The JI
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     
 

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Brauweiler, A.
Right arrow Articles by Cambier, J. C.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Brauweiler, A.
Right arrow Articles by Cambier, J. C.
The Journal of Immunology, 2007, 178: 3353-3357.
Copyright © 2007 by The American Association of Immunologists, Inc.

CUTTING EDGE

Cutting Edge: Acute and Chronic Exposure of Immature B Cells to Antigen Leads to Impaired Homing and SHIP1-Dependent Reduction in Stromal Cell-Derived Factor-1 Responsiveness1

Anne Brauweiler, Kevin Merrell, Stephen B. Gauld and John C. Cambier2

Integrated Department of Immunology, University of Colorado Health Sciences Center and National Jewish Medical and Research Center, Denver, CO 80206


   Abstract
Top
 Abstract
Introduction
 Materials and Methods
 Results and Discussion
 Disclosures
 References
 
An encounter of B cells with cognate self Ags in the periphery can lead to anergy, a condition characterized by altered anatomical localization, shortened life span, and refractility to Ag stimulation. We recently reported that an immature B cell encounter with cognate self-Ag in the bone marrow can also lead to anergy. In this study we show that anergic as well as acutely Ag-stimulated immature B cells are defective in stromal cell-derived factor-1 (SDF-1)-induced calcium mobilization and migration and do not localize to bone marrow following adoptive transfer. This hyporesponsiveness does not involve CXCR4 modulation. However, BCR signal-mediated hyporesponsiveness to SDF-1 is associated with phosphorylation of the 5-inositol phosphatase SHIP1 and requires SHIP1 expression. Therefore, an encounter with cognate Ag may, by preventing SDF-1-induced phosphatidylinositol 3,4,5-triphosphate accumulation, trigger premature emigration of immature B cells from bone marrow.


   Introduction
Top
 Abstract
 Introduction
Materials and Methods
 Results and Discussion
 Disclosures
 References
 
Mature B cells rendered anergic by exposure to self-Ag in the periphery are unable to enter lymphoid follicles (1, 2, 3). This is apparently a consequence of BCR signal modulation of responses to chemokines. It has been suggested that this cross-talk occurs via BCR-mediated by activation of protein kinase C (PKC), which phosphorylates and thereby desensitizes CXCL12 by causing receptor internalization (4).

We recently reported that anergy can be induced at the immature B cell stage in bone marrow (5). B cell development in the bone marrow is dependent on stromal cell-derived factor-1 (SDF-1)3/CXCL12-induced CXCR4 signaling, which promotes cell survival in supportive niches where CXCL12 is produced (6, 7, 8). CXCR4 signals are also required for the retention of immature B cells in the bone marrow (9). Mice reconstituted with CXCR4-deficient fetal liver have significantly reduced numbers of pre-B cells in the bone marrow and abnormally high numbers in the blood. In support of the importance of CXCL12 and CXCR4 in B cell development is the fact that mice deficient in either the ligand or the receptors lack B cells (10, 11).

Based on the described effects of BCR signaling on CXCR4 signaling in mature B cells, it seems likely that an immature B cell encounter with Ag in bone marrow may, by desensitizing responses to CXCL12, inhibit cell development, promote death, and cause premature egress from bone marrow niches. However, studies by King et al. (12) demonstrate that Ag receptor signaling does not lead to significant activation of protein kinase C in immature B cells. Thus, Ag receptor signaling in these cells may have no effect on CXCL12 regulation of development.

In this study we describe experiments that address whether acutely Ag-stimulated and anergic immature B lymphocytes display altered responses to CXCL12. We examined the effect of Ag receptor signaling in immature B cells from Ars/A1 transgenic mice (5). Ars/A1 B cells are specific for arsonate, but cross-reactive with ssDNA. Immature B cells from these animals are anergic as a consequence of Ag recognition in the bone marrow (5, 13). Our results demonstrate that anergic immature B cells are also inhibited in signaling responses, homing, and migration toward SDF-1.

