Leukotrienes are lipid mediators of inflammation, initially recognized for their role in asthma, but also having potent effects in for example cardiovascular and neurological diseases as well as in cancer. The initial pharmacological classification of leukotriene receptors based on antagonist selectivity in smooth muscle was shown to be valid at the gene and protein levels. Following the recent description of the CysLT1 receptor structure, Gusach et al. now describe the crystal structures of the CysLT2 receptor in complex with dual CysLT1/CysLT2 receptor antagonists (1). This is an important advancement, since it allows to reveal specific characteristics of the two CysLT receptors in terms of ligand recognition and subtype selectivity. In this context, differences in the intracellular helix 8 emerge as particular subtype determinants, which may affect G-protein regulation and β-arrestin binding. The study by Gusach et al. (1) further provides structural insights into the changes in ligand binding and downstream signaling by CysLT2R disease-related single nucleotide polymorphisms (SNP) associated with asthma and cancer. The deciphering of the crystal structures for the CysLT1 and CysLT2 receptors will open up for the design of CysLT receptor antagonists with improved affinity/efficacy or subtype selectivity profiles. The insights into the CysLT receptor genome-structure-function relations may facilitate the prediction of disease associations and potentially further expanding the therapeutic indications of CysLT receptor antagonists.
Comments by Magnus Bäck, MD PhD, (@TransCardio), Karolinska Institutet and University Hospital, Stockholm, Sweden; Chairman NC-IUPHAR subcommittee on Leukotriene Receptors
(1) Gusach, A., Luginina, A., Marin, E. et al. Structural basis of ligand selectivity and disease mutations in cysteinyl leukotriene receptors. Nat Commun 10, 5573 (2019) doi:10.1038/s41467-019-13348-2 [PMID:31811124]