TY - JOUR
T1 - GRK2 mediates TCR-induced transactivation of CXCR4 and TCR–CXCR4 complex formation that drives PI3K/PREX1 signaling and T cell cytokine secretion
AU - Dinkel, Brittney A.
AU - Kremer, Kimberly N.
AU - Rollins, Meagan R.
AU - Medlyn, Michael J.
AU - Hedin, Karen E.
N1 - Publisher Copyright:
© 2018 Dinkel et al.
PY - 2018/9/7
Y1 - 2018/9/7
N2 - 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.
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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U2 - 10.1074/jbc.RA118.003097
DO - 10.1074/jbc.RA118.003097
M3 - Article
C2 - 30018141
AN - SCOPUS:85053002613
SN - 0021-9258
VL - 293
SP - 14022
EP - 14039
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 36
ER -