Characterization of a new WHIM syndrome mutant reveals mechanistic differences in regulation of the chemokine receptor CXCR4

Abstract

WHIM syndrome is a rare immunodeficiency disorder that is characterized by warts, hypogammaglobulinemia, infections, and myelokathexis. While several gain-of-function mutations that lead to C-terminal truncations, frame shifts and point mutations in the chemokine receptor CXCR4 have been identified in WHIM syndrome patients, the functional effect of these mutations are not fully understood. Here, we report on a new WHIM syndrome mutation that results in a frame shift within the codon for Ser339 (S339fs5) and compare the properties of S339fs5 with wild-type CXCR4 and a previously identified WHIM syndrome mutant, R334X. The S339fs5 and R334X mutants exhibited significantly increased signaling compared to wild-type CXCR4 including agonist-promoted calcium flux and extracellular-signal-regulated kinase activation. This increase is at least partially due to a significant decrease in agonist-promoted phosphorylation, β-arrestin binding, and endocytosis of S339fs5 and R334X compared with wild-type CXCR4. Interestingly, there were also significant differences in receptor degradation, with S339fs5 having a very high basal level of degradation compared with that of R334X and wild-type CXCR4. In contrast to wild-type CXCR4, both R334X and S339fs5 were largely insensitive to CXCL12-promoted degradation. Moreover, while basal and agonist-promoted degradation of wild-type CXCR4 was effectively inhibited by the CXCR4 antagonist TE-14016, this had no effect on the degradation of the WHIM mutants. Taken together, these studies identify a new WHIM syndrome mutant, CXCR4-S339fs5, which promotes enhanced signaling, reduced phosphorylation, β-arrestin binding and endocytosis, and a very high basal rate of degradation that is not protected by antagonist treatment. WHIM syndrome is a rare immunodeficiency disorder that is characterized by warts, hypogammaglobulinemia, infections, and myelokathexis. While several gain-of-function mutations that lead to C-terminal truncations, frame shifts and point mutations in the chemokine receptor CXCR4 have been identified in WHIM syndrome patients, the functional effect of these mutations are not fully understood. Here, we report on a new WHIM syndrome mutation that results in a frame shift within the codon for Ser339 (S339fs5) and compare the properties of S339fs5 with wild-type CXCR4 and a previously identified WHIM syndrome mutant, R334X. The S339fs5 and R334X mutants exhibited significantly increased signaling compared to wild-type CXCR4 including agonist-promoted calcium flux and extracellular-signal-regulated kinase activation. This increase is at least partially due to a significant decrease in agonist-promoted phosphorylation, β-arrestin binding, and endocytosis of S339fs5 and R334X compared with wild-type CXCR4. Interestingly, there were also significant differences in receptor degradation, with S339fs5 having a very high basal level of degradation compared with that of R334X and wild-type CXCR4. In contrast to wild-type CXCR4, both R334X and S339fs5 were largely insensitive to CXCL12-promoted degradation. Moreover, while basal and agonist-promoted degradation of wild-type CXCR4 was effectively inhibited by the CXCR4 antagonist TE-14016, this had no effect on the degradation of the WHIM mutants. Taken together, these studies identify a new WHIM syndrome mutant, CXCR4-S339fs5, which promotes enhanced signaling, reduced phosphorylation, β-arrestin binding and endocytosis, and a very high basal rate of degradation that is not protected by antagonist treatment. WHIM syndrome is a rare, genetic disease, which is named for its four key clinical manifestations, Warts, Hypogammaglobulinemia, recurrent Infections, and Myelokathexis (1Heusinkveld L.E. Majumdar S. Gao J.L. McDermott D.H. Murphy P.M. WHIM syndrome: From pathogenesis towards personalized medicine and cure.J. Clin. Immunol. 