scholarly journals Formation of an Active Tissue-Specific Chromatin Domain Initiated by Epigenetic Marking at the Embryonic Stem Cell Stage

2005 ◽  
Vol 25 (5) ◽  
pp. 1804-1820 ◽  
Author(s):  
Henrietta Szutorisz ◽  
Claudia Canzonetta ◽  
Andrew Georgiou ◽  
Cheok-Man Chow ◽  
László Tora ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
B Cells ◽  
B Cell ◽  
Histone H3 ◽  
Embryonic Stem ◽  
Chromatin Domain ◽  
Cell Stage ◽  
General Transcription Factors ◽  
Regulated Gene Expression

ABSTRACT The differentiation potential of stem cells is determined by the ability of these cells to establish and maintain developmentally regulated gene expression programs that are specific to different lineages. Although transcriptionally potentiated epigenetic states of genes have been described for haematopoietic progenitors, the developmental stage at which the formation of lineage-specific gene expression domains is initiated remains unclear. In this study, we show that an intergenic cis-acting element in the mouse λ5-VpreB1 locus is marked by histone H3 acetylation and histone H3 lysine 4 methylation at a discrete site in embryonic stem (ES) cells. The epigenetic modifications spread from this site toward the VpreB1 and λ5 genes at later stages of B-cell development, and a large, active chromatin domain is established in pre-B cells when the genes are fully expressed. In early B-cell progenitors, the binding of haematopoietic factor PU.1 coincides with the expansion of the marked region, and the region becomes a center for the recruitment of general transcription factors and RNA polymerase II. In pre-B cells, E2A also binds to the locus, and general transcription factors are distributed across the active domain, including the gene promoters and the intergenic region. These results suggest that localized epigenetic marking is important for establishing the transcriptional competence of the λ5 and VpreB1 genes as early as the pluripotent ES cell stage.

Tumor Suppressors BTG1 and BTG2 Fulfill Both Unique and Overlapping Functions During Normal B Lymphocyte Development

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1303-1303
Author(s):  
Esther J.H. Tijchon ◽  
Liesbeth van Emst ◽  
Jørn Havinga ◽  
Jean-Pierre Rouault ◽  
Felice Tirone ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Transcription Factors ◽  
B Cells ◽  
B Cell ◽  
Tumor Suppressors ◽  
Cell Development ◽  
B Cell Development ◽  
B Cell Differentiation ◽  
B Cell Malignancies ◽  
Cell Stage

Abstract Abstract 1303 B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is the most common form of cancer in children, characterized by genetic aberrations affecting master regulators of lymphoid differentiation, such as RUNX1, IKZF1, TCF3, and PAX5, as well as tumor suppressor genes that control the cell cycle, including RB1 and CDKN2A. Another gene frequently altered in BCP-ALL is BTG1, which displays highly clustered mono-allelic deletions in childhood BCP-ALL (9%) and adult ALL (6%). The frequency of BTG1 deletions is two- to three-fold higher in ETV6-RUNX1- and BCR-ABL1-positive leukemias. BTG1, and its close homologue BTG2 regulate gene expression, for instance by associating with protein arginine methyltransferase 1 (PRMT1), affecting the activity of a variety of transcription factors, including several nuclear hormone receptors and HoxB9. In addition, BTG1 and BTG2 have been implicated in regulating mRNA stability by interacting with the Ccr4-Not complex. Recent studies have also identified missense point mutations in BTG1 and BTG2 in about 20% of non-Hodgkin lymphomas, arguing that altered function of these genes contributes to B cell malignancies. To investigate a role of BTG1 and BTG2 in B cell development, we studied the phenotype of Btg1 and Btg2 single knockout (KO) and Btg1;Btg2 double KO mice. Animals deficient for either BTG1 or BTG2 displayed a mild B cell phenotype with a moderate reduction of ∼20% in the total amount of B220+ progenitor B cells in bone marrow, while splenic B cells were present at normal frequencies. More detailed analyses revealed that Btg1−/− and Btg2−/− mice both showed a partial block at the pre-pro-B cell stage (Hardy fraction A). Methylcellulose colony assays in the presence of interleukin-7 (IL-7) demonstrated 30% fewer colonies using bone marrow from Btg2−/− mice, whereas 70% fewer colonies were obtained using bone marrow derived from Btg1−/− mice. To assess whether BTG1 and BTG2 fulfill redundant functions during B cell development, we analyzed the phenotype of Btg1−/−;Btg2−/− mice. Hence we observed that the combined loss of BTG1 and BTG2 led to a much stronger block in B cell differentiation, with the majority of progenitor B cells arrested at the pre-pro-B cell stage. In the spleens of these double knockout mice we observed a roughly 50% reduction in B220+ IgM+ B cells, suggesting that these genes act to modify the activity of B lineage transcription factors rather than to fully block their activities. This is consistent with a role for these genes as modifiers of transcriptional activity. Current studies are aimed at defining the molecular targets regulated by BTG1 and BTG2 during early B cell development using RNA sequencing and protein interaction experiments. In conclusion, our data demonstrate that BTG1 and BTG2 act as important regulators of normal B cell differentiation, and that this function might be critical for their role as tumor suppressors in (early) B cell malignancies. Disclosures: No relevant conflicts of interest to declare.

