Loss of ABHD15 Impairs the Anti-lipolytic Action of Insulin by Altering PDE3B Stability and Contributes to Insulin Resistance

Abstract

Elevated circulating fatty acids (FAs) contribute to obesity-associated metabolic complications, but the mechanisms by which insulin suppresses lipolysis are poorly understood. We show that α/β-hydrolase domain-containing 15 (ABHD15) is required for the anti-lipolytic action of insulin in white adipose tissue (WAT). Neither insulin nor glucose treatments can suppress FA mobilization in global and conditional Abhd15-knockout (KO) mice. Accordingly, insulin signaling is impaired in Abhd15-KO adipocytes, as indicated by reduced AKT phosphorylation, glucose uptake, and de novo lipogenesis. In vitro data reveal that ABHD15 associates with and stabilizes phosphodiesterase 3B (PDE3B). Accordingly, PDE3B expression is decreased in the WAT of Abhd15-KO mice, mechanistically explaining increased protein kinase A (PKA) activity, hormone-sensitive lipase (HSL) phosphorylation, and undiminished FA release upon insulin signaling. Ultimately, Abhd15-KO mice develop insulin resistance. Notably, ABHD15 expression is decreased in humans with obesity and diabetes compared to humans with obesity and normal glucose tolerance, identifying ABHD15 as a potential therapeutic target to mitigate insulin resistance. Xia et al. show that ABHD15 stabilizes PDE3B and, thereby, impacts the anti-lipolytic action of insulin. Loss of ABHD15 reduces PDE3B protein and leads to unrestrained fatty acid mobilization. Concomitantly, glucose uptake and de novo lipogenesis are reduced in Abhd15-knockout mice, which develop insulin resistance upon aging and dietary challenges.