Papers by David Tarlinton
Evidence from the generation of immunoglobulin G–secreting cells that stochastic mechanisms regulate lymphocyte differentiation
Nature Immunology, 2004
Naive B lymphocytes undergo isotype switching and develop into immunoglobulin-secreting cells to ... more Naive B lymphocytes undergo isotype switching and develop into immunoglobulin-secreting cells to generate the appropriate class and amount of antibody necessary for effective immunity. Although this seems complex, we report here that the generation of immunoglobulin G-secreting cells from naive precursors is highly predictable. The probabilities of isotype switching and development into secreting cells change with successive cell divisions and interleave independently. Cytokines alter the probability of each differentiation event, while leaving intact their independent assortment. As a result, cellular heterogeneity arises automatically as the cells divide. Stochastic division-linked regulation of heterogeneity challenges the conventional paradigms linking distinct phenotypes to unique combinations of signals and has the potential to simplify our concept of immune complexity considerably.
Plasma cells comprise a population of terminally differentiated B cells that are dependent on the... more Plasma cells comprise a population of terminally differentiated B cells that are dependent on the transcriptional regulator B lymphocyte-induced maturation protein 1 (Blimp-1) for their develop- ment. We have introduced a gfp reporter into the Blimp-1 locus and shown that heterozygous mice express the green fluorescent protein in all antibody-secreting cells (ASCs) in vivo and in vitro. In vitro, these
Initiation of Plasma-Cell Differentiation Is Independent of the Transcription Factor Blimp-1
Immunity, 2007
Blimp-1 is considered an essential regulator of the terminal differentiation of B cells into anti... more Blimp-1 is considered an essential regulator of the terminal differentiation of B cells into antibody-secreting plasma cells. We show here that Rag1-/- mice reconstituted with fetal liver cells homozygous for a DNA-binding-deficient mutant of Prdm1 (the gene encoding Blimp-1) lack a defined plasma-cell compartment, yet show detectable amounts of all immunoglobulin isotypes. In vitro analysis revealed that Blimp-1 is not required for the initiation of antibody secretion but is essential for subsequent high immunoglobulin production. Blimp-1-independent differentiation was blocked at a preplasmablast stage characterized by decreased Pax5 expression and the activation of plasma-cell genes. Analysis of Blimp-1-sufficient differentiation revealed a phase prior to Blimp-1 expression in which several genes normally repressed by Pax5 are re-expressed, suggesting that plasma-cell differentiation is initiated by the inhibition of Pax5 function. Our results indicate that full plasma-cell differentiation but not commitment to the plasma-cell fate requires the expression of functional Blimp-1.
Resting B cells can be cultured to induce antibody-secreting cell (ASC) differentiation in vitro.... more Resting B cells can be cultured to induce antibody-secreting cell (ASC) differentiation in vitro. A quantitative analysis of cell behavior during such a culture allows the influences of different stimuli and gene products to be measured. The application of this analytical system revealed that the OBF-1 transcriptional coactivator, whose loss impairs antibody production in vivo, has two effects on ASC
Transcriptional profiling of mouse B cell terminal differentiation defines a signature for antibody-secreting plasma cells
Nature immunology, Jan 20, 2015
When B cells encounter an antigen, they alter their physiological state and anatomical localizati... more When B cells encounter an antigen, they alter their physiological state and anatomical localization and initiate a differentiation process that ultimately produces antibody-secreting cells (ASCs). We have defined the transcriptomes of many mature B cell populations and stages of plasma cell differentiation in mice. We provide a molecular signature of ASCs that highlights the stark transcriptional divide between B cells and plasma cells and enables the demarcation of ASCs on the basis of location and maturity. Changes in gene expression correlated with cell-division history and the acquisition of permissive histone modifications, and they included many regulators that had not been previously implicated in B cell differentiation. These findings both highlight and expand the core program that guides B cell terminal differentiation and the production of antibodies.
