Document Type
Article
Publication Date
7-31-2023
Abstract
Prostaglandin E2 imparts diverse physiological effects on multiple airway cells through its actions on four distinct E-type prostanoid (EP) receptor subtypes (EP1–EP4). Gs-coupled EP2 and EP4 receptors are expressed on airway smooth muscle (ASM), yet their capacity to regulate the ASM contractile state remains subject to debate. We used EP2 and EP4 subtype-specific agonists (ONO-259 and ONO-329, respectively) in cell- and tissue-based models of human ASM contraction—magnetic twisting cytometry (MTC), and precision-cut lung slices (PCLSs), respectively—to study the EP2 and EP4 regulation of ASM contraction and signaling under conditions of histamine or methacholine (MCh) stimulation. ONO-329 was superior (<0.05) to ONO-259 in relaxing MCh-contracted PCLSs (log half maximal effective concentration [logEC50]: 4.9 × 10−7 vs. 2.2 × 10−6; maximal bronchodilation ± SE, 35 ± 2% vs. 15 ± 2%). However, ONO-259 and ONO-329 were similarly efficacious in relaxing histamine-contracted PCLSs. Similar differential effects were observed in MTC studies. Signaling analyses revealed only modest differences in ONO-329– and ONO-259–induced phosphorylation of the protein kinase A substrates VASP and HSP20, with concomitant stimulation with MCh or histamine. Conversely, ONO-259 failed to inhibit MCh-induced phosphorylation of the regulatory myosin light chain (pMLC20) and the F-actin/G-actin ratio (F/G-actin ratio) while effectively inhibiting their induction by histamine. ONO-329 was effective in reversing induced pMLC20 and the F/G-actin ratio with both MCh and histamine. Thus, the contractile-agonist–dependent differential effects are not explained by changes in the global levels of phosphorylated protein kinase A substrates but are reflected in the regulation of pMLC20 (cross-bridge cycling) and F/G-actin ratio (actin cytoskeleton integrity, force transmission), implicating a role for compartmentalized signaling involving muscarinic, histamine, and EP receptor subtypes.
Recommended Citation
Nayak AP, Javed E, Villalba DR, et al. Pro-relaxant EP receptors functionally partition to different pro-contractile receptors in airway smooth muscle. Am J Respir Cell Mol Biol. 2023;69(5):584-591. https://doi.org/10.1165/rcmb.2022-0445OC
Copyright
American Thoracic Society
Included in
Cell Biology Commons, Other Pharmacy and Pharmaceutical Sciences Commons, Respiratory System Commons, Respiratory Tract Diseases Commons
Comments
This is a pre-copy-editing, author-produced PDF of an article accepted for publication in American Journal of Respiratory Cell and Molecular Biology, volume 69, issue 5, in 2023 following peer review. This article may not exactly replicate the final published version. The definitive publisher-authenticated version is available online at https://doi.org/10.1165/rcmb.2022-0445OC.