2019; 39: 532-556Google Scholar). WHIM syndrome mainly results from heterozygous gain-of-function mutations in the chemokine receptor CXCR4, a 352 amino acid G-protein-coupled receptor (GPCR) that contains a Ser/Thr-rich C-terminal tail that is a primary region of regulation. CXCR4 is broadly expressed and has an important role in the immune system (1Heusinkveld L.E. Majumdar S. Gao J.L. McDermott D.H. Murphy P.M. WHIM syndrome: From pathogenesis towards personalized medicine and cure.J. Clin. Immunol. 2019; 39: 532-556Google Scholar, 2Hernandez P.A. Gorlin R.J. Lukens J.N. Taniuchi S. Bohinjec J. Francois F. Klotman M.E. Diaz G.A. Mutations in the chemokine receptor gene CXCR4 are associated with WHIM syndrome, a combined immunodeficiency disease.Nat. Genet. 2003; 34: 70-74Google Scholar, 3Bachelerie F. CXCL12/CXCR4-axis dysfunctions: Markers of the rare immunodeficiency disorder WHIM syndrome.Dis. Markers. 2010; 29: 189-198Google Scholar). Previous studies have identified a total of 11 autosomal dominant mutations in CXCR4 across 105 patients that result in WHIM syndrome with the most prevalent being a truncation after Lys333 (R334X) (1Heusinkveld L.E. Majumdar S. Gao J.L. McDermott D.H. Murphy P.M. WHIM syndrome: From pathogenesis towards personalized medicine and cure.J. Clin. Immunol. 2019; 39: 532-556Google Scholar). R334X has been the most extensively characterized mutation and has been shown to have increased agonist (CXCL12)-promoted signaling, increased G protein interaction, reduced interaction with GPCR kinase 6 (GRK6) and β-arrestin2, and impaired receptor internalization (1Heusinkveld L.E. Majumdar S. Gao J.L. McDermott D.H. Murphy P.M. WHIM syndrome: From pathogenesis towards personalized medicine and cure.J. Clin. Immunol. 2019; 39: 532-556Google Scholar, 4Balabanian K. Lagane B. Pablos J.L. Laurent L. Planchenault T. Verola O. Lebbe C. Kerob D. Dupuy A. Hermine O. Nicolas J.-F. Latger-Cannard V. Bensoussan D. Bordigoni P. Baleux F. et al.WHIM syndromes with different genetic anomalies are accounted for by impaired CXCR4 desensitization to CXCL12.Blood. 2005; 105: 2449-2457Google Scholar, 5McCormick P.J. Segarra M. Gasperini P. Gulino A.V. Tosato G. Impaired recruitment of Grk6 and beta-arrestin 2 causes delayed internalization and desensitization of a WHIM syndrome-associated CXCR4 mutant receptor.PLoS One. 2009; 4e8102Google Scholar, 6McDermott D.H. Lopez J. Deng F. Liu Q. Ojode T. Chen H. Ulrick J. Kwatemaa N. Kelly C. Anaya-O'Brien S. Garofalo M. Marquesen M. Hilligoss D. DeCastro R. Malech H.L. et al.AMD3100 is a potent antagonist at CXCR4R334X, a hyperfunctional mutant chemokine receptor and cause of WHIM syndrome.J. Cell. Mol. Med. 2011; 15: 2071-2081Google Scholar, 7Levy E. Reger R. Segerberg F. Lambert M. Leijonhufvud C. Baumer Y. Carlsten M. Childs R. Enhanced bone marrow homing of natural killer cells following mRNA transfection with gain-of-function variant CXCR4R334X.Front. Immunol. 2019; 10: 1262Google Scholar). An S338X mutation has also been extensively studied and has many properties similar to R334X with increased signaling and G protein interaction and decreased β-arrestin2 binding and receptor internalization (8Lagane B. Chow K.Y.C. Balabanian K. Levoye A. Harriague J. Planchenault T. Baleux F. Gunera-Saad N. Arenzana-Seisdedos F. Bachelerie F. CXCR4 dimerization and β-arrestin-mediated signaling account for the enhanced chemotaxis to CXCL12 in WHIM syndrome.Blood. 2008; 112: 34-44Google Scholar, 9Balabanian K. Brotin E. Biajoux V. Bouchet-Delbos L. Lainey E. Fenneteau O. Bonnet D. Fiette L. Emilie D. Bachelerie F. Proper desensitization of CXCR4 is required for lymphocyte development and peripheral compartmentalization in mice.Blood. 