Publications by authors named "Stephen L Nutt"

194 Publications

The role of PLCγ2 in immunological disorders, cancer, and neurodegeneration.

J Biol Chem 2021 Aug 19;297(2):100905. Epub 2021 Jun 19.

Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia; Immunology Laboratory, Guangzhou Institute of Paediatrics, Guangzhou Women and Children's Medical Centre, Guangzhou, Guangdong, China. Electronic address:

Phosphatidylinositol-specific phospholipase Cγ2 (PLCγ2) is a critical signaling molecule activated downstream from a variety of cell surface receptors that contain an intracellular immunoreceptor tyrosine-based activation motif. These receptors recruit kinases such as Syk, BTK, and BLNK to phosphorylate and activate PLCγ2, which then generates 1D-myo-inositol 1,4,5-trisphosphate and diacylglycerol. These well-known second messengers are required for diverse membrane functionality including cellular proliferation, endocytosis, and calcium flux. As a result, PLCγ2 dysfunction is associated with a variety of diseases including cancer, neurodegeneration, and immune disorders. The diverse pathologies associated with PLCγ2 are exemplified by distinct genetic variants. Inherited mutations at this locus cause PLCγ2-associated antibody deficiency and immune dysregulation, in some cases with autoinflammation. Acquired mutations at this locus, which often arise as a result of BTK inhibition to treat chronic lymphocytic leukemia, result in constitutive downstream signaling and lymphocyte proliferation. Finally, a third group of PLCγ2 variants actually has a protective effect in a variety of neurodegenerative disorders, presumably by increased uptake and degradation of deleterious neurological aggregates. Therefore, manipulating PLCγ2 activity either up or down could have therapeutic benefit; however, we require a better understanding of the signaling pathways propagated by these variants before such clinical utility can be realized. Here, we review the signaling roles of PLCγ2 in hematopoietic cells to help understand the effect of mutations driving immune disorders and cancer and extrapolate from this to roles which may relate to protection against neurodegeneration.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jbc.2021.100905DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8318911PMC
August 2021

The gene regulatory network controlling plasma cell function.

Immunol Rev 2021 09 9;303(1):23-34. Epub 2021 Jun 9.

The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.

Antibodies are an essential element of the immune response to infection, and in long-term protection upon re-exposure to the same micro-organism. Antibodies are produced by plasmablasts and plasma cells, the terminally differentiated cells of the B lymphocyte lineage. These relatively rare populations, collectively termed antibody secreting cells (ASCs), have developed highly specialized transcriptional and metabolic pathways to facilitate their extraordinarily high rates of antibody synthesis and secretion. In this review, we discuss the gene regulatory network that controls ASC identity and function, with a particular focus on the processes that influence the transcription, translation, folding, modification and secretion of antibodies. We will address how ASCs have adapted their transcriptional, metabolic and protein homeostasis pathways to sustain such high rates of antibody production, and the roles that the major ASC regulators, the transcription factors, Irf4, Blimp-1 and Xbp1, play in co-ordinating these processes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/imr.12988DOI Listing
September 2021

Blockade of the co-inhibitory molecule PD-1 unleashes ILC2-dependent antitumor immunity in melanoma.

Nat Immunol 2021 07 7;22(7):851-864. Epub 2021 Jun 7.

Innate Pharma Research Labs, Marseille, France.

Group 2 innate lymphoid cells (ILC2s) are essential to maintain tissue homeostasis. In cancer, ILC2s can harbor both pro-tumorigenic and anti-tumorigenic functions, but we know little about their underlying mechanisms or whether they could be clinically relevant or targeted to improve patient outcomes. Here, we found that high ILC2 infiltration in human melanoma was associated with a good clinical prognosis. ILC2s are critical producers of the cytokine granulocyte-macrophage colony-stimulating factor, which coordinates the recruitment and activation of eosinophils to enhance antitumor responses. Tumor-infiltrating ILC2s expressed programmed cell death protein-1, which limited their intratumoral accumulation, proliferation and antitumor effector functions. This inhibition could be overcome in vivo by combining interleukin-33-driven ILC2 activation with programmed cell death protein-1 blockade to significantly increase antitumor responses. Together, our results identified ILC2s as a critical immune cell type involved in melanoma immunity and revealed a potential synergistic approach to harness ILC2 function for antitumor immunotherapies.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41590-021-00943-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7611091PMC
July 2021

Type 1 conventional dendritic cell fate and function are controlled by DC-SCRIPT.

