Aims/hypothesis: High-energy diets are among the main causes of the global epidemic of metabolic disorders, including obesity and type 2 diabetes. The mechanisms of high-energy-diet-induced metabolic disorders are complex and largely unknown. The non-receptor tyrosine kinase c-Abl plays an important role in adipogenesis in vitro but its role in vivo in the regulation of metabolism is still elusive. Hence, we sought to address the role of c-Abl in diet-induced obesity and obesity-associated insulin resistance.
Methods: The expression of c-Abl in different fat tissues from obese humans or mice fed a high-fat diet (HFD) were first analysed by western blotting and quantitative PCR. We employed conditional deletion of the c-Abl gene (also known as Abl1) in adipose tissue using Fabp4-Cre and 6-week-old mice were fed with either a chow diet (CD) or an HFD. Age-matched wild-type mice were treated with the c-Abl inhibitor nilotinib or with vehicle and exposed to either CD or HFD, followed by analysis of body mass, fat mass, glucose and insulin tolerance. Histological staining, ELISA and biochemical analysis were used to clarify details of changes in physiology and molecular signalling.
Results: c-Abl was highly expressed in subcutaneous fat from obese humans and HFD-induced obese mice. Conditional knockout of c-Abl in adipose tissue improved insulin sensitivity and mitigated HFD-induced body mass gain, hyperglycaemia and hyperinsulinaemia. Consistently, treatment with nilotinib significantly reduced fat mass and improved insulin sensitivity in HFD-fed mice. Further biochemical analyses suggested that c-Abl inhibition improved whole-body insulin sensitivity by reducing HFD-triggered insulin resistance and increasing adiponectin in subcutaneous fat.
Conclusions/interpretation: Our findings define a new biological role for c-Abl in the regulation of diet-induced obesity through improving insulin sensitivity of subcutaneous fat. This suggests it may become a novel therapeutic target in the treatment of metabolic disorders.
Keywords: Adiponectin; Insulin resistance; Nilotinib; Obesity; c-Abl.