scholarly journals IgM-PRODUCING TUMORS IN THE BALB/c MOUSE

1974 ◽  
Vol 140 (3) ◽  
pp. 742-763 ◽  
Author(s):  
Jan Andersson ◽  
Joel Buxbaum ◽  
Ronald Citronbaum ◽  
Steven Douglas ◽  
Luciana Forni ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
B Cells ◽  
B Cell ◽  
Tumor Cells ◽  
Biochemical Study ◽  
Cell Maturation ◽  
B Cell Maturation ◽  
Electron Microscopy Analysis ◽  
65 H ◽  
Microscopy Analysis

Five adjuvant induced BALB/c tumors producing IgM—McPc 1748, W 3469, TEPC 183, McPc 774, and Y 5781—were characterized morphologically by electron microscopy, analysis of the distribution of surface-bound and intracytoplasmic IgM using immunofluorescence, and by biochemical study of IgM synthesis, turnover, and secretion. The cells of different tumors appear to represent different stages in B-cell maturation when compared to normal, lipopolysaccharide-stimulated B cells. Thus, McPc 1748 tumor cells resemble 10–25-h stimulated normal B cells, 3469 cells resemble 20–35-h stimulated B cells, TEPC 183 cells resemble 45–65-h stimulated B cells, Y 5781 cells resemble 80–110-h stimulated B cells, and McPc 774 cells resemble 100–130-h stimulated B cells.

Gene Expression of Gamma Secretase (GS) Complex-Related Proteins, the Enzyme That Sheds B-Cell Maturation Antigen (BCMA), Among Patients with Multiple Myeloma (MM) and Effects of the GS Inhibitor LSN424354 on Solubilized Bcma in MM and Chronic Lymphocytic Leukemia

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 5641-5641 ◽  
Author(s):  
Haiming Chen ◽  
Mingjie Li ◽  
Eric Sanchez ◽  
Cathy S Wang ◽  
Kyle A Udd ◽  
...  
Keyword(s):  
Gene Expression ◽  
Multiple Myeloma ◽  
B Cells ◽  
B Cell ◽  
Tumor Cells ◽  
Lymphocytic Leukemia ◽  
Cell Maturation ◽  
Gamma Secretase ◽  
B Cell Maturation ◽  
B Cell Maturation Antigen

Abstract Introduction: B-cell maturation antigen (BCMA) has been shown to be highly expressed on the surface of tumor cells from patients (pts) with multiple myeloma (MM) and chronic lymphocytic leukemia (CLL) and is the target for therapeutic approaches in these diseases. Our group has shown that serum and plasma levels of BCMA correlate with disease status and survival in MM and CLL patients. We have recently shown that solubilized BCMA prevents its ligand B cell activating factor (BAFF) from binding and stimulating B-cells to produce polyclonal antibody. Recently, γ-secretase has been identified as the enzyme that leads to shedding of BCMA from off of B-cells. Gamma secretase is a multi-subunit protease complex that includes four individual proteins: presenilin-1 (PSEN1), nicastrin, anterior pharynx-defective 1 (APH-1), and presenilin enhancer 2 (PEN-2). CD147 is as a non-essential regulator of the complex. We examined gene expression of PSEN1, APH-1, PEN-2, and CD147 in MM pts with progressive (PD) and in complete remission (CR). We also determined the effects of the gamma secretase inhibitor (GSI) LSN424354 (Eli Lilly), a selective small-molecule inhibitor, on solubilized BCMA levels in MM and CLL tumor cells. Methods: Bone marrow (BM) mononuclear cells (MCs) were isolated from MM pts following Western Institutional Review Board (WIRB) approval and informed consent in accordance with the Declaration of Helsinki. Total RNA was extracted using the Qiagen RNeasy kit (Qiagen, Louisville, KY 40219) following the manufacturer's instructions. Quantitative PCR (qPCR) was applied to measure the relative abundance of human PSEN1, APH-1, PEN-2, and CD147 mRNA compared to that of the housekeeping gene HPRT mRNA. qPCR was performed using TaqMan technology on an OneStepPlus instrument (Life Technology, Grand Island, NY 14072) and followed the standard procedure. Peripheral blood MCs were obtained from patients with CLL. The human MM LAGκ-1A xenograft was grown in the left superficial gluteal muscle of SCID mice for six weeks and removed. Single-cell suspensions were prepared. LAGκ-1A or CLL tumor cells were treated with the GSI LSN424354 in a concentration dependent fashion, and BCMA levels were determined using an ELISA (R&D Systems, Minneapolis, MN) assay. MM tumor cells were treated with the LSN424354 and performed non-radioactive MTS cell proliferation assay following a standard MTS protocol. Results: qPCR showed PEN-2 gene expression was slightly increased among MM patients in PD compared to those in CR or normal subjects whereas there was no change in expression of the PSEN1 or APH1 genes. CD147 gene expression was markedly increased in MM pts in PD (n=25) compared to those in CR (n=18; P=0.005) or MGUS (n=9; P=0.005). Next, we determined the effect of the GSI LSN424354 on cultured MM or CLL tumor cells. The GSI inhibitor LSN424354 markedly reduced BCMA levels (> 90%) in supernatants from human MM LAGκ-1A cells after 5 days of tissue culture in a dose dependent fashion at concentrations ranging from 100 pM to 10 nM. Similarly, freshly obtained CLL tumor cells exposed to LSN424354 at concentrations similarly from 100 pM to 10 nM also showed a marked reduction (also > 90%) in supernatant BCMA levels. Notably, MTS assay results showed LSN424354 did not inhibit cell proliferation in MM or CLL tumor cells at concentrations up to 100 nM. Conclusion: Gamma secretase sheds BCMA off of B-cells. CD147, a regulator of gamma secretase activity, shows markedly higher gene expression in MM pts with PD compared to those in CR or MGUS individuals. The GSI LSN424354 reduces solubilized BCMA from tumor cells from CLL patients and human MM xenografts. Since CD147 has been shown to be present in serum, we are currently evaluating CD147 in serum samples from pts with MM and other plasma cell dyscrasias. In addition, we are examining the expression of BCMA on the surface of tumor cells from MM and CLL pts following exposure to BCMA, whether this GSI by reducing solubilized BCMA levels can reverse the immune dysfunction in mice bearing MM, and improve the efficacy of anti-BCMA antibody therapies. Disclosures Berenson: OncoTracker: Employment, Equity Ownership.