Sci Immunol 2021 Apr;6(58)

Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia.

The functional diversification of dendritic cells (DCs) is a key step in establishing protective immune responses. Despite the importance of DC lineage diversity, its genetic basis is not fully understood. The transcription factor DC-SCRIPT is expressed in conventional DCs (cDCs) and their committed bone marrow progenitors but not in plasmacytoid DCs (pDCs). We show that mice lacking DC-SCRIPT displayed substantially impaired development of IRF8 (interferon regulatory factor 8)-dependent cDC1, whereas cDC2 numbers increased marginally. The residual DC-SCRIPT-deficient cDC1s had impaired capacity to capture and present cell-associated antigens and to secrete IL-12p40, two functional hallmarks of this population. Genome-wide mapping of DC-SCRIPT binding and gene expression analyses revealed a key role for DC-SCRIPT in maintaining cDC1 identity via the direct regulation of cDC1 signature genes, including Our study reveals DC-SCRIPT to be a critical component of the gene regulatory program shaping the functional attributes of cDC1s.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1126/sciimmunol.abf4432DOI Listing
April 2021

Single-cell analyses reveal the clonal and molecular aetiology of Flt3L-induced emergency dendritic cell development.

Nat Cell Biol 2021 03 1;23(3):219-231. Epub 2021 Mar 1.

Immunology Division, Walter and Eliza Hall Institute, Parkville, VIC, Australia.

Regulation of haematopoietic stem and progenitor cell (HSPC) fate is crucial during homeostasis and under stress conditions. Here we examine the aetiology of the Flt3 ligand (Flt3L)-mediated increase of type 1 conventional dendritic cells (cDC1s). Using cellular barcoding we demonstrate this occurs through selective clonal expansion of HSPCs that are primed to produce cDC1s and not through activation of cDC1 fate by other HSPCs. In particular, multi/oligo-potent clones selectively amplify their cDC1 output, without compromising the production of other lineages, via a process we term tuning. We then develop Divi-Seq to simultaneously profile the division history, surface phenotype and transcriptome of individual HSPCs. We discover that Flt3L-responsive HSPCs maintain a proliferative 'early progenitor'-like state, leading to the selective expansion of multiple transitional cDC1-primed progenitor stages that are marked by Irf8 expression. These findings define the mechanistic action of Flt3L through clonal tuning, which has important implications for other models of 'emergency' haematopoiesis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41556-021-00636-7DOI Listing
March 2021

OBF1 and Oct factors control the germinal center transcriptional program.

Blood 2021 May;137(21):2920-2934

Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.

OBF1 is a specific coactivator of the POU family transcription factors OCT1 and OCT2. OBF1 and OCT2 are B cell-specific and indispensable for germinal center (GC) formation, but their mechanism of action is unclear. Here, we show by chromatin immunoprecipitation-sequencing that OBF1 extensively colocalizes with OCT1 and OCT2. We found that these factors also often colocalize with transcription factors of the ETS family. Furthermore, we showed that OBF1, OCT2, and OCT1 bind widely to the promoters or enhancers of genes involved in GC formation in mouse and human GC B cells. Short hairpin RNA knockdown experiments demonstrated that OCT1, OCT2, and OBF1 regulate each other and are essential for proliferation of GC-derived lymphoma cell lines. OBF1 downregulation disrupts the GC transcriptional program: genes involved in GC maintenance, such as BCL6, are downregulated, whereas genes related to exit from the GC program, such as IRF4, are upregulated. Ectopic expression of BCL6 does not restore the proliferation of GC-derived lymphoma cells depleted of OBF1 unless IRF4 is also depleted, indicating that OBF1 controls an essential regulatory node in GC differentiation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1182/blood.2020010175DOI Listing
May 2021

Liver Immune Profiling Reveals Pathogenesis and Therapeutics for Biliary Atresia.

Cell 2020 12 27;183(7):1867-1883.e26. Epub 2020 Nov 27.

