Adcy8 deficiency contributes to impaired lipolysis and an increased prevalence of obesity in mice

Abstract

Obesity is a global chronic disease characterized by an imbalance in energy homeostasis. Dysfunction of adipocytes and adipose tissue are fundamental defects that contribute to the development of obesity. Adenylate cyclase 8 (ADCY8) serves as a key downstream signaling factor of G protein-coupled receptors, catalyzing the conversion of ATP to cyclic AMP (cAMP), which is essential for maintaining energy balance. Although ADCY8 is expressed in adipose tissue, its specific role in adipose energy homeostasis remains unclear and warrants further investigation. Our findings demonstrate that compared to individuals with a normal body mass index (BMI), obese individuals exhibit increased visceral adipose tissue (VAT) accumulation, significantly enlarged adipocytes, reduced ADCY8 expression in VAT, decreased cAMP levels, and diminished phosphorylation of key lipolytic enzymes. In Adcy8 knockout (Adcy8^−/−) mice, more severe lipid accumulation was observed under both normal and high-fat diet (HFD) conditions, accompanied by reduced activity of the adipose tissue cAMP-PKA signaling pathway. Notably, forskolin enhanced lipolysis and reduced adipocyte size in diet-induced obese wild-type mice, an effect abrogated in Adcy8^−/− mice. Collectively, these results indicate that adipose tissue ADCY8 regulates phosphorylation of lipolysis-related proteins via the cAMP-PKA signaling pathway, thereby influencing adipose tissue lipid accumulation. These findings establish ADCY8 as a novel molecular target and provide a theoretical foundation for obesity therapy.