A Dual Role for Src Homology 2 Domain–Containing Inositol-5-Phosphatase (Ship) in Immunity

In this report, we demonstrate that the Src homology 2 domain–containing inositol-5-phosphatase (SHIP) plays a critical role in regulating both B cell development and responsiveness to antigen stimulation. SHIP−/− mice exhibit a transplantable alteration in B lymphoid development that results in reduced numbers of precursor B (fraction C) and immature B cells in the bone marrow. In vitro, purified SHIP−/− B cells exhibit enhanced proliferation in response to B cell receptor stimulation in both the presence and absence of Fcγ receptor IIB coligation. This enhancement is associated with increased phosphorylation of both mitogen-activated protein kinase and Akt, as well as with increased survival and cell cycling. SHIP−/− mice manifest elevated serum immunoglobulin (Ig) levels and an exaggerated IgG response to the T cell–independent type 2 antigen trinitrophenyl Ficoll. However, only altered B cell development was apparent upon transplantation into nonobese diabetic–severe combined immunodeficient (NOD/SCID) mice. The in vitro hyperresponsiveness, together with the in vivo findings, suggests that SHIP regulates B lymphoid development and antigen responsiveness by both intrinsic and extrinsic mechanisms.

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Differential Regulation of B Cell Development, Activation, and Death by the Src Homology 2 Domain–Containing 5′ Inositol Phosphatase (Ship)

Journal of Experimental Medicine ◽

10.1084/jem.191.9.1545 ◽

2000 ◽

Vol 191 (9) ◽

pp. 1545-1554 ◽

Cited By ~ 96

Author(s):

Anne Brauweiler ◽

Idan Tamir ◽

Joseph Dal Porto ◽

Robert J. Benschop ◽

Cheryl D. Helgason ◽

...

Keyword(s):

Bone Marrow ◽

B Cells ◽

B Cell ◽

Cell Development ◽

B Cell Development ◽

Inositol Phosphatase ◽

Src Homology 2 ◽

Src Homology ◽

Src Homology 2 Domain ◽

Deficient Mice

Although the Src homology 2 domain–containing 5′ inositol phosphatase (SHIP) is a well-known mediator of inhibitory signals after B cell antigen receptor (BCR) coaggregation with the low affinity Fc receptor, it is not known whether SHIP functions to inhibit signals after stimulation through the BCR alone. Here, we show using gene-ablated mice that SHIP is a crucial regulator of BCR-mediated signaling, B cell activation, and B cell development. We demonstrate a critical role for SHIP in termination of phosphatidylinositol 3,4,5-triphosphate (PI[3,4,5]P3) signals that follow BCR aggregation. Consistent with enhanced PI(3,4,5)P3 signaling, we find that splenic B cells from SHIP-deficient mice display enhanced sensitivity to BCR-mediated induction of the activation markers CD86 and CD69. We further demonstrate that SHIP regulates the rate of B cell development in the bone marrow and spleen, as B cell precursors from SHIP-deficient mice progress more rapidly through the immature and transitional developmental stages. Finally, we observe that SHIP-deficient B cells have increased resistance to BCR-mediated cell death. These results demonstrate a central role for SHIP in regulation of BCR signaling and B cell biology, from signal driven development in the bone marrow and spleen, to activation and death in the periphery.

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Differential Regulation of Mouse B Cell Development by Transforming Growth Factor β1

Developmental Immunology ◽

10.1080/1044667031000088057 ◽

2002 ◽

Vol 9 (2) ◽

pp. 86-95 ◽

Cited By ~ 8

Author(s):

Denise A. Kaminski ◽

John J. Letterio ◽

Peter D. Burrows

Keyword(s):

