51
|
Ochiai K, Maienschein-Cline M, Simonetti G, Chen J, Rosenthal R, Brink R, Chong AS, Klein U, Dinner AR, Singh H, Sciammas R. Transcriptional regulation of germinal center B and plasma cell fates by dynamical control of IRF4. Immunity 2013; 38:918-29. [PMID: 23684984 DOI: 10.1016/j.immuni.2013.04.009] [Citation(s) in RCA: 302] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Accepted: 02/04/2013] [Indexed: 11/19/2022]
Abstract
The transcription factor IRF4 regulates immunoglobulin class switch recombination and plasma cell differentiation. Its differing concentrations appear to regulate mutually antagonistic programs of B and plasma cell gene expression. We show IRF4 to be also required for generation of germinal center (GC) B cells. Its transient expression in vivo induced the expression of key GC genes including Bcl6 and Aicda. In contrast, sustained and higher concentrations of IRF4 promoted the generation of plasma cells while antagonizing the GC fate. IRF4 cobound with the transcription factors PU.1 or BATF to Ets or AP-1 composite motifs, associated with genes involved in B cell activation and the GC response. At higher concentrations, IRF4 binding shifted to interferon sequence response motifs; these enriched for genes involved in plasma cell differentiation. Our results support a model of "kinetic control" in which signaling-induced dynamics of IRF4 in activated B cells control their cell-fate outcomes.
Collapse
Affiliation(s)
- Kyoko Ochiai
- Departments of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
52
|
Raghunandan R, Frissora FW, Muthusamy N. Modulation of Ets-1 expression in B lymphocytes is dependent on the antigen receptor-mediated activation signals and cell cycle status. Scand J Immunol 2013; 77:75-83. [PMID: 23216019 DOI: 10.1111/sji.12012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 10/29/2012] [Indexed: 01/30/2023]
Abstract
In this report, we tested the hypothesis that Ets-1 transcription factor is modulated at the mRNA level during B cell antigen receptor (BCR)-induced cell-signalling events. Quiescent B cells express high levels of Ets-1 mRNA. Stimulation through the BCR results in time-dependent inhibition of Ets-1 mRNA expression in primary splenic B cells with maximal inhibition observed by 16-h post-stimulation. Inhibition of Ets-1 expression is specific to antigen receptor but not CD40-mediated activation. Antigen receptor-induced inhibition of Ets-1 mRNA can be mimicked by phorbol myristate acetate (PMA) and/or ionomycin. PMA but not ionomycin-induced inhibition of Ets-1 expression is rescued by the inhibitors of protein kinase C and MEK. Extended time-course analysis revealed a time-dependent cyclical pattern in the re-expression of Ets-1 mRNA. While resting cells revealed maximal Ets-1 mRNA expression, activation events that induced exit from G(0) /G(1) or cells blocked in early S phase exhibited decreased Ets-1 mRNA levels. Interestingly, cells arrested at late G2 or M phase of the cell cycle failed to down modulate Ets-1 mRNA expression. Overexpression of Ets-1 in 70Z/3 B cell line caused abnormal accumulation of cells in S phase associated with increased cyclin A expression. Consistent with a requirement for Ets-1 in BCR-induced cell cycle entry, splenic B cells from mice deficient in Ets-1 showed defective antigen receptor-induced DNA synthesis and S phase entry. These results suggest a critical role for Ets-1 regulation during B cell activation and cell cycle entry.
Collapse
Affiliation(s)
- R Raghunandan
- Division of Hematology, Department of Internal Medicine, The Ohio State University, Columbus, OH, USA
| | | | | |
Collapse
|
53
|
Moore AJ, Anderson MK. Dendritic cell development: a choose-your-own-adventure story. Adv Hematol 2013; 2013:949513. [PMID: 23476654 PMCID: PMC3588201 DOI: 10.1155/2013/949513] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Accepted: 12/27/2012] [Indexed: 12/13/2022] Open
Abstract
Dendritic cells (DCs) are essential components of the immune system and contribute to immune responses by activating or tolerizing T cells. DCs comprise a heterogeneous mixture of subsets that are located throughout the body and possess distinct and specialized functions. Although numerous defined precursors from the bone marrow and spleen have been identified, emerging data in the field suggests many alternative routes of DC differentiation from precursors with multilineage potential. Here, we discuss how the combinatorial expression of transcription factors can promote one DC lineage over another as well as the integration of cytokine signaling in this process.
Collapse
Affiliation(s)
- Amanda J. Moore
- Division of Biological Sciences, Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON, Canada M4N 3M5
- Department of Immunology, University of Toronto, Toronto, ON, Canada M5S 1A8
| | - Michele K. Anderson
- Division of Biological Sciences, Sunnybrook Research Institute, 2075 Bayview Avenue, Toronto, ON, Canada M4N 3M5
- Department of Immunology, University of Toronto, Toronto, ON, Canada M5S 1A8
| |
Collapse
|
54
|
|
55
|
SPIB, a novel immunohistochemical marker for human blastic plasmacytoid dendritic cell neoplasms: characterization of its expression in major hematolymphoid neoplasms. Blood 2012; 121:643-7. [PMID: 23165482 DOI: 10.1182/blood-2012-08-447599] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
SPIB is an Ets transcription factor that is expressed exclusively in mature B cells, T-cell progenitors, and plasmacytoid dendritic cells. In the present study, we developed a novel mAb against the SPIB protein and characterized its expression in major hematolymphoid neoplasms, including a series of 45 cases of blastic plasmacytoid dendritic cell (BPDC) neoplasms and their potential cutaneous mimics. We found that SPIB is expressed heterogeneously among B- and T-cell lymphoma types. Interestingly, SPIB is expressed in a large proportion of nongerminal center type DLBCLs. In cutaneous neoplasms, SPIB is overexpressed in all BPDC neoplasms, but none of its cutaneous mimics. SPIB remains overexpressed in all cases that lack 1 or 2 of the markers used for BPDC neoplasms (ie, CD4, CD56, TCL1, and CD123). We conclude that SPIB expression can be used as a tool for diagnosing BPDC neoplasms, but it needs to be tested in conjunction with the growing arsenal of markers for human plasmacytoid dendritic cells.
Collapse
|
56
|
Abstract
Plasmacytoid dendritic cells (pDCs), originating from hematopoietic progenitor cells in the BM, are a unique dendritic cell subset that can produce large amounts of type I IFNs by signaling through the nucleic acid-sensing TLR7 and TLR9 (TLR7/9). The molecular mechanisms for pDC function and development remain largely unknown. In the present study, we focused on an Ets family transcription factor, Spi-B, that is highly expressed in pDCs. Spi-B could transactivate the type I IFN promoters in synergy with IFN regulatory factor 7 (IRF-7), which is an essential transcription factor for TLR7/9-induced type I IFN production in pDCs. Spi-B-deficient pDCs and mice showed defects in TLR7/9-induced type I IFN production. Furthermore, in Spi-B-deficient mice, BM pDCs were decreased and showed attenuated expression of a set of pDC-specific genes whereas peripheral pDCs were increased; this uneven distribution was likely because of defective retainment of mature nondividing pDCs in the BM. The expression pattern of cell-surface molecules in Spi-B-deficient mice indicated the involvement of Spi-B in pDC development. The developmental defects of pDCs in Spi-B-deficient mice were more prominent in the BM than in the peripheral lymphoid organs and were intrinsic to pDCs. We conclude that Spi-B plays critical roles in pDC function and development.
Collapse
|
57
|
de Lau W, Kujala P, Schneeberger K, Middendorp S, Li VSW, Barker N, Martens A, Hofhuis F, DeKoter RP, Peters PJ, Nieuwenhuis E, Clevers H. Peyer's patch M cells derived from Lgr5(+) stem cells require SpiB and are induced by RankL in cultured "miniguts". Mol Cell Biol 2012; 32:3639-47. [PMID: 22778137 PMCID: PMC3430189 DOI: 10.1128/mcb.00434-12] [Citation(s) in RCA: 171] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2012] [Accepted: 06/30/2012] [Indexed: 01/17/2023] Open
Abstract
Peyer's patches consist of domains of specialized intestinal epithelium overlying gut-associated lymphoid tissue (GALT). Luminal antigens reach the GALT by translocation through epithelial gatekeeper cells, the so-called M cells. We recently demonstrated that all epithelial cells required for the digestive functions of the intestine are generated from Lgr5-expressing stem cells. Here, we show that M cells also derive from these crypt-based Lgr5 stem cells. The Ets family transcription factor SpiB, known to control effector functions of bone marrow-derived immune cells, is specifically expressed in M cells. In SpiB(-/-) mice, M cells are entirely absent, which occurs in a cell-autonomous fashion. It has been shown that Tnfsf11 (RankL) can induce M cell development in vivo. We show that in intestinal organoid ("minigut") cultures, stimulation with RankL induces SpiB expression within 24 h and expression of other M cell markers subsequently. We conclude that RankL-induced expression of SpiB is essential for Lgr5 stem cell-derived epithelial precursors to develop into M cells.