Walter and Eliza Hall Institute of Medical Research and Department of Medical Biology, University of Melbourne, Parkville, Melbourne, VIC 3052, Australia.

Biliary atresia (BA) is a severe cholangiopathy that leads to liver failure in infants, but its pathogenesis remains to be fully characterized. By single-cell RNA profiling, we observed macrophage hypo-inflammation, Kupffer cell scavenger function defects, cytotoxic T cell expansion, and deficiency of CX3CR1effector T and natural killer (NK) cells in infants with BA. More importantly, we discovered that hepatic B cell lymphopoiesis did not cease after birth and that tolerance defects contributed to immunoglobulin G (IgG)-autoantibody accumulation in BA. In a rhesus-rotavirus induced BA model, depleting B cells or blocking antigen presentation ameliorated liver damage. In a pilot clinical study, we demonstrated that rituximab was effective in depleting hepatic B cells and restoring the functions of macrophages, Kupffer cells, and T cells to levels comparable to those of control subjects. In summary, our comprehensive immune profiling in infants with BA had educed that B-cell-modifying therapies may alleviate liver pathology.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.cell.2020.10.048DOI Listing
December 2020

Hhex Directly Represses BIM-Dependent Apoptosis to Promote NK Cell Development and Maintenance.

Cell Rep 2020 10;33(3):108285

The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, 3052, Australia; Department of Medical Biology, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Melbourne, Victoria, 3010, Australia; Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, 3800, Australia; oNKo-Innate Pty Ltd., 27 Norwood Cres, Moonee Ponds, Victoria, 3039, Australia. Electronic address:

Hhex encodes a homeobox transcriptional regulator important for embryonic development and hematopoiesis. Hhex is highly expressed in NK cells, and its germline deletion results in significant defects in lymphoid development, including NK cells. To determine if Hhex is intrinsically required throughout NK cell development or for NK cell function, we generate mice that specifically lack Hhex in NK cells. NK cell frequency is dramatically reduced, while NK cell differentiation, IL-15 responsiveness, and function at the cellular level remain largely normal in the absence of Hhex. Increased IL-15 availability fails to fully reverse NK lymphopenia following conditional Hhex deletion, suggesting that Hhex regulates developmental pathways extrinsic to those dependent on IL-15. Gene expression and functional genetic approaches reveal that Hhex regulates NK cell survival by directly binding Bcl2l11 (Bim) and repressing expression of this key apoptotic mediator. These data implicate Hhex as a transcriptional regulator of NK cell homeostasis and immunity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.celrep.2020.108285DOI Listing
October 2020

A new lymphoid-primed progenitor marked by Dach1 downregulation identified with single cell multi-omics.

Nat Immunol 2020 12 19;21(12):1574-1584. Epub 2020 Oct 19.

Immunology Division, The Walter & Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.

A classical view of blood cell development is that multipotent hematopoietic stem and progenitor cells (HSPCs) become lineage-restricted at defined stages. Linc-KitSca-1Flt3 cells, termed lymphoid-primed multipotent progenitors (LMPPs), have lost megakaryocyte and erythroid potential but are heterogeneous in their fate. Here, through single-cell RNA sequencing, we identify the expression of Dach1 and associated genes in this fraction as being coexpressed with myeloid/stem genes but inversely correlated with lymphoid genes. Through generation of Dach1-GFP reporter mice, we identify a transcriptionally and functionally unique Dach1-GFP subpopulation within LMPPs with lymphoid potential with low to negligible classic myeloid potential. We term these 'lymphoid-primed progenitors' (LPPs). These findings define an early definitive branch point of lymphoid development in hematopoiesis and a means for prospective isolation of LPPs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41590-020-0799-xDOI Listing
December 2020

Transcriptional Networks Driving Dendritic Cell Differentiation and Function.

