101
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Turner M, Schweighoffer E, Colucci F, Di Santo JP, Tybulewicz VL. Tyrosine kinase SYK: essential functions for immunoreceptor signalling. IMMUNOLOGY TODAY 2000; 21:148-54. [PMID: 10689303 DOI: 10.1016/s0167-5699(99)01574-1] [Citation(s) in RCA: 295] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The tyrosine kinase SYK plays critical roles in signalling through immune receptors. Gene-targeting studies have identified the cell types that require SYK for development and function, and the receptors that use SYK as well as their downstream signalling effectors. There is also evidence of a role for SYK in non-immune cells and in the maintenance of vascular integrity.
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Affiliation(s)
- M Turner
- Molecular Immunology Programme, The Babraham Institute, Cambridge, UK CB2 4AT.
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102
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Cornall RJ, Cheng AM, Pawson T, Goodnow CC. Role of Syk in B-cell development and antigen-receptor signaling. Proc Natl Acad Sci U S A 2000; 97:1713-8. [PMID: 10677523 PMCID: PMC26501 DOI: 10.1073/pnas.97.4.1713] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/1999] [Indexed: 12/13/2022] Open
Abstract
Antigen receptors (BCRs) on developing B lymphocytes play two opposing roles-promoting survival of cells that may later bind a foreign antigen and inhibiting survival of cells that bind too strongly to self-antigens. It is not known how these opposing outcomes are signaled by BCRs on immature B cells. Here we analyze the effect of a null mutation in the Syk tyrosine kinase on maturing B cells displaying a transgene-encoded BCR that binds hen egg lysozyme (HEL). In the absence of HEL antigen, HEL-specific BCRs are expressed normally on the surface of Syk-deficient immature B-lineage cells, but this fails to promote maturation beyond the earliest stages of B-lineage commitment. Binding of HEL antigen, nevertheless, triggers phosphorylation of CD79alpha/beta BCR subunits and modulation of receptors from the surface in Syk-deficient cells, but it cannot induce an intracellular calcium response. Continuous binding of low- or high-avidity forms of HEL, expressed as self-antigens, fails to restore the signal needed for maturation. Compared with the effects in the same system of null mutations in other BCR signaling elements, such as CD45 and Lyn kinase, these results indicate that Syk is essential for transmitting a signal that initiates the program of B-lymphocyte maturation.
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Affiliation(s)
- R J Cornall
- Howard Hughes Medical Institute, Stanford University, CA 94305, USA
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103
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Martin F, Kearney JF. Positive selection from newly formed to marginal zone B cells depends on the rate of clonal production, CD19, and btk. Immunity 2000; 12:39-49. [PMID: 10661404 DOI: 10.1016/s1074-7613(00)80157-0] [Citation(s) in RCA: 284] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Using immunoglobulin heavy chain transgenic mice, we show that B cell clones reaching the long-lived pool are heterogeneous: some are enriched in the CD21(high) compartment (mostly marginal zone [MZ]), others reside primarily in the follicles (FO). Altering the composition of the B cell receptor through N region additions decreases the rate of clonal production and the MZ enrichment. This process can be recapitulated by purified CD21(low) B cells and is due to a preferential clonal survival that requires a functional btk tyrosine kinase. We also show that generation of the MZ population is dependent on CD19. These findings suggest that the MZ B cell repertoire is positively selected and have functional implications for antigenic responses effected by B cells from this microenvironment.