In further studies exploring the molecular mechanisms underlying Ag-induced CXCR4 desensitization, we determined that BCR stimulation does not cause down-modulation of CXCR4 expression. Rather, the activation of inhibitory signaling pathways that mediate the degradation of phosphatidylinositol 3,4,5-triphosphate (PIP3) by the Src homology domain 2-containing 5-inositol phosphatase SHIP1 accounts for decreased SDF-1 sensitivity (14, 15). PIP3 is a necessary component of the signaling cascade required for SDF-1 induced migration (16, 17) and accumulates at the leading edge of migrating cells (18).


   Materials and Methods
Top
 Abstract
 Introduction
 Materials and Methods
Results and Discussion
 Disclosures
 References
 
Reagents and antibodies

Purified F(ab')2 of rabbit anti-mouse IgM (H+L) Abs were purchased from Zymed Laboratories and used for cell stimulation. Other Abs included biotinylated anti-CXCR4 (BD Pharmingen), anti-IgD (clone JA12.5), and anti-phosphotyrosine (clone 4G10) (Upstate) Abs. Purified Fabs of IgM (clone b-7-6) were generated and purified in the laboratory. Polyclonal rabbit anti-SHIP1 was prepared as previously described (19). Other reagents included SDF-1 (R&D Systems), PMA (Sigma-Aldrich), and CFMDA and Indo-AM (Molecular Probes).

Animals and cells

Ars/A1 and {kappa} Ig transgenic mice were from the laboratory of Dr. L. J. Wysocki (University of Colorado School of Medicine, Denver, CO) (5). Ship1–/– mice and control Ship1+/+ littermates were generated as the F1 progeny of Ship1+/– mice on a C57BL/6J background (20). Bone marrow was prepared by flushing the femurs with IMDM and depleting the erythrocytes. Cells were used ex vivo immediately or were first cultured for 6 days at 5 x 105 cells/ml per 10-cm dish with antibiotics, 10% FBS (HyClone), and 50–100 U of IL-7.

Calcium mobilization

For measurements of intracellular free calcium ([Ca2+]i), 106 cells/ml in IMDM were loaded with Indo-AM (Molecular Probes), and stimulated with F(ab')2 anti-IgM Ab or SDF-1 as previously described (21). Mean [Ca2+]i was evaluated over time using a flow cytometer (LSR; BD Biosciences) with appended data acquisition software (FlowJo).

Immunoblotting analysis

Cells were harvested, resuspended in IMDM at 3 x 107/ml, stimulated with 20 µg/ml F(ab')2 anti-IgM for 20 min, and lysed in 1% Nonidet P-40 lysis buffer. Cleared cell lysates (3 x 107 cell equivalents/ml/sample) were immunoprecipitated with 10 µg polyclonal anti-SHIP1 and 10 µl of protein A-Sepharose beads for 2–3 h at 4°C. Washed beads were eluted by boiling in Laemmli sample buffer, separated by 10% SDS-PAGE, and transferred to a polyvinylidene difluoride membrane (Millipore). After blocking, polyvinylidene difluoride membranes were blotted with the indicated Ab and binding was detected using the ECL blotting system (Amersham Biosciences). In some cases, the membranes were stripped to remove the Ab and subjected to sequential blotting with other Abs.

Measurement of immature B cell migration

Quantitative chemotaxis assays were performed as described previously (22). In some cases, cells were prestimulated for 1 h with hen egg lysozyme (HEL) Ag or F(ab')2 of an anti-IgM prior assay of migration. For these studies, one million cells were put into the upper chamber with SDF-1 in the lower chamber. Chemotaxis toward SDF-1 was assessed after 3 h. Cells migrating to the lower chamber were counted for 30 s at 60 µl/min on a FACScan cytometer. One hundred percent migration was obtained by counting cells added directly to the lower chamber. For studies of the migration of immediately ex vivo cells, RBC-depleted bone marrow cells were stained with Cy5-conjugated Fab of anti-IgM (clone b-7-6) and intact anti-IgD-PE to distinguish immature B cells (membrane (m)IgM+mIgD–). For all other experiments cells were cultured for 6 days in IL-7. Immature B cells in these cultures were identified by staining with Fabs of the anti-µ mAb b-7-6. These cultures contained <5% mIgD+ cells.

Cell surface staining

To analyze cell surface expression of CXCR4, propagated immature B cells were stained with biotinylated anti-CXCR4 Ab and FITC-conjugated streptavidin.

