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标题：Elovl5 regulates the mTORC2-Akt-FOXO1 pathway by controlling hepatic cis-vaccenic acid synthesis in diet-induced obese mice
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作者：Sasmita Tripathy ; Donald B. Jump
期刊名称：JLR Papers In Press
印刷版ISSN：0022-2275
电子版ISSN：1539-7262
出版年度：2013
卷号：54
期号：1
页码：71-84
DOI：10.1194/jlr.M028787
语种：English
出版社：American Society for Biochemistry and Molecular Biology
摘要：Elevated hepatic expression of fatty acid elongase-5 (Elovl5) induces FoxO1 phosphorylation, lowers FoxO1 nuclear content, and suppresses expression of genes involved in gluconeogenesis (GNG). In this report, we define the molecular and metabolic basis of Elovl5 control of FoxO1 phosphorylation. Adenoviral-mediated (Ad-Elovl5) induction of hepatic Elovl5 in diet-induced obese, glucose-intolerant mice and HepG2 cells increased the phosphorylation of Akt2-S⁴⁷³ [mammalian target of rapamycin complex-2 (mTORC2) site], but not Akt2-T³⁰⁸ (PDK1 site). The Akt2 inhibitor Akti1/2 blocked Elovl5 induction of FoxO1-S²⁵⁶ phosphorylation in HepG2 cells. Elevated Elovl5 activity in liver and HepG2 cells induced rictor mRNA, rictor protein, and rictor-mTOR interaction, whereas rictor knockdown (siRNA) attenuated Elovl5 induction of Akt2-S⁴⁷³ and FoxO1-S²⁵⁶ phosphorylation in HepG2 cells. FA analysis revealed that the abundance of cis-vaccenic acid (18:1,n-7) was increased in livers of obese mice and HepG2 cells following Ad-Elovl5 infection. Treating HepG2 cells with Elovl5 substrates established that palmitoleic acid (16:1,n-7), but not γ-linolenic acid (18:3,n-6), induced rictor protein, Akt-S⁴⁷³, and FoxO1-S²⁵⁶ phosphorylation. Inhibition of FA elongation blocked 16:1,n-7 but not 18:1,n-7 induction of rictor protein and Akt-S⁴⁷³ and FoxO1-S²⁵⁶ phosphorylation. These results establish a novel link between Elovl5-mediated synthesis of 18:1,n-7 and GNG through the control of the mTORC2-Akt-FoxO1 pathway.
关键词：fatty acid elongase-5 ; palmitoleic acid ; cis -vaccenic acid rictor ; gluconeogenesis forkhead box O1 ; mammalian target of rapamycin complex 2