Evidence for B cell maturation but not trained immunity in uninfected infants exposed to hepatitis C virus

Gut ◽  
2020 ◽  
Vol 69 (12) ◽  
pp. 2203-2213 ◽  
Author(s):  
Anton Lutckii ◽  
Benedikt Strunz ◽  
Anton Zhirkov ◽  
Olga Filipovich ◽  
Elena Rukoiatkina ◽  
...  
Keyword(s):  
Immune System ◽  
B Cells ◽  
B Cell ◽  
Immune Cells ◽  
Immune Cell ◽  
Innate Immune ◽  
Cell Maturation ◽  
Innate Immune Cells ◽  
B Cell Maturation ◽  
Exposed Uninfected

ObjectivesVertical transmission of hepatitis C virus (HCV) is rare compared with other chronic viral infections, despite that newborns have an immature, and possibly more susceptible, immune system. It further remains unclear to what extent prenatal and perinatal exposure to HCV affects immune system development in neonates.DesignTo address this, we studied B cells, innate immune cells and soluble factors in a cohort of 62 children that were either unexposed, exposed uninfected or infected with HCV. Forty of these infants were followed longitudinally from birth up until 18 months of age.ResultsAs expected, evidence for B cell maturation was observed with increased age in children, whereas few age-related changes were noticed among innate immune cells. HCV-infected children had a high frequency of HCV-specific IgG-secreting B cells. Such a response was also detected in some exposed but uninfected children but not in uninfected controls. Consistent with this, both HCV-exposed uninfected and HCV-infected infants had evidence of early B cell immune maturation with an increased proportion of IgA-positive plasma cells and upregulated CD40 expression. In contrast, actual HCV viraemia, but not mere exposure, led to alterations within myeloid immune cell populations, natural killer (NK) cells and a distinct soluble factor profile with increased levels of inflammatory cytokines and chemokines.ConclusionOur data reveal that exposure to, and infection with, HCV causes disparate effects on adaptive B cells and innate immune cell such as myeloid cells and NK cells in infants.

scholarly journals Baff Binds to the Tumor Necrosis Factor Receptor–Like Molecule B Cell Maturation Antigen and Is Important for Maintaining the Peripheral B Cell Population

2000 ◽  
Vol 192 (1) ◽  
pp. 129-136 ◽  
Author(s):  
Jeffrey S. Thompson ◽  
Pascal Schneider ◽  
Susan L. Kalled ◽  
LiChun Wang ◽  
Eric A. Lefevre ◽  
...  
Keyword(s):  
B Cells ◽  
Tumor Necrosis Factor ◽  
B Cell ◽  
Cell Population ◽  
Tumor Necrosis ◽  
Cell Maturation ◽  
Soluble Form ◽  
B Cell Maturation ◽  
Necrosis Factor ◽  
B Cell Maturation Antigen

The tumor necrosis factor (TNF) family member B cell activating factor (BAFF) binds B cells and enhances B cell receptor–triggered proliferation. We find that B cell maturation antigen (BCMA), a predicted member of the TNF receptor family expressed primarily in mature B cells, is a receptor for BAFF. Although BCMA was previously localized to the Golgi apparatus, BCMA was found to be expressed on the surface of transfected cells and tonsillar B cells. A soluble form of BCMA, which inhibited the binding of BAFF to a B cell line, induced a dramatic decrease in the number of peripheral B cells when administered in vivo. Moreover, culturing splenic cells in the presence of BAFF increased survival of a percentage of the B cells. These results are consistent with a role for BAFF in maintaining homeostasis of the B cell population.

