Research Identifies Autophagy-Regulated Amino Acid Homeostasis as Key Driver of Hepatic Foxo1 and Glucose Production

A study in mouse models and primary hepatocytes published in Diabetes, Obesity and Metabolism reports that autophagy maintains Foxo1 protein abundance via amino acid homeostasis to support glucagon-mediated hepatic glucose production during fasting.

Researchers investigated the role of autophagy in glucagon-Foxo1 signaling and hepatic metabolic responses during fasting using genetic and pharmacological autophagy inhibitors, including hydroxychloroquine (HCQ), chloroquine (CQ), siRNA-Atg7, and AAV8-shRNA-Atg7.

Inhibition of autophagy reduced pyruvate-stimulated glucose excursions in mice and glucose production in isolated primary hepatocytes, while attenuating glucagon-responsive gluconeogenic and fatty acid oxidation (FAO) gene expression.

The suppression of autophagy significantly decreased Foxo1 protein abundance in association with impaired hepatic amino acid homeostasis, without altering Foxo1 gene expression or being fully explained by proteasome-dependent degradation.

Supplementation with exogenous amino acids restored Foxo1 protein levels by 1.89-fold under basal conditions and 1.35-fold under glucagon-treated conditions (p < 0.05), and partially rescued hepatic glucose production under autophagy-inhibited conditions.

The findings establish a direct mechanistic link between cellular recycling (autophagy) and systemic glucose regulation via amino acid-mediated stabilization of the Foxo1 transcription factor.

By demonstrating that autophagy maintains Foxo1 abundance through amino acid homeostasis rather than transcriptional regulation, the study highlights the importance of nutrient-sensing pathways in metabolic adaptations.

This molecular insight clarifies how autophagy impairment in aged or diseased tissues can disrupt systemic energy homeostasis during nutrient deprivation.

For developers of autophagy-modulating therapies, this research highlights that downstream metabolic outcomes are closely linked to nutritional state and amino acid availability, which may influence clinical trial design and candidate selection.

The discovery provides a defined pathway (autophagy-amino acid-Foxo1) that could be leveraged to design more precise interventions for metabolic diseases and age-related decline in hepatic function.

Preclinical studies evaluating whether targeted amino acid supplementation or specific autophagy-upregulating therapeutics can restore Foxo1-driven metabolic responses in aged animal models.