Immunity 2020 06;52(6):942-956

The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia; Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia. Electronic address:

Dendritic cells (DCs) are the sentinels of the immune system, sensing a diverse array of pathogens to stimulate a robust and appropriate immune response. To initiate responses to highly disparate challenges, DCs have diversified into multiple phenotypically, anatomically, and functionally distinct cell types. As a result of the application of new single-cell technologies, the full extent of this diversity, as well as the developmental relationships of the DC lineages, is currently undergoing reassessment. Here, we review the cellular and molecular evidence that underpins current models of DC differentiation and functional diversification in the murine and human systems. We discuss these models in the context of the diversity revealed by single-cell studies and propose that understanding DC identity will require defining the regulatory interactions that control gene expression in these cells.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.immuni.2020.05.005DOI Listing
June 2020

An Erg-driven transcriptional program controls B cell lymphopoiesis.

Nat Commun 2020 06 15;11(1):3013. Epub 2020 Jun 15.

Blood Cells and Blood Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia.

B lymphoid development is initiated by the differentiation of hematopoietic stem cells into lineage committed progenitors, ultimately generating mature B cells. This highly regulated process generates clonal immunological diversity via recombination of immunoglobulin V, D and J gene segments. While several transcription factors that control B cell development and V(D)J recombination have been defined, how these processes are initiated and coordinated into a precise regulatory network remains poorly understood. Here, we show that the transcription factor ETS Related Gene (Erg) is essential for early B lymphoid differentiation. Erg initiates a transcriptional network involving the B cell lineage defining genes, Ebf1 and Pax5, which directly promotes expression of key genes involved in V(D)J recombination and formation of the B cell receptor. Complementation of Erg deficiency with a productively rearranged immunoglobulin gene rescued B lineage development, demonstrating that Erg is an essential and stage-specific regulator of the gene regulatory network controlling B lymphopoiesis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41467-020-16828-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7296042PMC
June 2020

Sex-specific adipose tissue imprinting of regulatory T cells.

Nature 2020 03 26;579(7800):581-585. Epub 2020 Feb 26.

Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia.

Adipose tissue is an energy store and a dynamic endocrine organ. In particular, visceral adipose tissue (VAT) is critical for the regulation of systemic metabolism. Impaired VAT function-for example, in obesity-is associated with insulin resistance and type 2 diabetes. Regulatory T (T) cells that express the transcription factor FOXP3 are critical for limiting immune responses and suppressing tissue inflammation, including in the VAT. Here we uncover pronounced sexual dimorphism in T cells in the VAT. Male VAT was enriched for T cells compared with female VAT, and T cells from male VAT were markedly different from their female counterparts in phenotype, transcriptional landscape and chromatin accessibility. Heightened inflammation in the male VAT facilitated the recruitment of T cells via the CCL2-CCR2 axis. Androgen regulated the differentiation of a unique IL-33-producing stromal cell population specific to the male VAT, which paralleled the local expansion of T cells. Sex hormones also regulated VAT inflammation, which shaped the transcriptional landscape of VAT-resident T cells in a BLIMP1 transcription factor-dependent manner. Overall, we find that sex-specific differences in T cells from VAT are determined by the tissue niche in a sex-hormone-dependent manner to limit adipose tissue inflammation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41586-020-2040-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7241647PMC
March 2020

EZH2 function in immune cell development.

Biol Chem 2020 07;401(8):933-943

The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3052, Australia.

The polycomb repressive complex 2 (PRC2) consists of three core components EZH2, SUZ12 and EED. EZH2 catalyzes the methylation of lysine 27 of histone H3, a modification associated with gene silencing. Through gene duplication higher vertebrate genomes also encode a second partially redundant methyltransferase, EZH1. Within the mammalian immune system most research has concentrated on EZH2 which is expressed predominantly in proliferating cells. EZH2 and other PRC2 components are required for hematopoietic stem cell function and lymphocyte development, at least in part by repressing cell cycle inhibitors. At later stages of immune cell differentiation, EZH2 plays essential roles in humoral and cell-mediated adaptive immunity, as well as the maintenance of immune homeostasis. EZH2 is often overactive in cancers, through both gain-of-function mutations and over-expression, an observation that has led to the development and clinical testing of specific EZH2 inhibitors. Such inhibitors may also be of use in inflammatory and autoimmune settings, as EZH2 inhibition dampens the immune response. Here, we will review the current state of understanding of the roles for EZH2, and PRC2 more generally, in the development and function of the immune system.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1515/hsz-2019-0436DOI Listing
July 2020

Plasmacytoid dendritic cells from parent strains of the NZB/W F1 lupus mouse contribute different characteristics to autoimmune propensity.