Dμ expression causes enrichment of MZ B cells, but is non permissive for B cell maturation in Rag2−/− mice even if combined with Bcl-2

2006 ◽  
Vol 43 (9) ◽  
pp. 1316-1324 ◽  
Author(s):  
Ingela Wikström ◽  
Ingela Bergqvist ◽  
Dan Holmberg ◽  
Johan Forssell
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Maturation ◽  
B Cell Maturation

scholarly journals E3 Ligase UBR5 HECT domain mutations in lymphoma control maturation of B cells via alternative splicing

2019 ◽  
Author(s):  
Samantha A. Swenson ◽  
Tyler J. Gilbreath ◽  
Heather Vahle ◽  
R. Willow Hynes-Smith ◽  
Jared H. Graham ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
B Cells ◽  
B Cell ◽  
Cell Lymphoma ◽  
B Cell Development ◽  
Cell Maturation ◽  
Hect Domain ◽  
B Cell Maturation ◽  
Mantle Cell

ABSTRACTCoordination of a number of molecular mechanisms including transcription, alternative splicing, and class switch recombination are required to facilitate development, activation, and survival of B cells. Disruption of these pathways can result in malignant transformation. Recently, next generation sequencing has identified a number of novel mutations in mantle cell lymphoma (MCL) patients including the ubiquitin E3 ligase UBR5. Approximately 18% of MCL patients were found to have mutations in UBR5 with the majority of mutations within the HECT domain of the protein which can accept and transfer ubiquitin molecules to the substrate. Determining if UBR5 controls the maturation of B cells is important to fully understand malignant transformation to MCL. To elucidate the role of UBR5 in B cell maturation and activation we generated a conditional mutant disrupting UBR5’s C-terminal HECT domain. Loss of the UBR5 HECT domain leads to a block in maturation of B cells in the spleen and up-regulation of proteins associated with mRNA splicing via the spliceosome. Our studies reveal a novel role of UBR5 in B cell maturation by regulating alternative splicing of key transcripts during B cell development and suggests UBR5 mutations may promote mantle cell lymphoma initiation.KEY POINTSUtilizing a novel mouse model mimicking MCL patient mutations, the loss of UBR5’s HECT domain causes alterations in B cell development.UBR5 mutations lead to stabilization of UBR5 and aberrant splicing.

scholarly journals Intracellular BH3 profiling reveals shifts in anti-apoptotic dependency in B-cell maturation and activation

2017 ◽  
Author(s):  
Joanne Dai ◽  
Micah A. Luftig
Keyword(s):  
B Cells ◽  
B Cell ◽  
Plasma Cells ◽  
Human Peripheral Blood ◽  
Survival Strategies ◽  
Cell Maturation ◽  
Barr Virus ◽  
B Cell Maturation ◽  
Human B Cells ◽  
Activated B Cells

AbstractApoptosis is critical to B-cell maturation, but studies of apoptotic regulation in primary human B cells is lacking. Previously, we found that infecting human B cells with Epstein-Barr virus induces two different survival strategies (Priceet al., 2017). Here, we sought to better understand the mechanisms of apoptotic regulation in normal and activated B cells. Using intracellular BH3 profiling (iBH3), we defined the Bcl2-dependency of B-cell subsets from human peripheral blood and tonsillar lymphoid tissue as well as mitogen-activated B cells. We found that naïve and memory B cells were BCL-2 dependent, while germinal center B cells were MCL-1 dependent and plasma cells were BCL-XL dependent. Proliferating B cells activated by CpG or CD40L/IL-4 became more dependent upon MCL-1 and BCL-XL. As B-cell lymphomas often rely on survival mechanisms derived from normal and activated B cells, these findings offer new insight into potential therapeutic strategies for lymphomas.

scholarly journals Telomere damage induces internal loops that generate telomeric circles

2020 ◽  
Author(s):  
Giulia Mazzucco ◽  
Armela Huda ◽  
Martina Galli ◽  
Daniele Piccini ◽  
Michele Giannattasio ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Tumor Cells ◽  
Telomere Maintenance ◽  
Telomeric Repeats ◽  
Single Stranded Dna ◽  
Alternative Lengthening ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
Internal Loops ◽  
Telomere Erosion

AbstractExtrachromosomal telomeric circles are commonly invoked as important players in telomere maintenance, but their origin has remained elusive. Using electron microscopy analysis on purified telomeres we show that, apart from known structures, telomeric repeats accumulate internal loops (i-loops), that occur in proximity of nicks and single-stranded DNA gaps. I-loops are induced by single-stranded damage at normal telomeres and represent the majority of telomeric structures detected in ALT (Alternative Lengthening of Telomeres) tumor cells. Our data indicate that i-loops form as a consequence of the exposure of single-stranded DNA at telomeric repeats. Finally, we show that these damage-induced i-loops can be excised to generate extrachromosomal telomeric circles resulting in loss of telomeric repeats. Our results identify damage-induced i-loops as a new intermediate in telomere metabolism and reveal a simple mechanism that links telomere damage with the accumulation of extrachromosomal telomeric circles and telomere erosion.