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MESH Headings
- Agammaglobulinaemia Tyrosine Kinase
- Animals
- Antigens, CD19/genetics
- Antigens, CD19/metabolism
- Antigens, CD19/physiology
- B-Lymphocytes/cytology
- B-Lymphocytes/immunology
- Bone Marrow Cells/cytology
- Bone Marrow Cells/immunology
- Cell Differentiation
- Cells, Cultured
- Clone Cells
- Hematopoietic Stem Cells/cytology
- Hematopoietic Stem Cells/immunology
- Immunoglobulin Idiotypes
- Immunophenotyping
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Inbred CBA
- Mice, Transgenic
- Protein-Tyrosine Kinases/metabolism
- Protein-Tyrosine Kinases/physiology
- Receptors, Antigen, B-Cell/metabolism
- Receptors, Complement 3d/metabolism
- Receptors, IgE/metabolism
- Spleen/cytology
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Affiliation(s)
- F Martin
- Department of Microbiology, University of Alabama at Birmingham, 35294-3300, USA
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104
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Pappu R, Cheng AM, Li B, Gong Q, Chiu C, Griffin N, White M, Sleckman BP, Chan AC. Requirement for B cell linker protein (BLNK) in B cell development. Science 1999; 286:1949-54. [PMID: 10583957 DOI: 10.1126/science.286.5446.1949] [Citation(s) in RCA: 231] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Linker proteins function as molecular scaffolds to localize enzymes with substrates. In B cells, B cell linker protein (BLNK) links the B cell receptor (BCR)-activated Syk kinase to the phosphoinositide and mitogen-activated kinase pathways. To examine the in vivo role of BLNK, mice deficient in BLNK were generated. B cell development in BLNK-/- mice was blocked at the transition from B220+CD43+ progenitor B to B220+CD43- precursor B cells. Only a small percentage of immunoglobulin M++ (IgM++), but not mature IgMloIgDhi, B cells were detected in the periphery. Hence, BLNK is an essential component of BCR signaling pathways and is required to promote B cell development.
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Affiliation(s)
- R Pappu
- Center for Immunology, Division of Rheumatology, Department of Medicine, Howard Hughes Medical Institute, Washington University School of Medicine, St. Louis, MO 63110, USA
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105
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Abstract
Blimp-1 (B lymphocyte-induced maturation protein 1) is strongly expressed during the late stages of B cell differentiation to immunoglobulin-secreting plasma cells. Overexpression of Blimp-1 in B lymphoma cells has been reported to induce either growth arrest and cell death or Ig secretion and terminal differentiation, depending on the developmental stage of the recipient lymphomas. By using a retroviral expression system we show that Blimp-1-transduced immature WEHI 231 murine B lymphoma cells produce J chain, increased levels of the secretory form of micro heavy chain mRNA and secrete IgM for a short period of time. Concomitantly, they exhibit altered ratios of c-myc/mad4 mRNA levels, a reduction in the expression of the anti-apoptotic bcl-2 family member A1 and a distinct growth disadvantage, followed by cell death. Reintroduction of A1 by retroviral transduction greatly extends the life span of Blimp-1-expressing WEHI 231 cells which continue to secrete IgM. These data suggest that levels of A1 may determine the checkpoint between death and survival of Blimp-1-expressing B cells at different stages of differentiation.
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Affiliation(s)
- M Knödel
- Institute for Virology and Immunobiology, University of Würzburg, Würzburg, Germany
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106
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Colucci F, Turner M, Schweighoffer E, Guy-Grand D, Di Bartolo V, Salcedo M, Tybulewicz VLJ, Di Santo JP. Redundant Role of the Syk Protein Tyrosine Kinase in Mouse NK Cell Differentiation. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.163.4.1769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Abstract
Syk and ZAP-70 subserve nonredundant functions in B and T lymphopoiesis. In the absence of Syk, B cell development is blocked, while T cell development is arrested in the absence of ZAP-70. The receptors and the signaling molecules required for differentiation of NK cells are poorly characterized. Here we investigate the role of the Syk protein tyrosine kinase in NK cell differentiation. Hemopoietic chimeras were generated by reconstituting alymphoid (B−, T−, NK−) recombinase-activating gene-2 × common cytokine receptor γ-chain double-mutant mice with Syk−/− fetal liver cells. The phenotypically mature Syk−/− NK cells that developed in this context were fully competent in natural cytotoxicity and in calibrating functional inhibitory receptors for MHC molecules. Syk-deficient NK cells demonstrated reduced levels of Ab-dependent cellular cytotoxicity. Nevertheless, Syk−/− NK cells could signal through NK1.1 and 2B4 activating receptors and expressed ZAP-70 protein. We conclude that the Syk protein tyrosine kinase is not essential for murine NK cell development, and that compensatory signaling pathways (including those mediated through ZAP-70) may sustain most NK cell functions in the absence of Syk.
