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 March 3, 2008; First published February 14, 2008
Citation Information: J Clin Invest. 2008;118(3):1074-1084. https://doi.org/10.1172/JCI33187.
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Categories: 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 5

Reduced levels of GRK3 products in P3 leukocytes.

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Reduced levels of GRK3 products in P3 leukocytes. (A and B) The steady-s...
(A and B) The steady-state levels of GRK proteins in leukocytes from P4 (A) and P3 (B) were compared with those obtained in leukocytes from family members and a healthy individual (CTRL#1), respectively. Total protein extracts (20 μg/lane) were analyzed by IB using an anti-GRK2/3, -GRK2, -GRK3, -GRK5/6, or -GRK6 Ab. (C and D) The steady-state levels of GRK transcripts in leukocytes from P3 (C) and P4 (D) were compared by PCR with those obtained in leukocytes from family members and healthy individuals (CTRL#2–5). Semi-quantitative (C, middle panel, and D) and real-time (C, right panel) PCRs were performed using specific primers flanking the full GRK ORFs or within them, respectively. One band corresponding to amplified LDH (~1.3 kb), GRK2 (~2.2 kb), GRK3 (~2.1 kb), GRK5 (~1.8 kb), or GRK6 (~1.8 kb) cDNA products was detected in each sample by semi-quantitative PCR. The thin horizontal lines in the gel indicate that the lanes were run on the same gel but were noncontiguous. Results are from 1 representative experiment of 3 (A–D) or are means ± SD of 3 independent determinations performed in triplicate (C, right panel). **P < 0.005 compared with III-1 individual.