Adoptive transfer and homing of immature B cells

Propagated immature MD4 B cells were either left untreated or stimulated with 2 µg/ml HEL overnight. MD4, 3-83µ{delta}, or Ars/A1 cells were subsequently washed and labeled using 2 µM CFMDA (1 h) and injected (107 cells) i.v. into the tail veins of congenic recipients that had been sublethally irradiated (400 rads) 3 days prior. Bone marrow was harvested 0.5 - 6.5 h posttransfer, RBCs were lysed, and CFMDA+ cells were enumerated by flow cytometry.


   Results and Discussion
Top
 Abstract
 Introduction
 Materials and Methods
 Results and Discussion
Disclosures
 References
 
Anergic immature B cells display impaired migration to SDF-1

To determine the effect of anergy on SDF-1 induced chemotaxis of immature B cells, we studied immediately ex vivo anergic bone marrow B cells from the Ars/A1 mouse. As shown in Fig. 1A, the migration of mIgM+mIgD– cells to SDF-1 was reduced at least 80% relative to wild-type C57BL/6J. Nonautoreactive immature B cells from Ars/A1 {kappa}-chain-only transgenic ({kappa}) (5) and 3-83µ{delta} (specific for H-2Kk)) (23) Ig transgenic mice migrated normally.


Figure 1
View larger version (30K):
[in this window]
[in a new window]

  		FIGURE 1. Anergic immature bone marrow B cells do not migrate efficiently to SDF-1. A, The SDF-1-induced chemotaxis of immediately ex vivo immature bone marrow B cells from C57BL/6J, {kappa}-chain transgenic, 3-83µ{delta} transgenic, and anergic (ssDNA binding) Ars/A1 transgenic mice was measured. RBC-depleted bone marrow cells (1 x 106) were placed in the upper chamber of a Transwell apparatus. Three hours later, cells migrating to 75 ng/ml SDF-1 in the lower chamber were harvested and counted by flow cytometry. The panel shows the percentage of input immature (IgM+IgD–) B cells that migrated. B, Acute as well as chronic BCR stimulation blocks SDF-1-induced migration of IL-7-propagated immature B cells. Immature B cells derived from the indicated strains of mice were left untreated or treated for 60 min with 10 ng/ml HEL or 20 µg/ml F(ab')2 of anti-BCR. SDF-1-induced migration of untreated (solid lines) vs anergic or BCR-stimulated cells (dashed lines) was assessed as described above. C, Ligand dose dependence of BCR-mediated inhibition of SDF-1-induced migration. IL-7-propagated immature B cells were stimulated by increasing the concentration of F(ab')2 of anti-IgM or by increasing the concentration of Ag (HEL). The migration toward 100 ng/ml SDF-1 was measured 3 h later. All experiments were performed in triplicate and mean ± SD is shown.

 
To determine the effects of acute Ag receptor signaling on responsiveness to SDF-1, IL-7-propagated B cells were stimulated and migration was analyzed. Provided that sufficient IL-7 was present, >95% of Ig transgenic B cells propagated for 6 days were IgM+ and mIgD– and displayed other markers consistent with the immature phenotype (5). Fig. 1B shows that propagated anergic B cells responded poorly to a range of doses of SDF-1 relative to immature B cells from mice transgenic only for the Ars/A1 {kappa}-chain. To determine whether acute Ag stimulation had the same inhibitory effect, propagated B cells from MD4 anti-HEL transgenic mice (24) were stimulated with HEL for 1 h before exposure to SDF-1. Fig. 2B demonstrates that acute Ag stimulation also blocks SDF-1-induced migration. Finally, propagated immature B cells from an unrelated nonautoreactive transgenic mouse, 3-83µ{delta}, were rendered significantly less responsive to SDF-1 by acute stimulation with F(ab')2 anti-IgM.