Collapse
Affiliation(s)
- Wim de Lau
- Hubrecht Institute for Developmental Biology and Stem Cell Research, Utrecht, and University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Pekka Kujala
- Antoni van Leeuwenhoek Hospital/Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Kerstin Schneeberger
- Department of Pediatric Gastroenterology, Wilhelmina Children's Hospital, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Sabine Middendorp
- Department of Pediatric Gastroenterology, Wilhelmina Children's Hospital, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Vivian S. W. Li
- Hubrecht Institute for Developmental Biology and Stem Cell Research, Utrecht, and University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Nick Barker
- Hubrecht Institute for Developmental Biology and Stem Cell Research, Utrecht, and University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Anton Martens
- Department of Immunology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Frans Hofhuis
- Department of Immunology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Rodney P. DeKoter
- Department of Microbiology & Immunology, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Ontario, Canada
| | - Peter J. Peters
- Antoni van Leeuwenhoek Hospital/Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Edward Nieuwenhuis
- Department of Pediatric Gastroenterology, Wilhelmina Children's Hospital, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Hans Clevers
- Hubrecht Institute for Developmental Biology and Stem Cell Research, Utrecht, and University Medical Centre Utrecht, Utrecht, The Netherlands
| |
Collapse
|
58
|
The Ets transcription factor Spi-B is essential for the differentiation of intestinal microfold cells. Nat Immunol 2012; 13:729-36. [PMID: 22706340 PMCID: PMC3704196 DOI: 10.1038/ni.2352] [Citation(s) in RCA: 146] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Accepted: 05/25/2012] [Indexed: 12/16/2022]
Abstract
Intestinal microfold cells (M cells) are an enigmatic lineage of intestinal epithelial cells that initiate mucosal immune responses through the uptake and transcytosis of luminal antigens. The mechanisms of M-cell differentiation are poorly understood, as the rarity of these cells has hampered analysis. Exogenous administration of the cytokine RANKL can synchronously activate M-cell differentiation in mice. Here we show the Ets transcription factor Spi-B was induced early during M-cell differentiation. Absence of Spi-B silenced the expression of various M-cell markers and prevented the differentiation of M cells in mice. The activation of T cells via an oral route was substantially impaired in the intestine of Spi-B-deficient (Spib(-/-)) mice. Our study demonstrates that commitment to the intestinal M-cell lineage requires Spi-B as a candidate master regulator.
Collapse
|
59
|
Zotos D, Tarlinton DM. Determining germinal centre B cell fate. Trends Immunol 2012; 33:281-8. [DOI: 10.1016/j.it.2012.04.003] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 04/03/2012] [Accepted: 04/05/2012] [Indexed: 12/13/2022]
|
60
|
Abstract
The germinal center (GC) is a unique histological structure found in peripheral lymphoid organs. GCs provide an important source of humoral immunity by generating high affinity antibodies against a pathogen. The GC response is tightly regulated during clonal expansion, immunoglobulin modification, and affinity maturation, whereas its deregulation has a detrimental effect on immune function, leading to development of diseases, such as lymphoma and autoimmunity. LRF (lymphoma/leukemia-related factor), encoded by the ZBTB7A gene, is a transcriptional repressor belonging to the POK (POZ and Krüppel)/ZBTB (zing finger and BTB) protein family. LRF was originally identified as a PLZF (promyelocytic leukemia zinc finger) homolog that physically interacts with BCL6 (B-cell lymphoma 6), whose expression is required for GC formation and associated with non-Hodgkin's lymphoma. Recently, our group demonstrated that LRF plays critical roles in regulating lymphoid lineage commitment, mature B-cell development, and the GC response via distinct mechanisms. Herein, we review POK/ZBTB protein function in lymphoid development, with particular emphasis on the role of LRF in GC B cells.
Collapse
Affiliation(s)
- Sung-Uk Lee
- Division of Hematopoietic Stem Cell and Leukemia Research, Beckman Research Institute of City of Hope, Duarte, CA, USA
- Division of Hematology, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Takahiro Maeda
- Division of Hematopoietic Stem Cell and Leukemia Research, Beckman Research Institute of City of Hope, Duarte, CA, USA
- Division of Hematology, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA
| |
Collapse
|
61
|
Pelletier AN, Guimont-Desrochers F, Ashton MP, Brodnicki TC, Lesage S. The Size of the Plasmacytoid Dendritic Cell Compartment Is a Multigenic Trait Dominated by a Locus on Mouse Chromosome 7. THE JOURNAL OF IMMUNOLOGY 2012; 188:5561-70. [DOI: 10.4049/jimmunol.1102136] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
|
62
|
Moore AJ, Sarmiento J, Mohtashami M, Braunstein M, Zúñiga-Pflücker JC, Anderson MK. Transcriptional priming of intrathymic precursors for dendritic cell development. Development 2012; 139:373-84. [PMID: 22186727 DOI: 10.1242/dev.069344] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Specialized dendritic cells (DCs) within the thymus are crucial for the deletion of autoreactive T cells. The question of whether these cells arise from intrathymic precursors with T-cell potential has been hotly debated, and the regulatory pathways and signals that direct their development remain unclear. Here, we compared the gene expression profiles of thymic DC subsets with those of four early thymic precursor subsets: early T-cell precursors (ETPs), double-negative 1c (DN1c), double-negative 1d (DN1d) and double-negative 1e (DN1e) subsets. We found that the DN1d subset expressed Spi-B, HEBCan, Ccr7 and Ccr4, similar to thymic plasmacytoid DCs, whereas the DN1e subset expressed Id2, Ccr7 and Ccr4, similar to thymic conventional DCs. The expression of Ccr7 and Ccr4 in DN1d and DN1e cells suggested that they might be able to migrate towards the medulla (low in Dll proteins) and away from the cortex (high in Dll proteins) where early T-cell development occurs. We therefore assessed the sensitivity of developing DC precursors to Dll-Notch signaling, and found that high levels of Dll1 or Dll4 were inhibitory to DC development, whereas medium levels of Dll4 allowed DC development but not myeloid development. To evaluate directly the lineage potential of the ETP, DN1d and DN1e subsets, we injected them into nonirradiated congenic hosts intrathymically or intravenously, and found that they were all able to form medullary DCs in vivo. Therefore, DN1d and DN1e cells are transcriptionally primed to home to the thymus, migrate into DC-permissive microenvironments and develop into medullary DCs.
Collapse
Affiliation(s)
- Amanda J Moore
- Sunnybrook Research Institute, Division of Biological Sciences, Toronto, Ontario, M4N 3M5, Canada
| | | | | | | | | | | |
Collapse
|
63
|
Tan LHC, Tan SY, Tang T, Lim ST, Tan D, Lim LC, Kam GLS, Loh TP, Tao M, Koay ESC. Angioimmunoblastic T-cell lymphoma with hyperplastic germinal centres (pattern 1) shows superior survival to patterns 2 and 3: a meta-analysis of 56 cases. Histopathology 2012; 60:570-85. [DOI: 10.1111/j.1365-2559.2011.04097.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
|
64
|
Abstract
The mechanisms that drive normal B cell differentiation and activation are frequently subverted by B cell lymphomas for their unlimited growth and survival. B cells are particularly prone to malignant transformation because the machinery used for antibody diversification can cause chromosomal translocations and oncogenic mutations. The advent of functional and structural genomics has greatly accelerated our understanding of oncogenic mechanisms in lymphomagenesis. The signaling pathways that normal B cells utilize to sense antigens are frequently derailed in B cell malignancies, leading to constitutive activation of prosurvival pathways. These malignancies co-opt transcriptional regulatory systems that characterize their normal B cell counterparts and frequently alter epigenetic regulators of chromatin structure and gene expression. These mechanistic insights are ushering in an era of targeted therapies for these cancers based on the principles of pathogenesis.
Collapse
Affiliation(s)
- Arthur L Shaffer
- Metabolism Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | | | | |
Collapse
|
65
|
Hollenhorst PC, McIntosh LP, Graves BJ. Genomic and biochemical insights into the specificity of ETS transcription factors. Annu Rev Biochem 2011; 80:437-71. [PMID: 21548782 DOI: 10.1146/annurev.biochem.79.081507.103945] [Citation(s) in RCA: 373] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
ETS proteins are a group of evolutionarily related, DNA-binding transcriptional factors. These proteins direct gene expression in diverse normal and disease states by binding to specific promoters and enhancers and facilitating assembly of other components of the transcriptional machinery. The highly conserved DNA-binding ETS domain defines the family and is responsible for specific recognition of a common sequence motif, 5'-GGA(A/T)-3'. Attaining specificity for biological regulation in such a family is thus a conundrum. We present the current knowledge of routes to functional diversity and DNA binding specificity, including divergent properties of the conserved ETS and PNT domains, the involvement of flanking structured and unstructured regions appended to these dynamic domains, posttranslational modifications, and protein partnerships with other DNA-binding proteins and coregulators. The review emphasizes recent advances from biochemical and biophysical approaches, as well as insights from genomic studies that detect ETS-factor occupancy in living cells.
Collapse
Affiliation(s)
- Peter C Hollenhorst
- Medical Sciences, Indiana University School of Medicine, Bloomington, Indiana 47405, USA.
| | | | | |
Collapse
|
66
|
Deletion of genes encoding PU.1 and Spi-B in B cells impairs differentiation and induces pre-B cell acute lymphoblastic leukemia. Blood 2011; 118:2801-8. [PMID: 21768304 DOI: 10.1182/blood-2011-02-335539] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The E26 transformation-specific (Ets) transcription factor PU.1 is required to generate lymphoid progenitor cells from hematopoietic stem cells, but it is not required to generate B cells from committed B-cell lineage progenitors. We hypothesized that PU.1 function in B-cell differentiation is complemented by the related Ets transcription factor Spi-B. To test this hypothesis, mice were generated lacking both PU.1 and Spi-B in the B-cell lineage. Unlike mice lacking PU.1 or Spi-B, mice deficient in both PU.1 and Spi-B in the B-cell lineage had reduced frequencies of B cells as well as impaired B-cell differentiation. Strikingly, all PU.1 and Spi-B-deficient mice developed pre-B cell acute lymphoblastic leukemia before 30 weeks of age. Pre-B cells accumulated in the thymus resulting in massive thymic enlargement and dyspnea. These findings demonstrate that PU.1 and Spi-B are essential transcriptional regulators of B-cell differentiation as well as novel tumor suppressors in the B-cell lineage.
Collapse
|
67
|
Sakurai N, Maeda M, Lee SU, Ishikawa Y, Li M, Williams JC, Wang L, Su L, Suzuki M, Saito TI, Chiba S, Casola S, Yagita H, Teruya-Feldstein J, Tsuzuki S, Bhatia R, Maeda T. The LRF transcription factor regulates mature B cell development and the germinal center response in mice. J Clin Invest 2011; 121:2583-98. [PMID: 21646720 DOI: 10.1172/jci45682] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Accepted: 04/13/2011] [Indexed: 12/19/2022] Open
Abstract
B cells play a central role in immune system function. Deregulation of normal B cell maturation can lead to the development of autoimmune syndromes as well as B cell malignancies. Elucidation of the molecular features of normal B cell development is important for the development of new target therapies for autoimmune diseases and B cell malignancies. Employing B cell-specific conditional knockout mice, we have demonstrated here that the transcription factor leukemia/lymphoma-related factor (LRF) forms an obligate dimer in B cells and regulates mature B cell lineage fate and humoral immune responses via distinctive mechanisms. Moreover, LRF inactivation in transformed B cells attenuated their growth rate. These studies identify what we believe to be a new key factor for mature B cell development and provide a rationale for targeting LRF dimers for the treatment of autoimmune diseases and B cell malignancies.
Collapse
Affiliation(s)
- Nagisa Sakurai
- Division of Hematopoietic Stem Cell and Leukemia Research, Beckman Research Institute of City of Hope, Duarte, California 91010, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
68
|
Abstract
Understanding the diversification of dendritic cell (DC) lineages is one of the last frontiers in mapping the developmental hierarchy of the hematopoietic system. DCs are a vital link between the innate and adaptive immune responses; thus, elucidating their developmental pathways is crucial for insight into the generation of natural immunity and for learning how to regulate DCs in clinical settings. DCs arise from hematopoietic stem cells through specialized progenitor subsets under the direction of FMS-like tyrosine kinase 3 ligand (Flt3L) and Flt3L receptor (Flt3) signaling. Recent studies have revealed important contributions from granulocyte-macrophage colony-stimulating factor (GM-CSF) and type I interferons (IFNs) in vivo. Furthermore, DC development is guided by lineage-restricted transcription factors such as IRF8, E2-2, and Batf3. A critical question centers on how cytokines and lineage-restricted transcription factors operate molecularly to direct DC diversification. Here, we review recent findings that provide new insight into the DC developmental process.
Collapse
Affiliation(s)
- Stephanie S Watowich
- Department of Immunology and Center for Cancer Immunology Research, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA.
| | | |
Collapse
|
69
|
Abstract
The understanding of the molecular pathogenesis of non-Hodgkin's lymphomas (NHL) has significantly improved in recent years. Advances in molecular biology and genetics lead to the identification and characterization of several oncogenic pathways involved in lymphomagenesis. This knowledge will ultimately lead to improved diagnostic and therapeutic strategies for patients with NHL. This review summarizes current concepts of the molecular pathogenesis of the most common NHL subtypes, with a special emphasis on diffuse large B-cell lymphoma, the most common lymphoma subtype.
Collapse
Affiliation(s)
- Hendrik Nogai
- Department of Hematology, Oncology and Tumor Immunology, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, Am Forum 4, Berlin 13353, Germany
| | | | | |
Collapse
|
70
|
Franke A, Niederfellner GJ, Klein C, Burtscher H. Antibodies against CD20 or B-cell receptor induce similar transcription patterns in human lymphoma cell lines. PLoS One 2011; 6:e16596. [PMID: 21364752 PMCID: PMC3041769 DOI: 10.1371/journal.pone.0016596] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Accepted: 01/05/2011] [Indexed: 11/19/2022] Open
Abstract
Background CD20 is a cell surface protein exclusively expressed on B cells. It is a clinically validated target for Non-Hodgkin's lymphomas (NHL) and autoimmune diseases. The B cell receptor (BCR) plays an important role for development and proliferation of pre-B and B cells. Physical interaction of CD20 with BCR and components of the BCR signaling cascade has been reported but the consequences are not fully understood. Methodology In this study we employed antibodies against CD20 and against the BCR to trigger the respective signaling. These antibodies induced very similar expression patterns of up- and down-regulated genes in NHL cell lines indicating that CD20 may play a role in BCR signaling and vice versa. Two of the genes that were rapidly and transiently induced by both stimuli are CCL3 and CCL4. 4 hours after stimulation the concentration of these chemokines in culture medium reaches a maximum. Spleen tyrosine kinase Syk is a cytoplasmic tyrosine kinase and a key component of BCR signaling. Both siRNA mediated silencing of Syk and inhibition by selective small molecule inhibitors impaired CCL3/CCL4 protein induction after treatment with either anti-CD20 or anti-BCR antibodies. Conclusion Our results suggest that treatment with anti-CD20 antibodies triggers at least partially a BCR activation-like response in NHL cell lines.
Collapse
MESH Headings
- Antibodies/pharmacology
- Antibodies, Monoclonal, Murine-Derived/pharmacology
- Antigens, CD20/immunology
- Cell Line, Tumor
- Cluster Analysis
- Gene Expression Profiling
- Gene Expression Regulation, Neoplastic/drug effects
- Gene Regulatory Networks/drug effects
- Humans
- Immunoglobulin G/pharmacology
- Immunoglobulin M/pharmacology
- Lymphoma, Non-Hodgkin/genetics
- Lymphoma, Non-Hodgkin/metabolism
- Lymphoma, Non-Hodgkin/pathology
- Microarray Analysis
- Receptors, Antigen, B-Cell/antagonists & inhibitors
- Receptors, Antigen, B-Cell/immunology
- Rituximab
- Transcription, Genetic/drug effects
- Up-Regulation/drug effects
Collapse
Affiliation(s)
- Andreas Franke
- Pharma Research and Early Development, Roche Diagnostics GmbH, Penzberg, Germany
| | | | | | | |
Collapse
|
71
|
Vinuesa CG, Linterman MA, Goodnow CC, Randall KL. T cells and follicular dendritic cells in germinal center B-cell formation and selection. Immunol Rev 2010; 237:72-89. [PMID: 20727030 DOI: 10.1111/j.1600-065x.2010.00937.x] [Citation(s) in RCA: 206] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Germinal centers (GCs) are specialized microenvironments formed after infection where activated B cells can mutate their B-cell receptors to undergo affinity maturation. A stringent process of selection allows high affinity, non-self-reactive B cells to become long-lived memory B cells and plasma cells. While the precise mechanism of selection is still poorly understood, the last decade has advanced our understanding of the role of T cells and follicular dendritic cells (FDCs) in GC B-cell formation and selection. T cells and non-T-cell-derived CD40 ligands on FDCs are essential for T-dependent (TD) and T-independent GC formation, respectively. TD-GC formation requires Bcl-6-expressing T cells capable of signaling through SAP, which promotes formation of stable T:B conjugates. By contrast, differentiation of B blasts along the extrafollicular pathway is less dependent on SAP. T-follicular helper (Tfh) cell-derived CD40L, interleukin-21, and interleukin-4 play important roles in GC B-cell proliferation, survival, and affinity maturation. A role for FDC-derived integrin signals has also emerged: GC B cells capable of forming an immune synapse with FDCs have a survival advantage. This emerges as a powerful mechanism to ensure death of B cells that bind self-reactive antigen, which would not normally be presented on FDCs.
Collapse
Affiliation(s)
- Carola G Vinuesa
- John Curtin School of Medical Research and Australian Phenomics Facility, Australian National University, Canberra, ACT, Australia.
| | | | | | | |
Collapse
|
72
|
Noxa mediates p18INK4c cell-cycle control of homeostasis in B cells and plasma cell precursors. Blood 2010; 117:2179-88. [PMID: 21163929 DOI: 10.1182/blood-2010-06-288027] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Inhibition of Cdk4/Cdk6 by p18(INK4c) (p18) is pivotal for generation of noncycling immunoglobulin (Ig)-secreting plasma cells (PCs). In the absence of p18, CD138(+) plasmacytoid cells continue to cycle and turnover rapidly, suggesting that p18 controls PC homeostasis. We now show that p18 selectively acts in a rare population of rapidly cycling CD138(hi)/B220(hi) intermediate PCs (iPCs). While retaining certain B-cell signatures, iPCs are poised to differentiate to end-stage PCs although the majority undergo apoptosis. p18 is dispensable for the development of the PC transcriptional circuitry, and Blimp-1 and Bcl-6 are expressed fully and mutually exclusively in individual iPCs. However, a minor proportion of iPCs express both, and they are preferentially protected by p18 or Bcl-xL overexpression, consistent with expansion of the iPC pool by Bcl-xL overexpression, or loss of proapoptotic Bim or Noxa. Expression of Noxa is induced during B-cell activation, peaks in iPCs, and selectively repressed by p18. It is required to promote apoptosis of cycling B cells, especially in the absence of p18. These findings define the first physiologic function for Noxa and suggest that by repressing Noxa, induction of G₁ arrest by p18 bypasses a homeostatic cell-cycle checkpoint in iPCs for PC differentiation.
