LAUSR

Description PGE2 receptors elicit shared, receptor-specific, and cell type–specific downstream signaling in T cells. PGE2 signaling networks The lipid mediator PGE2 suppresses antitumor immunity by activating its four related GPCRs on T cells. Lone et al. used quantitative phosphoproteomics and phosphoflow cytometry to analyze downstream signaling elicited by the stimulation of all receptors simultaneously or individually in different T cell subsets. The analysis revealed G protein–dependent and G protein–independent pathways that were activated by each receptor in all T cells, as well as pathways that were activated by only a subset of receptors, in only a subset of cells, or with receptor-specific kinetics. Network modeling predicted mechanisms of cross-talk and signal integration downstream of the receptors. These data are a comprehensive resource for future explorations of the functional consequences of PGE2 receptor–specific signaling in immune homeostasis, inflammation, and tumor-associated immunosuppression. Prostaglandin E2 (PGE2) promotes an immunosuppressive microenvironment in cancer, partly by signaling through four receptors (EP1, EP2, EP3, and EP4) on T cells. Here, we comprehensively characterized PGE2 signaling networks in helper, cytotoxic, and regulatory T cells using a phosphoproteomics and phosphoflow cytometry approach. We identified ~1500 PGE2-regulated phosphosites and several important EP1–4 signaling nodes, including PKC, CK2, PKA, PI3K, and Src. T cell subtypes exhibited distinct signaling pathways, with the strongest signaling in EP2-stimulated CD8+ cells. EP2 and EP4, both of which signal through Gαs, induced similar signaling outputs, but with distinct kinetics and intensity. Functional predictions from the observed phosphosite changes revealed PGE2 regulation of key cellular and immunological processes. Last, network modeling suggested signal integration between the receptors and a substantial contribution from G protein–independent signaling. This study offers a comprehensive view of the different PGE2-regulated phosphoproteomes in T cell subsets, providing a valuable resource for further research on this physiologically and pathophysiologically important signaling system.