Figure 2
View larger version (21K):
[in this window]
[in a new window]

  		FIGURE 2. The homing of adoptively transferred immature B cells to the bone marrow is inhibited by acute BCR stimulation. A, IL-7-propagated immature B cells were either left untreated or stimulated with 2 µg/ml HEL. Cells (1 x 107) were then labeled with CFMDA (Cell Tracker Green) and adoptively transferred into congenic recipient mice. At the indicated time points following transfer, bone marrow was removed and the percentage of CFMDA-labeled cells was determined by flow cytometry. B, Bone marrow localization of immature MD4 cells treated with HEL or left untreated as described above was compared with that of immature B cells derived from Ars/A1 or 3-83µ{delta} transgenic animals. Cells (1 x 107) were labeled with CFMDA and transferred into congenic recipients. Five hours posttransfer the bone marrow was removed and the percentage of CFMDA-labeled cells was determined. Shown is the mean ± SD of 2–4 mice per group.

 
To determine the Ag dose dependence of this effect, immature B cells were treated with increasing concentrations of F(ab')2 anti-IgM or Ag (HEL) (Fig. 1C). Surprisingly, low doses of anti-Ig caused an enhancement of SDF-1-induced migration of 3-83µ{delta} immature B cells. However, further increases in stimulus caused a significant inhibition of B cell migration. In comparison, immature MD4 B cell migration was inhibited by Ag at all concentrations used. These results indicate that acute as well as chronic BCR signaling inhibits subsequent migration of immature B cells toward SDF-1.

Anergic and acutely Ag-stimulated immature B cells display impaired localization in the bone marrow following adoptive transfer

We then used a similar adoptive transfer strategy described by Reif et al. (3) to determine whether BCR signals affect the retention of immature B cells to the bone marrow compartment. IL-7-propagated MD4 cells were either stimulated with HEL or left untreated, labeled with CFMDA (Cell Tracker Green), and transferred into recipient mice. Ag (HEL) stimulation caused a >90% reduction in the number of labeled B cells that could be recovered from the bone marrow of recipient animals (Fig. 2). A time course analysis revealed that most cells enter the bone marrow within 5 h of transfer; therefore, the remainder of adoptive transfer recipients were examined at this time point. As shown in Fig. 2B, fewer anergic immature Ars/A1 B cells homed than did unstimulated 3-83µ{delta} or MD4 B cells. Thus, both chronic and acute Ag stimulation inhibits immature B cell migration toward SDF-1 and retention in the bone marrow compartment.

Anergic immature B cells display impaired SDF-1 signaling despite normal expression of CXCR4

To begin to address the mechanisms by which BCR signals affect CXCR4 signaling in immature B cells, we tested whether BCR signals modulate CXCR4 expression. We compared levels of CXCR4 on IL-7-propagated B cells from autoreactive Ars/A1 cells and {kappa} transgenic controls. We also examined CXCR4 levels on immature MD4 and 3-83 cells following acute BCR stimulation. In all cases, Ag receptor stimulation had no detectable effect on surface CXCR4 expression (Fig. 3A). We conclude that, consistent with the findings of King et al. (12), BCR stimulation does not affect SDF-1-induced cell migration by down-modulation of CXCR4.


Figure 3
View larger version (32K):
[in this window]
[in a new window]

  		FIGURE 3. Anergic immature B cells express normal levels of CXCR4 but do not mobilize calcium in response to SDF-1. A, IL-7-cultured immature B cells expressing the indicated transgenic BCR were left untreated or treated for 2 h with 2 µg/ml HEL, 30 µg/ml F(ab')2 of anti-IgM, or 100 nM PMA. Cells were then stained with anti-CXCR4 mAb and analyzed by flow cytometry. The far right panel indicates down-modulation of CXCR4 induced by 100 nM PMA. B, Ars/A1 or {kappa} transgenic IL-7 cultured immature B cells were loaded with Indo-AM and calcium was monitored by flow cytometry. At the indicated point, cells were stimulated with either 10 µg/ml F(ab')2 anti-IgM to aggregate the BCR or 20 ng/ml SDF-1. Results shown are representative of three experiments.

 
We then examined whether BCR stimulation affects the ability of chemokine receptors to transmit signals leading to calcium mobilization. As shown in Fig. 3B, anergic immature Ars/A1 B cells displayed significantly reduced calcium mobilization, not only in response to BCR cross-linking but also in response to stimulation with SDF-1. In comparison, nonautoreactive {kappa} transgenic immature B cells responded robustly to both stimuli. Thus, immature anergic B cells are hyporesponsive to SDF-1 despite normal CXCR4 expression.