scholarly journals c-Myb expression is critical to maintain proliferation and glucose metabolism of large pre-B cells

2020 ◽  
Author(s):  
Andrea R. Daamen ◽  
Rowena B. Crittenden ◽  
Timothy P. Bender
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
B Cells ◽  
Glucose Metabolism ◽  
B Cell ◽  
Cell Survival ◽  
Myb Transcription Factor ◽  
Cell Cycle Exit ◽  
Cell Stage ◽  
B Cell Survival

AbstractThe c-Myb transcription factor is required for the differentiation of CD19+ B-lineage cells and plays significant roles from the specification of the B cell lineage to the survival of pro-B cells. c-Myb coordinates the survival of pro-B cells with the expression of genes required for transition to the large pre-B cell stage of differentiation. However, it is not known if c-Myb is important for the proliferative expansion or subsequent differentiation into small pre-B cells. Here we demonstrate that c-Myb expression is important for large pre-B cell survival, proliferation, and differentiation into small pre-B cells. Utilizing genome-wide analysis, we found that c-Myb was important for maintaining glucose uptake and utilization and exogenous expression of Glut1 and Hk1 rescued large pre-B cell recovery and survival. Furthermore, we found that c-Myb is important for repression of Ikaros and Aiolos and our c-Myb-dependent gene signature was enriched in an Ikaros footprint of genes that drive cell cycle exit and the large to small pre-B cell transition. However, upon loss of c-Myb expression, inhibition of Ikaros activity was able to restore certain Ikaros-mediated gene expression changes but was insufficient to rescue recovery of large pre-B cell numbers. We found that c-Myb regulates glucose utilization and glucose-dependent survival through Hk1 in an Ikaros-independent manner. Thus, c-Myb regulation of glucose metabolism is critical to maintain large pre-B cell survival while repression of the Ikaros-mediated gene expression program is critical to prevent premature cell cycle exit and premature differentiation into small pre-B cells.

scholarly journals Repression of BCL-6 is required for the formation of human memory B cells in vitro

2007 ◽  
Vol 204 (4) ◽  
pp. 819-830 ◽  
Author(s):  
Tracy C. Kuo ◽  
Arthur L. Shaffer ◽  
Joseph Haddad ◽  
Yong Sung Choi ◽  
Louis M. Staudt ◽  
...  
Keyword(s):  
Transcription Factors ◽  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
Ectopic Expression ◽  
Human Memory ◽  
Memory B Cells ◽  
Cell Stage ◽  
Germinal Center B Cells

