GRK2 mediates TCR-induced transactivation of CXCR4 and TCR–CXCR4 complex formation that drives PI3K/PREX1 signaling and T cell cytokine secretion

Brittney A. Dinkel, Kimberly N. Kremer, Meagan R. Rollins, Michael J. Medlyn, Karen Elaine Hedin

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

The immune system includes abundant examples of biologically-relevant cross-regulation of signaling pathways by the T cell antigen receptor (TCR) and the G protein– coupled chemokine receptor, CXCR4. TCR ligation induces transactivation of CXCR4 and TCR–CXCR4 complex formation, permitting the TCR to signal via CXCR4 to activate a phosphatidylinositol 3,4,5-trisphosphate– dependent Rac exchanger 1 protein (PREX1)– dependent signaling pathway that drives robust cytokine secretion by T cells. To understand this receptor heterodimer and its regulation, we characterized the molecular mechanisms required for TCR-mediated TCR–CXCR4 complex formation. We found that the cytoplasmic C-terminal domain of CXCR4 and specifically phosphorylation of Ser-339 within this region were required for TCR–CXCR4 complex formation. Interestingly, siRNA-mediated depletion of G protein– coupled receptor kinase-2 (GRK2) or inhibition by the GRK2-specific inhibitor, paroxetine, inhibited TCR-induced phosphorylation of CXCR4 –Ser-339 and TCR–CXCR4 complex formation. Either GRK2 siRNA or paroxetine treatment of human T cells significantly reduced T cell cytokine production. Upstream, TCR-activated tyrosine kinases caused inducible tyrosine phosphorylation of GRK2 and were required for the GRK2-dependent events of CXCR4 –Ser-339 phosphorylation and TCR–CXCR4 complex formation. Downstream of TCR–CXCR4 complex formation, we found that GRK2 and phosphatidylinositol 3-kinase (PI3K) were required for TCR-stimulated membrane recruitment of PREX1 and for stabilization of cytokine mRNAs and robust cytokine secretion. Together, our results identify a novel role for GRK2 as a target of TCR signaling that is responsible for TCR-induced transactivation of CXCR4 and TCR–CXCR4 complex formation that signals via PI3K/PREX1 to mediate cytokine production. Therapeutic regulation of GRK2 or PI3K may therefore be useful for limiting cytokines produced by T cell malignancies or autoimmune diseases.

Original languageEnglish (US)
Pages (from-to)14022-14039
Number of pages18
JournalJournal of Biological Chemistry
Volume293
Issue number36
DOIs
StatePublished - Jan 1 2018

Fingerprint

G-Protein-Coupled Receptor Kinase 2
Phosphatidylinositol 3-Kinase
T-cells
T-Cell Antigen Receptor
Transcriptional Activation
Cytokines
T-Lymphocytes
Phosphorylation
Paroxetine
Small Interfering RNA
Chemokine Receptors
Immune system
G-Protein-Coupled Receptors
GTP-Binding Proteins
Protein-Tyrosine Kinases
Autoimmune Diseases
Ligation
Tyrosine
Immune System
Stabilization

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

GRK2 mediates TCR-induced transactivation of CXCR4 and TCR–CXCR4 complex formation that drives PI3K/PREX1 signaling and T cell cytokine secretion. / Dinkel, Brittney A.; Kremer, Kimberly N.; Rollins, Meagan R.; Medlyn, Michael J.; Hedin, Karen Elaine.

In: Journal of Biological Chemistry, Vol. 293, No. 36, 01.01.2018, p. 14022-14039.

