Biology subjects

Eiger, D. S.

Publications and source records attributed to Eiger, D. S..

3 recordsLinked to original sources

bioRxiv2023

Phosphorylation barcodes direct biased chemokine signaling at CXCR3

G protein-coupled receptor (GPCR) biased agonism, the activation of some signaling pathways over others, is thought to largely be due to differential receptor phosphorylation, or "phosphorylation barcodes." At chemokine receptors, ligands act as "biased agonists" with complex signaling profiles, which contributes to the limited success in pharmacologically targeting these receptors. Here, mass spectrometry-based global phosphoproteomics revealed that CXCR3 chemokines generate different phosphorylation barcodes associated with differential transducer activation. Chemokine stimulation resulted in distinct changes throughout the kinome in global phosphoproteomic studies. Mutation of CXCR3 phosphosites altered {beta}-arrestin conformation in cellular assays and was confirmed by molecular dynamics simulations. T cells expressing phosphorylation-deficient CXCR3 mutants resulted in agonist- and receptor-specific chemotactic profiles. Our results demonstrate that CXCR3 chemokines are non-redundant and act as biased agonists through differential encoding of phosphorylation barcodes and lead to distinct physiological processes.

biochemistry↗

bioRxiv2022

Subcellular localization of GPCR kinases differentially modulate biased signaling at CXCR3

Some G protein-coupled receptors (GPCRs) demonstrate biased signaling, where ligands of the same receptor differentially activate specific downstream signaling pathways over others. Ligand-specific receptor phosphorylation by GPCR kinases (GRKs) is one mechanism underlying this phenomenon. Recent evidence demonstrates that GPCRs traffic to and signal from subcellular compartments beyond the plasma membrane, a paradigm termed location bias. Here, we show that GRKs translocate to endosomes following stimulation of the chemokine receptor CXCR3 and other GPCRs. The GRK recruitment patterns at the plasma membrane and endosome are distinct and depend on the identity of the ligand used to activate the receptor. Using cells deficient of GRKs, we demonstrate that biased ligands have unique signaling profiles upon rescue of location-specific GRK isoforms. Our work highlights a role of the GRKs in location-biased GPCR signaling and demonstrates the complex interactions between ligand, GRK isoform and cellular location that contribute to biased signaling.

biochemistry↗

bioRxiv2022

Location bias contributes to functionally selective responses of biased CXCR3 agonists

Some G protein-coupled receptor (GPCR) ligands act as "biased agonists" which preferentially activate specific signaling transducers over others. Although GPCRs are primarily found at the plasma membrane, GPCRs can traffic to and signal from many subcellular compartments. Here, we determine that differential subcellular signaling contributes to the biased signaling generated by three endogenous ligands of the chemokine GPCR CXCR3. The signaling profile of CXCR3 changed as it trafficked from the plasma membrane to endosomes in a ligand-specific manner. Endosomal signaling was critical for biased activation of G proteins, {beta}-arrestins, and ERK1/2. In CD8+ T cells, the chemokines promoted unique transcriptional responses predicted to regulate inflammatory pathways. In a mouse model of contact hypersensitivity, {beta}-arrestin-biased CXCR3-mediated inflammation was dependent on receptor internalization. Our work demonstrates that differential subcellular signaling is critical to the overall biased response observed at CXCR3, which has important implications for drugs targeting chemokine receptors and other GPCRs.

biochemistry↗