Collapse
|
73
|
DeKoter RP, Geadah M, Khoosal S, Xu LS, Thillainadesan G, Torchia J, Chin SS, Garrett-Sinha LA. Regulation of Follicular B Cell Differentiation by the Related E26 Transformation-Specific Transcription Factors PU.1, Spi-B, and Spi-C. THE JOURNAL OF IMMUNOLOGY 2010; 185:7374-84. [DOI: 10.4049/jimmunol.1001413] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
|
74
|
Marshall LJ, Dunham L, Major EO. Transcription factor Spi-B binds unique sequences present in the tandem repeat promoter/enhancer of JC virus and supports viral activity. J Gen Virol 2010; 91:3042-52. [PMID: 20826618 PMCID: PMC3052566 DOI: 10.1099/vir.0.023184-0] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Progressive multifocal leukoencephalopathy (PML) is an often fatal demyelinating disease caused by lytic infection of oligodendrocytes with JC virus (JCV). The development of PML in non-immunosuppressed individuals is a growing concern with reports of mortality in patients treated with mAb therapies. JCV can persist in the kidneys, lymphoid tissue and bone marrow. JCV gene expression is restricted by non-coding viral regulatory region sequence variation and cellular transcription factors. Because JCV latency has been associated with cells undergoing haematopoietic development, transcription factors previously reported as lymphoid specific may regulate JCV gene expression. This study demonstrates that one such transcription factor, Spi-B, binds to sequences present in the JCV promoter/enhancer and may affect early virus gene expression in cells obtained from human brain tissue. We identified four potential Spi-B-binding sites present in the promoter/enhancer elements of JCV sequences from PML variants and the non-pathogenic archetype. Spi-B sites present in the promoter/enhancers of PML variants alone bound protein expressed in JCV susceptible brain and lymphoid-derived cell lines by electromobility shift assays. Expression of exogenous Spi-B in semi- and non-permissive cells increased early viral gene expression. Strikingly, mutation of the Spi-B core in a binding site unique to the Mad-4 variant was sufficient to abrogate viral activity in progenitor-derived astrocytes. These results suggest that Spi-B could regulate JCV gene expression in susceptible cells, and may play an important role in JCV activity in the immune and nervous systems.
Collapse
Affiliation(s)
- Leslie J Marshall
- Laboratory of Molecular Medicine and Neuroscience, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892-1296, USA
| | | | | |
Collapse
|
75
|
Sahoo D, Seita J, Bhattacharya D, Inlay MA, Weissman IL, Plevritis SK, Dill DL. MiDReG: a method of mining developmentally regulated genes using Boolean implications. Proc Natl Acad Sci U S A 2010; 107:5732-7. [PMID: 20231483 PMCID: PMC2851930 DOI: 10.1073/pnas.0913635107] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
We present a method termed mining developmentally regulated genes (MiDReG) to predict genes whose expression is either activated or repressed as precursor cells differentiate. MiDReG does not require gene expression data from intermediate stages of development. MiDReG is based on the gene expression patterns between the initial and terminal stages of the differentiation pathway, coupled with "if-then" rules (Boolean implications) mined from large-scale microarray databases. MiDReG uses two gene expression-based seed conditions that mark the initial and the terminal stages of a given differentiation pathway and combines the statistically inferred Boolean implications from these seed conditions to identify the relevant genes. The method was validated by applying it to B-cell development. The algorithm predicted 62 genes that are expressed after the KIT+ progenitor cell stage and remain expressed through CD19+ and AICDA+ germinal center B cells. qRT-PCR of 14 of these genes on sorted B-cell progenitors confirmed that the expression of 10 genes is indeed stably established during B-cell differentiation. Review of the published literature of knockout mice revealed that of the predicted genes, 63.4% have defects in B-cell differentiation and function and 22% have a role in the B cell according to other experiments, and the remaining 14.6% are not characterized. Therefore, our method identified novel gene candidates for future examination of their role in B-cell development. These data demonstrate the power of MiDReG in predicting functionally important intermediate genes in a given developmental pathway that is defined by a mutually exclusive gene expression pattern.
Collapse
Affiliation(s)
- Debashis Sahoo
- Department of Electrical Engineering, Stanford University, Stanford, CA, 94305
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, CA, 94305
| | - Jun Seita
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, CA, 94305
| | - Deepta Bhattacharya
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, CA, 94305
| | - Matthew A. Inlay
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, CA, 94305
| | - Irving L. Weissman
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, CA, 94305
| | | | - David L. Dill
- Department of Computer Science, Stanford University, CA, 94305
| |
Collapse
|
76
|
Mice deficient for CD137 ligand are predisposed to develop germinal center–derived B-cell lymphoma. Blood 2009; 114:2280-9. [DOI: 10.1182/blood-2009-03-208215] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Abstract
In the germinal center (GC), B cells proliferate dramatically and diversify their immunoglobulin genes, which increases the risk of malignant transformation. The GC B-cell reaction relies on crosstalk with follicular dendritic cells (FDCs), to which the costimulatory receptor CD137 on FDCs and its ligand on GC B cells potentially contribute. We report that mice deficient for CD137 ligand (CD137L) are predisposed to develop B-cell lymphoma, with an incidence of approximately 60% at 12 months of age. Lymphoma membrane markers were characteristic of GC B cells. Longitudinal histologic analysis identified the GC as site of oncogenic transformation and classified 85% of the malignancies found in approximately 200 mice as GC-derived B-cell lymphoma. To delineate the mechanism underlying lymphomagenesis, gene expression profiles of wild-type and CD137L-deficient GC B cells were compared. CD137L deficiency was associated with enhanced expression of a limited gene set that included Bcl-10 and the GC response regulators Bcl-6, Spi-B, Elf-1, Bach2, and activation-induced cytidine deaminase. Among these are proto-oncogenes that mediate GC B-cell lymphoma development in humans. We conclude that CD137L ordinarily regulates the GC B-cell response and thereby acts as a tumor suppressor.
Collapse
|
77
|
Schmidlin H, Diehl SA, Blom B. New insights into the regulation of human B-cell differentiation. Trends Immunol 2009; 30:277-85. [PMID: 19447676 DOI: 10.1016/j.it.2009.03.008] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2009] [Revised: 03/25/2009] [Accepted: 03/26/2009] [Indexed: 10/20/2022]
Abstract
B lymphocytes provide the cellular basis of the humoral immune response. All stages of this process, from B-cell activation to formation of germinal centers and differentiation into memory B cells or plasma cells, are influenced by extrinsic signals and controlled by transcriptional regulation. Compared to naïve B cells, memory B cells display a distinct expression profile, which allows for their rapid secondary responses. Indisputably, many B-cell malignancies result from aberrations in the circuitry controlling B-cell function, particularly during the germinal centre (GC) reaction. Here, we review new insights into memory B-cell subtypes, recent literature on transcription factors regulating human B-cell differentiation and further evidence for B-cell lymphomagenesis emanating from errors during GC cell reactions.
Collapse
Affiliation(s)
- Heike Schmidlin
- Department of Cell Biology and Histology, Academic Medical Center, University of Amsterdam, The Netherlands
| | | | | |
Collapse
|
78
|
Kok K, Nock GE, Verrall EAG, Mitchell MP, Hommes DW, Peppelenbosch MP, Vanhaesebroeck B. Regulation of p110delta PI 3-kinase gene expression. PLoS One 2009; 4:e5145. [PMID: 19357769 PMCID: PMC2663053 DOI: 10.1371/journal.pone.0005145] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2008] [Accepted: 02/19/2009] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Despite an intense interest in the biological functions of the phosphoinositide 3-kinase (PI3K) signalling enzymes, little is known about the regulation of PI3K gene expression. This also applies to the leukocyte-enriched p110delta catalytic subunit of PI3K, an enzyme that has attracted widespread interest because of its role in immunity and allergy. PRINCIPAL FINDINGS We show that p110delta expression is mainly regulated at the transcriptional level. In fibroblasts, lymphocytes and myeloid cells, p110delta gene transcription appears to be constitutive and not subject to acute stimulation. 5'RACE experiments revealed that p110delta mRNA transcripts contain distinct upstream untranslated exons (named exon -1, -2a, -2b, -2c and -2d), which are located up to 81 kb upstream of the translational start codon in exon 1. The levels of all the different p110delta transcripts are higher in leukocytes compared to non-leukocytes, with the p110delta transcript containing exon -2a most abundantly expressed. We have identified a highly conserved transcription factor (TF) binding cluster in the p110delta gene which has enhanced promoter activity in leukocytes compared to non-leukocytes. In human, this TF cluster is located immediately upstream of exon -2a whilst in mouse, it is located within exon -2a. CONCLUSION This study identifies a conserved PIK3CD promoter region that may account for the predominant leukocyte expression of p110delta.