Three-Dimensional Reorganization of the Genome During B Cell Affinity Maturation

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 279-279
Author(s):  
Karen L. Bunting ◽  
David Soong ◽  
Yanwen Jiang ◽  
Brandon L. Swed ◽  
Katerina Hatzi ◽  
...  
Keyword(s):  
Gene Expression ◽  
B Cells ◽  
B Cell ◽  
Three Dimensional ◽  
Affinity Maturation ◽  
Cell Maturation ◽  
Transcriptional Reprogramming ◽  
B Cell Maturation ◽  
Genome Wide ◽  
Cell Affinity

Abstract Abstract 279 B cell affinity maturation is fundamental to the development of humoral immunity. To create a diverse antibody repertoire, B cells activated in the germinal centre (GC) must undergo a profound change in phenotype. This unique phenotypic change, which features simultaneous proliferation and somatic hypermutation and which can predispose to the development of lymphoma, requires radically altered gene expression programming in GC B cells. However, the way that this gene expression program is coordinated is unknown. Emerging evidence suggests that the higher-order organization of chromatin plays a role in the co-regulation of genes. We hypothesised that the three-dimensional organization of genes and chromosomes in the nucleus of B cells plays a key role in the epigenetic and transcriptional reprogramming that underlies acquisition of the GC B cell phenotype during B cell maturation. Using genome-wide mapping of chromatin interactions (Hi-C), combined with genome-wide profiles of gene expression (RNA-seq), histone modifications and transcription factor binding (ChIP-seq) in human naïve B (NB) and GC B cells, we have discovered that the three-dimensional structure of the genome undergoes widespread reorganization during B cell maturation to coordinate the GC transcriptional programme. Conformational maps of chromosome folding in these cells reveal a novel and profound loss of inter-arm interactions, reflecting lower chromosome compaction in GC B cells. Remarkably, we observed extensive differential partitioning of genes into NB- and GC B cell-specific compartments, and demonstrate for the first time that coordinated changes in histone modifications (H3K4Me2: P=3×10−35; H3K27Ac: P=3×10−33; Fisher's exact test) and transcription (P=1×10−9) required for cell type specification is mediated by the de novo formation of precisely delimited chromosome neighbourhoods. Most strikingly, we find that remodelling of the GC B cell genome involves the specific structural unlocking of genes that drive the GC transcriptional programme, such as AICDA, MTA3, and BCL6. Coordinate activation of these genes is mediated by the expansion of gene interaction neighbourhoods, increased promoter interactivity (P=3×10−35), engagement of long-range enhancer-promoter interactions (>2-fold increase), and the formation of gene body loops (P=3.18×10−15). Intriguingly, the master regulator of GC B cell differentiation, BCL6, shows a high propensity for all of these different types of interactions, suggesting that regulation of this gene in the context of chromatin is highly complex. Integration with genome-wide binding data for the structural organizing proteins, CTCF and cohesin, as well as the cell-specific factor, PU.1, supports a specific role for these proteins in the repositioning of activated promoters and enhancer regions during B cell maturation. This study shows for the first time that the architecture of the genome is critical for specification of cellular phenotype, and that epigenetic and transcriptional reprogramming in GC B cells is functionally linked to the structural reorganization of genes in the nucleus. Importantly, the higher-order organization of chromatin could represent a novel mechanism by which GC B cell gene expression is dysregulated in lymphoma. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Replacing mouse BAFF with human BAFF does not improve B-cell maturation in hematopoietic humanized mice

2017 ◽  
Vol 1 (27) ◽  
pp. 2729-2741 ◽  
Author(s):  
Julie Lang ◽  
Bicheng Zhang ◽  
Margot Kelly ◽  
Jacob N. Peterson ◽  
Jacob Barbee ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Full Length ◽  
Cell Maturation ◽  
Humanized Mice ◽  
B Cell Maturation ◽  
Human B Cells ◽  
Key Points

Key Points Expression of full-length hBAFF from cDNA in the endogenous murine locus does not improve maturation of human B cells in hu-mice. mBAFF is not limiting the maturation of human B cells in hu-mice.

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