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Affiliation(s)
- Francesco Colucci
- *Institut National de la Santé et de la Recherche Médicale, Unit 429, Hôpital Necker-Enfants Malades, Paris, France
- 2 Current address: Babraham Institute, Babraham, Cambridge, U.K
| | - Martin Turner
- †National Institute for Medical Research, The Ridgeway, Mill Hill, London, United Kingdom; and
- 2 Current address: Babraham Institute, Babraham, Cambridge, U.K
| | - Edina Schweighoffer
- †National Institute for Medical Research, The Ridgeway, Mill Hill, London, United Kingdom; and
- 2 Current address: Babraham Institute, Babraham, Cambridge, U.K
| | - Delphine Guy-Grand
- *Institut National de la Santé et de la Recherche Médicale, Unit 429, Hôpital Necker-Enfants Malades, Paris, France
- 2 Current address: Babraham Institute, Babraham, Cambridge, U.K
| | - Vincenzo Di Bartolo
- ‡Institute Pasteur, Paris, France
- 2 Current address: Babraham Institute, Babraham, Cambridge, U.K
| | - Margarita Salcedo
- ‡Institute Pasteur, Paris, France
- 2 Current address: Babraham Institute, Babraham, Cambridge, U.K
| | - Victor L. J. Tybulewicz
- †National Institute for Medical Research, The Ridgeway, Mill Hill, London, United Kingdom; and
- 2 Current address: Babraham Institute, Babraham, Cambridge, U.K
| | - James P. Di Santo
- *Institut National de la Santé et de la Recherche Médicale, Unit 429, Hôpital Necker-Enfants Malades, Paris, France
- 2 Current address: Babraham Institute, Babraham, Cambridge, U.K
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107
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Craxton A, Otipoby KL, Jiang A, Clark EA. Signal transduction pathways that regulate the fate of B lymphocytes. Adv Immunol 1999; 73:79-152. [PMID: 10399006 DOI: 10.1016/s0065-2776(08)60786-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- A Craxton
- Department of Microbiology, University of Washington, Seattle 98195, USA
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108
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Hirano S, Kanno S. Syk and paxillin are differentially phosphorylated following adhesion to the plastic substrate in rat alveolar macrophages. Immunology 1999; 97:414-9. [PMID: 10447762 PMCID: PMC2326867 DOI: 10.1046/j.1365-2567.1999.00777.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Adhesion is associated with tyrosine phosphorylation in many types of cells. Although macrophages are known to adhere and phagocytose foreign particles, the signal transduction pathway of macrophages in response to adhesion to the foreign substrate has not been fully investigated. In the present study we investigated tyrosine-phosphorylated proteins and phosphorylation of paxillin in alveolar macrophages (AMs) following adhesion to a plastic substrate. Adhesion to a plastic dish resulted in tyrosine phosphorylation of a 68 000 MW protein, which was shown, by immunoprecipitation and immunoblotting in the present study, to be a rat Syk kinase. Treatment with erbstatin reduced both tyrosine phosphorylation of Syk and adherence of AMs, while treatment with cytochalasin B inhibited spreading of AMs but did not inhibit tyrosine phosphorylation of Syk. These results suggest that tyrosine phosphorylation of Syk plays an important role in adhesion of AMs to the plastic substrate, but not in AM spreading. Paxillin is known to be tyrosine phosphorylated following adhesion to the extracellular matrix in many types of cells. However, paxillin appeared to be serine/threonine phosphorylated rather than tyrosine phosphorylated following adhesion of AMs to the plastic substrate. Treatment with A23187 (a calcium ionophore), but not phorbol 12-myristate 13-acetate (PMA; a protein kinase C stimulator), induced tyrosine phosphorylation of Syk in non-adherent AMs. Treatment with either A23187 or PMA caused electromobility changes of paxillin that were mainly a result of serine/threonine phosphorylation. These results suggest that adhesion to the plastic substrate leads to two differently regulated events in AMs: tyrosine phosphorylation of Syk and serine/threonine phosphorylation of paxillin, both of which are probably mediated by an increase in intracellular calcium.