Immunol Cell Biol 2020 03 5;98(3):203-214. Epub 2020 Feb 5.

The Walter & Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.

The NZB/W F1 (F1) mice develop severe disease that is similar to human systemic lupus erythematosus. By contrast, each parent strain, NZB or NZW, has limited autoimmunity, suggesting traits of both strains contribute to pathogenesis. Although many of the contributing genes have been identified, the contributing cellular abnormality associated with each parent strain remains unresolved. Given that plasmacytoid dendritic cells (pDCs) are key to the pathogenesis of lupus, we investigated the properties of pDCs from NZB and NZW mice. We found that NZB mouse had higher numbers of pDCs, with much of the increase being contributed by a more abundant CD8 pDC subset. This was associated with prolonged survival and stronger proliferation of CD4 T cells. By contrast, NZW pDCs had heightened capacity to produce interferon-α (IFNα) and IFNλ, and promoted stronger B-cell proliferation upon CpG stimulation. Thus, our data reveal the different functional and numerical characteristics of pDCs from NZW and NZB mouse.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/imcb.12313DOI Listing
March 2020

IRF4 Activity Is Required in Established Plasma Cells to Regulate Gene Transcription and Mitochondrial Homeostasis.

Cell Rep 2019 11;29(9):2634-2645.e5

Department of Immunology and Pathology, Monash University, 89 Commercial Road, Melbourne 3004, VIC, Australia. Electronic address:

The transcription factor interferon regulatory factor 4 (IRF4) is critical for the development, maintenance, and function of plasma cells. The mechanism by which IRF4 exerts its action in mature plasma cells has been elusive due to the death of all such cells upon IRF4 loss. While we identify apoptosis as a critical pathway for the death of plasma cells caused by IRF4 loss, we also determine that IRF4 did not regulate the intrinsic apoptotic pathway directly. By using an inducible IRF4 deletion system in the presence of the overexpression of anti-apoptotic BCL2, we identify genes whose expression is coordinated by IRF4 and that in turn specify plasma cell identity and mitochondrial homeostasis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.celrep.2019.10.097DOI Listing
November 2019

Selective deployment of transcription factor paralogs with submaximal strength facilitates gene regulation in the immune system.

Nat Immunol 2019 10 26;20(10):1372-1380. Epub 2019 Aug 26.

Lymphocyte Development Group, MRC London Institute for Medical Sciences, London, UK.

In multicellular organisms, duplicated genes can diverge through tissue-specific gene expression patterns, as exemplified by highly regulated expression of RUNX transcription factor paralogs with apparent functional redundancy. Here we asked what cell-type-specific biologies might be supported by the selective expression of RUNX paralogs during Langerhans cell and inducible regulatory T cell differentiation. We uncovered functional nonequivalence between RUNX paralogs. Selective expression of native paralogs allowed integration of transcription factor activity with extrinsic signals, while non-native paralogs enforced differentiation even in the absence of exogenous inducers. DNA binding affinity was controlled by divergent amino acids within the otherwise highly conserved RUNT domain and evolutionary reconstruction suggested convergence of RUNT domain residues toward submaximal strength. Hence, the selective expression of gene duplicates in specialized cell types can synergize with the acquisition of functional differences to enable appropriate gene expression, lineage choice and differentiation in the mammalian immune system.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41590-019-0471-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6754753PMC
October 2019

Context-Dependent Role for T-bet in T Follicular Helper Differentiation and Germinal Center Function following Viral Infection.

Cell Rep 2019 08;28(7):1758-1772.e4

Division of Immunology, Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, VIC 3010, Australia. Electronic address:

Following infection, inflammatory cues upregulate core transcriptional programs to establish pathogen-specific protection. In viral infections, T follicular helper (TFH) cells express the prototypical T helper 1 transcription factor T-bet. Several studies have demonstrated essential but conflicting roles for T-bet in TFH biology. Understanding the basis of this controversy is crucial, as modulation of T-bet expression instructs TFH differentiation and ultimately protective antibody responses. Comparing influenza and LCMV viral infections, we demonstrate that the role of T-bet is contingent on the environmental setting of TFH differentiation, IL-2 signaling, and T cell competition. Furthermore, we demonstrate that T-bet expression by either TFH or GC B cells independently drives antibody isotype class switching. Specifically, T cell-specific loss of T-bet promotes IgG1, whereas B cell-specific loss of T-bet inhibits IgG2a/c switching. Combined, this work highlights that the context-dependent induction of T-bet instructs the development of protective, neutralizing antibodies following viral infection or vaccination.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.celrep.2019.07.034DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6711398PMC
August 2019

Interconversion between Tumorigenic and Differentiated States in Acute Myeloid Leukemia.

