Gene expression profiling of GPR86 (P2RY13) KO mice

The purinergic receptor P2Y13 (P2RY13) has been shown to play a role in the uptake of holo-HDL particles in in vitro hepatocyte experiments. In order to determine the role of P2Y13 in lipoprotein metabolism in vivo, we ablated the expression of this gene in mice and found that P2Y13 knockout mice have lower plasma HDL (17%) and LDL (27%) levels as well as lower fecal concentrations of neutral sterols. In addition, significant decreases were detected in serum levels of fatty acids, glycerol and triglycerides in P2Y13 knockout mice. mRNA profiling analyses showed that ablation of P2Y13 affects hepatic gene expression in a gender-specific manner. Non-supervised agglomerative cluster analysis showed that expression changes in mice with the same genotype (KO or WT) cluster together and that distinct gene expression clusters can be observed for males and females. Subsequent gene set enrichment analysis showed increased expression of cholesterol and fatty acid biosynthesis genes, while fatty acid beta-oxidation genes were significantly decreased. Liver gene signatures also identified changes in SREBP-regulated and PPARgamma-regulated transcript levels. Differential gene expression upon P2RY13 gene ablation. Livers were isolated from male and female wildtype and P2RY13 knockout mice (6 per gender/genotype group, except for 5 per male/WT group). Isolated RNA was subjected to microarray analyses. The results of a one-way ANOVA analysis (p<0.05) showed 3471 transcripts whose relative expression changes were more than 20%.