Background

Sterol 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.

Objectives

We aimed to unravel the molecular mechanisms leading to reduced hepatic steatosis when Soat2 is depleted in mice.

Methods

Soat2−/− and wild-type mice were either fed a high-fat, a high-carbohydrate, or a chow diet, and parameters of lipid and glucose metabolism were assessed.

Results

Glucose, insulin, 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 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 (TG) (r = 0.89, p < 0.05), 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.

Conclusion

Our 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.

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