Cell Stem Cell 2019 08;25(2):258-272.e9

Baker Heart and Diabetes Institute, Melbourne, VIC 3004, Australia; Department of Immunology and Pathology, Monash University, Commercial Road, Melbourne, VIC 3004, Australia.

Tumors are composed of phenotypically heterogeneous cancer cells that often resemble various differentiation states of their lineage of origin. Within this hierarchy, it is thought that an immature subpopulation of tumor-propagating cancer stem cells (CSCs) differentiates into non-tumorigenic progeny, providing a rationale for therapeutic strategies that specifically eradicate CSCs or induce their differentiation. The clinical success of these approaches depends on CSC differentiation being unidirectional rather than reversible, yet this question remains unresolved even in prototypically hierarchical malignancies, such as acute myeloid leukemia (AML). Here, we show in murine and human models of AML that, upon perturbation of endogenous expression of the lineage-determining transcription factor PU.1 or withdrawal of established differentiation therapies, some mature leukemia cells can de-differentiate and reacquire clonogenic and leukemogenic properties. Our results reveal plasticity of CSC maturation in AML, highlighting the need to therapeutically eradicate cancer cells across a range of differentiation states.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.stem.2019.07.001DOI Listing
August 2019

New players in the gene regulatory network controlling late B cell differentiation.

Curr Opin Immunol 2019 06 24;58:68-74. Epub 2019 May 24.

The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia. Electronic address:

The differentiation of B cells into antibody-secreting plasma cells is associated with profound changes in morphology, lifespan, and cellular metabolism that are needed to support high rates of antibody production. These processes are driven by dramatic alterations to the transcriptional program and to the organization of the nucleus itself that in turn are regulated by the activity of a select group of transcription factors and epigenetic regulators. Although the core differentiation program is conserved in all mature B cells, subset-specific regulators, such as those found in B1 or memory B cells, provide additional complexity. Here, we review the key components of the gene regulatory network controlling B-cell terminal differentiation, with an emphasis on the new players and processes that have emerged in recent years.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.coi.2019.04.007DOI Listing
June 2019

Polycomb repressive complex 2 is a critical mediator of allergic inflammation.

JCI Insight 2019 05 16;4(10). Epub 2019 May 16.

The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.

Strategies that intervene with the development of immune-mediated diseases are urgently needed, as current treatments mostly focus on alleviating symptoms rather than reversing the disease. Targeting enzymes involved in epigenetic modifications to chromatin represents an alternative strategy that has the potential to perturb the function of the lymphocytes that drive the immune response. Here, we report that 2 major epigenetic silencing pathways are increased after T cell activation. By specific inactivation of these molecules in the T cell compartment in vivo, we demonstrate that the polycomb repressive complex 2 (PRC2) is essential for the generation of allergic responses. Furthermore, we show that small-molecule inhibition of the PRC2 methyltransferase, enhancer of zeste homolog 2 (Ezh2), reduces allergic inflammation in mice. Therefore, by systematically surveying the pathways involved in epigenetic gene silencing we have identified Ezh2 as a target for the suppression of allergic disease.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1172/jci.insight.127745DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6542604PMC
May 2019

Transcription factors IRF8 and PU.1 are required for follicular B cell development and BCL6-driven germinal center responses.

Proc Natl Acad Sci U S A 2019 05 18;116(19):9511-9520. Epub 2019 Apr 18.

Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852;

The IRF and Ets families of transcription factors regulate the expression of a range of genes involved in immune cell development and function. However, the understanding of the molecular mechanisms of each family member has been limited due to their redundancy and broad effects on multiple lineages of cells. Here, we report that double deletion of floxed and (encoding PU.1) by Mb1-Cre (designated DKO mice) in the B cell lineage resulted in severe defects in the development of follicular and germinal center (GC) B cells. Class-switch recombination and antibody affinity maturation were also compromised in DKO mice. RNA-seq (sequencing) and ChIP-seq analyses revealed distinct IRF8 and PU.1 target genes in follicular and activated B cells. DKO B cells had diminished expression of target genes vital for maintaining follicular B cell identity and GC development. Moreover, our findings reveal that expression of B-cell lymphoma protein 6 (BCL6), which is critical for development of germinal center B cells, is dependent on IRF8 and PU.1 in vivo, providing a mechanism for the critical role for IRF8 and PU.1 in the development of GC B cells.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1073/pnas.1901258116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6511064PMC
May 2019

A Regulatory Circuit Controlling the Dynamics of NFκB cRel Transitions B Cells from Proliferation to Plasma Cell Differentiation.

Immunity 2019 03 5;50(3):616-628.e6. Epub 2019 Mar 5.

Signaling Systems Laboratory, Institute for Quantitative and Computational Biosciences and Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA. Electronic address:

Humoral immunity depends on efficient activation of B cells and their subsequent differentiation into antibody-secreting cells (ASCs). The transcription factor NFκB cRel is critical for B cell proliferation, but incorporating its known regulatory interactions into a mathematical model of the ASC differentiation circuit prevented ASC generation in simulations. Indeed, experimental ectopic cRel expression blocked ASC differentiation by inhibiting the transcription factor Blimp1, and in wild-type (WT) cells cRel was dynamically repressed during ASC differentiation by Blimp1 binding the Rel locus. Including this bi-stable circuit of mutual cRel-Blimp1 antagonism into a multi-scale model revealed that dynamic repression of cRel controls the switch from B cell proliferation to ASC generation phases and hence the respective cell population dynamics. Our studies provide a mechanistic explanation of how dysregulation of this bi-stable circuit might result in pathologic B cell population phenotypes and thus offer new avenues for diagnostic stratification and treatment.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.immuni.2019.02.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6955201PMC
March 2019

Directing the conductor: TNF regulation of HSCs.

Authors:
Stephen L Nutt

Blood 2019 02;133(8):771-773

Walter and Eliza Hall Institute of Medical Research.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1182/blood-2018-10-880815DOI Listing
February 2019

PU.1 controls fibroblast polarization and tissue fibrosis.

Nature 2019 02 30;566(7744):344-349. Epub 2019 Jan 30.

Department of Chemistry, Georgia State University, Atlanta, GA, USA.

Fibroblasts are polymorphic cells with pleiotropic roles in organ morphogenesis, tissue homeostasis and immune responses. In fibrotic diseases, fibroblasts synthesize abundant amounts of extracellular matrix, which induces scarring and organ failure. By contrast, a hallmark feature of fibroblasts in arthritis is degradation of the extracellular matrix because of the release of metalloproteinases and degrading enzymes, and subsequent tissue destruction. The mechanisms that drive these functionally opposing pro-fibrotic and pro-inflammatory phenotypes of fibroblasts remain unknown. Here we identify the transcription factor PU.1 as an essential regulator of the pro-fibrotic gene expression program. The interplay between transcriptional and post-transcriptional mechanisms that normally control the expression of PU.1 expression is perturbed in various fibrotic diseases, resulting in the upregulation of PU.1, induction of fibrosis-associated gene sets and a phenotypic switch in extracellular matrix-producing pro-fibrotic fibroblasts. By contrast, pharmacological and genetic inactivation of PU.1 disrupts the fibrotic network and enables reprogramming of fibrotic fibroblasts into resting fibroblasts, leading to regression of fibrosis in several organs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41586-019-0896-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6526281PMC
February 2019

The cis-Regulatory Atlas of the Mouse Immune System.

Cell 2019 02 24;176(4):897-912.e20. Epub 2019 Jan 24.