BCR-mediated inhibition of SDF-1-induced migration requires SHIP1

The results discussed above indicate that BCR signals block the CXCR4 signaling cascade upstream from calcium mobilization. Because SDF-1 induced calcium mobilization and directed migration require continuous PIP3 generation (25), and Ag surrogate stimulates phosphorylation and activation of the Src homology domain 2-containing inositol 5-phosphatase SHIP1 (15) (Fig. 4A), we explored the role of SHIP1 in this effect.


Figure 4
View larger version (23K):
[in this window]
[in a new window]

  		FIGURE 4. BCR-mediated inhibition of SDF-1 induced migration requires SHIP1. A, IL-7 cultured Ars/A1 or 3-83µ{delta} transgenic immature B cells were assessed for SHIP1 phosphorylation before and after a 20-min stimulation with 12 µg/ml F(ab')2 anti-IgM. Cleared cell lysates were immunoprecipitated with anti-SHIP1 Ab. Western blotting was performed with anti-phosphotyrosine (clone 4G10) Ab. Blots were stripped and reprobed with anti-SHIP1. B, Wild-type or SHIP1-deficient immature B cells were left untreated or pretreated with 12 µg/ml F(ab')2 of anti-IgM for 60 min before migration toward 100 ng/ml SDF-1. Shown is the mean percentage of IgM+IgD– immature B cells responding ± SD. Experiments were performed in triplicate.

 
We compared SDF-1 induced migration by wild-type and SHIP1-deficient immature B cells (20). The response to SDF-1 was enhanced in Ship1–/– cells, suggesting constitutive SHIP1 regulation of CXCR4 signaling. Most importantly, however, BCR signaling did not block SDF-1-induced migration of Ship1–/– B cells. Thus, BCR-mediated inhibition of SDF-1-induced migration requires the SHIP1 signaling circuit.

An encounter of newly emerged immature B cells with cognate Ag in the bone marrow can lead to anergy. The results presented in this study indicate that BCR signals that induce and maintain anergy in immature B cells also disrupt CXCR4 signaling via the activation of SHIP1. BCR signals do not inhibit SDF-1-induced cell migration in SHIP1-deficient B cells. This is consistent with the fact that chemokine receptor-mediated signaling responses are dependent on PIP3 (17).

SHIP1 has been implicated previously in the regulation of cell migration. The initial characterization of SHIP1-deficient animals revealed massive spontaneous leukocyte infiltration into a host of organs (20). Further studies have demonstrated that splenocytes from SHIP1-deficient animals display enhanced chemokine-induced cell migration (22). Although SHIP1 appears to inhibit migration, no clear interaction between SHIP1 and chemokine receptors has ever been reported. Our findings indicate, however, that SHIP1 activated by Ag stimulation functions in trans to modulate responses to CXCL12.

Recent studies have demonstrated that B cell development depends on supportive bone marrow stromal cell niches that provide SDF-1 and IL-7 (8). Reduced CXCR4 signaling may result in premature emigration of cells to anatomical niches that lack important trophic factors needed for development. BCR-mediated inhibition of CXCR4 signals may therefore trigger premature egress of immature B cells from protective niches in the bone marrow.


   Acknowledgments
 
We thank Bill Townend and Shirley Sobus for assistance with flow cytometry.


   Disclosures
Top
 Abstract
 Introduction
 Materials and Methods
 Results and Discussion
 Disclosures
References
 
The authors have no financial conflict of interest.


   Footnotes
 
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

1 This work was supported by National Institutes of Health/National Institute of Diabetes and Digestive and Kidney Diseases Grant DK047121-11. J.C.C. is an Ida and Cecil Green endowed Professor of Cell Biology. Back

2 Address correspondence and reprint requests to Dr. John C. Cambier, Department of Immunology, National Jewish Medical and Research Center, 1400 Jackson Street, Denver CO 80206. E-mail address: cambierj{at}njc.org Back

3 Abbreviations used in this paper: SDF-1, stromal cell-derived factor-1; HEL, hen egg lysozyme; mIg, membrane Ig; PIP3, phosphatidylinositol 3,4,5-trisphosphate; Back

Received for publication August 4, 2006. Accepted for publication January 10, 2007.


