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

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.

Glucokinase and glucokinase activator

Glucokinase (GK) plays a pivotal role in glucose homeostasis as the glucose sensor in the pancreas and liver. Loss of function of GK results in hyperglycemia, and gain of function causes congenital hyperinsulinemic hypoglycemia. We speculate that the progressive loss of GK at both messenger RNA (mRNA) and protein levels in the islets and liver would be the key mechanism for Type 2 diabetes (T2D) pathogenesis. The development of GK activator (GKA) as an anti-diabetic drug has been endeavored for several decades. The failure of the early development of GKAs is due to the limitation of understanding the mode of GKA action. The success of dorzagliatin in the treatment of T2D has brought new hope for GK in setting a good model for repairing the underlying defects in the pancreatic islets and liver of T2D patients.

Establishment of Hypoglycemic Agent Screening Method Based on Human Glucokinase

Objective To establish a reliable platform for screening glucokinase activators （GKAs） in vitro. Methods Pancreatic glucokinase （PGK） protein expressed in a prokaryotic expression system as a histidine-tagged fusion protein from Homo sapiens was produced. Then, response surface methodology （RSM） was used to optimize the microplate-based GKA screening platform. In the f＇trst step of optimization with Plackett-Burman design （PBD）, initial pH, reaction time and MgC12 were found to be important factors affecting the activity ratio of GKA （RO-28-1675） significantly. In the second step, a 23 full factorial central composite design （CCD） and RSM were applied to the optimal condition determination of each significant variable. A second-order polynomial was determined by a multiple regression analysis of the experimental data. Results The following optimal values for the critical factors were obtained： initial pH 0 （7.0）, reaction time-0.63 （13.7 min） and MgC12 0.11 （2.11 mmol/L） with a predicted value of the maximum activity ratio of 34.1%. Conclusion Under the optimal conditions, the practical activity ratio is 34.8%. The determination coefficient （R2） is 0.9442, ensuring adequate credibility of the model. LLAE3, extracted from Folium nelumbinis in our laboratory, has prominently activated effects on PGK.

Novel N-(pyrimidin-4-yl)thiazol-2-amine derivatives as dual-action hypoglycemic agents that activate GK and PPARc

A series of novel N-(pyrimidin-4-yl)thiazol-2-amine derivatives have been synthesized and evaluated as glucokinase(GK)activators.Ethyl 2-(6-(4-(2-hydroxyethyl)piperazin-1-yl)-2-methylpyrimidin-4-yl-amino)thiazole-5-carboxylate was found to be a potent dual-acting hypoglycemic agent activating both GK and PPARg.When given orally to normal mice,the compound demonstrated significant efficacy in decreasing the glucose level after oral glucose loading.