Collapse
Affiliation(s)
- Klaartje Kok
- Centre for Cell Signalling, Institute of Cancer, Queen Mary University of London, Charterhouse Square, London, United Kingdom
- Department of Cell Biology, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands
| | - Gemma E. Nock
- Centre for Cell Signalling, Institute of Cancer, Queen Mary University of London, Charterhouse Square, London, United Kingdom
| | - Elizabeth A. G. Verrall
- Centre for Cell Signalling, Institute of Cancer, Queen Mary University of London, Charterhouse Square, London, United Kingdom
| | - Michael P. Mitchell
- Bioinformatics and Biostatistics, Cancer Research UK London Research Institute, London, United Kingdom
| | - Daan W. Hommes
- Department of Gastroenterology and Hepatology; Leiden University Medical Centre, Leiden, The Netherlands
| | - Maikel P. Peppelenbosch
- Department of Cell Biology, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands
| | - Bart Vanhaesebroeck
- Centre for Cell Signalling, Institute of Cancer, Queen Mary University of London, Charterhouse Square, London, United Kingdom
| |
Collapse
|
79
|
Bordon A, Bosco N, Du Roure C, Bartholdy B, Kohler H, Matthias G, Rolink AG, Matthias P. Enforced expression of the transcriptional coactivator OBF1 impairs B cell differentiation at the earliest stage of development. PLoS One 2008; 3:e4007. [PMID: 19104664 PMCID: PMC2603323 DOI: 10.1371/journal.pone.0004007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2008] [Accepted: 11/19/2008] [Indexed: 02/06/2023] Open
Abstract
OBF1, also known as Bob.1 or OCA-B, is a B lymphocyte-specific transcription factor which coactivates Oct1 and Oct2 on B cell specific promoters. So far, the function of OBF1 has been mainly identified in late stage B cell populations. The central defect of OBF1 deficient mice is a severely reduced immune response to T cell-dependent antigens and a lack of germinal center formation in the spleen. Relatively little is known about a potential function of OBF1 in developing B cells. Here we have generated transgenic mice overexpressing OBF1 in B cells under the control of the immunoglobulin heavy chain promoter and enhancer. Surprisingly, these mice have greatly reduced numbers of follicular B cells in the periphery and have a compromised immune response. Furthermore, B cell differentiation is impaired at an early stage in the bone marrow: a first block is observed during B cell commitment and a second differentiation block is seen at the large preB2 cell stage. The cells that succeed to escape the block and to differentiate into mature B cells have post-translationally downregulated the expression of transgene, indicating that expression of OBF1 beyond the normal level early in B cell development is deleterious. Transcriptome analysis identified genes deregulated in these mice and Id2 and Id3, two known negative regulators of B cell differentiation, were found to be upregulated in the EPLM and preB cells of the transgenic mice. Furthermore, the Id2 and Id3 promoters contain octamer-like sites, to which OBF1 can bind. These results provide evidence that tight regulation of OBF1 expression in early B cells is essential to allow efficient B lymphocyte differentiation.
Collapse
Affiliation(s)
- Alain Bordon
- Friedrich Miescher Institute for Biomedical Research, Novartis Research Foundation, Basel, Switzerland
| | | | | | | | | | | | | | | |
Collapse
|
80
|
Role for Spi-C in the development of red pulp macrophages and splenic iron homeostasis. Nature 2008; 457:318-21. [PMID: 19037245 PMCID: PMC2756102 DOI: 10.1038/nature07472] [Citation(s) in RCA: 327] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2008] [Accepted: 09/30/2008] [Indexed: 12/27/2022]
Abstract
Tissue macrophages comprise a heterogeneous group of cell types differing in location, surface markers and function1. Red pulp macrophages are a distinct splenic subset involved in removing senescent red blood cells2. Transcription factors such as PU.1 and C/EBPα play general roles in myelomonocytic development3,4, but the transcriptional basis for producing tissue macrophage subsets remains unknown. Here we show that Spi-C, a PU.1 related transcription factor, selectively controls the development of red pulp macrophages. Spi-C is highly expressed in red pulp macrophages, but not monocytes, dendritic cells or other tissue macrophages. Spi-C−/− mice exhibit a cell-autonomous defect in the development of red pulp macrophages that is corrected by retroviral Spi-C expression in bone marrow cells, but have normal monocyte and other macrophage subsets. Red pulp macrophages highly express genes involved in capturing circulating hemoglobin and iron regulation. Spi-C−/− mice show normal trapping of red blood cells in the spleen, but fail to phagocytose these red blood cells efficiently, and develop an iron overload localized selectively to splenic red pulp. Thus, Spi-C controls development of red pulp macrophages required for red blood cell recycling and iron homeostasis.
Collapse
|
81
|
Zhu X, Schweitzer BL, Romer EJ, Sulentic CEW, DeKoter RP. Transgenic expression of Spi-C impairs B-cell development and function by affecting genes associated with BCR signaling. Eur J Immunol 2008; 38:2587-99. [PMID: 18792411 DOI: 10.1002/eji.200838323] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Spi-C is an Ets family transcription factor closely related to PU.1 and Spi-B. Expression of Spi-C is developmentally regulated in the B-cell lineage, but its function remains unknown. To determine the function of Spi-C in B-cell development, we generated mice expressing a B-cell-specific Spi-C transgene under the control of the IgH intronic enhancer. Spi-C transgenic mice had 50% fewer B cells than wild-type littermates. Flow cytometric analyses showed that splenic transitional B cells and bone marrow pre-B or immature B cells from transgenic mice were dramatically reduced compared with those of wild type. Both nonspecific and Ag-specific serum IgM levels were significantly increased in transgenic mice, while serum IgG levels were significantly decreased compared with wild type. Spi-C transgenic B cells proliferated poorly after stimulation by anti-IgM or anti-CD40 in vitro, although they responded normally to LPS stimulation. Using real-time RT-PCR, we found that several BCR signaling-related mediators were downregulated at pre-B-cell and mature B-cell stages in transgenic mice, while an inhibitor of BCR signaling was upregulated. Taken together, these data indicate that ectopic expression of Spi-C can impair B-cell development and function by affecting genes associated with BCR signaling.
Collapse
Affiliation(s)
- Xiang Zhu
- Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0524, USA
| | | | | | | | | |
Collapse
|
82
|
Molecular subtypes of diffuse large B-cell lymphoma arise by distinct genetic pathways. Proc Natl Acad Sci U S A 2008; 105:13520-5. [PMID: 18765795 DOI: 10.1073/pnas.0804295105] [Citation(s) in RCA: 733] [Impact Index Per Article: 45.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Gene-expression profiling has been used to define 3 molecular subtypes of diffuse large B-cell lymphoma (DLBCL), termed germinal center B-cell-like (GCB) DLBCL, activated B-cell-like (ABC) DLBCL, and primary mediastinal B-cell lymphoma (PMBL). To investigate whether these DLBCL subtypes arise by distinct pathogenetic mechanisms, we analyzed 203 DLBCL biopsy samples by high-resolution, genome-wide copy number analysis coupled with gene-expression profiling. Of 272 recurrent chromosomal aberrations that were associated with gene-expression alterations, 30 were used differentially by the DLBCL subtypes (P < 0.006). An amplicon on chromosome 19 was detected in 26% of ABC DLBCLs but in only 3% of GCB DLBCLs and PMBLs. A highly up-regulated gene in this amplicon was SPIB, which encodes an ETS family transcription factor. Knockdown of SPIB by RNA interference was toxic to ABC DLBCL cell lines but not to GCB DLBCL, PMBL, or myeloma cell lines, strongly implicating SPIB as an oncogene involved in the pathogenesis of ABC DLBCL. Deletion of the INK4a/ARF tumor suppressor locus and trisomy 3 also occurred almost exclusively in ABC DLBCLs and was associated with inferior outcome within this subtype. FOXP1 emerged as a potential oncogene in ABC DLBCL that was up-regulated by trisomy 3 and by more focal high-level amplifications. In GCB DLBCL, amplification of the oncogenic mir-17-92 microRNA cluster and deletion of the tumor suppressor PTEN were recurrent, but these events did not occur in ABC DLBCL. Together, these data provide genetic evidence that the DLBCL subtypes are distinct diseases that use different oncogenic pathways.
Collapse
|
83
|
Abstract
Vertebrate blood formation occurs in 2 spatially and temporally distinct waves, so-called primitive and definitive hematopoiesis. Although definitive hematopoiesis has been extensively studied, the development of primitive myeloid blood has received far less attention. In Xenopus, primitive myeloid cells originate in the anterior ventral blood islands, the equivalent of the mammalian yolk sac, and migrate out to colonize the embryo. Using fluorescence time-lapse video microscopy, we recorded the migratory behavior of primitive myeloid cells from their birth. We show that these cells are the first blood cells to differentiate in the embryo and that they are efficiently recruited to embryonic wounds, well before the establishment of a functional vasculature. Furthermore, we isolated spib, an ETS transcription factor, specifically expressed in primitive myeloid precursors. Using spib antisense morpholino knockdown experiments, we show that spib is required for myeloid specification, and, in its absence, primitive myeloid cells retain hemangioblast-like characteristics and fail to migrate. Thus, we conclude that spib sits at the top of the known genetic hierarchy that leads to the specification of primitive myeloid cells in amphibians.
Collapse
|
84
|
Spi-B inhibits human plasma cell differentiation by repressing BLIMP1 and XBP-1 expression. Blood 2008; 112:1804-12. [PMID: 18552212 DOI: 10.1182/blood-2008-01-136440] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The terminal differentiation of B cells into antibody-secreting plasma cells is tightly regulated by a complex network of transcription factors. Here we evaluated the role of the Ets factor Spi-B during terminal differentiation of human B cells. All mature tonsil and peripheral blood B-cell subsets expressed Spi-B, with the exception of plasma cells. Overexpression of Spi-B in CD19(+) B cells inhibited, similar to the known inhibitor BCL-6, the expression of plasma cell-associated surface markers and transcription factors as well as immunoglobulin production, ie, in vitro plasma cell differentiation. The arrest in B-cell differentiation enforced by Spi-B was independent of the transactivation domain, but dependent on the Ets-domain. By chromatin immunoprecipitation and assays using an inducible Spi-B construct BLIMP1 and XBP-1 were identified as direct target genes of Spi-B mediated repression. We propose a novel role for Spi-B in maintenance of germinal center and memory B cells by direct repression of major plasma cell factors and thereby plasma cell differentiation.