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Affiliation(s)
- S Hirano
- Regional Environment Division, National Institute for Environmental Studies, Tsukuba, Ibaraki, Japan
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109
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Loder F, Mutschler B, Ray RJ, Paige CJ, Sideras P, Torres R, Lamers MC, Carsetti R. B cell development in the spleen takes place in discrete steps and is determined by the quality of B cell receptor-derived signals. J Exp Med 1999; 190:75-89. [PMID: 10429672 PMCID: PMC2195560 DOI: 10.1084/jem.190.1.75] [Citation(s) in RCA: 636] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Only mature B lymphocytes can enter the lymphoid follicles of spleen and lymph nodes and thus efficiently participate in the immune response. Mature, long-lived B lymphocytes derive from short-lived precursors generated in the bone marrow. We show that selection into the mature pool is an active process and takes place in the spleen. Two populations of splenic B cells were identified as precursors for mature B cells. Transitional B cells of type 1 (T1) are recent immigrants from the bone marrow. They develop into the transitional B cells of type 2 (T2), which are cycling and found exclusively in the primary follicles of the spleen. Mature B cells can be generated from T1 or T2 B cells. Mice with genetic deletions of elements participating in the B cell receptor signaling cascade display developmental arrest at the T1 or T2 stage. The analysis of these defects showed that the development of T2 and mature B cells from T1 precursors requires defined qualitative and quantitative signals derived from the B cell receptor and that the induction of longevity and maturation requires different signals.
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Affiliation(s)
- F Loder
- Department of Molecular Immunology, University of Freiburg, Germany
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110
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Abstract
In B lymphocytes, a signaling complex that contributes to cell fate decisions is the B cell antigen receptor (BCR). Data from knockout experiments in cell lines and mice have revealed distinct functions for the intracellular protein tyrosine kinases (Lyn, Syk, Btk) in BCR signaling and B cell development. Combinations of intracellular signaling pathways downstream of these PTKs determine the quality and quantity of BCR signaling. For example, concerted actions of the PLC-gamma 2 and PI3-K pathways are required for proper calcium responses. Similarly, the regulation of ERK and JNK responses involves both PLC-gamma 2 and GTPases pathways. Since the immune response in vivo is regulated by alteration of these signaling outcomes, achieving a precise understanding of intracellular molecular events leading to B lymphocyte proliferation, deletion, anergy, receptor editing, and survival still remains a challenge for the future.
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Affiliation(s)
- T Kurosaki
- Department of Molecular Genetics, Kansai Medical University, Moriguchi, Japan.
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111
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Maas A, Dingjan GM, Grosveld F, Hendriks RW. Early Arrest in B Cell Development in Transgenic Mice That Express the E41K Bruton’s Tyrosine Kinase Mutant Under the Control of the CD19 Promoter Region. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.162.11.6526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Bruton’s tyrosine kinase (Btk) is a nonreceptor protein kinase that is defective in X-linked agammaglobulinemia in humans and in X-linked immunodeficiency in mice. To study the effect of Btk activation in early B cell development in vivo, we have created transgenic mouse strains expressing Btk under the control of the human CD19 promoter region. The transgenic expression of wild-type human Btk corrected all X-linked immunodeficiency features in mice carrying a targeted disruption of the Btk gene. In contrast, expression of an activated form of Btk, the E41K mutant, resulted in an almost complete arrest of B cell development in the immature IgM+IgD− B cell stage in the bone marrow, irrespective of the presence of the endogenous intact Btk gene. Immature B cells were arrested at the progression from IgMlow into IgMhigh cells, which reflects the first immune tolerance checkpoint at which autoreactive B cells become susceptible to apoptosis. As the constitutive activation of Btk is likely to mimic B cell receptor occupancy by autoantigens in the bone marrow, our findings are consistent with a role for Btk as a mediator of B cell receptor-induced apoptotic signals in the immature B cell stage. Whereas the peripheral mature B cell pool was reduced to <1% of the normal size, significant numbers of IgM-secreting plasma cells were present in the spleen. Serum IgM levels were substantial and increased with age, but specific Ab responses in vivo were lacking. We conclude that the residual peripheral B cells were efficiently driven into IgM+ plasma cell differentiation, apparently without functional selection.
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Affiliation(s)
| | - Gemma M. Dingjan
- *Cell Biology and Genetics and
- †Immunology, Faculty of Medicine, Erasmus University, Rotterdam, The Netherlands
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112
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Affiliation(s)
- S Pillai
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston 02129, USA.