2012; 119: 5722-5730Google Scholar, 10Cao Y. Hunter Z.R. Liu X. Xu L. Yang G. Chen J. Patterson C.J. Tsakmaklis N. Kanan S. Rodig S. Castillo J.J. Treon S.P. The WHIM-like CXCR4S338X somatic mutation activates AKT and ERK, and promotes resistance to ibrutinib and other agents used in the treatment of Waldenstrom’s Macroglobulinemia.Leukemia. 2015; 29: 169-176Google Scholar, 11Biajoux V. Natt J. Freitas C. Alouche N. Sacquin A. Hemon P. Gaudin F. Fazilleau N. Espéli M. Balabanian K. Efficient plasma cell differentiation and trafficking require Cxcr4 desensitization.Cell Rep. 2016; 17: 193-205Google Scholar, C. M. J. V. Biajoux V. Gaudin F. S. Y. C. J. Bachelerie F. Espéli M. A. F. et differentiation of cells Cxcr4 Med. Scholar). WHIM mutation that has been studied is which has increased signaling and reduced receptor and internalization Q. Chen H. Ojode T. Gao X. Anaya-O'Brien S. Ulrick J. DeCastro R. Kelly C. Malech H.L. Murphy P.M. et al.WHIM syndrome by a amino acid in the of chemokine receptor 2012; Scholar, D. F. S. R. of at the CXCR4 One. Scholar, L. Q. P. Chen G. N. C. The of the is for of Mol. Scholar). Interestingly, WHIM syndrome has also been identified with a in the protein kinase in increased CXCL12-promoted signaling and impaired desensitization and internalization K. Levoye A. L. Lagane B. Hermine O. Harriague J. Baleux F. Arenzana-Seisdedos F. Bachelerie F. from WHIM syndrome patients a role for in CXCR4 Clin. 2008; Scholar, O. D. G receptor WHIM syndrome and Scholar). CXCR4 has been extensively and in several WHIM syndrome including immunodeficiency syndrome a for immunodeficiency and has a role in J.L. of CXCR4 Scholar, P. C. of the in and for in and J. Scholar). Moreover, CXCR4 mutations in WHIM syndrome also in of the of the plasma cell Waldenstrom’s Q. C. Lopez L. Gao J. D. Anaya-O'Brien S. Ulrick J. P. Malech H.L. Murphy P.M. McDermott D.H. WHIM syndrome by mutation Clin. Immunol. 2016; Scholar, Hunter Z.R. Treon S.P. C. CXCR4 in Waldenstrom’s and Scholar). have also a of mutations in CXCR4 in and S. C. S. A. R. M. on the of CXCR4 in from Scholar). The C-terminal mutations in CXCR4 that in WHIM syndrome to the in CXCR4 which of the receptor by and protein kinase desensitization by β-arrestin binding, by the endocytosis, and to the receptor is D. F. S. R. of at the CXCR4 One. Scholar, A. J.L. of the G-protein-coupled receptor CXCR4 Scholar, A. C. F. H. J.L. The and of the G receptor Cell. 2003; Scholar, S. R. O. M. J.L. of CXCR4 is by and results in of CXCR4 2010; Scholar, J. R. J.L. G receptor kinase and protein kinase the C-terminal tail of the chemokine receptor CXCR4 and recruitment of Scholar). CXCR4 has also been shown to several signaling its interaction with also J.L. of CXCR4 Scholar, H. P. S. P. M. R. M. a signaling of 2011; Scholar). While C-terminal and mutations in CXCR4 have been shown to CXCR4 signaling and lead to WHIM syndrome, we have an of these CXCR4 we on the of a new WHIM syndrome mutation in CXCR4 that we identified that contains a frame shift in the codon for Ser339 in that have this mutation many of WHIM syndrome including recurrent warts, infections, and with bone marrow of myelokathexis. the of S339fs5 that to its role in WHIM syndrome, we a cell S339fs5 and compared its properties with wild-type CXCR4 and with WHIM syndrome mutant, R334X. S339fs5 and R334X have a in the in CXCR4 including decreased agonist-promoted phosphorylation, β-arrestin binding, and endocytosis to enhanced signaling compared to CXCR4. S339fs5 also to have a basal rate of degradation compared with R334X and CXCR4 that S339fs5 compared with CXCR4 in these we report on a new a mutation in CXCR4 that results in a frame shift within the codon for Ser339 (S339fs5) from the with and decreased cells with Infections, other CXCR4 WHIM syndrome including and in and are to the of the of S339fs5 with other WHIM syndrome mutations is shown in the