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

2001 ◽  
Vol 193 (4) ◽  
pp. 417-426 ◽  
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.

Ott1 (Rbm15) Is Required for the Large to Small Pre B-Cell Transition

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 706-706
Author(s):  
Michael Kharas ◽  
John Manis ◽  
D. Gary Gilliland ◽  
Glen D. Raffel
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Lines ◽  
Fetal Liver ◽  
Cell Development ◽  
B Cell Development ◽  
Transformed Cell Lines ◽  
Cell Transition

Abstract The OTT1 gene is fused with the MAL gene in t(1;22) infant-associated acute megakaryocytic leukemia generating a chimeric protein, OTT1-MAL. OTT1 is a transcriptional activator/repressor related to the spen/SHARP/Mint family. Mint was shown to regulate follicular versus marginal zone B-cell development in the spleen; however, Ott1’s physiologic role in B cell development is not fully understood. Recent data utilizing conditional deletion of a targeted Ott1 allele in mice delineated multiple regulatory roles for Ott1 in myeloid and lymphoid differentiation. Previous work by our laboratory showed that loss of Ott1 in addition to causing a myeloid and megakaryocytic expansion, results in a block in B development prior to the B220+CD43-IgM+ stage. We have characterized Ott1-deficient B-cell progenitors to identify stage- and process-specific requirements for Ott1 in pre B development. Ott1-deleted bone marrow and fetal liver could not generate pre B colonies in methylcellulose, however, we were able to establish IL-7-dependent pro B cell lines in vitro and observed no significant differences in proliferation, apoptosis or the ability to form v-Abl-transformed cell lines. Activated Ras or overexpression of Bcl2 failed to rescue pre B colony formation. In vivo, Ott1 null fetal liver pre B-cells expressed Ig heavy chain but failed to express the B-cell receptor (BCR) on their surface even though kappa rearrangement was detectable in vitro. In comparison to wildtype cells, B220+CD43-IgH+ Ott1 null cells were larger in size, had lower levels of IL-7R, but proliferated at higher levels and with an associated increase in apoptosis. Moreover, these cells had normal pre-BCR proximal signaling as judged by phospho-Blnk and phospho-Erk, but increased phosphorylation of S6 after IL7 and Ig stimulation. Ott1 null large pre B-cells had normal expression of Myc, but higher levels of expression of Cyclin D1. Taken together, these data indicate that loss of Ott1 results in enhanced proliferation and apoptosis in the pre B-cell compartment causing a developmental block at the large to small pre B-cell transition. Differentiation blocks at the pro and pre B stage through mutations in B cell regulatory genes, such as PAX5, BTK and BLNK, have been recently demonstrated in acute lymphocytic leukemias. It is plausible that mutations in OTT1, given its position in the tightly regulated process of B cell development, may likewise contribute to pre B-leukemogenesis.

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

2002 ◽  
Vol 9 (2) ◽  
pp. 86-95 ◽  
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.

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

2018 ◽  
Vol 19 (9) ◽  
pp. 2522 ◽  
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.

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

2002 ◽  
Vol 196 (5) ◽  
pp. 705-711 ◽  
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.

B Cell Development in the Absence of PU.1.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 226-226 ◽  
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.

scholarly journals IKKα-mediated signaling circuitry regulates early B lymphopoiesis during hematopoiesis

Blood ◽  
2012 ◽  
Vol 119 (23) ◽  
pp. 5467-5477 ◽  
Author(s):  
Mumtaz Yaseen Balkhi ◽  
Jami Willette-Brown ◽  
Feng Zhu ◽  
Zhisong Chen ◽  
Shuang Liu ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Fetal Liver ◽  
Cell Development ◽  
B Cell Development ◽  
Erythroid Cell ◽  
Early Event ◽  
Lineage Differentiation ◽  
Iκb Kinase ◽  
Cell Commitment