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113
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Cariappa A, Kim TJ, Pillai S. Accelerated Emigration of B Lymphocytes in the Xid Mouse. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.162.8.4417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
The B cell receptor is required for the emigration of newly generated B lymphocytes and for their maintenance in the periphery. A specific maintenance defect was noted in fraction I (IgDhighIgMlow) B cells in Xid mice (which harbor a mutation in Btk). Although Bcl-2 levels in fractions I and II (IgDhighIgMhigh) are equivalent in normal and Xid B cells, a novel peak of Bcl-2low fraction III (IgDlowIgMhigh) B cells was noted in the Xid mouse. Since this B cell population resembled bone marrow immature B cells, we examined the emigration of newly formed B cells in normal and Xid mice. These studies revealed the accelerated emigration of newly formed Xid B cells. We conclude that distinct Btk-independent and Btk-dependent signals mediate emigration and maintenance events during peripheral B cell maturation.
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Affiliation(s)
- Annaiah Cariappa
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA 02129
| | - Tae Jin Kim
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA 02129
| | - Shiv Pillai
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA 02129
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114
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Benschop RJ, Cambier JC. B cell development: signal transduction by antigen receptors and their surrogates. Curr Opin Immunol 1999; 11:143-51. [PMID: 10322153 DOI: 10.1016/s0952-7915(99)80025-9] [Citation(s) in RCA: 150] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Constitutive signal transduction by B cell antigen-receptors and/or their surrogates appears to be critical for progression through multiple developmental checkpoints and for survival of mature B cells in the periphery. Antigen-induced signaling via the B cell receptor can compensate for defects in constitutive signaling and initiates receptor editing, apoptosis and anergy in normal mice - purging the repertoire of autoreactive cells. Thus development and survival of mature B cells seem to require continuous receptor signaling of a defined amplitude.
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Affiliation(s)
- R J Benschop
- Division of Basic Sciences, Department of Pediatrics, National Jewish Medical and Research Center, 1400 Jackson Street, Denver, CO 80206, USA
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115
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García de Vinuesa C, O'Leary P, Sze DM, Toellner KM, MacLennan IC. T-independent type 2 antigens induce B cell proliferation in multiple splenic sites, but exponential growth is confined to extrafollicular foci. Eur J Immunol 1999; 29:1314-23. [PMID: 10229099 DOI: 10.1002/(sici)1521-4141(199904)29:04<1314::aid-immu1314>3.0.co;2-4] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
During the primary splenic response to the T-independent type 2 (TI-2) antigen (4-hydroxy-3-nitrophenyl) acetyl (NP)-Ficoll, small numbers of antigen-specific B cells have entered S phase of the cell cycle 24 h after intraperitoneal immunization. These are distributed in all splenic compartments (T zones, marginal zones, follicles, and red pulp), indicating early proliferation induced by NP-Ficoll does not require accessory signals delivered in a particular splenic microenvironment. Subsequently B blasts accumulate selectively in the outer T zone areas, but exponential growth leading to plasma cell production occurs only in extrafollicular foci. This growth peaks after 5 days, but 20% of peak numbers of antibody-containing cells are still present 3 months after immunization and 9% of these cells are proliferating. It is unclear if these late plasmablasts are sustained by self-renewal or continued recruitment of virgin cells into the response. Unlike TD and TI-1 responses NP-specific memory cells do not accumulate in the splenic marginal zones. The level of Cgamma3 switch transcripts increases during the first 24 h of the response, but does not increase further during exponential plasmablast growth.
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Affiliation(s)
- C García de Vinuesa
- Division of Immunity and Infection, University of Birmingham Medical School, GB
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116
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Dingjan GM, Maas A, Nawijn MC, Smit L, Voerman JS, Grosveld F, Hendriks RW. Severe B cell deficiency and disrupted splenic architecture in transgenic mice expressing the E41K mutated form of Bruton's tyrosine kinase. EMBO J 1998; 17:5309-20. [PMID: 9736610 PMCID: PMC1170858 DOI: 10.1093/emboj/17.18.5309] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
To identify B-cell signaling pathways activated by Bruton's tyrosine kinase (Btk) in vivo, we generated transgenic mice in which Btk expression is driven by the MHC class II Ea gene locus control region. Btk overexpression did not have significant adverse effects on B cell function, and essentially corrected the X-linked immunodeficiency (xid) phenotype in Btk- mice. In contrast, expression of a constitutively activated form of Btk carrying the E41K gain-of-function mutation resulted in a B cell defect that was more severe than xid. The mice showed a marked reduction of the B cell compartment in spleen, lymph nodes, peripheral blood and peritoneal cavity. The levels in the serum of most immunoglobulin subclasses decreased with age, and B cell responses to both T cell-independent type II and T cell-dependent antigens were essentially absent. Expression of the E41K Btk mutant enhanced blast formation of splenic B cells in vitro in response to anti-IgM stimulation. Furthermore, the mice manifested a disorganization of B cell areas and marginal zones in the spleen. Our findings demonstrate that expression of constitutively activated Btk blocks the development of follicular recirculating B cells.