properties of the new S339fs5 we cells S339fs5 a WHIM mutant the most prevalent mutation in WHIM syndrome was used to compare the cell of S339fs5 and R334X with a that we had previously CXCR4 S. R. O. M. J.L. of CXCR4 is by and results in of CXCR4 2010; Scholar). This that S339fs5 and R334X were expressed at of the level in CXCR4 cells Previous studies have that CXCR4 mutations in WHIM syndrome have enhanced compare the signaling of S339fs5 with R334X and CXCR4, we at the of the CXCR4 agonist CXCL12 to a calcium CXCL12 was to a level of calcium flux in cells due to a level of CXCR4 This was increased in cells CXCR4, a that we previously in these cells S. R. O. M. J.L. of CXCR4 is by and results in of CXCR4 2010; Scholar). In calcium flux was increased several in cells R334X and in cells also the of the CXCR4 J. J. Y. S. V. J.L. M. the chemokine receptor a agonist S. A. to a calcium flux in the cells had a level of calcium cells CXCR4 had a level of to R334X cells were to and S339fs5 cells were increased compared with CXCR4 these studies that both S339fs5 and R334X have enhanced calcium signaling compared with CXCR4 with S339fs5 being the most CXCR4 also promotes the of extracellular-signal-regulated kinase and S. R. O. M. J.L. of CXCR4 is by and results in of CXCR4 2010; Scholar, J. J. Y. S. V. J.L. M. the chemokine receptor a agonist S. A. Scholar). results by CXCL12 in cells with a significant increase in cells CXCR4 previously and not R334X S339fs5 had enhanced CXCL12-promoted compared with CXCR4 cells with R334X being the most and by in cells with an increase in cells CXCR4 not The cell R334X S339fs5 both had enhanced compared with CXCR4 with R334X being the most and Taken together, these studies that both S339fs5 and R334X have enhanced compared with CXCR4 with R334X being the most signaling increased of due to a decrease in the that CXCR4 of Previous studies a role for and of CXCR4 in the desensitization S. R. O. M. J.L. of CXCR4 is by and results in of CXCR4 2010; Scholar). In of C-terminal by is to β-arrestin binding, which in the desensitization D. F. S. R. of at the CXCR4 One. Scholar, S. R. O. M. J.L. of CXCR4 is by and results in of CXCR4 2010; Scholar, J. R. J.L. G receptor kinase and protein kinase the C-terminal tail of the chemokine receptor CXCR4 and recruitment of Scholar). While these are not in R334X and are and also to the desensitization to CXCR4 endocytosis and degradation A. J.L. of the G-protein-coupled receptor CXCR4 Scholar). we CXCL12 and of that we previously and S. R. O. M. J.L. of CXCR4 is by and results in of CXCR4 2010; Scholar). While CXCL12 and and of in CXCR4, there was a basal level of and of S339fs5 and R334X and is also that we reduced of CXCR4 following agonist treatment due to of the receptor previously shown S. R. O. M. J.L. of CXCR4 is by and results in of CXCR4 2010; while no shift was with the WHIM mutants S339fs5 and R334X agonist-promoted of in CXCR4 Previous studies have shown that to CXCR4 in an and and an important role in signaling K. Levoye A. L. Lagane B. Hermine O. Harriague J. Baleux F. Arenzana-Seisdedos F. Bachelerie F. from WHIM syndrome patients a role for in CXCR4 Clin. 2008; Scholar, J.L. of CXCR4 Scholar, S. R. O. M. J.L. of CXCR4 is by and results in of CXCR4 2010; Scholar, J. R. J.L. G receptor kinase and protein kinase the C-terminal tail of the chemokine receptor CXCR4 and recruitment of Scholar). the WHIM mutants have a in β-arrestin binding, we a to the of β-arrestin2 from the to the plasma receptor P. Lambert to recruitment to and G 2015; Scholar). studies to the of β-arrestin2 in cells CXCR4 with no in cells also not significant of β-arrestin2 in the cells the S339fs5 and R334X WHIM mutants have a in β-arrestin binding most due to the and reduced C-terminal compared with CXCR4. important of CXCR4 is agonist-promoted endocytosis, which is in the and degradation