Abstract Multiple transcription factors regulate B-cell commitment, which is coordinated with myeloid-erythroid lineage differentiation. NF-κB has long been speculated to regulate early B-cell development; however, this issue remains controversial. IκB kinase-α (IKKα) is required for splenic B-cell maturation but not for BM B-cell development. In the present study, we unexpectedly found defective BM B-cell development and increased myeloid-erythroid lineages in kinase-dead IKKα (KA/KA) knock-in mice. Markedly increased cytosolic p100, an NF-κB2–inhibitory form, and reduced nuclear NF-κB p65, RelB, p50, and p52, and IKKα were observed in KA/KA splenic and BM B cells. Several B- and myeloid-erythroid–cell regulators, including Pax5, were deregulated in KA/KA BM B cells. Using fetal liver and BM congenic transplantations and deleting IKKα from early hematopoietic cells in mice, this defect was identified as being B cell–intrinsic and an early event during hematopoiesis. Reintroducing IKKα, Pax5, or combined NF-κB molecules promoted B-cell development but repressed myeloid-erythroid cell differentiation in KA/KA BM B cells. The results of the present study demonstrate that IKKα regulates B-lineage commitment via combined canonical and noncanonical NF-κB transcriptional activities to target Pax5 expression during hematopoiesis.

scholarly journals The transcription factor Gli3 promotes B cell development in fetal liver through repression of Shh

2017 ◽  
Vol 214 (7) ◽  
pp. 2041-2058 ◽  
Author(s):  
Anisha Solanki ◽  
Ching-In Lau ◽  
José Ignacio Saldaña ◽  
Susan Ross ◽  
Tessa Crompton
Keyword(s):  
B Cells ◽  
B Cell ◽  
Fetal Liver ◽  
Cell Receptor ◽  
Cell Development ◽  
B Cell Development ◽  
Pathway Activation ◽  
Genes Expression ◽  
B Lineage

Before birth, B cells develop in the fetal liver (FL). In this study, we show that Gli3 activity in the FL stroma is required for B cell development. In the Gli3-deficient FL, B cell development was reduced at multiple stages, whereas the Sonic hedgehog (Hh [Shh])–deficient FL showed increased B cell development, and Gli3 functioned to repress Shh transcription. Use of a transgenic Hh-reporter mouse showed that Shh signals directly to developing B cells and that Hh pathway activation was increased in developing B cells from Gli3-deficient FLs. RNA sequencing confirmed that Hh-mediated transcription is increased in B-lineage cells from Gli3-deficient FL and showed that these cells expressed reduced levels of B-lineage transcription factors and B cell receptor (BCR)/pre-BCR–signaling genes. Expression of the master regulators of B cell development Ebf1 and Pax5 was reduced in developing B cells from Gli3-deficient FL but increased in Shh-deficient FL, and in vitro Shh treatment or neutralization reduced or increased their expression, respectively.

scholarly journals A critical role of Rap1b in B-cell trafficking and marginal zone B-cell development

Blood ◽  
2008 ◽  
Vol 111 (9) ◽  
pp. 4627-4636 ◽  
Author(s):  
Yuhong Chen ◽  
Mei Yu ◽  
Andrew Podd ◽  
Renren Wen ◽  
Magdalena Chrzanowska-Wodnicka ◽  
...  
Keyword(s):  
B Cells ◽  
Lymph Nodes ◽  
B Cell ◽  
Marginal Zone ◽  
Cell Development ◽  
B Cell Development ◽  
Cell Trafficking

Abstract B-cell development is orchestrated by complex signaling networks. Rap1 is a member of the Ras superfamily of small GTP-binding proteins and has 2 isoforms, Rap1a and Rap1b. Although Rap1 has been suggested to have an important role in a variety of cellular processes, no direct evidence demonstrates a role for Rap1 in B-cell biology. In this study, we found that Rap1b was the dominant isoform of Rap1 in B cells. We discovered that Rap1b deficiency in mice barely affected early development of B cells but markedly reduced marginal zone (MZ) B cells in the spleen and mature B cells in peripheral and mucosal lymph nodes. Rap1b-deficient B cells displayed normal survival and proliferation in vivo and in vitro. However, Rap1b-deficient B cells had impaired adhesion and reduced chemotaxis in vitro, and lessened homing to lymph nodes in vivo. Furthermore, we found that Rap1b deficiency had no marked effect on LPS-, BCR-, or SDF-1–induced activation of mitogen-activated protein kinases and AKT but clearly impaired SDF-1–mediated activation of Pyk-2, a key regulator of SDF-1–mediated B-cell migration. Thus, we have discovered a critical and distinct role of Rap1b in mature B-cell trafficking and development of MZ B cells.

