scholarly journals A Modular Enhancer Is Differentially Regulated by GATA and NFAT Elements That Direct Different Tissue-Specific Patterns of Nucleosome Positioning and Inducible Chromatin Remodeling

2007 ◽  
Vol 27 (8) ◽  
pp. 2870-2885 ◽  
Author(s):  
Andrew G. Bert ◽  
Brett V. Johnson ◽  
Euan W. Baxter ◽  
Peter N. Cockerill
Keyword(s):  
T Cells ◽  
Mast Cells ◽  
Myeloid Cells ◽  
Cell Types ◽  
Dependent Manner ◽  
Tissue Specific ◽  
Gm Csf ◽  
Gata Factors ◽  
Gene Enhancer ◽  
High Level

ABSTRACT We investigated alternate mechanisms employed by enhancers to position and remodel nucleosomes and activate tissue-specific genes in divergent cell types. We demonstrated that the granulocyte-macrophage colony-stimulating factor (GM-CSF) gene enhancer is modular and recruits different sets of transcription factors in T cells and myeloid cells. The enhancer recruited distinct inducible tissue-specific enhanceosome-like complexes and directed nucleosomes to different positions in these cell types. In undifferentiated T cells, the enhancer was activated by inducible binding of two NFAT/AP-1 complexes which disrupted two specifically positioned nucleosomes (N1 and N2). In myeloid cells, the enhancer was remodeled by GATA factors which constitutively displaced an upstream nucleosome (N0) and cooperated with inducible AP-1 elements to activate transcription. In mast cells, which express both GATA-2 and NFAT, these two pathways combined to activate the enhancer and generate high-level gene expression. At least 5 kb of the GM-CSF locus was organized as an array of nucleosomes with fixed positions, but the enhancer adopted different nucleosome positions in T cells and mast cells. Furthermore, nucleosomes located between the enhancer and promoter were mobilized upon activation in an enhancer-dependent manner. These studies reveal that distinct tissue-specific mechanisms can be used either alternately or in combination to activate the same enhancer.

Hepatic Stellate Cell Conditioned Myeloid Cells Provide a Novel Therapy for Prevention of Factor VIII Antibody Formation in the Hemophilia A Mouse Model

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 4117-4117
Author(s):  
Sumantha Bhatt ◽  
Kathleen Brown ◽  
Feng Lin ◽  
Michael P Meyer ◽  
Margaret V. Ragni ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Hemophilia A ◽  
Myeloid Cells ◽  
Gm Csf ◽  
Cox 2

Abstract Abstract 4117 Background: Hemophilia is an X-linked bleeding disorder resulting from a mutation in coagulation factor VIII (F.VIII). A major drawback of current plasma-derived or recombinant F.VIII therapy is the formation of F.VIII antibodies (inhibitors). Inhibitor formation is a T cell-dependent, B cell-mediated immune response to foreign infused F.VIII. Myeloid derived suppressor cells (MDSCs) are potent suppressors of T cell and B cell responses and are currently under study for therapeutic applications in transplantation and autoimmune diseases. However, the mechanisms of MDSC development and function remain unknown, and in vitro propagation of MDSCs has been a challenge. We hypothesized that MDSCs might be effective in inhibiting F.VIII inhibitor formation in the hemophilia A model. Methods: We developed a novel method for generating MDSCs in vitro by culturing bone marrow cells from hemophilia A mice with hepatic stellate cells (HSCs), hereafter referred to as HSC-conditioned myeloid cells (H-MCs). DCs were propagated from the bone marrow with GM-CSF and IL-4, whereas H-MCs were propagated from the bone marrow with GM-CSF and HSCs. Granulocyte contaminants were removed on day 2 and the remaining monocytic populations were harvested on day 5. Expression of cell surface antigens was analyzed by flow cytometry. Arginase1 and iNOS levels were compared by qPCR, with or without LPS stimulation. The in vitro suppressive capacity of the H-MCs was determined by a mixed leukocyte reaction culture. Splenic T cells from hemophilia A mice were stimulated by irradiated DCs (at a 1–20 ratio, APC to T cell) and recombinant F.VIII. Additional irradiated DCs or H-MCs were added in graded numbers as regulators. The proliferative response was determined by 3H-thymidine incorporation. The phenotype of cultured CD4+ T cells was characterized by intracellular staining for Foxp3 and IFN-gamma and analyzed by flow cytometry. Inhibition of B cells by H-MCs was determined by a CFSE dilution assay. Purified splenic B cells were labeled with CFSE and stimulated by Ig-M and IL-4. APCs (spleen cells) or H-MCs were added at a ratio of 1:10 (APC to B cell). The proportion of proliferating B cells was determined by CFSE dilution of B220 stained cells. In the COX-2 suppression assay, CFSE labeled B cells were treated with varying concentrations of the selective inhibitor of COX-2, NS398. The suppressive effect of H-MCs on B cells in vivo was determined by simultaneously administering H-MCs (I.V) and F.VIII (I.V.) to hemophila A mice on day 0 and rechallenging with recombinant F.VIII on days 2 and 4. WT B6 mice and hemophilia A mice without H-MC transfer served as controls. Plasma anti-F.VIII antibody titers were measured on day 12 by a modified ELISA assay. Results: H-MCs expressed low levels of costimulatory molecules but high levels of the inhibitory molecule B7-H1 and immunoregulatory enzyme arginase-1. In contrast, DCs expressed high levels of costimulatory molecules and MHC class II. In vitro studies demonstrated that the H-MCs markedly inhibited antigen specific T cell proliferation induced by dendritic cells in response to recombinant F.VIII (Fig. 1). H-MCs altered the T cell response in hemophilia A mice by promoting the expansion of regulatory T cells and inhibiting IFN-γ producing CD4+ T cells. When the H-MCs were cocultured with B cells isolated from hemophilia A mice, in the presence of Ig-M and IL-4, the H-MCs abrogated B cell activation and proliferation directly (Fig. 2). H-MCs may be modulating the B cell response through the Cox-2 pathway, as inhibition of Cox-2 through NS398 led to the restoration of B cell proliferation. More importantly, adoptive transfer of H-MCs into hemophilia Amice, at the time of F.VIII infusion, markedly suppressed anti-F.VIII antibody formation (Fig. 3). Conclusion: These results suggest that HSC conditioned myeloid cells may represent a potential therapeutic approach to induction of immune tolerance in patients with hemophilia A andother immune disorders. Disclosures: No relevant conflicts of interest to declare.

scholarly journals The Blockade of Interleukin-2 During the Acute Phase of Trypanosoma cruzi Infection Reveals Its Dominant Regulatory Role

2021 ◽  
Vol 11 ◽  
Author(s):  
Jorge Nihei ◽  
Fabiola Cardillo ◽  
Jose Mengel
Keyword(s):  
Immune Response ◽  
T Cells ◽  
Regulatory T Cells ◽  
Trypanosoma Cruzi ◽  
Immune Responses ◽  
Chagas Disease ◽  
Acute Phase ◽  
Acute Infection ◽  
Dependent Manner ◽  
Tissue Specific

Trypanosoma cruzi infection causes Chagas’ disease in humans. The infection activates the innate and adaptative immunity in an orchestrated immune response to control parasite growth, guaranteeing host survival. Despite an effective immune response to the parasite in the acute phase, the infection progresses to a chronic stage. The parasite infects different tissues such as peripheral neurons, the brain, skeletal muscle, and heart muscle, among many others. It is evident now that tissue-specific immune responses may develop along with anti-parasite immunity. Therefore, mechanisms to regulate immunity and to ensure tissue-specific tolerance are operating during the infection. Studying those immunoregulatory mechanisms is fundamental to improve host protection or control inflammatory reactions that may lead to pathology. The role of IL-2 during T. cruzi infection is not established. IL-2 production by T cells is strongly down-modulated early in the disease by unknown mechanisms and remains low during the chronic phase of the disease. IL-2 activates NK cells, CD4, and CD8 T cells and may be necessary to immunity development. Also, the expansion and maintenance of regulatory T cells require IL-2. Thus, IL-2 may be a key cytokine involved in promoting or down-regulating immune responses, probably in a dose-dependent manner. This study blocked IL-2 during the acute T. cruzi infection by using a neutralizing monoclonal antibody. The results show that parasitemia and mortality rate was lower in animals treated with anti-IL-2. The percentages and total numbers of CD4+CD25+Foxp3+ T cells diminished within three weeks of infection. The numbers of splenic activated/memory CD4 and CD8 splenic T cells increased during the acute infection. T cells producing IFN-γ, TNF-α and IL-10 also augmented in anti-IL-2-treated infected mice. The IL-2 blockade also increased the numbers of inflammatory cells in the heart and skeletal muscles and the amount of IL-17 produced by heart T cells. These results suggest that IL-2 might be involved in the immune regulatory response during the acute T. cruzi infection, dampening T cell activation through the expansion/maintenance of regulatory T cells and regulating IL-17 production. Therefore, the IL-2 pathway is an attractive target for therapeutic purposes in acute and chronic phases of Chagas’ disease.

scholarly journals Single-Cell Sequencing of Mouse Heart Immune Infiltrate in Pressure Overload–Driven Heart Failure Reveals Extent of Immune Activation

Circulation ◽  
2019 ◽  
Vol 140 (25) ◽  
pp. 2089-2107 ◽  
Author(s):  
Elisa Martini ◽  
Paolo Kunderfranco ◽  
Clelia Peano ◽  
Pierluigi Carullo ◽  
Marco Cremonesi ◽  
...  
Keyword(s):  
Heart Failure ◽  
T Cells ◽  
Mast Cells ◽  
Natural Killer Cells ◽  
Regulatory T Cells ◽  
Natural Killer ◽  
Immune Activation ◽  
Immune Cell ◽  
Pressure Overload ◽  
Cell Types

Background: Inflammation is a key component of cardiac disease, with macrophages and T lymphocytes mediating essential roles in the progression to heart failure. Nonetheless, little insight exists on other immune subsets involved in the cardiotoxic response. Methods: Here, we used single-cell RNA sequencing to map the cardiac immune composition in the standard murine nonischemic, pressure-overload heart failure model. By focusing our analysis on CD45 + cells, we obtained a higher resolution identification of the immune cell subsets in the heart, at early and late stages of disease and in controls. We then integrated our findings using multiparameter flow cytometry, immunohistochemistry, and tissue clarification immunofluorescence in mouse and human. Results: We found that most major immune cell subpopulations, including macrophages, B cells, T cells and regulatory T cells, dendritic cells, Natural Killer cells, neutrophils, and mast cells are present in both healthy and diseased hearts. Most cell subsets are found within the myocardium, whereas mast cells are found also in the epicardium. Upon induction of pressure overload, immune activation occurs across the entire range of immune cell types. Activation led to upregulation of key subset-specific molecules, such as oncostatin M in proinflammatory macrophages and PD-1 in regulatory T cells, that may help explain clinical findings such as the refractivity of patients with heart failure to anti–tumor necrosis factor therapy and cardiac toxicity during anti–PD-1 cancer immunotherapy, respectively. Conclusions: Despite the absence of infectious agents or an autoimmune trigger, induction of disease leads to immune activation that involves far more cell types than previously thought, including neutrophils, B cells, Natural Killer cells, and mast cells. This opens up the field of cardioimmunology to further investigation by using toolkits that have already been developed to study the aforementioned immune subsets. The subset-specific molecules that mediate their activation may thus become useful targets for the diagnostics or therapy of heart failure.

Network analysis to reveal BTK as a link between myeloid and T cells in TLR signaling in colorectal cancer.

2020 ◽  
Vol 38 (5_suppl) ◽  
pp. 30-30
Author(s):  
Justin Hummel ◽  
Yuanyuan Shen ◽  
Iiulia Innokenteva ◽  
Christos Papageorgiou ◽  
Chi-Ren Shyu ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
T Cells ◽  
Network Analysis ◽  
Tumor Microenvironment ◽  
Myeloid Cells ◽  
Cell Types ◽  
The Cancer Genome Atlas ◽  
P Value ◽  
Tlr Signaling ◽  
Critical Link

30 Background: Colorectal cancer (CRC) is the second-leading cause of cancer mortality in the US today. Recent advances in immunotherapy have only been shown to benefit a limited subgroup of patients with CRC. In other malignancies, activation of Toll-like receptors (TLRs) has been shown to overcome resistance to immunotherapy, such as immune checkpoint inhibition (ICI). In this study, using publicly available data and informatics-based analysis, we identified BTK as a critical link between TLR signaling and T cells in the CRC tumor microenvironment. Methods: Using RNA-seq data from The Cancer Genome Atlas (TCGA) and the Microenvironment Cell Populations (MCP)-Counter, abundance scores were generated for the tumor microenvironment of each patient. A curated TLR gene panel was generated using Reactome and GO. Pearson analysis was used to evaluate each pairwise combination of genes and cell-types. Significance was determined by the correlation coefficient, r ≥ | 0.7 | with a p-value < 0.05. Network analysis was performed using the Girvan–Newman algorithm to establish critical connections across these features. Results: After establishing a 453 gene TLR panel and creating MCP-Counter scores, correlation analysis demonstrated strong correlations between 54 different genes and 7 cell-types. As expected the most genes were associated with monocytic lineage cells' (30) and 'myeloid dendritic cells' (7). Only 5 genes were significantly associated with 'T cells'. Genes and cell-types that were highly correlated were then further analyzed for network association. From this analysis, BTK was identified as a critical edge acting as the primary link between ‘myeloid cells’ and ‘T cells’. Conclusions: Developing novel strategies for the treatment of CRC is critical and immunotherapy represents an area ripe for advancement. Informatics based analysis combined with publicly available data provides us with an opportunity to shape pre-clinical and translational studies. Using this approach, we have identified BTK as a critical link between myeloid cells and T cells in the tumor microenvironment in CRC. Further studies in our laboratory will focus confirming these findings for translation into patients.

Immunomodulatory Effects of STI571 in Chronic Myeloid Leukaemia.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 2198-2198
Author(s):  
Dagmar Bund ◽  
Ting Yang ◽  
Raymund Buhmann ◽  
Hans-Jochem Kolb
Keyword(s):  
Immune Response ◽  
T Cells ◽  
Chronic Myeloid Leukaemia ◽  
Myeloid Leukaemia ◽  
Cellular Immune Response ◽  
Myeloid Cells ◽  
Dependent Manner ◽  
Activation Markers ◽  
Cellular Immune ◽  
Antigen Presenting

Abstract Background: The tyrosine kinase inhibitor imatinib (imatinib, STI571, Glivec, and Gleevec) is highly effective in the treatment of chronic myeloid leukaemia (CML) and has already been shown to be effective in the setting of allogeneic stem cell transplantation. But until now, less is known with respect to its immunomodulating effects. Objective: In the present survey we investigated, whether imatinib could modify the antigen-presenting capacity of myeloid cells and in turn affects the cellular immune response. Method: For this purpose, patient derived chronic myeloid cells were incubated with different concentrations of imatinib (0, 1, 2, or 5microM), characterized for their antigen-presenting profile and their stimulatory capacity in the context of HLA-matched and mismatched T-cells. After 5 days, the proliferative immune response was evaluated in presence or absence of different concentrations of imatinib and altered effector-to-target ratios. Thereby, proliferation was detected via a CFDA, SE (5,6-carboxyfluorescein diacetate succinimidyl ester) based assay. Result: The proliferative capacity of the T- cells (allogeneic, HLA-mismatched) was inhibited by imatinib in a dose-dependent manner. Also, the expression of the activation markers was reduced in the presence of the different STI571 concentrations. Moreover, myeloid blasts were sensitized for T cell mediated effector functions by pre-treatment with increasing concentrations of imatinib. Conclusion: Taken together, imatinib can interfere with the T cellular immune response in vitro, and its impact on graft-versus-leukemia (GvL) and graft-versus-host (GvH) reactions will be further investigated.

scholarly journals Infection of immune mast cells by Harvey sarcoma virus: immortalization without loss of requirement for interleukin-3.

1985 ◽  
Vol 5 (9) ◽  
pp. 2257-2264 ◽  
Author(s):  
A Rein ◽  
J Keller ◽  
A M Schultz ◽  
K L Holmes ◽  
R Medicus ◽  
...  
Keyword(s):  
Mast Cells ◽  
Cell Lines ◽  
Normal Growth ◽  
Cell Types ◽  
Growth Potential ◽  
Interleukin 3 ◽  
Sarcoma Virus ◽  
High Level

Cells from adult mouse spleens were cultured in WEHI-3 cell-conditioned medium, which contains the lymphokine interleukin-3 (IL-3). Under these conditions, cells grow well for 4 to 8 weeks; the cultures contain a variety of cell types for the first 1 to 2 weeks but are subsequently composed largely of immune mast cells. We found that infection of these cultures with Harvey sarcoma virus (HaSV) profoundly enhanced the growth potential of the cells, resulting in the reproducible isolation of long-term cell lines. These HaSV-infected cells appeared to be phenotypically identical to the immune mast cells found in uninfected cultures as determined by biochemical, immunological, and cytological tests. Although the cells expressed protein p21Ha-ras at levels similar to those in HaSV-transformed fibroblasts, they continued to require IL-3 for growth in vitro. Similar IL-3-dependent, long-term mast cell lines were also cultured from the enlarged spleens present in HaSV-infected mice. These results suggest that high-level expression of an activated Ha-ras oncogene enhances growth in these cells, perhaps by stimulating the progression of the cells into S, without affecting differentiation or altering the requirements for normal growth factor.

scholarly journals Rapid Expansion of Virus-Specific CD4+ T Cell Types in the CNS of Susceptible Mice Infected with Theiler’s Virus

2020 ◽  
Vol 21 (20) ◽  
pp. 7719
Author(s):  
Hyun Seok Kang ◽  
Wanqiu Hou ◽  
Byung S. Kim
Keyword(s):  
T Cells ◽  
T Cell ◽  
Viral Infection ◽  
Cd4 T Cells ◽  
Demyelinating Disease ◽  
Cell Types ◽  
Rapid Expansion ◽  
Infection Model ◽  
Dependent Manner ◽  
Encephalomyelitis Virus

The infection of susceptible mice with Theiler’s murine encephalomyelitis virus (TMEV) induces a T cell-mediated demyelinating disease. This system has been studied as a relevant infection model for multiple sclerosis (MS). Therefore, defining the type of T cell responses and their functions is critically important for understanding the relevant pathogenic mechanisms. In this study, we adoptively transferred naive VP2-specific TCR-Tg CD4+ T cells into syngeneic susceptible SJL mice and monitored the development of the disease and the activation and proliferation of CD4+ T cells during the early stages of viral infection. The preexisting VP2-specific naive CD4+ T cells promoted the pathogenesis of the disease in a dose-dependent manner. The transferred VP2-specific CD4+ T cells proliferated rapidly in the CNS starting at 2–3 dpi. High levels of FoxP3+CD4+ T cells were found in the CNS early in viral infection (3 dpi) and persisted throughout the infection. Activated VP2-specific FoxP3+CD4+ T cells inhibited the production of IFN-γ, but not IL-17, via the same VP2-specific CD4+ T cells without interfering in proliferation. Thus, the early presence of regulatory T cells in the CNS with viral infection may favor the induction of pathogenic Th17 cells over protective Th1 cells in susceptible mice, thereby establishing the pathogenesis of virus-induced demyelinating disease.

scholarly journals Murine CD14 gene expression in vivo: extramyeloid synthesis and regulation by lipopolysaccharide.

1995 ◽  
Vol 181 (3) ◽  
pp. 857-866 ◽  
Author(s):  
C Fearns ◽  
V V Kravchenko ◽  
R J Ulevitch ◽  
D J Loskutoff
Keyword(s):  
Gene Expression ◽  
Blot Analysis ◽  
Myeloid Cells ◽  
Cell Types ◽  
Dependent Manner ◽  
Mouse Tissues ◽  
Dose Dependent ◽  
Cd14 Mrna ◽  
Cd14 Gene

A murine model system was used to study the distribution and regulation of CD14 gene expression in vivo. Western blot analysis failed to detect CD14 in plasma from untreated CB6 (BALB/c x C57Bl6) mice, but showed markedly increased levels of CD14 in plasma from mice treated with lipopolysaccharide (LPS). Plasma levels of CD14 increased in a time- and dose-dependent manner, reaching a maximum between 8 and 16 h. Northern blot analysis of total RNA extracted from mouse tissues revealed low, but significant, levels of CD14 mRNA in many tissues of untreated animals with the highest levels in uterus, adipose tissue, and lung. After intraperitoneal injection of LPS, induction of CD14 gene expression was detected in all organs examined with the extent of induction varying between organs. Induction of CD14 mRNA was both time and dose dependent. Maximum induction in the heart and lung was observed 2-4 h after injection of LPS, while liver and kidney showed maximal induction between 8 and 16 h. In situ hybridization showed that CD14 mRNA was expressed in myeloid cells in many tissues, and that expression in these cells was upregulated by LPS. Unexpectedly, CD14 mRNA was also detected in other cells within tissues, including epithelial cells, and expression in these cell types also was upregulated by LPS. Immunochemical analysis revealed that CD14 antigen colocalized to the cytoplasm of cells expressing CD14 mRNA. These studies demonstrate that CD14 gene expression is not restricted to myeloid cells, and that the level of expression of CD14 is influenced by exposure to LPS.

scholarly journals Derepression of the DNA Methylation Machinery of the Gata1 Gene Triggers the Differentiation Cue for Erythropoiesis

2017 ◽  
Vol 37 (8) ◽  
Author(s):  
Lei Yu ◽  
Jun Takai ◽  
Akihito Otsuki ◽  
Fumiki Katsuoka ◽  
Mikiko Suzuki ◽  
...  
Keyword(s):  
Dna Methyltransferase ◽  
Erythroid Differentiation ◽  
Artificial Chromosome ◽  
Dependent Manner ◽  
Hematopoietic Stem ◽  
Gene Enhancer ◽  
Initial Activation ◽  
High Level ◽  
Silencer Element ◽  
Suppressive Mechanism

ABSTRACT GATA1 is a critical regulator of erythropoiesis. While the mechanisms underlying the high-level expression of GATA1 in maturing erythroid cells have been studied extensively, the initial activation of the Gata1 gene in early hematopoietic progenitors remains to be elucidated. We previously identified a hematopoietic stem and progenitor cell (HSPC)-specific silencer element (the Gata1 methylation-determining region [G1MDR]) that recruits DNA methyltransferase 1 (Dnmt1) and provokes methylation of the Gata1 gene enhancer. In the present study, we hypothesized that removal of the G1MDR-mediated silencing machinery is the molecular basis of the initial activation of the Gata1 gene and erythropoiesis. To address this hypothesis, we generated transgenic mouse lines harboring a Gata1 bacterial artificial chromosome in which the G1MDR was deleted. The mice exhibited abundant GATA1 expression in HSPCs, in a GATA2-dependent manner. The ectopic GATA1 expression repressed Gata2 transcription and induced erythropoiesis and apoptosis of HSPCs. Furthermore, genetic deletion of Dnmt1 in HSPCs activated Gata1 expression and depleted HSPCs, thus recapitulating the HSC phenotype associated with GATA1 gain of function. These results demonstrate that the G1MDR holds the key to HSPC maintenance and suggest that release from this suppressive mechanism is a fundamental requirement for subsequent initiation of erythroid differentiation.

scholarly journals Changes in Chromatin Accessibility Across the GM-CSF Promoter upon T Cell Activation Are Dependent on Nuclear Factor κB Proteins

2003 ◽  
Vol 197 (4) ◽  
pp. 413-423 ◽  
Author(s):  
Adele F. Holloway ◽  
Sudha Rao ◽  
Xinxin Chen ◽  
M. Frances Shannon
Keyword(s):  
T Cells ◽  
T Cell ◽  
Chromatin Remodeling ◽  
T Cell Activation ◽  
Cell Activation ◽  
Proximal Promoter ◽  
Dependent Manner ◽  
Nuclear Factor ◽  
Aberrant Expression ◽  
Gm Csf

Granulocyte/macrophage colony-stimulating factor (GM-CSF) is a key cytokine in myelopoiesis and aberrant expression is associated with chronic inflammatory disease and myeloid leukemias. This aberrant expression is often associated with constitutive nuclear factor (NF)-κB activation. To investigate the relationship between NF-κB and GM-CSF transcription in a chromatin context, we analyzed the chromatin structure of the GM-CSF gene in T cells and the role of NF-κB proteins in chromatin remodeling. We show here that chromatin remodeling occurs across a region of the GM-CSF gene between −174 and +24 upon T cell activation, suggesting that remodeling is limited to a single nucleosome encompassing the proximal promoter. Nuclear NF-κB levels appear to play a critical role in this process. In addition, using an immobilized template assay we found that the ATPase component of the SWI/SNF chromatin remodeling complex, brg1, is recruited to the GM-CSF proximal promoter in an NF-κB–dependent manner in vitro. These results suggest that chromatin remodeling across the GM-CSF promoter in T cells is a result of recruitment of SWI/SNF type remodeling complexes by NF-κB proteins binding to the CD28 response region of the promoter.

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