Collapse
|
85
|
Klein U, Dalla-Favera R. Germinal centres: role in B-cell physiology and malignancy. Nat Rev Immunol 2008; 8:22-33. [PMID: 18097447 DOI: 10.1038/nri2217] [Citation(s) in RCA: 605] [Impact Index Per Article: 37.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Over the past several years, studies on normal and malignant B cells have provided new insights into the unique physiology of the germinal centre (GC). In particular, advances in technology have allowed a more precise dissection of the phenotypes of GC B cells and the specific transcriptional programmes that are responsible for this phenotype. Furthermore, substantial progress has been made in the understanding of the mechanism controlling the exit of B cells from the GC and the decision to become a memory B cell or plasma cell. This Review focuses on these recent advances and discusses their implications for the pathogenesis of B-cell lymphomas.
Collapse
Affiliation(s)
- Ulf Klein
- Institute for Cancer Genetics, Departments of Pathology and Genetics & Development, and Herbert Irving Comprehensive Cancer Center, Columbia University, 1130 St Nicholas Avenue, New York, New York 10032, USA
| | | |
Collapse
|
86
|
Schebesta A, McManus S, Salvagiotto G, Delogu A, Busslinger GA, Busslinger M. Transcription factor Pax5 activates the chromatin of key genes involved in B cell signaling, adhesion, migration, and immune function. Immunity 2007; 27:49-63. [PMID: 17658281 DOI: 10.1016/j.immuni.2007.05.019] [Citation(s) in RCA: 201] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2007] [Revised: 05/21/2007] [Accepted: 05/24/2007] [Indexed: 01/03/2023]
Abstract
The transcription factor Pax5 represses B lineage-inappropriate genes and activates B cell-specific genes in B lymphocytes. Here we have identified 170 Pax5-activated genes. Conditional mutagenesis demonstrated that the Pax5-regulated genes require continuous Pax5 activity for normal expression in pro-B and mature B cells. Expression of half of the Pax5-activated genes is either absent or substantially reduced upon Pax5 loss in plasma cells. Direct Pax5 target genes were identified based on their protein synthesis-independent activation by a Pax5-estrogen receptor fusion protein. Chromatin immunoprecipitation (ChIP) of Pax5 together with chromatin profiling by ChIP-on-chip analysis demonstrated that Pax5 directly activates the chromatin at promoters or putative enhancers of Pax5 target genes. The Pax5-activated genes code for key regulatory and structural proteins involved in B cell signaling, adhesion, migration, antigen presentation, and germinal-center B cell formation, thus revealing a complex regulatory network that is activated by Pax5 to control B cell development and function.
Collapse
Affiliation(s)
- Alexandra Schebesta
- Research Institute of Molecular Pathology, Vienna Biocenter, Dr. Bohr-Gasse 7, A-1030 Vienna, Austria
| | | | | | | | | | | |
Collapse
|
87
|
Lenz G, Nagel I, Siebert R, Roschke AV, Sanger W, Wright GW, Dave SS, Tan B, Zhao H, Rosenwald A, Muller-Hermelink HK, Gascoyne RD, Campo E, Jaffe ES, Smeland EB, Fisher RI, Kuehl WM, Chan WC, Staudt LM. Aberrant immunoglobulin class switch recombination and switch translocations in activated B cell-like diffuse large B cell lymphoma. ACTA ACUST UNITED AC 2007; 204:633-43. [PMID: 17353367 PMCID: PMC2137913 DOI: 10.1084/jem.20062041] [Citation(s) in RCA: 160] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
To elucidate the mechanisms underlying chromosomal translocations in diffuse large B cell lymphoma (DLBCL), we investigated the nature and extent of immunoglobulin class switch recombination (CSR) in these tumors. We used Southern blotting to detect legitimate and illegitimate CSR events in tumor samples of the activated B cell-like (ABC), germinal center B cell-like (GCB), and primary mediastinal B cell lymphoma (PMBL) subgroups of DLBCL. The frequency of legitimate CSR was lower in ABC DLBCL than in GCB DLBCL and PMBL. In contrast, ABC DLBCL had a higher frequency of internal deletions within the switch mu (Smu) region compared with GCB DLBCL and PMBL. ABC DLBCLs also had frequent deletions within Sgamma and other illegitimate switch recombinations. Sequence analysis revealed ongoing Smu deletions within ABC DLBCL tumor clones, which were accompanied by ongoing duplications and activation-induced cytidine deaminase-dependent somatic mutations. Unexpectedly, short fragments derived from multiple chromosomes were interspersed within Smu in one case. These findings suggest that ABC DLBCLs have abnormalities in the regulation of CSR that could predispose to chromosomal translocations. Accordingly, aberrant switch recombination was responsible for translocations in ABC DLBCLs involving BCL6, MYC, and a novel translocation partner, SPIB.
Collapse
MESH Headings
- Cell Line, Tumor
- Humans
- Immunoglobulin Class Switching/genetics
- Immunoglobulin Class Switching/immunology
- Lymphocyte Activation/genetics
- Lymphoma, B-Cell/genetics
- Lymphoma, B-Cell/immunology
- Lymphoma, B-Cell, Marginal Zone/genetics
- Lymphoma, B-Cell, Marginal Zone/immunology
- Lymphoma, Large B-Cell, Diffuse/genetics
- Lymphoma, Large B-Cell, Diffuse/immunology
- Recombination, Genetic
- Translocation, Genetic
- Tumor Cells, Cultured
Collapse
Affiliation(s)
- Georg Lenz
- Metabolism Branch, Division of Cancer Treatment and Diagnosis, National Cancer Institute (NCI), National Institutes of Health (NIH), Bethesda, MD 20892, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
88
|
Abstract
B-cell memory is provided by populations of quiescent memory B cells and long-lived plasma cells. Whereas it is clear that both of these cell populations arise from germinal centres, the signals and circumstances that trigger germinal-centre B cells to enter and then persist in memory compartments are poorly defined. Here, I propose that germinal centres produce memory B cells and plasma cells throughout the immune response and that memory B cells arise by the emigration of B cells that are chosen at random from the pool available in the germinal centre. The ability of such emigrants to survive as memory B cells depends on their germinal-centre 'history', with the persistence of high-affinity B-cell variants being favoured.
Collapse
Affiliation(s)
- David Tarlinton
- David Tarlinton is at The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3050, Australia.
| |
Collapse
|
89
|
Schweitzer BL, Huang KJ, Kamath MB, Emelyanov AV, Birshtein BK, DeKoter RP. Spi-C has opposing effects to PU.1 on gene expression in progenitor B cells. THE JOURNAL OF IMMUNOLOGY 2006; 177:2195-207. [PMID: 16887979 DOI: 10.4049/jimmunol.177.4.2195] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The Ets transcription factor Spi-C, expressed in B cells and macrophages, is closely related to PU.1 and has the ability to recognize the same DNA consensus sequence. However, the function of Spi-C has yet to be determined. The purpose of this study is to further examine Spi-C activity in B cell development. First, using retroviral vectors to infect PU.1(-/-) fetal liver progenitors, Spi-C was found to be inefficient at inducing cytokine-dependent proliferation and differentiation of progenitor B (pro-B) cells or macrophages relative to PU.1 or Spi-B. Next, Spi-C was ectopically expressed in fetal liver-derived, IL-7-dependent pro-B cell lines. Wild-type (WT) pro-B cells ectopically expressing Spi-C (WT-Spi-C) have several phenotypic characteristics of pre-B cells such as increased CD25 and decreased c-Kit surface expression. In addition, WT-Spi-C pro-B cells express increased levels of IgH sterile transcripts and reduced levels of expression and transcription of the FcgammaRIIb gene. Gel-shift analysis suggests that Spi-C, ectopically expressed in pro-B cells, can bind PU.1 consensus sites in the IgH intronic enhancer and FcgammaRIIb promoter. Transient transfection analysis demonstrated that PU.1 functions to repress the IgH intronic enhancer and activate the FcgammaRIIb promoter, while Spi-C opposes these activities. WT-Spi-C pro-B cells have reduced levels of dimethylation on lysine 9 of histone H3 within the IgH 3' regulatory region, indicating that Spi-C can contribute to removal of repressive features in the IgH locus. Overall, these studies suggest that Spi-C may promote B cell differentiation by modulating the activity of PU.1-dependent genes.