of the While the of this endocytosis has not been fully has been shown that CXCR4 endocytosis a that is β-arrestin A. A. of CXCR4 2019; Scholar). CXCR4 was to endocytosis after of agonist treatment endocytosis of R334X was significantly reduced with a of at while S339fs5 was reduced with a of the of an important role in the A. J.L. of the G-protein-coupled receptor CXCR4 is not that endocytosis of S339fs5 and R334X is significantly the level of that was CXCR4 is also by to is A. J.L. of the G-protein-coupled receptor CXCR4 Scholar, A. C. F. H. J.L. The and of the G receptor Cell. 2003; Scholar). differences in the degradation of and R334X CXCR4, we the cells with for to new protein the cells with CXCL12 for to 6 and CXCR4 by CXCR4 significant basal degradation in this system with a of while CXCL12 significantly increased the rate of degradation with a of and also enhanced the rate of CXCR4 degradation was not significant with CXCL12 and While R334X had a basal rate of degradation similar to CXCR4, there was no significant effect of CXCL12 treatment Interestingly, S339fs5 had a basal rate of degradation with a of similar to was largely insensitive to agonist treatment the of degradation of and S339fs5 are significantly different with being to agonist R334X and S339fs5 being and S339fs5 having a basal rate of degradation. to differences the degradation of CXCR4 and the WHIM we cells with the high CXCR4 antagonist the significantly inhibited basal degradation CXCL12-promoted degradation of CXCR4 while partially inhibited basal degradation and In we not a significant effect of treatment on the degradation of S339fs5 and R334X and the basal rate of degradation of S339fs5 not to due to of the In the we report on a new a mutation in CXCR4 that results in a frame shift within the codon for Ser339 in the of new after the properties of S339fs5 compared with CXCR4 and other WHIM syndrome mutants we cell mutant CXCR4. S339fs5 had enhanced agonist-promoted signaling, decreased phosphorylation, decreased β-arrestin binding, decreased endocytosis, and an increased rate of basal degradation compared with CXCR4. Previous studies on a of patients that have a different frame shift in CXCR4 within the codon for Ser339 this mutation was have similar to the S339fs5 mutation that we identified in the is that the after lead to in CXCR4 we that patients that have a frame shift within the Ser339 codon have significantly enhanced signaling, reduced receptor phosphorylation, β-arrestin binding, and endocytosis, and an increased rate of basal degradation that is not by CXCR4 that these patients with a CXCR4 antagonist the high level of signaling and to CXCR4 Previous studies have extensively characterized the in the of CXCR4. CXCR4 is following by CXCL12 with primary being and D. F. S. R. of at the CXCR4 One. Scholar, A. C. F. H. J.L. The and of the G receptor Cell. 2003; Scholar, S. R. O. M. J.L. of CXCR4 is by and results in of CXCR4 2010; Scholar). The primary that of these and for for and and for D. F. S. R. of at the CXCR4 One. Scholar, S. R. O. M. J.L. of CXCR4 is by and results in of CXCR4 2010; Scholar, J. R. J.L. G receptor kinase and protein kinase the C-terminal tail of the chemokine receptor CXCR4 and recruitment of Scholar). of CXCR4 enhanced β-arrestin binding and desensitization S. R. O. M. J.L. of CXCR4 is by and results in of CXCR4 2010; Scholar, J. R. J.L. G receptor kinase and protein kinase the C-terminal tail of the chemokine receptor CXCR4 and recruitment of of C-terminal by the A. C. F. H. J.L. The and of the G receptor Cell. 2003; and endocytosis and of the receptor for degradation A. J.L. of the G-protein-coupled receptor CXCR4 Scholar, A. C. F. H. J.L. The and of the G receptor Cell. 2003; Scholar). of these have been with of of this are mutation of to results in a of agonist-promoted degradation and significant decrease