Leukocyte analysis from WHIM syndrome patients reveals a pivotal role for GRK3 in CXCR4 signaling
Karl Balabanian, … , Fernando Arenzana-Seisdedos, Françoise Bachelerie
Karl Balabanian, … , Fernando Arenzana-Seisdedos, Françoise Bachelerie
Published February 14, 2008
Citation Information: J Clin Invest. 2008;118(3):1074-1084. https://doi.org/10.1172/JCI33187.
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Research Article Immunology

Leukocyte analysis from WHIM syndrome patients reveals a pivotal role for GRK3 in CXCR4 signaling

Abstract

Leukocytes from individuals with warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome, a rare immunodeficiency, and bearing a wild-type CXCR4 ORF (WHIMWT) display impaired CXCR4 internalization and desensitization upon exposure to CXCL12. The resulting enhanced CXCR4-dependent responses, including chemotaxis, probably impair leukocyte trafficking and account for the immunohematologic clinical manifestations of WHIM syndrome. We provided here evidence that GPCR kinase-3 (GRK3) specifically regulates CXCL12-promoted internalization and desensitization of CXCR4. GRK3-silenced control cells displayed altered CXCR4 attenuation and enhanced chemotaxis, as did WHIMWT cells. These findings identified GRK3 as a negative regulator of CXCL12-induced chemotaxis and as a candidate responsible for CXCR4 dysfunction in WHIMWT leukocytes. Consistent with this, we showed that GRK3 overexpression in both leukocytes and skin fibroblasts from 2 unrelated WHIMWT patients restored CXCL12-induced internalization and desensitization of CXCR4 and normalized chemotaxis. Moreover, we found in cells derived from one patient a profound and selective decrease in GRK3 products that probably resulted from defective mRNA synthesis. Taken together, these results have revealed a pivotal role for GRK3 in regulating CXCR4 attenuation and have provided a mechanistic link between the GRK3 pathway and the CXCR4-related WHIMWT disorder.

Authors

Karl Balabanian, Angélique Levoye, Lysiane Klemm, Bernard Lagane, Olivier Hermine, Julie Harriague, Françoise Baleux, Fernando Arenzana-Seisdedos, Françoise Bachelerie

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Figure 1

Analysis of CXCR4 expression in WHIMWT-derived cells.

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Selective alteration of CXCR4 functioning in WHIMWT cells. ...
(A) Membrane expression levels of endogenous CXCR4 in fibroblasts and EBV-B cells from healthy (CTRL), P3, and P4 subjects (upper panels) were determined by flow cytometry using the PE-conjugated 12G5 anti-CXCR4 mAb (white histograms) and compared with control staining measured in the CXCR4-negative CHO and A0.01 cell lines (lower panels). Gray histograms correspond to isotype control Ab. (B) Cell surface expression levels of endogenous CXCR4 in CD4+ T cells from a healthy donor and the Jurkat T cell line (left panels) were compared with those of ectopically expressed CXCR4 following transduction of fibroblasts, EBV-B cells, CHO, and A0.01 cell lines (middle and right panels) with a WT or mutant (1013) CXCR4 cDNA. (C) Lysates of EBV-B cells from CTRL and P4 subjects, A0.01 T cells, and PBLs from a healthy individual, either nontransduced (NT) or transduced with CXCR4WT (WT) or CXCR41013 (1013) cDNA, were incubated with the 12G5 anti-CXCR4 mAb precoated on γ-bind sepharose beads. Immunodetection of precipitated receptors using the SZ1567 anti-CXCR4 Ab revealed bands with molecular weights close to those expected for CXCR4WT and CXCR41013 (~39 and ~36 kDa, respectively). The thin vertical lines on the gel indicate that the lanes were run on the same gel but were noncontiguous. A representative experiment out of 2 (C) or >5 (A and B) independent determinations is shown.