   References
Top
 Abstract
 Introduction
 Materials and Methods
 Results and Discussion
 Disclosures
 References
 

  1. Cyster, J. G., S. B. Hartley, C. C. Goodnow. 1994. Competition for follicular niches excludes self-reactive cells from the recirculating B-cell repertoire. Nature 371: 389-395. [Medline]
  2. Bleul, C. C., J. L. Schultze, T. A. Springer. 1998. B lymphocyte chemotaxis regulated in association with microanatomic localization, differentiation state, and B cell receptor engagement. J. Exp. Med. 187: 753-762. [Abstract/Free Full Text]
  3. Reif, K., E. H. Ekland, L. Ohl, H. Nakano, M. Lipp, R. Forster, J. G. Cyster. 2002. Balanced responsiveness to chemoattractants from adjacent zones determines B-cell position. Nature 416: 94-99. [Medline]
  4. Guinamard, R., N. Signoret, M. Ishiai, M. Marsh, T. Kurosaki, J. V. Ravetch. 1999. B cell antigen receptor engagement inhibits stromal cell-derived factor (SDF)-1{alpha} chemotaxis and promotes protein kinase C (PKC)-induced internalization of CXCR4. J. Exp. Med. 189: 1461-1466. [Abstract/Free Full Text]
  5. Benschop, R. J., K. Aviszus, X. Zhang, T. Manser, J. C. Cambier, L. J. Wysocki. 2001. Activation and anergy in bone marrow B cells of a novel immunoglobulin transgenic mouse that is both hapten specific and autoreactive. Immunity 14: 33-43. [Medline]
  6. Bleul, C. C., M. Farzan, H. Choe, C. Parolin, I. Clark-Lewis, J. Sodroski, T. A. Springer. 1996. The lymphocyte chemoattractant SDF-1 is a ligand for LESTR/fusin and blocks HIV-1 entry. Nature 382: 829-833. [Medline]
  7. Egawa, T., K. Kawabata, H. Kawamoto, K. Amada, R. Okamoto, N. Fujii, T. Kishimoto, Y. Katsura, T. Nagasawa. 2001. The earliest stages of B cell development require a chemokine stromal cell-derived factor/pre-B cell growth-stimulating factor. Immunity 15: 323-334. [Medline]
  8. Tokoyoda, K., T. Egawa, T. Sugiyama, B. I. Choi, T. Nagasawa. 2004. Cellular niches controlling B lymphocyte behavior within bone marrow during development. Immunity 20: 707-718. [Medline]
  9. Ma, Q., D. Jones, T. A. Springer. 1999. The chemokine receptor CXCR4 is required for the retention of B lineage and granulocytic precursors within the bone marrow microenvironment. Immunity 10: 463-471. [Medline]
  10. Nagasawa, T., S. Hirota, K. Tachibana, N. Takakura, S. Nishikawa, Y. Kitamura, N. Yoshida, H. Kikutani, T. Kishimoto. 1996. Defects of B-cell lymphopoiesis and bone-marrow myelopoiesis in mice lacking the CXC chemokine PBSF/SDF-1. Nature 382: 635-638. [Medline]
  11. Zou, Y. R., A. H. Kottmann, M. Kuroda, I. Taniuchi, D. R. Littman. 1998. Function of the chemokine receptor CXCR4 in haematopoiesis and in cerebellar development. Nature 393: 595-599. [Medline]
  12. King, L. B., A. Norvell, J. G. Monroe. 1999. Antigen receptor-induced signal transduction imbalances associated with the negative selection of immature B cells. J. Immunol. 162: 2655-2662. [Abstract/Free Full Text]
  13. Healy, J. I., R. E. Dolmetsch, L. A. Timmerman, J. G. Cyster, M. L. Thomas, G. R. Crabtree, R. S. Lewis, C. C. Goodnow. 1997. Different nuclear signals are activated by the B cell receptor during positive versus negative signaling. Immunity 6: 419-428. [Medline]
  14. Brauweiler, A., I. Tamir, J. Dal Porto, R. J. Benschop, C. D. Helgason, R. K. Humphries, J. H. Freed, J. C. Cambier. 2000. Differential regulation of B cell development, activation, and death by the src homology 2 domain-containing 5' inositol phosphatase (SHIP). J. Exp. Med. 191: 1545-1554. [Abstract/Free Full Text]