Research output: Contribution to journalArticle

Dinkel, Brittney A. ; Kremer, Kimberly N. ; Rollins, Meagan R. ; Medlyn, Michael J. ; Hedin, Karen Elaine. / GRK2 mediates TCR-induced transactivation of CXCR4 and TCR–CXCR4 complex formation that drives PI3K/PREX1 signaling and T cell cytokine secretion. In: Journal of Biological Chemistry. 2018 ; Vol. 293, No. 36. pp. 14022-14039.
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abstract = "The immune system includes abundant examples of biologically-relevant cross-regulation of signaling pathways by the T cell antigen receptor (TCR) and the G protein– coupled chemokine receptor, CXCR4. TCR ligation induces transactivation of CXCR4 and TCR–CXCR4 complex formation, permitting the TCR to signal via CXCR4 to activate a phosphatidylinositol 3,4,5-trisphosphate– dependent Rac exchanger 1 protein (PREX1)– dependent signaling pathway that drives robust cytokine secretion by T cells. To understand this receptor heterodimer and its regulation, we characterized the molecular mechanisms required for TCR-mediated TCR–CXCR4 complex formation. We found that the cytoplasmic C-terminal domain of CXCR4 and specifically phosphorylation of Ser-339 within this region were required for TCR–CXCR4 complex formation. Interestingly, siRNA-mediated depletion of G protein– coupled receptor kinase-2 (GRK2) or inhibition by the GRK2-specific inhibitor, paroxetine, inhibited TCR-induced phosphorylation of CXCR4 –Ser-339 and TCR–CXCR4 complex formation. Either GRK2 siRNA or paroxetine treatment of human T cells significantly reduced T cell cytokine production. Upstream, TCR-activated tyrosine kinases caused inducible tyrosine phosphorylation of GRK2 and were required for the GRK2-dependent events of CXCR4 –Ser-339 phosphorylation and TCR–CXCR4 complex formation. Downstream of TCR–CXCR4 complex formation, we found that GRK2 and phosphatidylinositol 3-kinase (PI3K) were required for TCR-stimulated membrane recruitment of PREX1 and for stabilization of cytokine mRNAs and robust cytokine secretion. Together, our results identify a novel role for GRK2 as a target of TCR signaling that is responsible for TCR-induced transactivation of CXCR4 and TCR–CXCR4 complex formation that signals via PI3K/PREX1 to mediate cytokine production. Therapeutic regulation of GRK2 or PI3K may therefore be useful for limiting cytokines produced by T cell malignancies or autoimmune diseases.",
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AU - Hedin, Karen Elaine

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AB - The immune system includes abundant examples of biologically-relevant cross-regulation of signaling pathways by the T cell antigen receptor (TCR) and the G protein– coupled chemokine receptor, CXCR4. TCR ligation induces transactivation of CXCR4 and TCR–CXCR4 complex formation, permitting the TCR to signal via CXCR4 to activate a phosphatidylinositol 3,4,5-trisphosphate– dependent Rac exchanger 1 protein (PREX1)– dependent signaling pathway that drives robust cytokine secretion by T cells. To understand this receptor heterodimer and its regulation, we characterized the molecular mechanisms required for TCR-mediated TCR–CXCR4 complex formation. We found that the cytoplasmic C-terminal domain of CXCR4 and specifically phosphorylation of Ser-339 within this region were required for TCR–CXCR4 complex formation. Interestingly, siRNA-mediated depletion of G protein– coupled receptor kinase-2 (GRK2) or inhibition by the GRK2-specific inhibitor, paroxetine, inhibited TCR-induced phosphorylation of CXCR4 –Ser-339 and TCR–CXCR4 complex formation. Either GRK2 siRNA or paroxetine treatment of human T cells significantly reduced T cell cytokine production. Upstream, TCR-activated tyrosine kinases caused inducible tyrosine phosphorylation of GRK2 and were required for the GRK2-dependent events of CXCR4 –Ser-339 phosphorylation and TCR–CXCR4 complex formation. Downstream of TCR–CXCR4 complex formation, we found that GRK2 and phosphatidylinositol 3-kinase (PI3K) were required for TCR-stimulated membrane recruitment of PREX1 and for stabilization of cytokine mRNAs and robust cytokine secretion. Together, our results identify a novel role for GRK2 as a target of TCR signaling that is responsible for TCR-induced transactivation of CXCR4 and TCR–CXCR4 complex formation that signals via PI3K/PREX1 to mediate cytokine production. Therapeutic regulation of GRK2 or PI3K may therefore be useful for limiting cytokines produced by T cell malignancies or autoimmune diseases.

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