Memory B cells provide rapid protection to previously encountered antigens; however, how these cells develop from germinal center B cells is not well understood. A previously described in vitro culture system using human tonsillar germinal center B cells was used to study the transcriptional changes that occur during differentiation of human memory B cells. Kinetic studies monitoring the expression levels of several known late B cell transcription factors revealed that BCL-6 is not expressed in memory B cells generated in vitro, and gene expression profiling studies confirmed that BCL-6 is not expressed in these memory B cells. Furthermore, ectopic expression of BCL-6 in human B cell cultures resulted in formation of fewer memory B cells. In addition, the expression profile of in vitro memory B cells showed a unique pattern that includes expression of genes encoding multiple costimulatory molecules and cytokine receptors, antiapoptotic proteins, T cell chemokines, and transcription factors. These studies establish new molecular criteria for defining the memory B cell stage in human B cells.

Extinction of immunoglobulin gene expression in B cells upon fusion with HeLa cells is preceded by rapid nuclear depletion of essential transcription factors and is accompanied by widespread inactivation of genes expressed in a B cell-specific manner

1997 ◽  
Vol 110 (20) ◽  
pp. 2579-2587 ◽  
Author(s):  
S. Junker ◽  
M. Lamm ◽  
V. Nielsen ◽  
P. Matthias
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
B Cells ◽  
B Cell ◽  
Molecular Mechanism ◽  
Gene Transcription ◽  
Hela Cells ◽  
Immunoglobulin Gene ◽  
Nf Kappa B ◽  
Specific Manner

When immunoglobulin (Ig) expressing B cells are fused with non-B cells, Ig expression is rapidly suppressed at the level of transcription, a phenomenon termed extinction. Here we demonstrate that fusion of HeLa cells with either diploid or tetraploid B cells (Daudi) results in widespread extinction of several other B cell-encoded genes that are expressed in a B cell-specific manner. In contrast, expression of B cell-expressed genes that are not dependent on cell-specific controls is unaffected. We show that the molecular mechanism(s) underlying Ig gene extinction can be explained, at least in part, by a lack of transcription factors that are essential for Ig gene transcription. These transcription factors are either not produced due to block of transcription of their respective genes (Oct-2, OBF-1, PU.1), or are rendered inactive posttranslationally (NF-kappa B, E47). By isolating Daudi × HeLa heterokaryons a few hours after fusion, we have studied the initial fate of two B cell-specific transcription factors involved in Ig gene transcription, Oct-2 and NF-kappa B. This report provides the first demonstration that upon fusion with HeLa cells, the nuclear contents of B cell-expressed transcription factors are depleted within a few hours with kinetics that are as fast or faster than that of Ig gene extinction. Thus, the extinguishing mechanism is effective very early after fusion. We suggest that extinction of Ig genes is part of a global mechanism that suppresses the differentiation program foreign to the HeLa phenotype.

scholarly journals Tet2 and Tet3 cooperate with B-lineage transcription factors to regulate DNA modification and chromatin accessibility

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Chan-Wang Lio ◽  
Jiayuan Zhang ◽  
Edahí González-Avalos ◽  
Patrick G Hogan ◽  
Xing Chang ◽  
...  
Keyword(s):  
Transcription Factors ◽  
B Cells ◽  
B Cell ◽  
Catalytic Domain ◽  
Chromatin Accessibility ◽  
Dna Demethylation ◽  
Cell Stage ◽  
Tet Proteins ◽  
B Lineage ◽  
Tet Enzymes

Ten-eleven translocation (TET) enzymes oxidize 5-methylcytosine, facilitating DNA demethylation and generating new epigenetic marks. Here we show that concomitant loss of Tet2 and Tet3 in mice at early B cell stage blocked the pro- to pre-B cell transition in the bone marrow, decreased Irf4 expression and impaired the germline transcription and rearrangement of the Igκ locus. Tet2/3-deficient pro-B cells showed increased CpG methylation at the Igκ 3’ and distal enhancers that was mimicked by depletion of E2A or PU.1, as well as a global decrease in chromatin accessibility at enhancers. Importantly, re-expression of the Tet2 catalytic domain in Tet2/3-deficient B cells resulted in demethylation of the Igκ enhancers and restored their chromatin accessibility. Our data suggest that TET proteins and lineage-specific transcription factors cooperate to influence chromatin accessibility and Igκ enhancer function by modulating the modification status of DNA.