  15. Damen, J. E., L. Liu, P. Rosten, R. K. Humphries, A. B. Jefferson, P. W. Majerus, G. Krystal. 1996. The 145-kDa protein induced to associate with Shc by multiple cytokines is an inositol tetraphosphate and phosphatidylinositol 3,4,5-triphosphate 5-phosphatase. Proc. Natl. Acad. Sci. USA 93: 1689-1693. [Abstract/Free Full Text]
  16. Ganju, R. K., S. A. Brubaker, J. Meyer, P. Dutt, Y. Yang, S. Qin, W. Newman, J. E. Groopman. 1998. The {alpha}-chemokine, stromal cell-derived factor-1{alpha}, binds to the transmembrane G-protein-coupled CXCR-4 receptor and activates multiple signal transduction pathways. J. Biol. Chem. 273: 23169-23175. [Abstract/Free Full Text]
  17. Reif, K., K. Okkenhaug, T. Sasaki, J. M. Penninger, B. Vanhaesebroeck, J. G. Cyster. 2004. Cutting edge: differential roles for phosphoinositide 3-kinases, p110{gamma} and p110{delta}, in lymphocyte chemotaxis and homing. J. Immunol. 173: 2236-2240. [Abstract/Free Full Text]
  18. Stephens, L., C. Ellson, P. Hawkins. 2002. Roles of PI3Ks in leukocyte chemotaxis and phagocytosis. Curr. Opin. Cell Biol. 14: 203-213. [Medline]
  19. Nakamura, K., A. Brauweiler, J. C. Cambier. 2000. Effects of Src homology domain 2 (SH2)-containing inositol phosphatase (SHIP), SH2-containing phosphotyrosine phosphatase (SHP)-1, and SHP-2 SH2 decoy proteins on Fc {gamma} RIIB1-effector interactions and inhibitory functions. J. Immunol. 164: 631-638. [Abstract/Free Full Text]
  20. Helgason, C. D., J. E. Damen, P. Rosten, R. Grewal, P. Sorensen, S. M. Chappel, A. Borowski, F. Jirik, G. Krystal, R. K. Humphries. 1998. Targeted disruption of SHIP leads to hemopoietic perturbations, lung pathology, and a shortened life span. Genes Dev. 12: 1610-1620. [Abstract/Free Full Text]
  21. Buhl, A. M., C. M. Pleiman, R. C. Rickert, J. C. Cambier. 1997. Qualitative regulation of B cell antigen receptor signaling by CD19: selective requirement for PI3-kinase activation, inositol-1,4,5-trisphosphate production and Ca2+ mobilization. J. Exp. Med. 186: 1897-1910. [Abstract/Free Full Text]
  22. Kim, C. H., G. Hangoc, S. Cooper, C. D. Helgason, S. Yew, R. K. Humphries, G. Krystal, H. E. Broxmeyer. 1999. Altered responsiveness to chemokines due to targeted disruption of SHIP. J. Clin. Invest. 104: 1751-1759. [Medline]
  23. Nemazee, D. A., K. Burki. 1989. Clonal deletion of B lymphocytes in a transgenic mouse bearing anti-MHC class I antibody genes. Nature 337: 562-566. [Medline]
  24. Goodnow, C. C., J. Crosbie, S. Adelstein, T. B. Lavoie, S. J. Smith-Gill, R. A. Brink, H. Pritchard-Briscoe, J. S. Wotherspoon, R. H. Loblay, K. Raphael, et al 1988. Altered immunoglobulin expression and functional silencing of self-reactive B lymphocytes in transgenic mice. Nature 334: 676-682. [Medline]
  25. Servant, G., O. D. Weiner, P. Herzmark, T. Balla, J. W. Sedat, H. R. Bourne. 2000. Polarization of chemoattractant receptor signaling during neutrophil chemotaxis. Science 287: 1037-1040. [Abstract/Free Full Text]




This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Brauweiler, A.
Right arrow Articles by Cambier, J. C.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Brauweiler, A.
Right arrow Articles by Cambier, J. C.

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS