Clarifying the role of Stat5 in lymphoid development and Abelson-induced transformation

AbstractThe Stat5 transcription factors Stat5a and Stat5b have been implicated in lymphoid development and transformation. Most studies have employed Stat5a/b-deficient mice where gene targeting disrupted the first protein-coding exon, resulting in the expression of N-terminally truncated forms of Stat5a/b (Stat5a/bΔN/ΔN mice). We have now reanalyzed lymphoid development in Stat5a/bnull/null mice having a complete deletion of the Stat5a/b gene locus. The few surviving Stat5a/bnull/null mice lacked CD8+ T lymphocytes. A massive reduction of CD8+ T cells was also found in Stat5a/bfl/fllck-cre transgenic animals. While γδ T-cell receptor–positive (γδTCR+) cells were expressed at normal levels in Stat5a/bΔN/ΔN mice, they were completely absent in Stat5a/bnull/null animals. Moreover, B-cell maturation was abrogated at the pre–pro-B-cell stage in Stat5a/bnull/null mice, whereas Stat5a/bΔN/ΔN B-lymphoid cells developed to the early pro-B-cell stage. In vitro assays using fetal liver-cell cultures confirmed this observation. Most strikingly, Stat5a/bnull/null cells were resistant to transformation and leukemia development induced by Abelson oncogenes, whereas Stat5a/bΔN/ΔN-derived cells readily transformed. These findings show distinct lymphoid defects for Stat5a/bΔN/ΔN and Stat5a/bnull/null mice and define a novel functional role for the N-termini of Stat5a/b in B-lymphoid transformation.

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JunB inhibits proliferation and transformation in B-lymphoid cells

Blood ◽

10.1182/blood-2003-03-0915 ◽

2003 ◽

Vol 102 (12) ◽

pp. 4159-4165 ◽

Cited By ~ 55

Author(s):

Agnieszka P. Szremska ◽

Lukas Kenner ◽

Eva Weisz ◽

Rene G. Ott ◽

Emmanuelle Passegué ◽

...

Keyword(s):

Transgenic Mice ◽

B Cell ◽

Transgenic Animals ◽

Inhibitory Effect ◽

Lymphoid Cells ◽

Negative Regulator ◽

Transgenic Cells ◽

B Lymphoid

Abstract The activator protein 1 (AP-1) member JunB has recently been implicated in leukemogenesis. Here we surveyed human lymphoma samples for expression of JunB and other AP-1 members (c-Jun, c-Fos, Fra1, JunD). JunB was strongly expressed in T-cell lymphomas, but non-Hodgkin B-cell lymphomas do not or only weakly express JunB. We therefore asked whether JunB acted as a negative regulator of B-cell development, proliferation, and transformation. We used transgenic mice that expressed JunB under the control of the ubiquitin C promoter; these displayed increased JunB levels in both B- and T-lymphoid cells. JunB transgenic cells of B-lymphoid, but not of T-lymphoid, origin responded poorly to mitogenic stimuli. Furthermore, JunB transgenic cells were found to be less susceptible to the transforming potential of the Abelson oncogene in vitro. In addition, overexpression of JunB partially protected transgenic mice against the oncogenic challenge in vivo. However, transformed B cells eventually escaped from the inhibitory effect of JunB: the proliferative response was similar in explanted tumor-derived cells from transgenic animals and those from wild-type controls. Our results identify JunB as a novel regulator of B-cell proliferation and transformation. (Blood. 2003;102:4159-4165)

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

Journal of Experimental Medicine ◽

10.1084/jem.191.5.781 ◽

2000 ◽

Vol 191 (5) ◽

pp. 781-794 ◽

Cited By ~ 115

Author(s):

Cheryl D. Helgason ◽

Christian P. Kalberer ◽

Jacqueline E. Damen ◽

Suzanne M. Chappel ◽

Nicolas Pineault ◽

...

Keyword(s):

B Cells ◽

B Cell ◽

Cell Development ◽

B Cell Development ◽

Lymphoid Development ◽

Src Homology 2 ◽

Src Homology ◽

Src Homology 2 Domain ◽

B Lymphoid

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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The development of functional B lymphocytes in conditional PU.1 knock-out mice

Blood ◽

10.1182/blood-2005-01-0283 ◽

2005 ◽

Vol 106 (6) ◽

pp. 2083-2090 ◽

Cited By ~ 55

Author(s):

Matthew Polli ◽

Aleksandar Dakic ◽

Amanda Light ◽

Li Wu ◽

David M. Tarlinton ◽

...

Keyword(s):

B Cells ◽

B Cell ◽

B Lymphocytes ◽

Fetal Liver ◽

Cell Receptor ◽

Interleukin 4 ◽

Knock Out ◽

B Lineage ◽

And Function

Abstract An abundance of research has entrenched the view that the Ets domain containing transcription factor PU.1 is fundamental to the development and function of B lymphocytes. In this study, we have made use of a conditional PU.1 allele to test this notion. Complete deletion of PU.1 resulted in the loss of B cells and all other lineage-positive cells in the fetal liver and death between E18.5 and birth; however, specific deletion of PU.1 in the B lineage had no effect on B-cell development. Furthermore, deletion of PU.1 in B cells did not compromise their ability to establish and maintain an immune response. An increased level of apoptosis was observed in vitro upon B-cell receptor (BCR) cross-linking; however, this was partially rescued by interleukin-4 (IL-4). These findings suggest that PU.1 is not essential for the development of functional B lymphocytes beyond the pre-B stage. (Blood. 2005;106:2083-2090)

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Mimicry of Pre–B Cell Receptor Signaling by Activation of the Tyrosine Kinase Blk

Journal of Experimental Medicine ◽

10.1084/jem.20030729 ◽

2003 ◽

Vol 198 (12) ◽

pp. 1863-1873 ◽

Cited By ~ 52

Author(s):

Theresa Tretter ◽

Ashley E. Ross ◽

Dominic I. Dordai ◽

Stephen Desiderio

Keyword(s):

B Cell ◽

Cell Receptor ◽

B Cell Receptor ◽

Cell Stage ◽

Interleukin 7 ◽

B Cell Receptor Signaling ◽

B Lymphoid ◽

Cell Receptor Signaling ◽

Developmental Maturation ◽

Sustained Activation

During B lymphoid ontogeny, assembly of the pre–B cell receptor (BCR) is a principal developmental checkpoint at which several Src-related kinases may play redundant roles. Here the Src-related kinase Blk is shown to effect functions associated with the pre-BCR. B lymphoid expression of an active Blk mutant caused proliferation of B progenitor cells and enhanced responsiveness of these cells to interleukin 7. In mice lacking a functional pre-BCR, active Blk supported maturation beyond the pro–B cell stage, suppressed VH to DJH rearrangement, relieved selection for productive heavy chain rearrangement, and stimulated κ rearrangement. These alterations were accompanied by tyrosine phosphorylation of immunoglobulin β and Syk, as well as changes in gene expression consistent with developmental maturation. Thus, sustained activation of Blk induces responses normally associated with the pre-BCR.

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Mef2C is a lineage-restricted target of Scl/Tal1 and regulates megakaryopoiesis and B-cell homeostasis

Blood ◽

10.1182/blood-2008-07-167577 ◽

2009 ◽

Vol 113 (15) ◽

pp. 3461-3471 ◽

Cited By ~ 37

Author(s):

Christos Gekas ◽

Katrin E. Rhodes ◽

Laurraine M. Gereige ◽

Hildur Helgadottir ◽

Roberto Ferrari ◽

...

Keyword(s):

Transcription Factor ◽

B Cell ◽

Fetal Liver ◽

Premature Aging ◽

Functional Requirements ◽

Helix Loop Helix ◽

B Cell Homeostasis ◽

B Lymphoid ◽

Deficient Mice

Abstract The basic helix-loop-helix transcription factor stem cell leukemia gene (Scl) is a master regulator for hematopoiesis essential for hematopoietic specification and proper differentiation of the erythroid and megakaryocyte lineages. However, the critical downstream targets of Scl remain undefined. Here, we identified a novel Scl target gene, transcription factor myocyte enhancer factor 2 C (Mef2C) from Sclfl/fl fetal liver progenitor cell lines. Analysis of Mef2C−/− embryos showed that Mef2C, in contrast to Scl, is not essential for specification into primitive or definitive hematopoietic lineages. However, adult VavCre+Mef2Cfl/fl mice exhibited platelet defects similar to those observed in Scl-deficient mice. The platelet counts were reduced, whereas platelet size was increased and the platelet shape and granularity were altered. Furthermore, megakaryopoiesis was severely impaired in vitro. Chromatin immunoprecipitation microarray hybridization analysis revealed that Mef2C is directly regulated by Scl in megakaryocytic cells, but not in erythroid cells. In addition, an Scl-independent requirement for Mef2C in B-lymphoid homeostasis was observed in Mef2C-deficient mice, characterized as severe age-dependent reduction of specific B-cell progenitor populations reminiscent of premature aging. In summary, this work identifies Mef2C as an integral member of hematopoietic transcription factors with distinct upstream regulatory mechanisms and functional requirements in megakaryocyte and B-lymphoid lineages.

