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Keiko Ozato - One of the best experts on this subject based on the ideXlab platform.
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abstract 3226 the irf8 osteopontin cd44 axis functions as an immune checkpoint to control cd8 t cell activation and tumor immune evasion
Immunology, 2019Co-Authors: John D Klement, Mohammed L. Ibrahim, Chunwan Lu, Amy V Paschall, Priscilla S. Redd, Esteban Celis, Scott I Abrams, Dafeng Yang, Keiko OzatoAbstract:Despite breakthroughs in immune checkpoint inhibitor (ICI) immunotherapy, not all human cancers respond to ICI immunotherapy and only fraction of patients with responsive tumors have a durable response to current ICI immunotherapy. This clinical conundrum suggests that additional immune checkpoints may exist, particularly in cancers resistant to current ICI immunotherapy, such as colorectal cancer. We report here that Interferon Regulatory factor 8 (IRF8) deficiency led to impairment of cytotoxic T lymphocyte (CTL) activation in a peptide vaccine model and allowed allograft transplant tumor tolerance. These effects were associated with upregulation of the CTL surface marker CD44. However, analysis of chimeric mice with competitive reconstitution of wild type and IRF8 KO bone marrow cells as well as mice with IRF8 deficiency only in T cells indicated that IRF8 plays no intrinsic role in CTL activation. Instead, IRF8 functioned as a repressor of osteopontin (OPN), the physiological ligand for CD44 on T cells, in CD11b+Ly6CloLy6G+ myeloid cells and OPN acted as a potent T cell suppressor. In vitro stimulation of CTLs in the presence of OPN resulted in decreased expression of activation markers CD69 and CD25 and inhibited proliferation and Interferon gamma (IFNg) secretion. Expression of OPN was found to be upregulated in both myeloid cells and colon epithelial cells following silencing of IRF8 expression. IRF8 bound to the Spp1 promoter, which encodes OPN, to repress OPN expression in colon epithelial cells. Correspondingly, human colon carcinoma cells exhibited decreased IRF8 and increased OPN expression. These increased OPN levels inhibited human PBMC proliferation and IFNg secretion. The elevated expression of OPN in human colon carcinoma was correlated with decreased patient survival. Our data indicates that myeloid and tumor cell-expressed OPN acts as a novel immune checkpoint to suppress T cell activation and confer host tumor immune tolerance. Blockade of this checkpoint may expand the pool of patients who may benefit from ICI immunotherapy. Citation Format: John D. Klement, Amy V. Paschall, Priscilla S. Redd, Mohammed L. Ibrahim, Chunwan Lu, Dafeng Yang, Esteban Celis, Scott I. Abrams, Keiko Ozato, Kebin Liu. The IRF8-osteopontin-CD44 axis functions as an immune checkpoint to control CD8+ T cell activation and tumor immune evasion [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3226.
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abstract 4682 irf8 controls t cell development and survival to regulate t cell antitumor activity
Cancer Research, 2018Co-Authors: John D Klement, Mohammed L. Ibrahim, Hussein Sultan, Chunwan Lu, Amy V Paschall, Priscilla S. Redd, Mary Zimmerman, Esteban Celis, Keiko OzatoAbstract:Interferon Regulatory Factor 8 (IRF8, or ICSBP1) is a member of the Interferon Regulatory transcription factor family, and functions as a key hematopoietic transcription factor. Loss of IRF8 leads to defective antigen-presenting cell activity, perturbations in B cell development and, in mouse models, an accumulation of CD11b + Gr1 + immature myeloid cells. However, the role of IRF8 in T cell development and antitumor activity remains unclear. Whole body and chimeric IRF8-knockout mice (IRF8-KO) demonstrate increased susceptibility to both allogenic transplant and carcinogen-induced tumor models. T cell function is crucial for the immune system9s endogenous antitumor response. Analysis of the T cell compartment of IRF8-KO mice demonstrated a deficiency in both naive T cell percentages and total number. Despite this peripheral decrease in T cell numbers, early T cell progenitors in both the bone marrow and thymus were significantly increased in IRF8-KO mice compared to wild-type. To further investigate the role of IRF8 in T cell development and survival, IRF8-KO:WT mixed chimera mice were generated by lethal irradiation of CD45.1 + CD45.2 + recipient mice, followed by transfer of CD45.2 + IRF8-KO and CD45.1 + WT bone marrow (BM). Surprisingly, analysis of blood obtained from reconstituted mice demonstrated preferential engraftment and survival of T cells derived from WT, rather than IRF8-KO BM. This imbalanced phenotype was not rescued by increasing the proportion of IRF8-KO BM administered to mice, suggesting the effect was not due to failure of IRF8-KO BM engraftment. Furthermore, analysis of T cell populations in both primary (thymus) and secondary (spleen) lymphoid organs showed a progressive loss of IRF8-KO T cells during their maturation and development process, while WT T cells remained unaltered. Given that IRF8 has been shown in tumor cells to regulate a variety of pro- and anti-apoptotic molecules, we hypothesized that IRF8 controls the peripheral survival of T cells. To test this hypothesis, resting T cells were isolated from the spleen of mixed chimera mice and viability was measured by Annexin V/PI staining. Resting IRF8-KO cells, but not WT, demonstrated a pro-apoptotic phenotype, as shown by increased Annexin V staining. Accordingly, upon in vitro stimulation and activation, IRF8-KO T cells demonstrated increased apoptosis. Our data determine that IRF8 controls both T cell development and peripheral survival, and that loss of IRF8 impairs the T cell antitumor immune response. Citation Format: John D. Klement, Amy V. Paschall, Mary A. Zimmerman, Mohammed L. Ibrahim, Priscilla S. Redd, Chunwan Lu, Hussein Sultan, Esteban Celis, Keiko Ozato, Kebin Liu. IRF8 controls T cell development and survival to regulate T cell antitumor activity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4682.
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Interferon Regulatory factor 8 irf8 impairs induction of Interferon induced with tetratricopeptide repeat motif ifit gene family members
Journal of Biological Chemistry, 2016Co-Authors: Christine L White, Patricia M Kessler, Benjamin K. Dickerman, Keiko OzatoAbstract:Abstract The chromosomally clustered Interferon-induced with tetratricopeptide repeat motif (IFIT) gene family members share structural features at the gene and protein levels. Despite these similarities, different IFIT genes have distinct inducer- and cell type-specific induction patterns. Here, we investigated the mechanism for the observed differential induction of the mouse Ifit1, Ifit2, and Ifit3 genes in B cells and demonstrated that the repressive effect of the transcription factor Interferon Regulatory factor 8 (IRF8), which is highly expressed in B cells, played an essential role in this regulation. Although IRF8 could impair induction of all three IFIT genes following stimulation of retinoic acid-inducible gene I (RIG-I), it could selectively impair the induction of the Ifit1 gene following IFN stimulation. The above properties could be imparted to IRF8-non-expressing cells by ectopic expression of the protein. Induction of reporter genes, driven by truncated Ifit1 promoters, identified the regions that mediate the repression, and a chromatin immunoprecipitation assay revealed that more IRF8 bound to the IFN-stimulated response element of the Ifit1 gene than to those of the Ifit2 and the Ifit3 genes. Mutational analyses of IRF8 showed that its ability to bind DNA, interact with other proteins, and undergo sumoylation were all necessary to selectively repress Ifit1 gene induction in response to IFN. Our study revealed a new role for IRFs in differentially regulating the induction patterns of closely related IFN-stimulated genes that are located adjacent to one another in the mouse genome.
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a dual cis Regulatory code links irf8 to constitutive and inducible gene expression in macrophages
Genes & Development, 2015Co-Authors: Alessandra Mancino, Serena Ghisletti, Elena Prosperini, Iros Barozzi, Renato Ostuni, Keiko Ozato, Alberto Termanini, Gioacchino NatoliAbstract:The transcription factor (TF) Interferon Regulatory factor 8 (IRF8) controls both developmental and inflammatory stimulus-inducible genes in macrophages, but the mechanisms underlying these two different functions are largely unknown. One possibility is that these different roles are linked to the ability of IRF8 to bind alternative DNA sequences. We found that IRF8 is recruited to distinct sets of DNA consensus sequences before and after lipopolysaccharide (LPS) stimulation. In resting cells, IRF8 was mainly bound to composite sites together with the master regulator of myeloid development PU.1. Basal IRF8–PU.1 binding maintained the expression of a broad panel of genes essential for macrophage functions (such as microbial recognition and response to purines) and contributed to basal expression of many LPS-inducible genes. After LPS stimulation, increased expression of IRF8, other IRFs, and AP-1 family TFs enabled IRF8 binding to thousands of additional regions containing low-affinity multimerized IRF sites and composite IRF–AP-1 sites, which were not premarked by PU.1 and did not contribute to the basal IRF8 cistrome. While constitutively expressed IRF8-dependent genes contained only sites mediating basal IRF8/PU.1 recruitment, inducible IRF8-dependent genes contained variable combinations of constitutive and inducible sites. Overall, these data show at the genome scale how the same TF can be linked to constitutive and inducible gene regulation via distinct combinations of alternative DNA-binding sites.
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the transcription factor irf8 is a key transcription factor for basophil development
Blood, 2013Co-Authors: Haruka Sasaki, Naoki Osato, Izumi Sasaki, Chika Kaneda, Herbert C. Morse, Hideaki Sato, Tsuneyasu Kaisho, Hiroyuki Aburatani, Akira Nishiyama, Keiko OzatoAbstract:Basophils are the rarest granulocytes circulating in the peripheral blood. They play critical roles in anti-parasite Th2-type immune responses and chronic allergic disorders. The developmental pathway for basophils has been recently demonstrated; myeloid progenitors pass through common myeloid progenitors, granulocyte-monocyte progenitors, granulocyte-committed progenitors (GPs), and basophil-committed progenitors (BaPs) in the bone marrow. BaPs then give rise to mature basophils. However, our understanding of how this pathway is regulated remains still elusive. Interferon Regulatory Factor-8 (IRF8), a hematopoietic cell-specific IRF transcription factor, is essential for the development of monocytes, dendritic cells, and eosinophils, while it inhibits neutrophil differentiation. Its role in the development of basophils has yet to be analyzed. In this study, we investigated whether IRF8 has any role in the development of the basophil lineage. We found that Irf8 –/– mice displayed a severe reduction of basophil counts in the bone marrow, peripheral blood and spleen compared to wild-type (WT) mice. Irf8 –/– mice retained GPs but lacked BaPs. Cell transfer experiments revealed that the defect of basophil development in Irf8 –/– mice resides in bone marrow cells. We utilized IRF8-GFP chimera knock-in mice to examine IRF8 protein expression in the basophil lineage at a single cell level. We found that GPs, but not BaPs and mature basophils, expressed IRF8. Furthermore, purified Irf8 –/– GPs failed to efficiently give rise to basophils in vitro . These results indicate that IRF8 acts at the stage of GPs in a cell-intrinsic manner. To understand the mechanism by which IRF8 promotes basophil development, we performed transcriptome analysis of purified GPs from WT and Irf8 –/– mice by microarray. Because IRF8 is no more expressed in BaPs, we envisaged that IRF8 acts by inducing downstream transcription factors in GPs. The expression of several transcription factor genes such as Gata2 and Spib was reduced in Irf8 –/– GPs compared to WT GPs. Analysis of DNA motifs in the promoter regions of genes downregulated in Irf8 –/– GPs predicted that GATA transcription factor(s) may act downstream of IRF8. Indeed, retroviral transduction of GATA2, known to be essential for basophil development, into Irf8 –/– hematopoietic progenitor cells rescued basophil differentiation in vitro . On the other hand, Spib –/– mice showed no obvious defects in basophil development. Taken together, these results suggest that the IRF8-GATA2 axis in GPs critically regulates basophil development. Disclosures: No relevant conflicts of interest to declare.
Tomohiko Tamura - One of the best experts on this subject based on the ideXlab platform.
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transcription factor irf1 is responsible for irf8 mediated il 1β expression in reactive microglia
Journal of Pharmacological Sciences, 2015Co-Authors: Takahiro Masuda, Shosuke Iwamoto, Satsuki Mikuriya, Hidetoshi Tozakisaitoh, Makoto Tsuda, Tomohiko Tamura, Kazuhide InoueAbstract:Interferon Regulatory Factor-8 (IRF8) plays a crucial role in the transformation of microglia to a reactive state by regulating the expression of various genes. In the present study, we show that IRF1 is required for IRF8-induced gene expression in microglia. Peripheral nerve injury induced IRF1 gene upregulation in the spinal microglia in an IRF8-dependent manner. IRF8 transduction in cultured microglia induced de novo gene expression of IRF1. Importantly, knockdown of the IRF1 gene in IRF8-transduced microglia prevented upregulation of interleukin-1β (IL-1β). Therefore, our findings suggest that expression of IL-1β is dependent on IRF1 in IRF8-expressing reactive microglia.
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Guest editorial: Transcriptional control in myeloid cell development and related diseases.
International Journal of Hematology, 2015Co-Authors: Tomohiko TamuraAbstract:four review articles focusing on the biology of these important transcriptional regulators. Rapid advances in recent years in high-throughput experimental techniques, including microarrays, next-generation sequencing (such as chromatin immunoprecipitation sequencing and RNA sequencing), and high-sensitivity mass spectrometry, as well as developments in bioinformatics, have ushered in a new era in the study of transcriptional control. Comprehensive gene expression profiles and even the precise locations of transcription regulator binding and chromatin modifications throughout the genome can now be obtained. Systematic identification of the components of large protein complexes is also now achievable. Using such techniques, research into transcriptional control in myeloid cell development and related diseases has produced major advances in recent years. In the first of the four reviews, Bonifer and colleagues provide an update on the developmental stage-specific function of RUNX1 and its important target, PU.1, during myelopoiesis from both cellular and molecular aspects. They also describe the close relationship between these two critical factors, which show reciprocal regulation of gene expression and synergistic function. Moreover, these authors summarize the known mutations and translocations involving RUNX1 or PU.1, as well as the ‘addiction’ to naive RUNX1 and PU.1 in the development of acute myeloid leukemia (AML) [1]. Friedman describes the molecular basis of how C/ EBPα activates transcription as a homodimer and through its interactions with other bZIP transcription factors, such as AP-1, during myelopoiesis. The role of C/EBPα in the development of myeloid cells, particularly granulocytes and monocytes, and in the regulation of the cell cycle, survival, and quiescence, is highlighted. Moreover, Friedman summarizes the known mutations in CEBPA, the The diverse cell types of the body exhibit distinct morphologies and functions, despite the fact that (with the exception of antigen receptor genes in lymphocytes) the genome sequence is essentially identical among all cell types in an individual. The molecular basis for this diversity is that among the approximately 22,000 genes encoded by the human genome, only a specific set is expressed in a given cell type. The differentiation of stem or progenitor cells to mature cells is a sequential process of activation, inactivation, or maintenance of the selected genes—i.e., transcriptional control—that ultimately determines cell fate. Numerous studies have shown that transcription factors and epigenetic regulators play essential roles in cell differentiation. Dysregulation of these processes can result in various diseases, including cancers, such as leukemias in the case of hematopoiesis. Myeloid cells, e.g., granulocytes, monocytes/macrophages, dendritic cells, and mast cells, are generated from hematopoietic stem cells in the bone marrow via multipotent progenitors, common myeloid progenitors, granulocyte–monocyte progenitors, and more committed progenitors. Multiple factors have been identified as essential for the regulation of myelopoiesis. These include the transcription factors runt-related transcription factor 1 (RUNX1), PU.1, CCAAT/enhancer binding proteins (C/ EBPs), and Interferon Regulatory Factor-8 (IRF8), and the chromatin regulator mixed-lineage leukemia (MLL). In this issue of International Journal of Hematology, we present Transcriptional control in myeloid cell development and related diseases
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regulation of myelopoiesis by the transcription factor irf8
International Journal of Hematology, 2015Co-Authors: Tomohiko Tamura, Daisuke Kurotaki, Shinichi KoizumiAbstract:Interferon Regulatory Factor-8 (IRF8) is a transcription factor expressed in hematopoietic cells, particularly in mononuclear phagocytes [monocytes/macrophages and dendritic cells (DCs)] and their progenitors. Various studies have demonstrated that IRF8 is essential for the development of monocytes, DCs, eosinophils, and basophils. Conversely, IRF8 suppresses the generation of neutrophils. Accordingly, Irf8−/− mice develop immunodeficiency and a chronic myeloid leukemia (CML)-like disease. Mutations and loss of expression of the human IRF8 gene are also associated with immunodeficiency and CML, respectively. Recent findings have begun to reveal the transcription factor network and epigenetic changes governed by IRF8. For example, in mononuclear phagocyte progenitors, IRF8 cooperates with PU.1 to promote the formation of promoter-distal enhancers to induce monocyte-related genes including the critical downstream transcription factor gene Klf4. On the other hand, IRF8 blocks C/EBPα activity to suppress the neutrophil differentiation program. Indeed, Irf8−/− mononuclear phagocyte progenitors fail to efficiently generate monocytes and DCs and, instead, aberrantly give rise to neutrophils. This article provides an overview of recent advances in our understanding of the role of IRF8 in myelopoiesis and related diseases.
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Interferon Regulatory factor 8 expressed in microglia contributes to tactile allodynia induced by repeated cold stress in rodents
Journal of pharmacological sciences, 2014Co-Authors: Takanori Akagi, Tomohiko Tamura, Takahiro Masuda, Hidetoshi Tozaki-saitoh, Yuta Matsumura, Masaya Yasui, Emiko Minami, Hidemasa Inoue, Kazue Mizumura, Makoto TsudaAbstract:We investigated the role of Interferon Regulatory factor 8 (IRF8) in a model of chronic pain in which repeated cold stress (RCS) exposure produces tactile allodynia. RCS exposure produced a decrease in paw withdrawal threshold (PWT) to mechanical stimulation. Spinal microglia of RCS-exposed mice were morphologically activated. Expression of IRF8 was significantly increased in the spinal cord of RCS-exposed mice and was localized in microglia. IRF8-knockout mice failed to show the RCS-induced decrease in PWT. Thus, RCS exposure activates spinal microglia and upregulation of IRF8 in these cells is involved in the development of tactile allodynia after RCS exposure.
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226 the transcription factor irf8 is required for the development of basophils
Cytokine, 2013Co-Authors: Haruka Sasaki, Daisuke Kurotak, Herbert C. Morse, Keiko Ozato, Hideaki Sato, Tomohiko TamuraAbstract:Basophils are the rarest granulocytes circulating in the peripheral blood. Although their non-redundant roles in Th2-type immunity and allergic disorders have been clarified, little is known about the pathways and regulators of their development. Interferon Regulatory Factor-8 (IRF8) is a transcription factor known to promote the development of monocytes/macrophages and dendritic cells while inhibiting that of neutrophils. In this report, we show that this transcription factor is required for the development of the basophil lineage. Irf8−/− mice display a severe reduction of basophil counts in the bone marrow, peripheral blood and spleen. Bone marrow transfer experiments showed that IRF8 functions in a bone marrow cell-intrinsic manner. Analysis of bone marrow progenitors revealed that the number of granulocyte-committed progenitors (GPs) in Irf8−/− mice is comparable to that of wild-type mice, while that of basophil-committed progenitors (BaPs) is diminished. Using IRF8-GFP knock-in mice, we found that GPs but not BaPs and mature basophils express IRF8, suggesting that IRF8 may act in the stage of GPs. Indeed, GPs purified from Irf8−/− mice failed to efficiently give rise to basophils in vitro in the presence of IL-3. Taken together, these results uncover a previously unrecognized role of IRF8 in granulocyte development.
Herbert C. Morse - One of the best experts on this subject based on the ideXlab platform.
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Interferon regulator factor 8 irf8 limits ocular pathology during hsv 1 infection by restraining the activation and expansion of cd8 t cells
PLOS ONE, 2016Co-Authors: Lin Sun, Herbert C. Morse, Hongsheng Wang, Anthony J St Leger, Rashid M Mahdi, Chichao Chan, Charles E EgwuaguAbstract:Interferon Regulatory Factor-8 (IRF8) is constitutively expressed in monocytes and B cell lineages and plays important roles in immunity to pathogens and cancer. Although IRF8 expression is induced in activated T cells, the functional relevance of IRF8 in T cell-mediated immunity is not well understood. In this study, we used mice with targeted deletion of Irf8 in T-cells (IRF8KO) to investigate the role of IRF8 in T cell-mediated responses during herpes simplex virus 1 (HSV-1) infection of the eye. In contrast to wild type mice, HSV-1-infected IRF8KO mice mounted a more robust anti-HSV-1 immune response, which included marked expansion of HSV-1-specific CD8+ T cells, increased infiltration of inflammatory cells into the cornea and trigeminal ganglia (TG) and enhanced elimination of virus within the trigeminal ganglion. However, the consequence of the enhanced immunological response was the development of ocular inflammation, limbitis, and neutrophilic infiltration into the cornea of HSV-1-infected IRF8KO mice. Surprisingly, we observed a marked increase in virus-specific memory precursor effector cells (MPEC) in IRF8KO mice, suggesting that IRF8 might play a role in regulating the differentiation of effector CD8+ T cells to the memory phenotype. Together, our data suggest that IRF8 might play a role in restraining excess lymphocyte proliferation. Thus, modulating IRF8 levels in T cells can be exploited therapeutically to prevent immune-mediated ocular pathology during autoimmune and infectious diseases of the eye.
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Interferon Regulatory factor 8 irf8 interacts with the b cell lymphoma 6 bcl6 corepressor bcor
Journal of Biological Chemistry, 2014Co-Authors: Jeongheon Yoon, Dongmi Shin, Xianxum Feng, Katerina Hatzi, Hongsheng Wang, Herbert C. MorseAbstract:Abstract B cell lymphoma 6 (BCL6) corepressor (BCOR) was discovered as a BCL6-interacting corepressor, but little is known about its other biological activities in normal B cell development and function. Previously, we found that Interferon Regulatory factor 8 (IRF8), also known as Interferon consensus sequence-binding protein, directly targets a large number of genes in germinal center B cells including BCL6. In this study, we screened potential binding partners of IRF8 using a retrovirus-based protein complementation assay screen in a mouse pre-B cell line. We found that IRF8 interacts directly with BCOR and that the α-helical region of IRF8 and the BCL6 binding domain of BCOR are required for this interaction. In addition, IRF8 protein interacts directly with BCL6. Using an siRNA-mediated IRF8 knockdown mouse B cell lymphoma cell line, we showed that IRF8 represses Bcor and enhances Bcl6 transcription. Taken together, these data suggest that a complex comprising BCOR-BCL6-IRF8 modulates BCL6-associated transcriptional regulation of germinal center B cell function.
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the transcription factor irf8 is a key transcription factor for basophil development
Blood, 2013Co-Authors: Haruka Sasaki, Naoki Osato, Izumi Sasaki, Chika Kaneda, Herbert C. Morse, Hideaki Sato, Tsuneyasu Kaisho, Hiroyuki Aburatani, Akira Nishiyama, Keiko OzatoAbstract:Basophils are the rarest granulocytes circulating in the peripheral blood. They play critical roles in anti-parasite Th2-type immune responses and chronic allergic disorders. The developmental pathway for basophils has been recently demonstrated; myeloid progenitors pass through common myeloid progenitors, granulocyte-monocyte progenitors, granulocyte-committed progenitors (GPs), and basophil-committed progenitors (BaPs) in the bone marrow. BaPs then give rise to mature basophils. However, our understanding of how this pathway is regulated remains still elusive. Interferon Regulatory Factor-8 (IRF8), a hematopoietic cell-specific IRF transcription factor, is essential for the development of monocytes, dendritic cells, and eosinophils, while it inhibits neutrophil differentiation. Its role in the development of basophils has yet to be analyzed. In this study, we investigated whether IRF8 has any role in the development of the basophil lineage. We found that Irf8 –/– mice displayed a severe reduction of basophil counts in the bone marrow, peripheral blood and spleen compared to wild-type (WT) mice. Irf8 –/– mice retained GPs but lacked BaPs. Cell transfer experiments revealed that the defect of basophil development in Irf8 –/– mice resides in bone marrow cells. We utilized IRF8-GFP chimera knock-in mice to examine IRF8 protein expression in the basophil lineage at a single cell level. We found that GPs, but not BaPs and mature basophils, expressed IRF8. Furthermore, purified Irf8 –/– GPs failed to efficiently give rise to basophils in vitro . These results indicate that IRF8 acts at the stage of GPs in a cell-intrinsic manner. To understand the mechanism by which IRF8 promotes basophil development, we performed transcriptome analysis of purified GPs from WT and Irf8 –/– mice by microarray. Because IRF8 is no more expressed in BaPs, we envisaged that IRF8 acts by inducing downstream transcription factors in GPs. The expression of several transcription factor genes such as Gata2 and Spib was reduced in Irf8 –/– GPs compared to WT GPs. Analysis of DNA motifs in the promoter regions of genes downregulated in Irf8 –/– GPs predicted that GATA transcription factor(s) may act downstream of IRF8. Indeed, retroviral transduction of GATA2, known to be essential for basophil development, into Irf8 –/– hematopoietic progenitor cells rescued basophil differentiation in vitro . On the other hand, Spib –/– mice showed no obvious defects in basophil development. Taken together, these results suggest that the IRF8-GATA2 axis in GPs critically regulates basophil development. Disclosures: No relevant conflicts of interest to declare.
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226 the transcription factor irf8 is required for the development of basophils
Cytokine, 2013Co-Authors: Haruka Sasaki, Daisuke Kurotak, Herbert C. Morse, Keiko Ozato, Hideaki Sato, Tomohiko TamuraAbstract:Basophils are the rarest granulocytes circulating in the peripheral blood. Although their non-redundant roles in Th2-type immunity and allergic disorders have been clarified, little is known about the pathways and regulators of their development. Interferon Regulatory Factor-8 (IRF8) is a transcription factor known to promote the development of monocytes/macrophages and dendritic cells while inhibiting that of neutrophils. In this report, we show that this transcription factor is required for the development of the basophil lineage. Irf8−/− mice display a severe reduction of basophil counts in the bone marrow, peripheral blood and spleen. Bone marrow transfer experiments showed that IRF8 functions in a bone marrow cell-intrinsic manner. Analysis of bone marrow progenitors revealed that the number of granulocyte-committed progenitors (GPs) in Irf8−/− mice is comparable to that of wild-type mice, while that of basophil-committed progenitors (BaPs) is diminished. Using IRF8-GFP knock-in mice, we found that GPs but not BaPs and mature basophils express IRF8, suggesting that IRF8 may act in the stage of GPs. Indeed, GPs purified from Irf8−/− mice failed to efficiently give rise to basophils in vitro in the presence of IL-3. Taken together, these results uncover a previously unrecognized role of IRF8 in granulocyte development.
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irf8 governs expression of genes involved in innate and adaptive immunity in human and mouse germinal center b cells
PLOS ONE, 2011Co-Authors: Dongmi Shin, Herbert C. MorseAbstract:IRF8 (Interferon Regulatory Factor 8) is a transcription factor expressed throughout B cell differentiation except for mature plasma cells. Previous studies showed it is part of the transcriptional network governing B cell specification and commitment in the bone marrow, regulates the distribution of mature B cells into the splenic follicular and marginal zone compartments, and is expressed at highest levels in germinal center (GC) B cells. Here, we investigated the transcriptional programs and signaling pathways affected by IRF8 in human and mouse GC B cells as defined by ChIP-chip analyses and transcriptional profiling. We show that IRF8 binds a large number of genes by targeting two distinct motifs, half of which are also targeted by PU.1. Over 70% of the binding sites localized to proximal and distal promoter regions with ~25% being intragenic. There was significant enrichment among targeted genes for those involved in innate and adaptive immunity with over 30% previously defined as Interferon stimulated genes. We also showed that IRF8 target genes contributes to multiple aspects of the biology of mature B cells including critical components of the molecular crosstalk among GC B cells, T follicular helper cells, and follicular dendritic cells.
Byung Kiu Park - One of the best experts on this subject based on the ideXlab platform.
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upregulation of transforming growth factor beta type i receptor by Interferon consensus sequence binding protein in osteosarcoma cells
Biochimica et Biophysica Acta, 2019Co-Authors: Jee Young Sung, Kyungsil Yoon, Sungho Goh, Seog Yun Park, June Hyuk Kim, Hyun Guy Kang, Yong Nyun Kim, Byung Kiu ParkAbstract:Transforming growth factor-beta (TGF-β) is a known tumor suppressor, which also exerts a tumor promoting activity at an advanced stage of cancer. Previously, we reported that expression of Interferon consensus sequence-binding protein (ICSBP), also known as Interferon Regulatory Factor-8, is positively correlated with TGF-β type I receptor (TGF-β RI) expression in osteosarcoma patient tissues. In this study, we demonstrated that ICSBP upregulated TGF-β RI and induced epithelial-to-mesenchymal transition-like phenomena in human osteosarcoma cell lines. As determined by soft agar growth of osteosarcoma cells and xenografted mouse models, ICSBP increased tumorigenicity, which was reversed by ICSBP knock-down or a TGF-β RI inhibitor. To test whether ICSBP directly regulates the promoter activity of TGF-β RI, we performed a TGF-β RI promoter assay, an electro mobility shift assay, and a chromatin immunoprecipitation assay. We observed that TGF-β RI promoter was activated in ICSBP-overexpressing osteosarcoma cells. Exploiting serial deletions and mutations of the TGF-β RI promoter, we found a putative ICSBP-binding site at nucleotides -216/-211 (GGXXTC) in the TGF-β RI promoter. Our data suggest that ICSBP upregulates TGF-β RI expression by binding to this site, causing ICSBP-mediated tumor progression in osteosarcoma cells. In addition, we found a positive correlation between ICSBP and TGF-β RI expression in several types of tumors using the cBioportal database. SUMMARY: We demonstrated that Interferon consensus sequence-binding protein upregulates transforming growth factor-beta type I receptor (TGF-β RI) expression by binding to nucleotides -216/-211 (GGXXTC) in the TGF-β RI promoter, which resulted in increased tumorigenicity and tumor progression in human osteosarcoma cells.
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abstract 2208 Interferon consensus sequence binding protein icsbp regulates the transforming growth factor beta type i receptor expression in osteosarcoma cells
Cancer Research, 2015Co-Authors: Jee Young Sung, Kyungsil Yoon, Yong Nyun Kim, Hyeryeong Kim, Byung Kiu ParkAbstract:Transforming growth factor-beta (TGF-β), known as a tumor suppressor, may exert tumor promoting activity in the advanced stage of cancer. Previously, we reported that Interferon consensus sequence-binding protein (ICSBP), also known as Interferon Regulatory Factor-8, up-regulates TGF-β type I receptor (TGF-βR I), and augments growth in HL-60 leukemic cells. In the current study, we demonstrate that ICSBP expression up-regulates TGF-βR I and increase in cell growth in U2OS human osteosarcoma cells. To further investigate the mechanism of TGF-βR I up-regulation by ICSBP, we tested the possibility that ICSBP regulates promoter activity of TGF-βR I gene. We analyzed the promoter region of the human TGF-βR I gene in U2OS cells to find putative transcription elements regulated by ICSBP. Luciferase reporter gene assays indicated that ICSBP expression could enhance TGF-βR I gene expression, and by promoter deletion analysis we identified a functional ICSBP-dependent region located at nucleotides -220 to +5 in the TGF-βR I promoter. We also performed EMSA (Electro Mobility Shift Assay) using probe and found that there are putative ICSBP binding sites between -222 to -204 regions. In conclusion, ICSBP increased TGF-βR I expression by binding to TGF-βR I promoter (-220/218) regions in U2OS cells. Note: This abstract was not presented at the meeting. Citation Format: Jee Young Sung, Hyeryeong Kim, Kyung-Sil Yoon, Yong-Nyun Kim, Byung-Kiu Park. Interferon Consensus Sequence-Binding Protein (ICSBP) regulates the transforming growth factor-beta type I receptor expression in osteosarcoma cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2208. doi:10.1158/1538-7445.AM2015-2208
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abstract 3065 Interferon consensus sequence binding protein icsbp regulates the transforming growth factor beta type i receptor expression in osteosarcoma cells
Cancer Research, 2012Co-Authors: Jee Young Sung, Yong Nyun Kim, Byung Kiu ParkAbstract:Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL Transforming growth factor-beta (TGF-β), known as a tumor suppressor, may exert tumor promoting activity in the advanced stage of cancer. Previously, we reported that Interferon consensus sequence-binding protein (ICSBP), also known as Interferon Regulatory Factor-8, up-regulates TGF-βtype I receptor (TGF-βR I), and augments growth in HL-60 leukemic cells. In the current study, we demonstrate that ICSBP expression up-regulates TGF-βR I and increase in cell growth in U2OS human osteosarcoma cells. To further investigate the mechanism of TGF-βR I up-regulation by ICSBP, we tested the possibility that ICSBP regulates promoter activity of TGF-βR I gene. We analyzed the promoter region of the human TGF-βR I gene in U2OS cells to find putative transcription elements regulated by ICSBP. Luciferase reporter gene assays indicated that ICSBP expression could enhance TGF-βR I gene expression, and by promoter deletion analysis we identified a functional ICSBP-dependent region located at nucleotides −300 to −1 in the TGF-βR I promoter. We also performed chromatin immunoprecipitation using anti-ICSBP and found that there are putative ICSBP binding sites in −300 to −1 region. In conclusion, ICSBP increased TGF-βR I expression by binding to TGF-βR I promoter (−300/−1) in U2OS cells. Exploration for the specific ICSBP binding sequences within TGF-βR I promoter (−300/−1) is under way, which may be helpful in understanding the Regulatory mechanism involved in TGF-βR I expression by ICSBP. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3065. doi:1538-7445.AM2012-3065
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th17 cell differentiation proceeds independently of irf8
Immunology and Cell Biology, 2016Co-Authors: Dane M Newman, Patrick Sk Leung, Erika Cretney, Stephen L Nutt, Tracy L PutoczkiAbstract:Abstract The transcriptional repressor/activator Interferon Regulatory factor 8 (IRF8) modulates the differentiation of a multitude of hematopoietic lineages. However, the role of IRF8 in CD4(+) T-cell development is less well defined, with a recent study implicating IRF8 as an intrinsic repressor of interleukin-17 (IL-17) expressing T helper type 17 (Th17) cell differentiation. Using an IRF8-EGFP reporter strain we have confirmed that IRF8 is expressed in all T helper lineages, including Th17 cells. The loss of IRF8 did not affect Th17 differentiation in vitro, beyond a small increase in IL-22 expression. Moreover, IRF8 deficiency did not enhance the Th17 immune response in experimental T-cell transfer colitis. Together, these results suggest that IRF8 does not play an essential intrinsic role in Th17 cell differentiation.