Francesco Schianchi, Jeroen Guns, Freek G. Bouwman, Jeroen F.J. Bogie, M. Nabben, Agnieszka E. Strzelecka, Rick van Leeuwen, Dimitris Kapsokalyvas, Kaitlyn MJH Dennis, Lisa C. Heather, Shujin Wang, J. F.C. Glatz, Dietbert Neumann, Joost J. F. P. Luiken
Excessive accumulation of long-chain fatty acids (LCFAs) in cardiomyocytes leads to cardiac lipid-induced insulin resistance (CLIR), impairing insulin signaling and glucose uptake. This metabolic disruption marks a prediabetic state in which cardiomyocytes rely predominantly on lipids for energy provision, leading to lipotoxicity and reduced contractile function over time. Palmitate, the most common dietary LCFA, also serves as a substrate for protein S-palmitoylation, a reversible lipid-based post-translational modification (PTM) that governs protein localization and trafficking through distinct palmitoyl acyltransferase (PATs) isoforms, also denominated as DHHC. In this study, we demonstrate that pharmacological inhibition of protein S-palmitoylation with 2-bromopalmitate (2BP) prevents contractile dysfunction and CLIR in palmitate-overloaded cardiomyocytes. Analysis of the cardiomyocyte palmitoylome disclosed, among other proteins, the insulin-regulated aminopeptidase (IRAP). IRAP translocates together with glucose transporter GLUT4 to the plasma membrane in response to insulin. LCFA-induced hyper-S-palmitoylation of IRAP, mediated by DHHC5, disrupts glucose uptake. Knockdown of DHHC5 or transduction with S-palmitoylation-deficient IRAP rescues both cardiomyocyte glucose uptake and contractile function. These findings identify protein S-palmitoylation, particularly IRAP hyper-S-palmitoylation, as a novel driver of CLIR and associated myocardial dysfunction.