GLP1R (glucagon-like-peptide-1 incretin receptor), diabetes and obesity phenotypes: An in silico approach revealed new pathogenic variants

Abstract

Objective: Glucagon-like peptide-1 receptor belongs to the B family of G protein-coupled receptors, serving as a binding protein in membranes and is widely expressed in human tissues. Upon stimulation by its agonist, the glucagon-like peptide-1, the receptor plays a role in glucose metabolism, enhancing insulin secretion, and regulating appetite in the hypothalamus. Mutations in the glucagon-like peptide-1 receptor gene can lead to physiological changes that may explain phenotypic variations in individuals with obesity and diabetes. Therefore, this study aimed to evaluate missense variants of the glucagon-like peptide-1 receptor gene.

Methods: Data mining was performed on the single nucleotide polymorphism database, retrieving a total of 16,399 variants. Among them, 356 were missense. These 356 variants were analyzed using the PolyPhen-2 and filtered based on allele frequency, resulting in 6 pathogenic variants.

Results: D344E, A239T, R310Q, R227H, R421P, and R176G were analyzed using four different prediction tools. The D344E and A239T resulted in larger amino acid residues compared to their wild-type counterparts. The D344E showed a slightly destabilized structure, while A239T affected the transmembrane helices. Conversely, the R310Q, R227H, R421P, and R176G resulted in smaller amino acid residues than the wild-type, leading to a loss of positive charge and increased hydrophobicity. Particularly, the R421P, due to the presence of proline, significantly destabilized the α-helix structure and caused severe damage to the receptor.

Conclusion: Elucidating the glucagon-like peptide-1 receptor variants and their potentially detrimental effects on receptor functionality can contribute to an understanding of metabolic diseases and the response to available pharmacological treatments.

Keywords: Diabetes; GLP1R; Genes; Obesity; Single nucleotide polymorphism; Variant.