Hepatic Is Not an Essential Mediator of the Metabolic Phenotype Produced by Dietary Methionine Restriction.

The principal sensing of dietary methionine restriction (MR) occurs in the liver, where it activates multiple transcriptional programs that mediate various biological components of the response. Hepatic is a key target and essential endocrine mediator of the metabolic phenotype produced by dietary MR. The transcription factor, , is also activated by MR and functions in tandem with hepatic to transactivate multiple, antioxidative components of the integrated stress response. However, it is unclear whether the transcriptional responses linked to activation by dietary MR are essential to the biological efficacy of the diet. Using mice with liver-specific deletion of () and their floxed littermates () fed either Control or MR diets, the absence of hepatic had no effect on the ability of the MR diet to increase FGF21, reduce body weight and adiposity, and increase energy expenditure. Moreover, the primary elements of the hepatic transcriptome were similarly affected by MR in both genotypes, with the only major differences occurring in induction of the P450-associated drug metabolism pathway and the pentose glucuronate interconversion pathway. The biological significance of these pathways is uncertain but we conclude that hepatic is not essential in mediating the metabolic effects of dietary MR.