Soat2 ties cholesterol metabolism to β-oxidation and glucose tolerance in male mice
Camilla Pramfalk, Ahmed, O, Matteo Pedrelli, Mirko E. Minniti, Serge Luquet, R Denis, Maria Olin, Jennifer Härdfeldt, Vedin, L-L, Knut R. Steffensen, Mikael Rydén, Leanne Hodson, Mats Eriksson, Paolo Parini
Abstract
<p><strong>Background</strong></p>\nSterol O-acyltransferase 2 (Soat2) encodes acyl-coenzyme A:cholesterol acyltransferase 2 (ACAT2), which synthesizes cholesteryl esters in hepatocytes and enterocytes fated either to storage or to secretion into nascent triglyceride-rich lipoproteins.\n\n<p><strong>Objectives</strong></p>\nWe aimed to unravel the molecular mechanisms leading to reduced hepatic steatosis when Soat2 is depleted in mice.\n\n<p><strong>Methods</strong></p>\nSoat2−/− and wild-type mice were fed a high-fat, a high-carbohydrate, or a chow diet, and parameters of lipid and glucose metabolism were assessed.\n\n<p><strong>Results</strong></p>\nGlucose, insulin, homeostatic model assessment for insulin resistance (HOMA-IR), oral glucose tolerance (OGTT), and insulin tolerance tests significantly improved in Soat2−/− mice, irrespective of the dietary regimes (2-way ANOVA). The significant positive correlations between area under the curve (AUC) OGTT (r = 0.66, p < 0.05), serum fasting insulin (r = 0.86, p < 0.05), HOMA-IR (r = 0.86, p < 0.05), Adipo-IR (0.87, p < 0.05), hepatic triglycerides (TGs) (r = 0.89, p < 0.05), very-low-density lipoprotein (VLDL)-TG (r = 0.87, p < 0.05) and the hepatic cholesteryl esters in wild-type mice disappeared in Soat2−/− mice. Genetic depletion of Soat2 also increased whole-body oxidation by 30% (p < 0.05) compared to wild-type mice.\n\n<p><strong>Conclusion</strong></p>\nOur data demonstrate that ACAT2-generated cholesteryl esters negatively affect the metabolic control by retaining TG in the liver and that genetic inhibition of Soat2 improves liver steatosis via partitioning of lipids into secretory (VLDL-TG) and oxidative (fatty acids) pathways.