Abstract Tu105: Inhibition of Queuine tRNA-Ribosyltransferase 1 Ameliorates Heaptic Lipogenesis and Atherosclerosis

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Background: Atherosclerosis threatens cardiovascular health, which is featured by abnormal lipid metabolism and chronic inflammation in arterial wall. Queuine tRNA-Ribosyltransferase 1 (QTRT1) , is an enzyme responsible for tRNA modification at the wobble base. Research Questions: It is unclear whether the function of QTRT1 is involved in metabolism of non-cancer cells and tissues, especially lipid metabolism mainly orchestrated by liver. Aims: We aimed to explore the role of QTRT1 deficiency in hyperlipidemia, liver steatosis and atherosclerosis. Methods: Transgenic mice such as Qtrt1fl/flAlb-iCre+/- (Qtrt1LKO), Qtrt1fl/fl(WT), ApoE-/-, and gain of function of PCSK9 by adeno-associated virus gene transfer were used to determine the functional significance of QTRT1 in atherosclerosis. Synthesis, transportation and oxidation of lipids in livers and hepatocytes were examined by quantitative real-time polymerase chain reaction. Moreover, primary hepatocytes with overexpression and downregulation of QTRT1 were followed by RNA sequencing to identify downstream targets. Results: Deficiency of hepatic QTRT1 significantly attenuated hyperlipidemia, liver steatosis and atherosclerotic burden, but increased plaque stability in the aorta of mice. Depletion of QTRT1 markedly downregulated de novo lipogenesis (DNL) without influence on lipoprotein transportation and fatty acid oxidation. Qtrt1LKO mice on a high-carbohydrate diet displayed relatively reduced hyperlipidemia and alleviation of DNL. RNA-seq indicated that odorant binding protein 2A (OBP2A) was upregulated in Qtrt1LKO hepatocytes, which reversed the promotion of DNL by QTRT1 in hepatocytes. Conclusion: Inhibition of QTRT1 in hepatocytes ameliorates hepatic lipogenesis and atherosclerosis in mice. Targeting of QTRT1 is a promising strategy to improve therapeutic effectiveness in both hyperlipidemia and atherosclerosis.

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