scholarly journals Constitutive activation of NF-κB during early bone marrow development results in loss of B cells at the pro-B-cell stage

2021 ◽  
Vol 5 (3) ◽  
pp. 745-755
Author(s):  
Andrea Paun ◽  
Estefania Claudio ◽  
Ulrich K. Siebenlist
Keyword(s):  
Bone Marrow ◽  
Transcription Factors ◽  
B Cells ◽  
B Cell ◽  
Cell Development ◽  
B Cell Development ◽  
Cell Stage ◽  
Constitutive Activation ◽  
Similar Phenotype ◽  
Antibody Levels

Abstract There is a considerable body of work exploring the role of NF-κB family of transcription factors in the maturation and functions of later stage B cells; however, their role in the earlier bone marrow stages of development is less well understood despite the demonstration that NF-κB activity is present at all early stages of B-cell development. To explore the consequences of early, B cell–targeted constitutive activation of both NF-κB pathways on B-cell development, we generated mice that have either or both. NF-κB pathways constitutively activated beginning in early pro-B cells. In marked contrast to activating a single pathway, we found mice with both pathways constitutively activated displayed a profound loss of B cells, starting with early pro-B cells and peaking at the late pro-B-cell stage, at least in part as a result of increased apoptosis. This effect was found to be cell autonomous and to have striking phenotypic consequences on the secondary lymphoid organs and circulating antibody levels. This effect was also found to be temporal in nature as similar activation under a Cre expressed later in development did not result in generation of a similar phenotype. Taken together, these findings help to shed further light on the need for tight regulation of the NF-κB family of transcription factors during the various stages of B-cell development in the bone marrow.

scholarly journals Ras Mediates Effector Pathways Responsible for Pre-B Cell Survival, Which Is Essential for the Developmental Progression to the Late Pre-B Cell Stage

2000 ◽  
Vol 192 (2) ◽  
pp. 171-182 ◽  
Author(s):  
Hitoshi Nagaoka ◽  
Yoshimasa Takahashi ◽  
Reiko Hayashi ◽  
Tohru Nakamura ◽  
Kumiko Ishii ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Survival ◽  
Chain Gene ◽  
B Cell Differentiation ◽  
Antigen Receptors ◽  
Cell Stage ◽  
Light Chain Gene ◽  
B Cell Survival ◽  
Effector Pathways

Ras is essential for the transition from early B cell precursors to the pro-B stage, and is considered to be involved in the signal cascade mediated by pre-B cell antigen receptors. To examine the role of p21ras in the late stage of B cell differentiation, we established transgenic mice (TG) expressing a dominant-inhibitory mutant of Ha-ras (Asn-17 Ha-ras) in B lineage cells at high levels after the early B cell precursor stage. Expression of p21Asn-17 Ha-ras was associated with a prominent reduction in the number of late pre-B cells, but had little effect on proliferation of early pre-B cells. Inhibition of p21ras activity markedly reduced the life span of pre-B cells, due, at least in part, to downregulation of the expression of an antiapoptotic protein, Bcl-xL. Thus, the apparent role for p21ras activity in pre-B cell survival may explain the decreased numbers of late pre-B cells in Asn-17 Ha-ras TG. Consistent with this possibility, overexpression of Bcl-2 in Asn-17 Ha-ras TG reversed the reduction in the number of late pre-B cells undergoing immunoglobulin light chain gene (IgL) rearrangement and progressing to immature B cells. These results suggest that p21ras mediates effector pathways responsible for pre-B cell survival, which is essential for progression to the late pre-B and immature B stages.

scholarly journals The B-cell tumor–associated antigen ROR1 can be targeted with T cells modified to express a ROR1-specific chimeric antigen receptor

