361-OR: A Multiomics Approach to Identify Genes Important for the Regulation of Antidiabetic and Anti-inflammatory Lipids

Introduction: Palmitic Acid esters of Hydroxy Stearic Acids (PAHSAs) are signaling lipids with beneficial metabolic effects. Serum and adipose tissue (AT) PAHSA levels correlate highly with insulin sensitivity in people. PAHSAs enhance insulin sensitivity in diabetic mice. Thus, low PAHSA levels could contribute to the etiology of insulin resistance and T2D. PAHSAs are regulated by synthesis, degradation and incorporation into other lipids. We aimed to identify candidate enzymes that regulate PAHSAs using genetic mouse models in which large changes in PAHSAs are associated with major changes in glucose tolerance and/or insulin sensitivity.

Methods: AT PAHSA levels are increased in mice with Adipose-specific Glucose Transporter 4 overexpression (AG4OX) which induces expression of the lipogenic transcription factor, Carbohydrate-response element-binding protein (ChREBP). Thus, we performed lipidomics and bulk RNA sequencing in perigonadal AT from wildtype, AG4OX, ChREBP knockout and AG4OX crossed to ChREBP KO which reverses the massive elevation of PAHSAs in AG4OX. We also measured PAHSAs in 8 genetically inbred mouse strains. We merged these datasets to identify genes strongly associated with PAHSAs in both models. A subsequent GWAS query for lipid-related SNPs delivered a discrete number of genes to validate as important PAHSA regulators.

Results: All PAHSA regioisomers increase in AT with upregulation of glucose transport and decrease with ChREBP downregulation. PAHSA levels are higher in insulin-sensitive genetic strains. Many genes that strongly associate with 9-PAHSA belong to lipid metabolism pathways. Our single-gene queries in human GWAS support a role for 27 genes in the regulation of lipid metabolism in humans and, potentially, in PAHSA regulation.

Conclusions: These studies provide novel insights into the metabolic pathways and enzymatic machinery responsible for PAHSA metabolism, which may be targeted to prevent or treat T2D in humans.