in endocytosis of CXCR4 while mutation results in an in degradation and no effect on endocytosis A. J.L. of the G-protein-coupled receptor CXCR4 Scholar). Interestingly, studies have also shown that the of C-terminal to in the of including and D. F. S. R. of at the CXCR4 One. Scholar, A. J. H. R. M. S. Y. A. K. The for Med. 2019; Scholar). This due to reduced binding of to a of recruitment and reduced of that to endocytosis, and degradation A. J. H. R. M. S. Y. A. K. The for Med. 2019; Scholar). While we have not binding, we a significant in agonist-promoted of in S339fs5 and R334X a reduced of to these Previous studies have also extensively characterized the properties of a other WHIM syndrome mutants. R334X has increased CXCL12-promoted signaling and increased interaction with G protein K. Lagane B. Pablos J.L. Laurent L. Planchenault T. Verola O. Lebbe C. Kerob D. Dupuy A. Hermine O. Nicolas J.-F. Latger-Cannard V. Bensoussan D. Bordigoni P. Baleux F. et al.WHIM syndromes with different genetic anomalies are accounted for by impaired CXCR4 desensitization to CXCL12.Blood. 2005; 105: 2449-2457Google Scholar, 6McDermott D.H. Lopez J. Deng F. Liu Q. Ojode T. Chen H. Ulrick J. Kwatemaa N. Kelly C. Anaya-O'Brien S. Garofalo M. Marquesen M. Hilligoss D. DeCastro R. Malech H.L. et al.AMD3100 is a potent antagonist at CXCR4R334X, a hyperfunctional mutant chemokine receptor and cause of WHIM syndrome.J. Cell. Mol. Med. 2011; 15: 2071-2081Google Scholar, 7Levy E. Reger R. Segerberg F. Lambert M. Leijonhufvud C. Baumer Y. Carlsten M. Childs R. Enhanced bone marrow homing of natural killer cells following mRNA transfection with gain-of-function variant CXCR4R334X.Front. Immunol. 2019; 10: 1262Google a in and β-arrestin2 binding delayed receptor internalization and desensitization P.J. Segarra M. Gasperini P. Gulino A.V. Tosato G. Impaired recruitment of Grk6 and beta-arrestin 2 causes delayed internalization and desensitization of a WHIM syndrome-associated CXCR4 mutant receptor.PLoS One. 2009; 4e8102Google these studies not on receptor reduced agonist-promoted and degradation of R334X. has increased signaling and G protein interaction and decreased β-arrestin2 binding and receptor internalization (8Lagane B. Chow K.Y.C. Balabanian K. Levoye A. Harriague J. Planchenault T. Baleux F. Gunera-Saad N. Arenzana-Seisdedos F. Bachelerie F. CXCR4 dimerization and β-arrestin-mediated signaling account for the enhanced chemotaxis to CXCL12 in WHIM syndrome.Blood. 2008; 112: 34-44Google Scholar, 9Balabanian K. Brotin E. Biajoux V. Bouchet-Delbos L. Lainey E. Fenneteau O. Bonnet D. Fiette L. Emilie D. Bachelerie F. Proper desensitization of CXCR4 is required for lymphocyte development and peripheral compartmentalization in mice.Blood. 2012; 119: 5722-5730Google Scholar, 10Cao Y. Hunter Z.R. Liu X. Xu L. Yang G. Chen J. Patterson C.J. Tsakmaklis N. Kanan S. Rodig S. Castillo J.J. Treon S.P. The WHIM-like CXCR4S338X somatic mutation activates AKT and ERK, and promotes resistance to ibrutinib and other agents used in the treatment of Waldenstrom’s Macroglobulinemia.Leukemia. 2015; 29: 169-176Google Scholar, 11Biajoux V. Natt J. Freitas C. Alouche N. Sacquin A. Hemon P. Gaudin F. Fazilleau N. Espéli M. Balabanian K. Efficient plasma cell differentiation and trafficking require Cxcr4 desensitization.Cell Rep. 2016; 17: 193-205Google Scholar, C. M. J. V. Biajoux V. Gaudin F. S. Y. C. J. Bachelerie F. Espéli M. A. F. et differentiation of cells Cxcr4 Med. similar to R334X. Interestingly, a gain-of-function mutation in CXCR4 was in a by Liu et Q. Chen H. Ojode T. Gao X. Anaya-O'Brien S. Ulrick J. DeCastro R. Kelly C. Malech H.L. Murphy P.M. et al.WHIM syndrome by a amino acid in the of chemokine receptor 2012; Scholar). was shown to in agonist-promoted of C-terminal including and D. F. S. R. of at the CXCR4 One. Scholar). This mutation was characterized