Collapse
Affiliation(s)
- Brock L Schweitzer
- Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, OH 45267, USA
| | | | | | | | | | | |
Collapse
|
90
|
Rizzo F, Fernandez-Serra M, Squarzoni P, Archimandritis A, Arnone MI. Identification and developmental expression of the ets gene family in the sea urchin (Strongylocentrotus purpuratus). Dev Biol 2006; 300:35-48. [PMID: 16997294 DOI: 10.1016/j.ydbio.2006.08.012] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2006] [Revised: 08/02/2006] [Accepted: 08/03/2006] [Indexed: 11/29/2022]
Abstract
A systematic search in the available scaffolds of the Strongylocentrotus purpuratus genome has revealed that this sea urchin has 11 members of the ets gene family. A phylogenetic analysis of these genes showed that almost all vertebrate ets subfamilies, with the exception of one, so far found only in mammals, are each represented by one orthologous sea urchin gene. The temporal and spatial expression of the identified ETS factors was also analyzed during embryogenesis. Five ets genes (Sp-Ets1/2, Sp-Tel, Sp-Pea, Sp-Ets4, Sp-Erf) are also maternally expressed. Three genes (Sp-Elk, Sp-Elf, Sp-Erf) are ubiquitously expressed during embryogenesis, while two others (Sp-Gabp, Sp-Pu.1) are not transcribed until late larval stages. Remarkably, five of the nine sea urchin ets genes expressed during embryogenesis are exclusively (Sp-Ets1/2, Sp-Erg, Sp-Ese) or additionally (Sp-Tel, Sp-Pea) expressed in mesenchyme cells and/or their progenitors. Functional analysis of Sp-Ets1/2 has previously demonstrated an essential role of this gene in the specification of the skeletogenic mesenchyme lineage. The dynamic, and in some cases overlapping and/or unique, developmental expression pattern of the latter five genes suggests a complex, non-redundant function for ETS factors in sea urchin mesenchyme formation and differentiation.
Collapse
Affiliation(s)
- Francesca Rizzo
- Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Naples, Italy
| | | | | | | | | |
Collapse
|
91
|
Bartholdy B, Du Roure C, Bordon A, Emslie D, Corcoran LM, Matthias P. The Ets factor Spi-B is a direct critical target of the coactivator OBF-1. Proc Natl Acad Sci U S A 2006; 103:11665-70. [PMID: 16861304 PMCID: PMC1513538 DOI: 10.1073/pnas.0509430103] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
OBF-1 (Bob.1, OCA-B) is a lymphoid-specific transcriptional coactivator that associates with the transcription factors Oct-1 or Oct-2 on the conserved octamer element present in the promoters of several ubiquitous and lymphoid-specific genes. OBF-1-deficient mice have B cell-intrinsic defects, lack germinal centers, and have severely impaired immune responses to T cell-dependent antigens. Crucial genes that are regulated by OBF-1 and that might explain the observed phenotype of OBF-1 deficiency have remained elusive to date. Here we have generated transgenic mice expressing OBF-1 specifically in T cells and examined these together with mice lacking OBF-1 to discover transcriptional targets of this coactivator. Using microarray analysis, we have identified the Ets transcription factor Spi-B as a direct target gene critically regulated by OBF-1 that can help explain the phenotype of OBF-1-deficient mice. Spi-B has been implicated in signaling pathways downstream of the B cell receptor and is essential for germinal center formation and maintenance. The present findings establish a hierarchy between these two factors and provide a molecular link between OBF-1 and B cell receptor signaling.
Collapse
Affiliation(s)
- Boris Bartholdy
- *Friedrich Miescher Institute for Biomedical Research, Novartis Research Foundation, Maulbeerstrasse 66, CH-4058 Basel, Switzerland; and
| | - Camille Du Roure
- *Friedrich Miescher Institute for Biomedical Research, Novartis Research Foundation, Maulbeerstrasse 66, CH-4058 Basel, Switzerland; and
| | - Alain Bordon
- *Friedrich Miescher Institute for Biomedical Research, Novartis Research Foundation, Maulbeerstrasse 66, CH-4058 Basel, Switzerland; and
| | - Dianne Emslie
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3050, Australia
| | - Lynn M. Corcoran
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3050, Australia
| | - Patrick Matthias
- *Friedrich Miescher Institute for Biomedical Research, Novartis Research Foundation, Maulbeerstrasse 66, CH-4058 Basel, Switzerland; and
- To whom correspondence should be addressed. E-mail:
| |
Collapse
|
92
|
Chen HC, Byrd JC, Muthusamy N. Differential Role for Cyclic AMP Response Element Binding Protein-1 in Multiple Stages of B Cell Development, Differentiation, and Survival. THE JOURNAL OF IMMUNOLOGY 2006; 176:2208-18. [PMID: 16455977 DOI: 10.4049/jimmunol.176.4.2208] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
CREB-1 is expressed in the bone marrow and in developing B cells. To determine the role of CREB-1 in developing B cells in the bone marrow, several lines of transgenic (Tg) mice overexpressing a dominant-negative Ser(119-ala) phosphomutant CREB-1 in the bone marrow were generated. Analysis of RNA and protein revealed expression of the transgene in the bone marrow. Flow cytometric analysis of bone marrow cells from Tg mice revealed approximately 70% increase in pre-B1 (CD43(+)B220(+)CD24(+(int))) and approximately 60% decreased pre-BII (CD43(+)B220(+)CD24(++(high))) cells, indicating a developmental block in pre-BI to pre-BII transition. Consistent with this, the Tg mice showed approximately 4-fold decrease in immature and mature B cells in the bone marrow. RT-PCR analysis of RNA from Tg mice revealed increased JunB and c-Jun in pre-BII cells associated with decreased S-phase entry. Adoptive transfer of bone marrow cells into RAG-2(-/-) mice resulted in reconstitution of non-Tg but not Tg bone marrow-derived CD43(+)B220(+)CD24(high) population that is normally absent in RAG-2(-/-) mice. In the periphery, the Tg mice exhibited decreased CD21(dim)CD23(high)IgM(+) follicular B cells in the spleen and increased B1a and B1b B cells in the peritoneum. While exhibiting normal Ab responses to T-independent Ags and primary response to the T-dependent Ag DNP-keyhole limpet hemocyanin, the Tg mice exhibited severely impaired secondary Ab responses. These studies provide the first evidence for a differential role for CRE-binding proteins in multiple stages of B cell development, functional maturation, and B1 and B2 B cells.
Collapse
Affiliation(s)
- Hui-Chen Chen
- Division of Hematology and Oncology, Department of Internal Medicine, The Ohio State University, Columbus, 43210, USA
| | | | | |
Collapse
|
93
|
van Zelm MC, van der Burg M, de Ridder D, Barendregt BH, de Haas EFE, Reinders MJT, Lankester AC, Révész T, Staal FJT, van Dongen JJM. Ig Gene Rearrangement Steps Are Initiated in Early Human Precursor B Cell Subsets and Correlate with Specific Transcription Factor Expression. THE JOURNAL OF IMMUNOLOGY 2005; 175:5912-22. [PMID: 16237084 DOI: 10.4049/jimmunol.175.9.5912] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The role of specific transcription factors in the initiation and regulation of Ig gene rearrangements has been studied extensively in mouse models, but data on normal human precursor B cell differentiation are limited. We purified five human precursor B cell subsets, and assessed and quantified their IGH, IGK, and IGL gene rearrangement patterns and gene expression profiles. Pro-B cells already massively initiate D(H)-J(H) rearrangements, which are completed with V(H)-DJ(H) rearrangements in pre-B-I cells. Large cycling pre-B-II cells are selected for in-frame IGH gene rearrangements. The first IGK/IGL gene rearrangements were initiated in pre-B-I cells, but their frequency increased enormously in small pre-B-II cells, and in-frame selection was found in immature B cells. Transcripts of the RAG1 and RAG2 genes and earlier defined transcription factors, such as E2A, early B cell factor, E2-2, PAX5, and IRF4, were specifically up-regulated at stages undergoing Ig gene rearrangements. Based on the combined Ig gene rearrangement status and gene expression profiles of consecutive precursor B cell subsets, we identified 16 candidate genes involved in initiation and/or regulation of Ig gene rearrangements. These analyses provide new insights into early human precursor B cell differentiation steps and represent an excellent template for studies on oncogenic transformation in precursor B acute lymphoblastic leukemia and B cell differentiation blocks in primary Ab deficiencies.
Collapse
Affiliation(s)
- Menno C van Zelm
- Department of Immunology, Erasmus MC, University Medical Center, Rotterdam, The Netherlands
| | | | | | | | | | | | | | | | | | | |
Collapse
|
94
|
Polli M, Dakic A, Light A, Wu L, Tarlinton DM, Nutt SL. The development of functional B lymphocytes in conditional PU.1 knock-out mice. Blood 2005; 106:2083-90. [PMID: 15933053 DOI: 10.1182/blood-2005-01-0283] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
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)
Collapse
Affiliation(s)
- Matthew Polli
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria, Australia 3050
| | | | | | | | | | | |
Collapse
|
95
|
Abstract
The developmental program that commits a hematopoietic stem cell to the B lymphocyte lineage employs transcriptional regulators to enable the assembly of an antigen receptor complex with a useful specificity and with signalling competence. Once a naive IgM+ B cell is generated, it must correctly integrate signals from the antigen receptor with those from cytokine receptors and co-receptors delivering T cell help. The B cell responds through the regulated expression of genes that implement specific cell expansion and differentiation, secretion of high levels of high-affinity antibody, and generation of long-term memory. The transcriptional regulators highlighted in this chapter are those for which genetic evidence of function in IgM+ B cells in vivo has been provided, often in the form of mutant mice generated by conventional or conditional gene targeting. A critical developmental step is the maturation of bone marrow emigrant "transitional" B cells into the mature, long-lived cells of the periphery, and a number of the transcription factors discussed here impact on this process, yielding B cells with poor mitogenic responses in vitro. For mature B cells, it is clear that not only the nature, but the duration and amplitude of an activating signal are major determinants of the transcription factor activities enlisted, and so the ultimate outcome. The current challenge is the identification of the target genes that are activated to implement the correct response, so that we may more precisely and safely manipulate B cell behavior to predictably and positively influence humoral immune responses.