B Cells ◽

Growth Factor ◽

B Cell ◽

Transforming Growth Factor ◽

Plasma Cells ◽

Population Analysis ◽

Cell Development ◽

B Cell Development

Transforming growth factor β (TGFβ) can inhibit thein vitroproliferation, survival and differentiation of B cell progenitors, mature B lymphocytes and plasma cells. Here we demonstrate unexpected, age-dependent reductions in the bone marrow (BM) B cell progenitors and immature B cells in TGFβ1-/-mice. To evaluate TGFβ responsiveness during normal B lineage development, cells were cultured in interleukin 7 (IL7)±TGFβ. Picomolar doses of TGFβ1 reduced pro-B cell recoveries at every timepoint. By contrast, the pre-B cells were initially reduced in number, but subsequently increased compared to IL7 alone, resulting in a 4-fold increase in the growth rate for the pre-B cell population. Analysis of purified BM sub-populations indicated that pro-B cells and the earliest BP1-pre-B cells were sensitive to the inhibitory effects of TGFβ1. However, the large BP1+pre-B cells, although initially reduced, were increased in number at days 5 and 7 of culture. These results indicate that TGFβ1 is important for normal B cell developmentin vivo, and that B cell progenitors are differentially affected by the cytokine according to their stage of differentiation.

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Src homology 2 domain–containing inositol-5-phosphatase and CCAAT enhancer-binding protein β are targeted by miR-155 in B cells of Eμ-MiR-155 transgenic mice

Blood ◽

10.1182/blood-2009-05-220814 ◽

2009 ◽

Vol 114 (7) ◽

pp. 1374-1382 ◽

Cited By ~ 212

Author(s):

Stefan Costinean ◽

Sukhinder K. Sandhu ◽

Irene M. Pedersen ◽

Esmerina Tili ◽

Rossana Trotta ◽

...

Keyword(s):

Acute Lymphoblastic Leukemia ◽

B Cells ◽

Transgenic Mice ◽

B Cell ◽

Lymphoblastic Leukemia ◽

High Grade ◽

Src Homology 2 ◽

Enhancer Binding Protein ◽

Src Homology ◽

Src Homology 2 Domain

AbstractWe showed that Eμ-MiR-155 transgenic mice develop acute lymphoblastic leukemia/high-grade lymphoma. Most of these leukemias start at approximately 9 months irrespective of the mouse strain. They are preceded by a polyclonal pre–B-cell proliferation, have variable clinical presentation, are transplantable, and develop oligo/monoclonal expansion. In this study, we show that in these transgenic mice the B-cell precursors have the highest MiR-155 transgene expression and are at the origin of the leukemias. We determine that Src homology 2 domain–containing inositol-5-phosphatase (SHIP) and CCAAT enhancer-binding protein β (C/EBPβ), 2 important regulators of the interleukin-6 signaling pathway, are direct targets of MiR-155 and become gradually more down-regulated in the leukemic than in the preleukemic mice. We hypothesize that miR-155, by down-modulating Ship and C/EBPβ, initiates a chain of events that leads to the accumulation of large pre-B cells and acute lymphoblastic leukemia/high-grade lymphoma.

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Identification of an Essential Cytoplasmic Region of Interleukin-7 Receptor α Subunit in B-Cell Development

International Journal of Molecular Sciences ◽

10.3390/ijms19092522 ◽

2018 ◽

Vol 19 (9) ◽

pp. 2522 ◽

Cited By ~ 2

Author(s):

Hirotake Kasai ◽

Taku Kuwabara ◽

Yukihide Matsui ◽

Koichi Nakajima ◽

Motonari Kondo

Keyword(s):

B Cells ◽

B Cell ◽

Myeloid Cell ◽

Cell Development ◽

B Cell Development ◽

Α Subunit ◽

Interleukin 7 ◽

In Cells

Interleukin-7 (IL-7) is essential for lymphocyte development. To identify the functional subdomains in the cytoplasmic tail of the IL-7 receptor (IL-7R) α chain, here, we constructed a series of IL-7Rα deletion mutants. We found that IL-7Rα-deficient hematopoietic progenitor cells (HPCs) gave rise to B cells both in vitro and in vivo when a wild-type (WT) IL-7Rα chain was introduced; however, no B cells were observed under the same conditions from IL-7Rα-deficient HPCs with introduction of the exogenous IL-7Rα subunit, which lacked the amino acid region at positions 414–441 (d414–441 mutant). Signal transducer and activator of transcription 5 (STAT5) was phosphorylated in cells with the d414–441 mutant, similar to that in WT cells, in response to IL-7 stimulation. In contrast, more truncated STAT5 (tSTAT5) was generated in cells with the d414–441 mutant than in WT cells. Additionally, the introduction of exogenous tSTAT5 blocked B lymphopoiesis but not myeloid cell development from WT HPCs in vivo. These results suggested that amino acids 414–441 in the IL-7Rα chain formed a critical subdomain necessary for the supportive roles of IL-7 in B-cell development.

