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In 1975, Arion and colleagues discovered that hepatocytes release glucose into the bloodstream in response to hypoglycaemia using the glucose-6-phosphatase (G6Pase) system. This system is in the endoplasmic reticulum (ER) and is composed of two functionally linked proteins, a G6P transporter subunit (G6PT) and a catalytic subunit called G6P phosphatase (G6Pase). The G6PT subunit promotes the storage of G6P inside the ER, while G6Pase, which has its catalytic domain in the reticular lumen, hydrolyses G6P to yield free glucose + phosphate. The free glucose stored in the reticular lumen can be transported to the cytosol and from there to the extracellular space in hypoglycaemic conditions by a direct mechanism that has not yet been established, but eventually by glucose transporters (GLUTs).

 

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Current Issue

The novel adrenergic agonist ATR-127 targets skeletal muscle and brown adipose tissue to tackle diabesity and steatohepatitis

Emanuela Talamonti, Jelena Davegardh, Anastasia Kalinovich, Sten M.M. van Beek, ... Tore Bengtsson

 

Objective

Simultaneous activation of β2- and β3-adrenoceptors (ARs) improves whole-body metabolism via beneficial effects in skeletal muscle and brown adipose tissue (BAT). Nevertheless, high-efficacy agonists simultaneously targeting these receptors whilst limiting activation of β1-ARs – and thus inducing cardiovascular complications – are currently non-existent. Therefore, we here developed and evaluated the therapeutic potential of a novel β2-and β3-AR, named ATR-127, for the treatment of obesity and its associated metabolic perturbations in preclinical models.

Methods

In the developmental phase, we assessed the impact of ATR-127's on cAMP accumulation in relation to the non-selective β-AR agonist isoprenaline across various rodent β-AR subtypes, including neonatal rat cardiomyocytes. Following these experiments, L6 muscle cells were stimulated with ATR-127 to assess the impact on GLUT4-mediated glucose uptake and intramyocellular cAMP accumulation. Additionally, in vitro, and in vivo assessments are conducted to measure ATR-127's effects on BAT glucose uptake and thermogenesis. Finally, diet-induced obese mice were treated with 5 mg/kg ATR-127 for 21 days to investigate the effects on glucose homeostasis, body weight, fat mass, skeletal muscle glucose uptake, BAT thermogenesis and hepatic steatosis.

Results

Exposure of L6 muscle cells to ATR-127 robustly enhanced GLUT4-mediated glucose uptake despite low intramyocellular cAMP accumulation. Similarly, ATR-127 markedly increased BAT glucose uptake and thermogenesis both in vitro and in vivo. Prolonged treatment of diet-induced obese mice with ATR-127 dramatically improved glucose homeostasis, an effect accompanied by decreases in body weight and fat mass. These effects were paralleled by an enhanced skeletal muscle glucose uptake, BAT thermogenesis, and improvements in hepatic steatosis.

Conclusions

Our results demonstrate that ATR-127 is a highly effective, novel β2- and β3-ARs agonist holding great therapeutic promise for the treatment of obesity and its comorbidities, whilst potentially limiting cardiovascular complications. As such, the therapeutic effects of ATR-127 should be investigated in more detail in clinical studies.

Keywords

Obesity

Type 2 diabetes

β-Adrenergic agonists

Hepatic steatosis

Skeletal muscle

 

Articles in Press

The novel adrenergic agonist ATR-127 targets skeletal muscle and brown adipose tissue to tackle diabesity and steatohepatitis

Emanuela Talamonti, Jelena Davegardh, Anastasia Kalinovich, Sten M.M. van Beek, ... Tore Bengtsson

 

Objective

Simultaneous activation of β2- and β3-adrenoceptors (ARs) improves whole-body metabolism via beneficial effects in skeletal muscle and brown adipose tissue (BAT). Nevertheless, high-efficacy agonists simultaneously targeting these receptors whilst limiting activation of β1-ARs – and thus inducing cardiovascular complications – are currently non-existent. Therefore, we here developed and evaluated the therapeutic potential of a novel β2-and β3-AR, named ATR-127, for the treatment of obesity and its associated metabolic perturbations in preclinical models.

Methods

In the developmental phase, we assessed the impact of ATR-127's on cAMP accumulation in relation to the non-selective β-AR agonist isoprenaline across various rodent β-AR subtypes, including neonatal rat cardiomyocytes. Following these experiments, L6 muscle cells were stimulated with ATR-127 to assess the impact on GLUT4-mediated glucose uptake and intramyocellular cAMP accumulation. Additionally, in vitro, and in vivo assessments are conducted to measure ATR-127's effects on BAT glucose uptake and thermogenesis. Finally, diet-induced obese mice were treated with 5 mg/kg ATR-127 for 21 days to investigate the effects on glucose homeostasis, body weight, fat mass, skeletal muscle glucose uptake, BAT thermogenesis and hepatic steatosis.

Results

Exposure of L6 muscle cells to ATR-127 robustly enhanced GLUT4-mediated glucose uptake despite low intramyocellular cAMP accumulation. Similarly, ATR-127 markedly increased BAT glucose uptake and thermogenesis both in vitro and in vivo. Prolonged treatment of diet-induced obese mice with ATR-127 dramatically improved glucose homeostasis, an effect accompanied by decreases in body weight and fat mass. These effects were paralleled by an enhanced skeletal muscle glucose uptake, BAT thermogenesis, and improvements in hepatic steatosis.

Conclusions

Our results demonstrate that ATR-127 is a highly effective, novel β2- and β3-ARs agonist holding great therapeutic promise for the treatment of obesity and its comorbidities, whilst potentially limiting cardiovascular complications. As such, the therapeutic effects of ATR-127 should be investigated in more detail in clinical studies.

Keywords

Obesity

Type 2 diabetes

β-Adrenergic agonists

Hepatic steatosis

Skeletal muscle

 

2021 impact factor: 8.568

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