Department of Immunology, Harvard Medical School, Boston, MA, USA. Electronic address:

A complete chart of cis-regulatory elements and their dynamic activity is necessary to understand the transcriptional basis of differentiation and function of an organ system. We generated matched epigenome and transcriptome measurements in 86 primary cell types that span the mouse immune system and its differentiation cascades. This breadth of data enable variance components analysis that suggests that genes fall into two distinct classes, controlled by either enhancer- or promoter-driven logic, and multiple regression that connects genes to the enhancers that regulate them. Relating transcription factor (TF) expression to the genome-wide accessibility of their binding motifs classifies them as predominantly openers or closers of local chromatin accessibility, pinpointing specific cis-regulatory elements where binding of given TFs is likely functionally relevant, validated by chromatin immunoprecipitation sequencing (ChIP-seq). Overall, this cis-regulatory atlas provides a trove of information on transcriptional regulation through immune differentiation and a foundational scaffold to define key regulatory events throughout the immunological genome.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.cell.2018.12.036DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6785993PMC
February 2019

Viral Replicative Capacity, Antigen Availability via Hematogenous Spread, and High T:T Ratios Drive Induction of Potent Neutralizing Antibody Responses.

J Virol 2019 03 5;93(6). Epub 2019 Mar 5.

John Curtin School of Medical Research, The Australian National University, Canberra, Australian Capital Territory, Australia

Live viral vaccines elicit protective, long-lived humoral immunity, but the underlying mechanisms through which this occurs are not fully elucidated. Generation of affinity matured, long-lived protective antibody responses involve close interactions between T follicular helper (T) cells, germinal center (GC) B cells, and T follicular regulatory (T) cells. We postulated that escalating concentrations of antigens from replicating viruses or live vaccines, spread through the hematogenous route, are essential for the induction and maintenance of long-lived protective antibody responses. Using replicating and poorly replicating or nonreplicating orthopox and influenza A viruses, we show that the magnitude of TFH cell, GC B cell, and neutralizing antibody responses is directly related to virus replicative capacity. Further, we have identified that both lymphoid and circulating T:T cell ratios during the peak GC response can be used as an early predictor of protective, long-lived antibody response induction. Finally, administration of poorly or nonreplicating viruses to allow hematogenous spread generates significantly stronger T:T ratios and robust T, GC B cell and neutralizing antibody responses. Neutralizing antibody response is the best-known correlate of long-term protective immunity for most of the currently licensed clinically effective viral vaccines. However, the host immune and viral factors that are critical for the induction of robust and durable antiviral humoral immune responses are not well understood. Our study provides insight into the dynamics of key cellular mediators of germinal center reaction during live virus infections and the influence of viral replicative capacity on the magnitude of antiviral antibody response and effector function. The significance of our study lies in two key findings. First, the systemic spread of even poorly replicating or nonreplicating viruses to mimic the spread of antigens from replicating viruses due to escalating antigen concentration is fundamental to the induction of durable antibody responses. Second, the T:T ratio may be used as an early predictor of protective antiviral humoral immune responses long before memory responses are generated.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1128/JVI.01795-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6401457PMC
March 2019

Transcription Factor PU.1 Promotes Conventional Dendritic Cell Identity and Function via Induction of Transcriptional Regulator DC-SCRIPT.

Immunity 2019 01 2;50(1):77-90.e5. Epub 2019 Jan 2.

Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, VIC 3010, Australia. Electronic address:

Dendritic cells (DCs) are can be broadly divided into conventional (cDC) and plasmacytoid (pDC) subsets. Despite the importance of this lineage diversity, its genetic basis is not fully understood. We found that conditional ablation of the Ets-family transcription factor PU.1 in DC-restricted progenitors led to increased pDC production at the expense of cDCs. PU.1 controlled many of the cardinal functions of DCs, such as antigen presentation by cDCs and type I interferon production by pDCs. Conditional ablation of PU.1 de-repressed the pDC transcriptional signature in cDCs. The combination of genome-wide mapping of PU.1 binding and gene expression analysis revealed a key role for PU.1 in maintaining cDC identity through the induction of the transcriptional regulator DC-SCRIPT. PU.1 activated DC-SCRIPT expression, which in turn promoted cDC formation, particularly of cDC1s, and repressed pDC development. Thus, cDC identity is regulated by a transcriptional node requiring PU.1 and DC-SCRIPT.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.immuni.2018.11.010DOI Listing
January 2019
-->