Collapse
Affiliation(s)
- L M Corcoran
- The Walter and Eliza Hall Institute of Medical Research, Victoria, Australia.
| |
Collapse
|
96
|
Garrett-Sinha LA, Hou P, Wang D, Grabiner B, Araujo E, Rao S, Yun TJ, Clark EA, Simon MC, Clark MR. Spi-1 and Spi-B control the expression of the Grap2 gene in B cells. Gene 2005; 353:134-46. [PMID: 15936902 DOI: 10.1016/j.gene.2005.04.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2004] [Revised: 03/21/2005] [Accepted: 04/07/2005] [Indexed: 11/16/2022]
Abstract
The Ets family members Spi-1 and Spi-B have been implicated in the regulation of genes important for B cell antigen receptor (BCR) signaling. Mice deficient in Spi-B exhibit reduced B cell proliferation in response to BCR cross-linking and impaired T cell-dependent immune responses. This defect is exacerbated in the presence of Spi-1 haplo-insufficiency (Spi1+/- SpiB-/-). Tyrosine phosphorylation and calcium mobilization induced by BCR engagement is diminished in Spi1+/- SpiB-/- B lymphocytes, although many key BCR signaling proteins are expressed, suggesting that Spi-1 and Spi-B regulate expression of additional, unidentified signaling molecules. We now demonstrate that expression of the adaptor protein Grap2 is impaired in Spi1+/- SpiB+/- and Spi1+/- SpiB-/- B lymphocytes. Analysis of two alternate murine Grap2 promoters revealed a functionally important Spi-1 and Spi-B DNA binding element located in the downstream promoter. Ectopic expression of Grap2 in Grap2-deficient B cells reduced the recruitment of BLNK to Igalpha and the phosphorylation of specific substrates. Regulation of BLNK recruitment was dependent upon the Grap2 proline-rich domain, while modulation of phosphorylation was dependent upon both the proline-rich and SH2 domains. These data indicate that Spi-1 and Spi-B directly regulate the expression of Grap2 and that Grap2 functions to modulate BCR signaling, but that reduced Grap2 expression is unlikely to account for the BCR signaling defects observed in Spi1+/- SpiB-/- B cells.
Collapse
MESH Headings
- Adaptor Proteins, Signal Transducing/genetics
- Adaptor Proteins, Signal Transducing/metabolism
- Animals
- B-Lymphocytes/metabolism
- Base Sequence
- Binding Sites/genetics
- Blotting, Northern
- Blotting, Western
- Cell Line, Tumor
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Down-Regulation/genetics
- Electrophoretic Mobility Shift Assay
- Gene Expression/genetics
- Genotype
- Heterozygote
- Mice
- Mice, Knockout
- Molecular Sequence Data
- Mutation
- Oligonucleotides/genetics
- Oligonucleotides/metabolism
- Promoter Regions, Genetic/genetics
- Protein Binding
- Proto-Oncogene Proteins/genetics
- Proto-Oncogene Proteins/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Antigen, B-Cell/metabolism
- Sequence Alignment
- Sequence Homology, Nucleic Acid
- Signal Transduction
- Spleen/cytology
- Spleen/metabolism
- Trans-Activators/genetics
- Trans-Activators/metabolism
- Transcription Factors/genetics
- Transcription Factors/metabolism
Collapse
Affiliation(s)
- Lee Ann Garrett-Sinha
- Department of Biochemistry, State University of New York at Buffalo, 140 Farber Hall, 3435 Main Street, Buffalo, NY 14214, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
97
|
Abstract
The development of B cells from haematopoietic stem cells proceeds along a highly ordered, yet flexible, pathway. At multiple steps along this pathway, cells are instructed by transcription factors on how to further differentiate, and several check-points have been identified. These check-points are initial commitment to lymphocytic progenitors, specification of pre-B cells, entry to the peripheral B-cell pool, maturation of B cells and differentiation into plasma cells. At each of these regulatory nodes, there are transcriptional networks that control the outcome, and much progress has recently been made in dissecting these networks. This article reviews our current understanding of this exciting field.
Collapse
Affiliation(s)
- Patrick Matthias
- Friedrich Miescher Institute for Biomedical Research, Novartis Research Foundation, Maulbeerstrasse 66, 4058 Basel, Switzerland.
| | | |
Collapse
|
98
|
Lefebvre JM, Haks MC, Carleton MO, Rhodes M, Sinnathamby G, Simon MC, Eisenlohr LC, Garrett-Sinha LA, Wiest DL. Enforced Expression of Spi-B Reverses T Lineage Commitment and Blocks β-Selection. THE JOURNAL OF IMMUNOLOGY 2005; 174:6184-94. [PMID: 15879115 DOI: 10.4049/jimmunol.174.10.6184] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The molecular changes that restrict multipotent murine thymocytes to the T cell lineage and render them responsive to Ag receptor signals remain poorly understood. In this study, we report our analysis of the role of the Ets transcription factor, Spi-B, in this process. Spi-B expression is acutely induced coincident with T cell lineage commitment at the CD4(-)CD8(-)CD44(-)CD25(+) (DN3) stage of thymocyte development and is then down-regulated as thymocytes respond to pre-TCR signals and develop beyond the beta-selection checkpoint to the CD4(-)CD8(-)CD44(-)CD25(-) (DN4) stage. We found that dysregulation of Spi-B expression in DN3 thymocytes resulted in a dose-dependent perturbation of thymocyte development. Indeed, DN3 thymocytes expressing approximately five times the endogenous level of Spi-B were arrested at the beta-selection checkpoint, due to impaired induction of Egr proteins, which are important molecular effectors of the beta-selection checkpoint. T lineage-committed DN3 thymocytes expressing even higher levels of Spi-B were diverted to the dendritic cell lineage. Thus, we demonstrate that the prescribed modulation of Spi-B expression is important for T lineage commitment and differentiation beyond the beta-selection checkpoint; and we provide insight into the mechanism underlying perturbation of development when that expression pattern is disrupted.
Collapse
Affiliation(s)
- Juliette M Lefebvre
- Immunobiology Working Group, Division of Basic Sciences, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
99
|
Schotte R, Nagasawa M, Weijer K, Spits H, Blom B. The ETS transcription factor Spi-B is required for human plasmacytoid dendritic cell development. ACTA ACUST UNITED AC 2005; 200:1503-9. [PMID: 15583020 PMCID: PMC2211952 DOI: 10.1084/jem.20041231] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A number of transcription factors that act as molecular switches for hematopoietic lineage decisions have been identified. We recently described the ETS transcription factor Spi-B to be exclusively expressed in plasmacytoid dendritic cells (pDCs), but not in myeloid DCs. To assess whether Spi-B is required for pDC development we used an RNA interference knock down approach to specifically silence Spi-B protein synthesis in CD34(+) precursor cells. We observed that a knock down of Spi-B mRNA strongly inhibited the ability of CD34(+) precursor cells to develop into pDCs in both in vitro assays as well as in vivo upon injection into recombination activating gene 2(-/-) gamma common(-/-) mice. The observed effects were restricted to the pDC lineage as the differentiation of pro-B cells and CD14(+) myeloid cells was not inhibited but slightly elevated by Spi-B knock down. Knock down of the related ETS factor PU.1 also inhibited in vitro development of CD34(+) cells into pDCs. However, in contrast to Spi-B, PU.1 knock down inhibited B cell and myeloid cell development as well. These results identify Spi-B as a key regulator of human pDC development.
Collapse
Affiliation(s)
- Remko Schotte
- Department of Cell Biology and Histology, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, Netherlands
| | | | | | | | | |
Collapse
|
100
|
Steinke JW, Hodsdon W, Parenti S, Ostraat R, Lutz R, Borish L, Hagman J. Identification of an Sp factor-dependent promoter in GCET, a gene expressed at high levels in germinal center B cells. Mol Immunol 2005; 41:1145-53. [PMID: 15482850 DOI: 10.1016/j.molimm.2004.06.031] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2004] [Accepted: 06/09/2004] [Indexed: 10/26/2022]
Abstract
Antigen-stimulated B lymphocytes undergo genetic and phenotypic changes in germinal centers (GCs), including affinity maturation of immunoglobulin (Ig) genes and Ig heavy chain isotype switching. Expression of the Germinal Center Expressed Transcript (GCET) gene is up-regulated in murine GC B cells. The human homolog of GCET, HGAL/GCET2, is an important prognostic marker for staging lymphomas derived from GCs. To identify mechanisms that control cell type-specific transcription of GCET, we localized promoter sequences using S1 nuclease protection and functional assays. Sequences comprising a TATA-less promoter were localized to a short region upstream of multiple mRNA start sites. In functional assays, the promoter is active in cells irrespectively of endogenous GCET gene expression. In vitro binding assays identified a non-consensus binding site for Sp factors near sites of transcriptional initiation. The site binds Spl and Sp3 in nuclear extracts and recombinant Spl in vitro, and is required for full promoter function in transient promoter assays. Activation of the promoter by Spl or Sp3 in Spl/3-deficient cells was largely dependent on the Sp site. Together, these data provide the first analysis of regulatory modules necessary for GCET expression, a model for GC B cell-specific transcription.
Collapse
Affiliation(s)
- John W Steinke
- Allergy Division, University of Virginia Health Sciences Center, Charlottesville, VA 22908, USA
| | | | | | | | | | | | | |
Collapse
|