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Affiliation(s)
- G M Dingjan
- Department of Cell Biology and Genetics, Faculty of Medicine, Erasmus University Rotterdam, Dr Molewaterplein 50, P.O. Box 1738, 3000 DR Rotterdam, The Netherlands
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117
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Kiefer F, Brumell J, Al-Alawi N, Latour S, Cheng A, Veillette A, Grinstein S, Pawson T. The Syk protein tyrosine kinase is essential for Fcgamma receptor signaling in macrophages and neutrophils. Mol Cell Biol 1998; 18:4209-20. [PMID: 9632805 PMCID: PMC109005 DOI: 10.1128/mcb.18.7.4209] [Citation(s) in RCA: 289] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The cytoplasmic protein tyrosine kinase Syk has two amino-terminal SH2 domains that engage phosphorylated immunoreceptor tyrosine-based activation motifs in the signaling subunits of immunoreceptors. Syk, in conjunction with Src family kinases, has been implicated in immunoreceptor signaling in both lymphoid and myeloid cells. We have investigated the role of Syk in Fcgamma receptor (FcgammaR)-dependent and -independent responses in bone marrow-derived macrophages and neutrophils by using mouse radiation chimeras reconstituted with fetal liver cells from Syk-/- embryos. Chimeric mice developed an abdominal hemorrhage starting 2 to 3 months after transplantation that was ultimately lethal. Syk-deficient neutrophils derived from the bone marrow were incapable of generating reactive oxygen intermediates in response to FcgammaR engagement but responded normally to tetradecanoyl phorbol acetate stimulation. Syk-deficient macrophages were defective in phagocytosis induced by FcgammaR but showed normal phagocytosis in response to complement. The tyrosine phosphorylation of multiple cellular polypeptides, including the FcgammaR gamma chain, as well as Erk2 activation, was compromised in Syk-/- macrophages after FcgammaR stimulation. In contrast, the induction of nitric oxide synthase in macrophages stimulated with lipopolysaccharide and gamma interferon was not dependent on Syk. Surprisingly, Syk-deficient macrophages were impaired in the ability to survive or proliferate on plastic petri dishes. Taken together, these results suggest that Syk has specific physiological roles in signaling from FcgammaRs in neutrophils and macrophages and raise the possibility that in vivo, Syk is involved in signaling events other than those mediated by immunoreceptors.
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Affiliation(s)
- F Kiefer
- Programme in Molecular Biology and Cancer, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5
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118
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Martin F, Won WJ, Kearney JF. Generation of the Germline Peripheral B Cell Repertoire: VH81X-λ B Cells Are Unable to Complete All Developmental Programs. THE JOURNAL OF IMMUNOLOGY 1998. [DOI: 10.4049/jimmunol.160.8.3748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
The generation of VH81X heavy chain λ-light chain-expressing B cells (VH81X-λ+ B cells) was studied in VH81X heavy chain transgenic mice as well as in VH81X JH −/− and VH81X JH −/− Ck −/− mice, in which competition resulting from expression of heavy and light chains from the endogenous heavy and κ light chain loci was prevented. We show that although λ light chain gene rearrangements occur normally and give rise to light chains that associate with the transgenic heavy chain to form surface and soluble IgM molecules, further B cell development is almost totally blocked. The few VH81X-λ+ B cells that are generated progress into a mature compartment (expressing surface CD21, CD22, CD23, and low CD24 and having a relatively long life span) but they also have reduced levels of surface Ig receptor and express higher amounts of Fas Ag than VH81X-κ+ B cells. These VH81X-λ+ B cells reach the peripheral lymphoid organs and accumulate in the periarteriolar lymphoid sheath but are unable to generate primary B cell follicles. In other heavy chain transgenic mice (MD2, M167, and M54), λ+ B cells are generated. However, they seem to be preferentially selected in the peripheral repertoire of some transgenic heavy chain mice (M54) but not in others (MD2, M167). These studies show that a crucial selection step is necessary for B cell survival and maintenance in which B cells, similar to T cells, receive signals depending on their clonal receptors.
