Membrane-bound sn-1,2-diacylglycerols explain the dissociation of hepatic insulin resistance from hepatic steatosis in MTTP knockout mice [Research Articles]

Microsomal triglyceride transfer protein (MTTP) deficiency results in a syndrome of hypolipidemia and accelerated NAFLD. Animal models of decreased hepatic MTTP activity have revealed an unexplained dissociation between hepatic steatosis and hepatic insulin resistance. Here, we performed comprehensive metabolic phenotyping of liver-specific MTTP knockout (L-Mttp–/–) mice and age-weight matched wild-type control mice. Young (10–12-week-old) L-Mttp–/– mice exhibited hepatic steatosis and increased DAG content; however, the increase in hepatic DAG content was partitioned to the lipid droplet and was not increased in the plasma membrane. Young L-Mttp–/– mice also manifested normal hepatic insulin sensitivity, as assessed by hyperinsulinemic-euglycemic clamps, no PKC activation, and normal hepatic insulin signaling from the insulin receptor through AKT Ser/Thr kinase. In contrast, aged (10-month-old) L-Mttp–/– mice exhibited glucose intolerance and hepatic insulin resistance along with an increase in hepatic plasma membrane sn-1,2-DAG content and PKC activation. Treatment with a functionally liver-targeted mitochondrial uncoupler protected the aged L-Mttp–/– mice against the development of hepatic steatosis, increased plasma membrane sn-1,2-DAG content, PKC activation, and hepatic insulin resistance. Furthermore, increased hepatic insulin sensitivity in the aged controlled-release mitochondrial protonophore-treated ...

Source: The Journal of Lipid Research - December 1, 2020 Category: Lipidology Authors: Abulizi, A., Vatner, D. F., Ye, Z., Wang, Y., Camporez, J.-P., Zhang, D., Kahn, M., Lyu, K., Sirwi, A., Cline, G. W., Hussain, M. M., Aspichueta, P., Samuel, V. T., Shulman, G. I. Tags: Research Articles Source Type: research