Gene expression profiles of white adipose tissues from C57BL/6 mice in the effect of high fat diet. Mus musculus

Metabolic disorders including obesity and insulin resistance have their basis in dysregulated lipid metabolism and low-grade inflammation. In a microarray search of unique lipase-related genes whose expressions are associated with obesity, we found that two secreted phospholipase A2s (sPLA2s), PLA2G5 and PLA2G2E, were robustly induced in adipocytes of obese mice. Analyses of Pla2g5-/- and Pla2g2e-/- mice revealed distinct and previously unrecognized roles of these sPLA2s in diet-induced obesity. PLA2G5 hydrolyzed phosphatidylcholine in fat-overladen low-density lipoprotein to release unsaturated fatty acids, which prevented palmitate-induced M1 macrophage polarization. As such, PLA2G5 tipped the immune balance toward an M2 state, thereby counteracting adipose tissue inflammation, insulin resistance, hyperlipidemia and obesiy. PLA2G2E altered minor lipoprotein phospholipids, phosphatidylserine and phosphatidylethanolamine, and moderately facilitated lipid accumulation in adipose tissue and liver. Collectively, the identification of metabolic sPLA2s adds this gene family to a growing list of lipolytic enzymes that act as metabolic coordinators. Overall design: Model, high fat diet-induced obesity; Condition, two condition experiments: high fat diet versus low fat diet feeding for 18 weeks; Samples, 2 replicates of mixed sample of adipose tissues from 3 mice (C57BL/6 strain), respectively