mice (n=3 mice per group).

(J) Quantitative polymerase chain reaction (qPCR) expression analysis of cholesterol biosynthetic genes in liver of 6-hour refed male and female Gpr146^+/+ mice and Gpr146^−/− littermates (n=5 mice per group, by Student’s t-test).

(K and L) Western blot (K) and relative quantification (L) of SREBP2 precursor (P-SREBP2), mature SREBP2 (M-SREBP2), APOB100, HMGCR, HMGCS1 and LDLR in liver of 6-hour refed male Gpr146^+/+ mice and Gpr146^−/− littermates (n=5 mice per group, by Student’s t-test).

* p< 0.05, ** p< 0.01; bars in A-D, J and L indicate mean± s.e.m., bars in E-G indicate mean ± s.d..