scholarly journals Interactions Between c-kit and Stem Cell Factor Are Not Required for B-Cell Development In Vivo

Blood ◽  
1997 ◽  
Vol 89 (2) ◽  
pp. 518-525 ◽  
Author(s):  
Shunichi Takeda ◽  
Takeyuki Shimizu ◽  
Hans-Reimer Rodewald
Keyword(s):  
Bone Marrow ◽  
B Cells ◽  
B Cell ◽  
Fetal Liver ◽  
Critical Role ◽  
Cell Development ◽  
B Cell Development ◽  
Wild Type ◽  
Hematopoietic Stem

Abstract The receptor-type tyrosine kinase, c-kit is expressed in hematopoietic stem cells (HSC), myeloid, and lymphoid precursors. In c-kit ligand-deficient mice, absolute numbers of HSC are mildly reduced suggesting that c-kit is not essential for HSC development. However, c-kit− HSC cannot form spleen colonies or reconstitute hematopoietic functions in lethally irradiated recipient mice. Based on in in vitro experiments, a critical role of c-kit in B-cell development was suggested. Here we have investigated the B-cell development of c-kitnull mutant (W/W ) mice in vivo. Furthermore, day 13 fetal liver cells from wild type or W/W mice were transferred into immunodeficient RAG-2−/− mice. Surprisingly, transferred c-kit− cells gave rise to all stages of immature B cells in the bone marrow and subsequently to mature conventional B2, as well as B1, type B cells in the recipients to the same extent as transferred wild type cells. Hence, in contrast to important roles of c-kit in the expansion of HSC and the generation of erythroid and myeloid lineages and T-cell precursors, c-kit− HSC can colonize the recipient bone marrow and differentiate into B cells in the absence of c-kit.

scholarly journals Regulation of Constitutive p50/c-Rel Activity via Proteasome Inhibitor-Resistant IκBα Degradation in B Cells

2004 ◽  
Vol 24 (11) ◽  
pp. 4895-4908 ◽  
Author(s):  
Shelby O'Connor ◽  
Stuart D. Shumway ◽  
Ian J. Amanna ◽  
Colleen E. Hayes ◽  
Shigeki Miyamoto
Keyword(s):  
B Cells ◽  
B Cell ◽  
Proteasome Inhibitor ◽  
Consensus Sequence ◽  
Physiological Role ◽  
Cell Development ◽  
B Cell Development ◽  
Selective Degradation ◽  
Iκb Kinase

ABSTRACT Constitutive NF-κB activity has emerged as an important cell survival component of physiological and pathological processes, including B-cell development. In B cells, constitutive NF-κB activity includes p50/c-Rel and p52/RelB heterodimers, both of which are critical for proper B-cell development. We previously reported that WEHI-231 B cells maintain constitutive p50/c-Rel activity via selective degradation of IκBα that is mediated by a proteasome inhibitor-resistant, now termed PIR, pathway. Here, we examined the mechanisms of PIR degradation by comparing it to the canonical pathway that involves IκB kinase-dependent phosphorylation and β-TrCP-dependent ubiquitylation of the N-terminal signal response domain of IκBα. We found a distinct consensus sequence within this domain of IκBα for PIR degradation. Chimeric analyses of IκBα and IκBβ further revealed that the ankyrin repeats of IκBα, but not IκBβ, contained information necessary for PIR degradation, thereby explaining IκBα selectivity for the PIR pathway. Moreover, we found that PIR degradation of IκBα and constitutive p50/c-Rel activity in primary murine B cells were maintained in a manner different from B-cell-activating-factor-dependent p52/RelB regulation. Thus, our findings suggest that nonconventional PIR degradation of IκBα may play a physiological role in the development of B cells in vivo.

Sign in / Sign up

Export Citation Format

Share Document