Cell Death and Differentiation, 2010
BH3-only proteins, such as Bim and Bad, contribute to tissue homeostasis by initiating apoptosis ... more BH3-only proteins, such as Bim and Bad, contribute to tissue homeostasis by initiating apoptosis in a cell type-and stimulusspecific manner. Loss of Bim provokes lymphocyte accumulation in vivo and renders lymphocytes more resistant to diverse apoptotic stimuli and Bad has been implicated in the apoptosis of haematopoietic cells upon cytokine deprivation. To investigate whether their biological roles in apoptosis overlap, we generated mice lacking both Bim and Bad and compared their haematopoietic phenotype with that of the single-knockout and wild-type (wt) animals. Unexpectedly, bad À/À mice had excess platelets due to prolonged platelet life-span. The bim À/À bad À/À mice were anatomically normal and fertile. Their haematopoietic phenotype resembled that of bim À/À mice but lymphocytes were slightly more elevated in their lymph nodes. Although resting B and T lymphocytes from bim À/À bad À/À and bim À/À animals displayed similar resistance to diverse apoptotic stimuli, mitogen activated bim À/À bad À/À B cells were more refractory to cytokine deprivation. Moreover, combined loss of Bim and Bad-enhanced survival of thymocytes after DNA damage and accelerated development of c-irradiation-induced thymic lymphoma. Unexpectedly, their cooperation in the thymus depended upon thymocyte-stromal interaction. Collectively, these results show that Bim and Bad can cooperate in the apoptosis of thymocytes and activated B lymphocytes and in the suppression of thymic lymphoma development.
Science, 2010
Lymphocyte survival during immune responses is controlled by the relative expression of pro-and a... more Lymphocyte survival during immune responses is controlled by the relative expression of pro-and anti-apoptotic molecules, regulating the magnitude, quality and duration of the response. Here we investigate the consequences of deleting genes encoding the anti-apoptotic molecules Mcl1 and Bcl2l1 (Bcl-x L ) from B cells using an inducible system synchronized with expression of activation induced cytidine deaminase (Aicda) following immunization. This revealed Mcl1 and not Bcl2l1 to be indispensable for formation and persistence of germinal centers (GC). Limiting Mcl1 expression reduced the magnitude of the GC response with an equivalent, but not greater, effect on memory B cell formation and no effect on persistence. Our results identify Mcl1 as the main antiapoptotic regulator of activated B cell survival and suggest distinct mechanisms controlling survival of GC and memory B cells.
Nature Immunology, 2005
To segregate the many contributions that B cell receptor (BCR)-mediated signals make to immune re... more To segregate the many contributions that B cell receptor (BCR)-mediated signals make to immune responses, we have analyzed here B cells deficient in the 'pan-leukocyte' marker CD45. BCR ligation of Cd45 -/-B cells failed to activate phosphatidylinositol-3-OH kinase, NF-jB, Erk1 or Erk2 kinases or to upregulate cell survival proteins and instead induced apoptosis. Immunization of Cd45 -/-B cell chimeras induced germinal centers and antigen-specific immunoglobulin G1 antibody-forming cells early, but both cellular compartments decreased by day 14. Proliferation of Cd45 -/-B cells induced by CD40 ligand in vitro was impaired as a result of abrogation by BCR ligation of the upregulation of prosurvival proteins. In contrast, enforced expression of the antiapoptotic factor Bcl-x L prevented the collapse of Cd45 -/-B cell germinal centers. These results show mechanistic differences in B cell survival during germinal center initiation and propagation; CD40 signaling is sufficient for the former, whereas the latter requires signaling from the BCR.
Mcl-1 is essential for the survival of plasma cells
Nature Immunology, 2013
The long-term survival of plasma cells is entirely dependent on signals derived from their enviro... more The long-term survival of plasma cells is entirely dependent on signals derived from their environment. These extrinsic factors presumably induce and sustain the expression of antiapoptotic proteins of the Bcl-2 family. It is uncertain whether there is specificity among Bcl-2 family members in the survival of plasma cells and whether their expression is linked to specific extrinsic factors. We found here that deletion of the gene encoding the antiapoptotic protein Mcl-1 in plasma cells resulted in rapid depletion of this population in vivo. Furthermore, we found that the receptor BCMA was needed to establish high expression of Mcl-1 in bone marrow but not spleen plasma cells and that establishing this survival pathway preceded the component of plasma cell differentiation that depends on the transcriptional repressor Blimp-1. Our results identify a critical role for Mcl-1 in the maintenance of plasma cells.
Proceedings of the National Academy of Sciences, 2002
Transcription factors NF-B1 and c-Rel, individually dispensable during embryogenesis, serve simil... more Transcription factors NF-B1 and c-Rel, individually dispensable during embryogenesis, serve similar, yet distinct, roles in the function of mature hemopoietic cells. Redundancy among Rel͞ NF-B family members prompted an examination of the combined roles of c-Rel and NF-B1 by using mice that lack both proteins. Embryonic development and the maturation of hemopoietic progenitors were unaffected in nfkb1 Ϫ/Ϫ c-rel Ϫ/Ϫ mice. Peripheral T cell populations developed normally, but follicular, marginal zone, and CD5 ؉ peritoneal B cell populations all were reduced. In culture, a failure of mitogen-stimulated nfkb1 Ϫ/Ϫ c-rel Ϫ/Ϫ B cells to proliferate was caused by a cell cycle defect in early G 1 that prevented growth. In vivo, defects in humoral immunity and splenic architecture seen in nfkb1 Ϫ/Ϫ and c-rel Ϫ/Ϫ mice were exacerbated in the double mutant mice. These findings demonstrate that in the B lineage overlapping roles for NF-B1 and c-Rel appear to be restricted to regulating the activation and function of mature cells.
Journal of Experimental Medicine, 2003
During development, the stochastic process assembling the genes encoding antigen receptors invari... more During development, the stochastic process assembling the genes encoding antigen receptors invariably generates B and T lymphocytes that can recognize self-antigens. Several mechanisms have evolved to prevent the activation of these cells and the concomitant development of autoimmune disease. One such mechanism is the induction of apoptosis in developing or mature B cells by engagement of the B cell antigen receptor (BCR) in the absence of T cell help. Here we report that B lymphocytes lacking the pro-apoptotic Bcl-2 family member Bim are refractory to apoptosis induced by BCR ligation in vitro. The loss of Bim also inhibited deletion of autoreactive B cells in vivo in two transgenic systems of B cell tolerance. Bim loss prevented deletion of autoreactive B cells induced by soluble self-antigen and promoted accumulation of self-reactive B cells developing in the presence of membrane-bound self-antigen, although their numbers were considerably lower compared with antigen-free mice. Mechanistically, we determined that BCR ligation promoted interaction of Bim with Bcl-2, inhibiting its survival function. These findings demonstrate that Bim is a critical player in BCR-mediated apoptosis and in B lymphocyte deletion.
Genes & Development, 1995
Nature immunology, 2007
Interleukin 15 (IL-15) promotes the survival of natural killer (NK) cells by preventing apoptosis... more Interleukin 15 (IL-15) promotes the survival of natural killer (NK) cells by preventing apoptosis through mechanisms unknown at present. Here we identify Bim, Noxa and Mcl-1 as key regulators of IL-15-dependent survival of NK cells. IL-15 suppressed apoptosis by limiting Bim expression through the kinases Erk1 and Erk2 and mechanisms dependent on the transcription factor Foxo3a, while promoting expression of Mcl-1, which was necessary and sufficient for the survival of NK cells. Withdrawal of IL-15 led to upregulation of Bim and, accordingly, both Bim-deficient and Foxo3a-/- NK cells were resistant to cytokine deprivation. Finally, IL-15-mediated inactivation of Foxo3a and cell survival were dependent on phosphotidylinositol-3-OH kinase. Thus, IL-15 regulates the survival of NK cells at multiple steps, with Bim and Noxa being key antagonists of Mcl-1, the critical survivor factor in this process.
Genetic Evidence for Lyn as a Negative Regulator of IL4 Signaling
IL-4 has multiple effects on B lymphocytes, many of which are concentration dependent. This is pa... more IL-4 has multiple effects on B lymphocytes, many of which are concentration dependent. This is particularly so for Ig isotype switching, where different thresholds of IL-4 stimulation are needed to induce switching from IgM to either IgG1 or IgE. In this report we describe a critical role for the tyrosine kinase Lyn in setting IL-4 signaling thresholds in mouse B lymphocytes. Upon CD40 ligand stimulation of lyn-/- B cells, 10-fold less IL-4 was required to induce switching from IgM to IgG1 and IgE and an increased proportion of B cells isotype switched at each IL-4 concentration. These in vitro results correlate with the in vivo findings that in lyn-/- mice, IgG1 Ab-forming cells develop prematurely in ontogeny and that adult lyn-/- mice have an abnormally high proportion of IgG1-expressing B cells in their spleens. Adult lyn-/- mice also have significantly higher levels of IgE in their serum. These results identify Lyn as a molecule involved in modulating the IL-4 signal in B cells and provide insights into its regulation and how a B cell signaling imbalance may contribute to atopy.
Manipulation of B-cell responses with histone deacetylase inhibitors
Nature Communications, 2015
Histone deacetylase inhibitors (HDACi) are approved for treating certain haematological malignanc... more Histone deacetylase inhibitors (HDACi) are approved for treating certain haematological malignancies, however, recent evidence also illustrates they are modulators of the immune system. In experimental models, HDACi are particularly potent against malignancies originating from the B-lymphocyte lineage. Here we examine the ability of this class of compounds to modify both protective and autoimmune antibody responses. In vitro, HDACi affect B-cell proliferation, survival and differentiation in an HDAC-class-dependent manner. Strikingly, treatment of lupus-prone Mrl/lpr mice with the HDACi panobinostat significantly reduces autoreactive plasma-cell numbers, autoantibodies and nephritis, while other immune parameters remain largely unaffected. Immunized control mice treated with panobinostat or the clinically approved HDACi vorinostat have significantly impaired primary antibody responses, but these treatments surprisingly spare circulating memory B cells. These studies indicate that panobinostat is a potential therapy for B-cell-driven autoimmune conditions and HDACi do not induce major long-term detrimental effects on B-cell memory.
