In vivo functional profiling and structural characterization of the human <i>GLP1R</i> A316T variant.

Abstract

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are effective therapies for type 2 diabetes (T2D) and obesity, yet patient responses are variable, with <i>GLP1R</i> gene variation potentially linked to therapeutic outcomes. A <i>GLP1R</i> natural missense variant, A316T, protects against T2D and cardiovascular disease. Here, we generated and characterized a human <i>GLP1R</i> A316T mouse model. Human <i>GLP1R</i>^A316T/A316T mice displayed lower fasting blood glucose versus wild-type littermates even under metabolic stress, as well as slower weight gain and alterations in islet cytoarchitecture, glucagon secretion, and liver metabolism under a high-fat, high-sucrose diet. This was however associated with blunted responses to pharmacological GLP-1RAs in vivo. Further investigations in β cell models demonstrated that human <i>GLP1R</i> A316T exhibits characteristics of constitutive activation but dampened GLP-1RA responses. Results are further supported by cryo-EM analyses and molecular dynamics simulations of GLP-1R A316T structure, collectively demonstrating that the A316T variant governs basal GLP-1R activity and pharmacological responses to GLP-1R-targeting therapies.