Cardiac <i>GLP1R</i> gene Expression: A Cross-Species Single-Cell Transcriptomic Analysis

Abstract Glucagon-like peptide-1 receptor (GLP1R) agonists improve glycaemic control, induce weight loss, and consistently reduce major adverse cardiovascular events. However, the mechanistic basis of their cardioprotective effects remains incompletely understood, particularly whether benefits arise solely from systemic actions or also involve direct cardiac GLP1R signalling. To address this, we performed integrated single-cell and single-nucleus transcriptomics to map GLP1R gene expression across human and murine organs, cardiac cell types, disease states, and hiPSC-derived cardiac organoids. In humans, GLP1R expression was predominantly pancreatic, with low cardiac expression largely restricted to cardiomyocytes and consistently upregulated across ischaemic, dilated, and hypertrophic cardiomyopathy. In contrast, murine cardiac Glp1r expression was confined to endocardial cells and remained unchanged in heart disease. Other cardiac cell types, including fibroblasts, endothelial cells, and mural cells, showed minimal GLP1R expression in both species. Human cardiac organoids recapitulated ventricular GLP1R patterns closer to adult human myocardium than murine tissue. Together, these findings indicate that GLP1R is primarily extracardiac but selectively induced in failing human myocardium, supporting a model in which myocardial GLP1R signalling augments systemic mechanisms to confer GLP1R agonist-mediated cardioprotection.