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Affiliation(s)
- Flavius Martin
- Division of Developmental and Clinical Immunology, Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35394
| | - Woong-Jai Won
- Division of Developmental and Clinical Immunology, Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35394
| | - John F. Kearney
- Division of Developmental and Clinical Immunology, Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35394
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119
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Abstract
Gene targeting in mice has enabled the study of antigen receptor signalling in primary lymphocytes. Furthermore, it has provided the tools to directly assess the function of individual signalling proteins by mutation of the genes that code for them. Some of the results that gene targeting has produced have confirmed previous views of the function of particular proteins. Others have given surprising results and overturned accepted viewpoints.
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Affiliation(s)
- V L Tybulewicz
- National Institute for Medical Research, Mill Hill, London, UK.
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120
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Abstract
Recent studies indicate that immature B cells compete with recirculating B cells for survival signals. The signals, delivered through the B-cell receptor for antigen, induce immature cells to differentiate into recirculating cells and maintain the survival of recirculating cells. They do not induce proliferation or differentiation to antibody-producing cells.
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Affiliation(s)
- I C MacLennan
- Department of Immunology, University of Birmingham Medical School, UK.
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121
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Schmidt KN, Hsu CW, Griffin CT, Goodnow CC, Cyster JG. Spontaneous follicular exclusion of SHP1-deficient B cells is conditional on the presence of competitor wild-type B cells. J Exp Med 1998; 187:929-37. [PMID: 9500795 PMCID: PMC2212192 DOI: 10.1084/jem.187.6.929] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/1997] [Revised: 01/15/1998] [Indexed: 11/04/2022] Open
Abstract
Engagement of antigen receptors on mature B lymphocytes is known to block cell entry into lymphoid follicles and promote accumulation in T cell zones, yet the molecular basis for this change in cell distribution is not understood. Previous studies have shown that follicular exclusion requires a threshold level of antigen receptor engagement combined with occupancy of follicles by B cells without equivalent receptor engagement. The possibility has been raised that follicular composition affects B cell positioning by altering the amount of available antigen and the degree of receptor occupancy. Here we show that follicular composition affects migration of mature B cells under conditions that are independent of antigen receptor occupancy. B cells deficient in the negative regulatory protein tyrosine phosphatase, SHP1, which have elevated intracellular signaling by the B cell receptor, are shown to accumulate in the T zone in the absence of their specific antigen. Follicular exclusion of SHP1-deficient B cells was found to be conditional on the presence of excess B cells that lack elevated intracellular signaling, and was not due to a failure of SHP-1-deficient cells to mature and express the follicle-homing chemokine receptor Burkitt's lymphoma receptor 1. These findings strongly suggest that signals that are negatively regulated by SHP1 promote B cell localization in T cell zones by reducing competitiveness for follicular entry, and provide further evidence that follicular composition influences the positioning of antigen-engaged B cells.
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MESH Headings
- Animals
- Antigens, CD/physiology
- Antigens, Differentiation, B-Lymphocyte/physiology
- B-Lymphocytes/physiology
- Cell Adhesion Molecules
- GTP-Binding Proteins/analysis
- Intracellular Signaling Peptides and Proteins
- Lectins
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Protein Tyrosine Phosphatase, Non-Receptor Type 11
- Protein Tyrosine Phosphatase, Non-Receptor Type 6
- Protein Tyrosine Phosphatases/deficiency
- Protein Tyrosine Phosphatases/physiology
- Receptors, CXCR5
- Receptors, Chemokine
- Receptors, Cytokine/analysis
- Sialic Acid Binding Ig-like Lectin 2
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Affiliation(s)
- K N Schmidt
- Department of Microbiology and Immunology, University of California at San Francisco, San Francisco, California 94143, USA
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