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IRF-4 functions as a tumor suppressor in early B-cell development

Blood ◽

10.1182/blood-2007-10-117838 ◽

2008 ◽

Vol 112 (9) ◽

pp. 3798-3806 ◽

Cited By ~ 30

Author(s):

Jaime Acquaviva ◽

Xiaoren Chen ◽

Ruibao Ren

Keyword(s):

Tumor Suppressor ◽

B Cell ◽

Kinase Inhibitor ◽

Lymphoblastic Leukemia ◽

Cell Development ◽

B Cell Development ◽

Lymphoid Progenitors ◽

B Lymphoid

Interferon regulatory factor-4 (IRF-4) is a hematopoietic cell–restricted transcription factor important for hematopoietic development and immune response regulation. It was also originally identified as the product of a proto-oncogene involved in chromosomal translocations in multiple myeloma. In contrast to its oncogenic function in late stages of B lymphopoiesis, expression of IRF-4 is down-regulated in certain myeloid and early B-lymphoid malignancies. In this study, we found that the IRF-4 protein levels are increased in lymphoblastic cells transformed by the BCR/ABL oncogene in response to BCR/ABL tyrosine kinase inhibitor imatinib. We further found that IRF-4 deficiency enhances BCR/ABL transformation of B-lymphoid progenitors in vitro and accelerates disease progression of BCR/ABL-induced acute B-lymphoblastic leukemia (B-ALL) in mice, whereas forced expression of IRF-4 potently suppresses BCR/ABL transformation of B-lymphoid progenitors in vitro and BCR/ABL-induced B-ALL in vivo. Further analysis showed that IRF-4 inhibits growth of BCR/ABL+ B lymphoblasts primarily through negative regulation of cell-cycle progression. These results demonstrate that IRF-4 functions as tumor suppressor in early B-cell development and may allow elucidation of new molecular pathways significant to the lymphoid leukemogenesis by BCR/ABL. The context dependent roles of IRF-4 in oncogenesis should be an important consideration in developing cancer therapies targeting IRF-4.

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The Earliest Step in B Lineage Differentiation from Common Lymphoid Progenitors Is Critically Dependent upon Interleukin 7

Journal of Experimental Medicine ◽

10.1084/jem.20020784 ◽

2002 ◽

Vol 196 (5) ◽

pp. 705-711 ◽

Cited By ~ 141

Author(s):

Juli P. Miller ◽

David Izon ◽

William DeMuth ◽

Rachel Gerstein ◽

Avinash Bhandoola ◽

...

Keyword(s):

B Cells ◽

B Cell ◽

Cell Development ◽

B Cell Development ◽

Gamma Chain ◽

Lineage Differentiation ◽

Lymphoid Progenitors ◽

B Lineage

Little is known about the signals that promote early B lineage differentiation from common lymphoid progenitors (CLPs). Using a stromal-free culture system, we show that interleukin (IL)-7 is sufficient to promote the in vitro differentiation of CLPs into B220+ CD19+ B lineage progenitors. Consistent with current models of early B cell development, surface expression of B220 was initiated before CD19 and was accompanied by the loss of T lineage potential. To address whether IL-7 receptor (R) activity is essential for early B lineage development in vivo, we examined the frequencies of CLPs and downstream pre–pro- and pro-B cells in adult mice lacking either the α chain or the common gamma chain (γc) of the IL-7R. The data indicate that although γc−/− mice have normal frequencies of CLPs, both γc−/− and IL-7Rα−/− mice lack detectable numbers of all downstream early B lineage precursors, including pre–pro-B cells. These findings challenge previous notions regarding the point in B cell development affected by the loss of IL-7R signaling and suggest that IL-7 plays a key and requisite role during the earliest phases of B cell development.

