Glucokinase activator improves glucose tolerance and induces hepatic lipid accumulation in mice with diet-induced obesity

Abstract

Background and aims

Type 2 diabetes mellitus remains a substantial medical problem with increasing global prevalence. Pharmacological research is becoming increasingly focused on personalized treatment strategies. Drug development based on glucokinase (GK) activation is an important strategy for lowering blood glucose. This study aimed to investigate the effect of GK activation on glucose and lipid metabolism in diet-induced obese mice.

Materials and methods

Mice were fed with a high-fat diet (HFD) for 16 weeks to induce obesity, followed by a GK activator (GKA, AZD1656) or vehicle treatment by gavage for 4 weeks. The effect of GKA treatment on glucose metabolism was evaluated using glucose and insulin tolerance tests. Hepatic lipid accumulation was assessed by hematoxylin and eosin staining, Oil Red O staining, and transmission electron microscopy. The underlying mechanism of GK activation in glucose and lipid metabolism in the liver was studied using transcriptomic analysis, with a mechanistic study in mouse livers in vivo and AML12 cells in vitro.

Results

GK activation by GKA treatment improved glucose tolerance in HFD-fed mice while increasing hepatic lipid accumulation. Transcriptomic analysis of liver tissues indicated the lipogenesis and protein kinase RNA-like endoplasmic reticulum kinase (PERK)-unfolded protein response (UPR) pathway activations in GKA-treated HFD-fed mice. Inhibition of the ACC activity, which is an important protein in lipogenesis, attenuated GKA treatment-induced lipid accumulation and PERK-UPR activation in vitro.

Conclusions

GK activation improved glucose tolerance and insulin sensitivity while inducing hepatic lipid accumulation by increasing the lipogenic gene expression, which subsequently activated the hepatic PERK-UPR signaling pathway.