by et L. Q. P. Chen G. N. C. The of the is for of Mol. that having an at was in and that mutation to enhanced agonist-promoted signaling and impaired desensitization of CXCR4. While the of reduced was not the mutation results in reduced of C-terminal that are by D. F. S. R. of at the CXCR4 One. Scholar, S. R. O. M. J.L. of CXCR4 is by and results in of CXCR4 2010; Scholar, J. R. J.L. G receptor kinase and protein kinase the C-terminal tail of the chemokine receptor CXCR4 and recruitment of these in an J. K. R.J. J.L. of amino in of the receptor kinase and Scholar). Taken together, studies on a new mutation in CXCR4 that results in WHIM syndrome and to the in the of WHIM mutants including S339fs5 and R334X. cells were from while and were from were from were previously S. R. O. M. J.L. of CXCR4 is by and results in of CXCR4 2010; Scholar). and and were from The CXCR4 was by The is a was to have at there was no associated with the no was at that and in and were at of of was to have a cell of and was to the for for the was had due to recurrent of was to of a bone marrow was Myelokathexis was no was was to have with a The to recurrent of and of was to have a the on a the was to had a of warts, and of which were at at of was to a has is a with a of and is a with warts, and with has been at in had has a is CXCR4 of and has identified the S339fs5 This was by the of and to CXCR4 was previously A. C. F. H. J.L. The and of the G receptor Cell. 2003; and was used to for the WHIM mutations S339fs5 and R334X the following cells were in with and amino in a at cells CXCR4 were previously S. R. O. M. J.L. of CXCR4 is by and results in of CXCR4 2010; while cell S339fs5 and R334X were with the and and in with and were and for were with for to with were with and with and of and at on a for The were by at in an for at protein in cell was the An of total protein was on a to and with the following primary and were extensively with with a with and were The were and an were and a and cells mutant CXCR4 at in were for and with CXCL12 and with and was on the cells were at for and was by at for of cell were by on a to and were by were for at in a of and a of primary at and in were with the at were for with The were for at with a of and a the were with for was the system of was to total and are basal cells CXCR4 were at to in of and at was and cells were with in and were at for in the the was and the was with were with CXCL12 in and the calcium flux was with a used a β-arrestin to the of a β-arrestin2 from the to the plasma GPCR previously P. Lambert to recruitment to and G 2015; Scholar). in a were with the and with of after cells were with of CXCL12 in the of for were with a of and mutant CXCR4 was by previously A. J.L. of the of and of in the that receptor Scholar). cells CXCR4 were with The following the was and cells were for at with in were with and for with in were for with a for and for with were and binding was by to and at for were at in a agonist-promoted internalization of and mutant CXCR4, cells CXCR4 in were with and with CXCL12 for to The was cells were and cell was a and CXCR4 degradation, we a previously A. J.L. of the G-protein-coupled receptor CXCR4 Scholar). cells mutant CXCR4 were in with for at were in the at with CXCL12 for 6 were by of on and at for was by at for and were by and were with an and by were and an primary were a and for total protein the were on a are shown the with by the from from at least a in the of that were are within the and to the This contains The no of with the of this The Lambert for the and and for J. L. B. J. L. and F. D. P. J. L. and F. D. P. G. R. and A. M. K. J. L. B. J. L. and F. D. P. J. L. J. F. D. G. A. M. and J. L. B. J. F. D. G. A. M. and J. L. B. and This was in a from the of and by of J. L. The is the of the and not the of the of

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