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Differential expression of CD21 identifies developmentally and functionally distinct subsets of human transitional B cells

Blood ◽

10.1182/blood-2009-07-234799 ◽

2010 ◽

Vol 115 (3) ◽

pp. 519-529 ◽

Cited By ~ 77

Author(s):

Santi Suryani ◽

David A. Fulcher ◽

Brigitte Santner-Nanan ◽

Ralph Nanan ◽

Melanie Wong ◽

...

Keyword(s):

B Cells ◽

B Cell ◽

Differential Expression ◽

Cell Development ◽

B Cell Development ◽

Cell Repertoire ◽

Molecular Features ◽

Transitional B Cells ◽

Transitional Cells

Abstract The transitional stage of B-cell development represents an important step where autoreactive cells are deleted, allowing the generation of a mature functional B-cell repertoire. In mice, 3 subsets of transitional B cells have been identified. In contrast, most studies of human transitional B cells have focused on a single subset defined as CD24hiCD38hi B cells. Here, we have identified 2 subsets of human transitional B cells based on the differential expression of CD21. CD21hi transitional cells displayed higher expression of CD23, CD44, and IgD, and exhibited greater proliferation and Ig secretion in vitro than CD21lo transitional B cells. In contrast, the CD21lo subset expressed elevated levels of LEF1, a transcription factor highly expressed by immature lymphocytes, and produced higher amounts of autoreactive Ab. These phenotypic, functional, and molecular features suggest that CD21lo transitional B cells are less mature than the CD21hi subset. This was confirmed by analyzing X-linked agammaglobulinemia patients and the kinetics of B-cell reconstitution after stem cell transplantation, which revealed that the development of CD21lo transitional B cells preceded that of CD21hi transitional cells. These findings provide important insights into the process of human B-cell development and have implications for understanding the processes underlying perturbed B-cell maturation in autoimmune and immunodeficient conditions.

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Iκb Kinase α Is Essential for Mature B Cell Development and Function

Journal of Experimental Medicine ◽

10.1084/jem.193.4.417 ◽

2001 ◽

Vol 193 (4) ◽

pp. 417-426 ◽

Cited By ~ 147

Author(s):

Tsuneyasu Kaisho ◽

Kiyoshi Takeda ◽

Tohru Tsujimura ◽

Taro Kawai ◽

Fumiko Nomura ◽

...

Keyword(s):

B Cells ◽

B Cell ◽

Fetal Liver ◽

Cell Development ◽

B Cell Development ◽

Cytokine Signaling ◽

Iκb Kinase ◽

And Function

IκB kinase (IKK) α and β phosphorylate IκB proteins and activate the transcription factor, nuclear factor (NF)-κB. Although both are highly homologous kinases, gene targeting experiments revealed their differential roles in vivo. IKKα is involved in skin and limb morphogenesis, whereas IKKβ is essential for cytokine signaling. To elucidate in vivo roles of IKKα in hematopoietic cells, we have generated bone marrow chimeras by transferring control and IKKα-deficient fetal liver cells. The mature B cell population was decreased in IKKα−/− chimeras. IKKα−/− chimeras also exhibited a decrease of serum immunoglobulin basal level and impaired antigen-specific immune responses. Histologically, they also manifested marked disruption of germinal center formation and splenic microarchitectures that depend on mature B cells. IKKα−/− B cells not only showed impairment of survival and mitogenic responses in vitro, accompanied by decreased, although inducible, NF-κB activity, but also increased turnover rate in vivo. In addition, transgene expression of bcl-2 could only partially rescue impaired B cell development in IKKα−/− chimeras. Taken together, these results demonstrate that IKKα is critically involved in the prevention of cell death and functional development of mature B cells.