The Journal of experimental medicine, Jan 22, 2014
The importance of IκB kinase (IKK)-induced proteolysis of NF-κB1 p105 in B cells was investigated... more The importance of IκB kinase (IKK)-induced proteolysis of NF-κB1 p105 in B cells was investigated using Nfkb1(SSAA/SSAA) mice, in which this NF-κB signaling pathway is blocked. Nfkb1(SSAA) mutation had no effect on the development and homeostasis of follicular mature (FM) B cells. However, analysis of mixed bone marrow chimeras revealed that Nfkb1(SSAA/SSAA) FM B cells were completely unable to mediate T cell-dependent antibody responses. Nfkb1(SSAA) mutation decreased B cell antigen receptor (BCR) activation of NF-κB in FM B cells, which selectively blocked BCR stimulation of cell survival and antigen-induced differentiation into plasmablasts and germinal center B cells due to reduced expression of Bcl-2 family proteins and IRF4, respectively. In contrast, the antigen-presenting function of FM B cells and their BCR-induced migration to the follicle T cell zone border, as well as their growth and proliferation after BCR stimulation, were not affected. All of the inhibitory effects o...
Prosurvival Bcl-2 family members reveal a distinct apoptotic identity between conventional and plasmacytoid dendritic cells
Proceedings of the National Academy of Sciences, 2015
Dendritic cells (DCs) are heterogeneous, comprising subsets with functional specializations that ... more Dendritic cells (DCs) are heterogeneous, comprising subsets with functional specializations that play distinct roles in immunity as well as immunopathology. We investigated the molecular control of cell survival of two main DC subsets: plasmacytoid DCs (pDCs) and conventional DCs (cDCs) and their dependence on individual antiapoptotic BCL-2 family members. Compared with cDCs, pDCs had higher expression of BCL-2, lower A1, and similar levels of MCL-1 and BCL-XL. Transgenic overexpression of BCL-2 increased the pDC pool size in vivo with only minor impact on cDCs. With a view to immune intervention, we tested BCL-2 inhibitors and found that ABT-199 (the BCL-2 specific inhibitor) selectively killed pDCs but not cDCs. Conversely, genetic knockdown of A1 profoundly reduced the proportion of cDCs but not pDCs. We also found that conditional ablation of MCL-1 significantly reduced the size of both DC populations in mice and impeded DC-mediated immune responses. Thus, we revealed that the two DC types have different cell survival requirements. The molecular basis of survival of different DC subsets thus advocates the antagonism of selective BCL-2 family members for treating diseases pertaining to distinct DC subsets.
Regulation of germinal center responses and B-cell memory by the chromatin modifier MOZ
Proceedings of the National Academy of Sciences of the United States of America, 2014
Memory B cells and long-lived bone marrow-resident plasma cells maintain humoral immunity. Little... more Memory B cells and long-lived bone marrow-resident plasma cells maintain humoral immunity. Little is known about the intrinsic mechanisms that are essential for forming memory B cells or endowing them with the ability to rapidly differentiate upon reexposure while maintaining the population over time. Histone modifications have been shown to regulate lymphocyte development, but their role in regulating differentiation and maintenance of B-cell subsets during an immune response is unclear. Using stage-specific deletion of monocytic leukemia zinc finger protein (MOZ), a histone acetyltransferase, we demonstrate that mutation of this chromatin modifier alters fate decisions in both primary and secondary responses. In the absence of MOZ, germinal center B cells were significantly impaired in their ability to generate dark zone centroblasts, with a concomitant decrease in both cell-cycle progression and BCL-6 expression. In contrast, there was increased differentiation to IgM and low-aff...
The generation of antibody-secreting plasma cells
Nature Reviews Immunology, 2015
The regulation of antibody production is linked to the generation and maintenance of plasmablasts... more The regulation of antibody production is linked to the generation and maintenance of plasmablasts and plasma cells from their B cell precursors. Plasmablasts are the rapidly produced and short-lived effector cells of the early antibody response, whereas plasma cells are the long-lived mediators of lasting humoral immunity. An extraordinary number of control mechanisms, at both the cellular and molecular levels, underlie the regulation of this essential arm of the immune response. Despite this complexity, the terminal differentiation of B cells can be described as a simple probabilistic process that is governed by a central gene-regulatory network and modified by environmental stimuli.
Immunology: To affinity and beyond
Nature, 2014
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Papers by David Tarlinton