Diiodothyronines regulate metabolic homeostasis in primary human hepatocytes by modulating mTORC1 and mTORC2 activity

Publication date: Available online 30 September 2019Source: Molecular and Cellular EndocrinologyAuthor(s): Davide Gnocchi, Ewa C.S. Ellis, Helene Johansson, Mats Eriksson, Giovannella Bruscalupi, Knut R. Steffensen, Paolo PariniAbstractUntil three decades, ago 3,5-diiodothyronine (3,5-T2) and 3,3′-diiodothyronine (3,3′-T2) were considered products of thyroid hormone catabolism without biological activity. Some metabolic effects have been described in rodents, but the physiological relevance in humans and the mechanisms of action are unknown. Aim of this work was to investigate the role and the mechanisms of action of 3,5-T2 and 3,3′-T2 in the regulation of metabolic homeostasis in human liver. We used primary human hepatocytes freshly isolated from donors and grown on Matrigel as the golden standard in vitro model to study human hepatic metabolism. Results show that diiodothyronines in the range of plasma physiological concentrations reduced hepatic lipid accumulation, by modulating the activity of the mTORC1/Raptor complex through an AMPK-mediated mechanism, and stimulated the mTORC2/Rictor complex-activated pathway, leading to the down regulation of the expression of key gluconeogenic genes. Hence, we propose that diiodothyronines act as key regulators of hepatic metabolic homeostasis in humans.Graphical abstract
Source: Molecular and Cellular Endocrinology - Category: Endocrinology Source Type: research