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Arhgap25 deficiency leads to decreased numbers of peripheral blood B cells and defective germinal center reactions

10.1101/2020.03.05.965228 ◽

2020 ◽

Author(s):

Silke E. Lindner ◽

Colt A. Egelston ◽

Stephanie M. Huard ◽

Peter P. Lee ◽

Leo D. Wang

Keyword(s):

B Cells ◽

B Cell ◽

Germinal Center ◽

Peripheral Blood ◽

Cell Development ◽

B Cell Development ◽

Dependent Manner ◽

B Cell Differentiation ◽

Nucleotide Exchange

ABSTRACTRho family GTPases are critical for normal B cell development and function and their activity is regulated by a large and complex network of guanine nucleotide exchange factors (GEFs) and GTPase activating proteins (GAPs). However, the role of GAPs in B cell development is poorly understood. Here we show that the novel Rac-GAP ARHGAP25 is important for B cell development in mice in a CXCR4-dependent manner. We show that Arhgap25 deficiency leads to a significant decrease in peripheral blood B cell numbers, as well as defects in mature B cell differentiation. Arhgap25-/- B cells respond to antigen stimulation in vitro and in vivo but have impaired germinal center formation and decreased IgG1 class switching. Additionally, Arhgap25-/- B cells exhibit increased chemotaxis to CXCL12. Taken together, these studies demonstrate an important role for Arhgap25 in peripheral B cell development and antigen response.

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B Cell Development in the Absence of PU.1.

Blood ◽

10.1182/blood.v104.11.226.226 ◽

2004 ◽

Vol 104 (11) ◽

pp. 226-226 ◽

Cited By ~ 1

Author(s):

Min Ye ◽

Olga Ermaermakova-Cirilli ◽

Thomas Graf

Keyword(s):

Bone Marrow ◽

B Cells ◽

B Cell ◽

Target Genes ◽

Fetal Liver ◽

Cell Formation ◽

Cell Development ◽

B Cell Development ◽

B Lineage

Abstract Mice deficient of the ETS-family transcription factor PU.1 lack B cells as well as macrophages. While most macrophage specific genes are known to be regulated by high levels of PU.1, the reason for the defect in B cell formation is not known. Here we analyzed a mouse strain in which a floxed version of the PU.1 gene, surrounding exon 4 and 5, which encode the DNA, binding and PEST domains (developed by C. Somoza and D. Tenen), was excised by Cre mediated recombination. As expected, this strain lacks both B cells and macrophages and die at birth. Surprisingly, however, we were able to establish lymphoid cell lines from fetal livers of these mice (day 14 to day 18), which proliferated on S17 stromal cells supplemented with IL-7 and stem cell factor. These cells expressed the B lineage cell surface markers CD19, CD43, BP-1 and CD24, but not B220. They also expressed B cell transcription factors, EBF, E47, Pax5, and their target genes, Rag1, IL7R, λ5 and v-preB, as detected by RT-PCR, exhibited DJ and VDJ immunoglobulin heavy chain rearrangements, and expressed IgM after IL-7 withdrawal. We then tested the effect of PU.1 deletion in B cells in adult animals by crossing the floxed PU.1 strain with a CD19 Cre mouse line. The spleen and peripheral blood (but not bone marrow) of these mice contained B cells that were CD19+ IgMlow, IgDhigh but B220 negative and instead expressed CD43. Thus PU.1 is not essential for immunoglobulin production and late B cell development. Although PU.1−/− fetal liver cells can give rise to cells, resembling Pre-B in vitro, the process of B cell formation was delayed by almost 12 days, compared with wt fetal liver, and the efficiency was reduced approximately 25-fold. In addition, PU.1 deficient B cells demonstrated an impaired ability to engraft into the bone marrow, when injected into irradiated SCID mice. We have found that PU.1 deficient B progenitors showed reduced or undetectable levels of the SDF1 receptor CXCR4, a receptor that has been implicated in B cell homing. Taken together, our observations suggest that PU.1 plays two different roles during B cell development: for early B cell formation and for proper migration and engraftment, which might be mediated through regulation of CXCR4 expression.

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