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The promoter of the CD19 gene is a target for the B-cell-specific transcription factor BSAP

Molecular and Cellular Biology ◽

10.1128/mcb.12.6.2662-2672.1992 ◽

1992 ◽

Vol 12 (6) ◽

pp. 2662-2672

Author(s):

Z Kozmik ◽

S Wang ◽

P Dörfler ◽

B Adams ◽

M Busslinger

Keyword(s):

Transcription Factor ◽

Dna Binding ◽

B Cell ◽

Lymphoid Cells ◽

Binding Studies ◽

Specific Transcription Factor ◽

High Affinity ◽

B Lymphoid

The CD19 protein is expressed on the surface of all B-lymphoid cells with the exception of terminally differentiated plasma cells and has been implicated as a signal-transducing receptor in the control of proliferation and differentiation. Here we demonstrate complete correlation between the expression pattern of the CD19 gene and the B-cell-specific transcription factor BSAP in a large panel of B-lymphoid cell lines. The human CD19 gene has been cloned, and several BSAP-binding sites have been mapped by in vitro protein-DNA binding studies. In particular, a high-affinity BSAP-binding site instead of a TATA sequence is located in the -30 promoter region upstream of a cluster of heterogeneous transcription start sites. Moreover, this site is occupied by BSAP in vivo in a CD19-expressing B-cell line but not in plasma or HeLa cells. This high-affinity site has been conserved in the promoters of both human and mouse CD19 genes and was furthermore shown to confer B-cell specificity to a beta-globin reporter gene in transient transfection experiments. In addition, BSAP was found to be the only abundant DNA-binding activity of B-cell nuclear extracts that interacts with the CD19 promoter. Together, this evidence strongly implicates BSAP in the regulation of the CD19 gene.

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The promoter of the CD19 gene is a target for the B-cell-specific transcription factor BSAP.

Molecular and Cellular Biology ◽

10.1128/mcb.12.6.2662 ◽

1992 ◽

Vol 12 (6) ◽

pp. 2662-2672 ◽

Cited By ~ 232

Author(s):

Z Kozmik ◽

S Wang ◽

P Dörfler ◽

B Adams ◽

M Busslinger

Keyword(s):

Transcription Factor ◽

Dna Binding ◽

B Cell ◽

Lymphoid Cells ◽

Binding Studies ◽

Specific Transcription Factor ◽

High Affinity ◽

B Lymphoid

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B-1a cells acquire their unique characteristics by bypassing the pre-BCR selection stage

10.1101/214908 ◽

2017 ◽

Cited By ~ 2

Author(s):

Jason B Wong ◽

Susannah L Hewitt ◽

Lynn M Heltemes-Harris ◽

Malay Mandal ◽

Kristen Johnson ◽

...

Keyword(s):

B Cells ◽

B Cell ◽

Fetal Liver ◽

Cell Receptor ◽

Cell Stage ◽

Surrogate Light Chain ◽

Immunoglobulin Kappa ◽

Alternate Pathway ◽

Receptor Repertoire ◽

Selection Stage

SUMMARYB-1a cells are long-lived, self-renewing innate like B cells that predominantly inhabit the peritoneal and pleural cavities. In contrast to conventional B-2 cells they have a receptor repertoire that is biased towards bacterial and self-antigens, promoting a rapid response to infection and clearing of apoptotic cells. Although B-1a cells are known to primarily originate from fetal tissues the mechanisms by which they arise has been a topic of debate for many years. Here we show that in the fetal liver (FL) versus bone marrow (BM) environment, reduced IL-7R/STAT5 levels promote immunoglobulin kappa (Igk) recombination at the early pro-B cell stage. As a result, B cells can directly generate a mature B cell receptor (BCR) and bypass the requirement for a pre-BCR and pairing with surrogate light chain (SLC). This ‘alternate pathway’ of development enables the production of B cells with self reactive, skewed specificity receptors that are peculiar to the B-1a compartment. Together our findings connect seemingly opposing models of B-1a cell development and explain how these cells acquire their unique properties.

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Elevated myc expression and c-myc amplification in spontaneously occurring B lymphoid cell lines.

Journal of Experimental Medicine ◽

10.1084/jem.165.4.1188 ◽

1987 ◽

Vol 165 (4) ◽

pp. 1188-1194 ◽

Cited By ~ 17

Author(s):

Y Citri ◽

J Braun ◽

D Baltimore

Keyword(s):

B Cell ◽

Cell Lines ◽

B Lymphocyte ◽

Malignant Cell ◽

Lymphoid Cells ◽

Growth Property ◽

B Lymphoid ◽

A Minor

Recently, a minor subpopulation of murine B lymphocytes, Ly-1+ B cells, has been distinguished by its unique ontogeny, tissue distribution, and prominence in certain autoimmune and neoplastic B cell diseases. We have previously described a simple murine spleen culture system that results in the spontaneous and exclusive outgrowth of long-term Ly-1+ B cell lines (B Ly-1 cells). Here, we report that the immortal growth property of B Ly-1 cells correlates with a 10-45-fold elevation of steady-state myc RNA and 2-10-fold amplification of the c-myc locus. While c-myc amplification has been observed in malignant cell lines derived from several tissues of origin, its occurrence in lymphoid cells has not been previously reported. The consistent c-myc amplification in B Ly-1 cells may reflect a unique state of this locus in the Ly-1+ B lymphocyte lineage, and contribute to the spontaneous immortalization of this B cell population in vitro, and its apparent predilection for malignant transformation in vivo.

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

Journal of Experimental Medicine ◽

10.1084/jem.20160852 ◽

2017 ◽

Vol 214 (7) ◽

pp. 2041-2058 ◽

Cited By ~ 9

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.

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