{"title":"Growth factor–dependent phosphorylation of Gαi shapes canonical signaling by G protein–coupled receptors","authors":"Suchismita Roy, Saptarshi Sinha, Ananta James Silas, Majid Ghassemian, Irina Kufareva, Pradipta Ghosh","doi":"10.1126/scisignal.ade8041","DOIUrl":null,"url":null,"abstract":"<div >A long-standing question in the field of signal transduction is how distinct signaling pathways interact with each other to control cell behavior. Growth factor receptors and G protein–coupled receptors (GPCRs) are the two major signaling hubs in eukaryotes. Given that the mechanisms by which they signal independently have been extensively characterized, we investigated how they may cross-talk with each other. Using linear ion trap mass spectrometry and cell-based biophysical, biochemical, and phenotypic assays, we found at least three distinct ways in which epidermal growth factor affected canonical G protein signaling by the G<sub>i</sub>-coupled GPCR CXCR4 through the phosphorylation of Gα<sub>i</sub>. Phosphomimicking mutations in two residues in the α<sub>E</sub> helix of Gα<sub>i</sub> (tyrosine-154/tyrosine-155) suppressed agonist-induced Gα<sub>i</sub> activation while promoting constitutive Gβγ signaling. Phosphomimicking mutations in the P loop (serine-44, serine-47, and threonine-48) suppressed G<sub>i</sub> activation entirely, thus completely segregating growth factor and GPCR pathways. As expected, most of the phosphorylation events appeared to affect intrinsic properties of Gα<sub>i</sub> proteins, including conformational stability, nucleotide binding, and the ability to associate with and to release Gβγ. However, one phosphomimicking mutation, targeting the carboxyl-terminal residue tyrosine-320, promoted mislocalization of Gα<sub>i</sub> from the plasma membrane, a previously uncharacterized mechanism of suppressing GPCR signaling through G protein subcellular compartmentalization. Together, these findings elucidate not only how growth factor and chemokine signals cross-talk through the phosphorylation-dependent modulation of Gα<sub>i</sub> but also how such cross-talk may generate signal diversity.</div>","PeriodicalId":21658,"journal":{"name":"Science Signaling","volume":"17 839","pages":""},"PeriodicalIF":6.7000,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Science Signaling","FirstCategoryId":"99","ListUrlMain":"https://www.science.org/doi/10.1126/scisignal.ade8041","RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"BIOCHEMISTRY & MOLECULAR BIOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
A long-standing question in the field of signal transduction is how distinct signaling pathways interact with each other to control cell behavior. Growth factor receptors and G protein–coupled receptors (GPCRs) are the two major signaling hubs in eukaryotes. Given that the mechanisms by which they signal independently have been extensively characterized, we investigated how they may cross-talk with each other. Using linear ion trap mass spectrometry and cell-based biophysical, biochemical, and phenotypic assays, we found at least three distinct ways in which epidermal growth factor affected canonical G protein signaling by the Gi-coupled GPCR CXCR4 through the phosphorylation of Gαi. Phosphomimicking mutations in two residues in the αE helix of Gαi (tyrosine-154/tyrosine-155) suppressed agonist-induced Gαi activation while promoting constitutive Gβγ signaling. Phosphomimicking mutations in the P loop (serine-44, serine-47, and threonine-48) suppressed Gi activation entirely, thus completely segregating growth factor and GPCR pathways. As expected, most of the phosphorylation events appeared to affect intrinsic properties of Gαi proteins, including conformational stability, nucleotide binding, and the ability to associate with and to release Gβγ. However, one phosphomimicking mutation, targeting the carboxyl-terminal residue tyrosine-320, promoted mislocalization of Gαi from the plasma membrane, a previously uncharacterized mechanism of suppressing GPCR signaling through G protein subcellular compartmentalization. Together, these findings elucidate not only how growth factor and chemokine signals cross-talk through the phosphorylation-dependent modulation of Gαi but also how such cross-talk may generate signal diversity.
期刊介绍:
"Science Signaling" is a reputable, peer-reviewed journal dedicated to the exploration of cell communication mechanisms, offering a comprehensive view of the intricate processes that govern cellular regulation. This journal, published weekly online by the American Association for the Advancement of Science (AAAS), is a go-to resource for the latest research in cell signaling and its various facets.
The journal's scope encompasses a broad range of topics, including the study of signaling networks, synthetic biology, systems biology, and the application of these findings in drug discovery. It also delves into the computational and modeling aspects of regulatory pathways, providing insights into how cells communicate and respond to their environment.
In addition to publishing full-length articles that report on groundbreaking research, "Science Signaling" also features reviews that synthesize current knowledge in the field, focus articles that highlight specific areas of interest, and editor-written highlights that draw attention to particularly significant studies. This mix of content ensures that the journal serves as a valuable resource for both researchers and professionals looking to stay abreast of the latest advancements in cell communication science.