Blood ◽  
2010 ◽  
Vol 116 (22) ◽  
pp. 4532-4541 ◽  
Author(s):  
Michael Hudecek ◽  
Thomas M. Schmitt ◽  
Sivasubramanian Baskar ◽  
Maria Teresa Lupo-Stanghellini ◽  
Tetsuya Nishida ◽  
...  
Keyword(s):  
T Cells ◽  
B Cells ◽  
B Cell ◽  
Mantle Cell Lymphoma ◽  
Chimeric Antigen Receptor ◽  
Cell Lymphoma ◽  
Embryonic Stem ◽  
Antigen Receptor ◽  
Orphan Receptor ◽  
Mantle Cell

Monoclonal antibodies and T cells modified to express chimeric antigen receptors specific for B-cell lineage surface molecules such as CD20 exert antitumor activity in B-cell malignancies, but deplete normal B cells. The receptor tyrosine kinase-like orphan receptor 1 (ROR1) was identified as a highly expressed gene in B-cell chronic lymphocytic leukemia (B-CLL), but not normal B cells, suggesting it may serve as a tumor-specific target for therapy. We analyzed ROR1-expression in normal nonhematopoietic and hematopoietic cells including B-cell precursors, and in hematopoietic malignancies. ROR1 has characteristics of an oncofetal gene and is expressed in undifferentiated embryonic stem cells, B-CLL and mantle cell lymphoma, but not in major adult tissues apart from low levels in adipose tissue and at an early stage of B-cell development. We constructed a ROR1-specific chimeric antigen receptor that when expressed in T cells from healthy donors or CLL patients conferred specific recognition of primary B-CLL and mantle cell lymphoma, including rare drug effluxing chemotherapy resistant tumor cells that have been implicated in maintaining the malignancy, but not mature normal B cells. T-cell therapies targeting ROR1 may be effective in B-CLL and other ROR1-positive tumors. However, the expression of ROR1 on some normal tissues suggests the potential for toxi-city to subsets of normal cells.

scholarly journals Transcription factors of the alternative NF-κB pathway are required for germinal center B-cell development

2016 ◽  
Vol 113 (32) ◽  
pp. 9063-9068 ◽  
Author(s):  
Nilushi S. De Silva ◽  
Michael M. Anderson ◽  
Amanda Carette ◽  
Kathryn Silva ◽  
Nicole Heise ◽  
...  
Keyword(s):  
Transcription Factors ◽  
B Cells ◽  
B Cell ◽  
Germinal Center ◽  
Plasma Cells ◽  
Alternative Pathway ◽  
Cell Development ◽  
B Cell Development ◽  
Cell Surface Receptor ◽  
Signaling Cascade

The NF-κB signaling cascade relays external signals essential for B-cell growth and survival. This cascade is frequently hijacked by cancers that arise from the malignant transformation of germinal center (GC) B cells, underscoring the importance of deciphering the function of NF-κB in these cells. The NF-κB signaling cascade is comprised of two branches, the canonical and alternative NF-κB pathways, mediated by distinct transcription factors. The expression and function of the transcription factors of the alternative pathway, RELB and NF-κB2, in late B-cell development is incompletely understood. Using conditional deletion of relb and nfkb2 in GC B cells, we here report that ablation of both RELB and NF-κB2, but not of the single transcription factors, resulted in the collapse of established GCs. RELB/NF-κB2 deficiency in GC B cells was associated with impaired cell-cycle entry and reduced expression of the cell-surface receptor inducible T-cell costimulator ligand that promotes optimal interactions between B and T cells. Analysis of human tonsillar tissue revealed that plasma cells and their precursors in the GC expressed high levels of NF-κB2 relative to surrounding lymphocytes. Accordingly, deletion of nfkb2 in murine GC B cells resulted in a dramatic reduction of antigen-specific antibody-secreting cells, whereas deletion of relb had no effect. These results demonstrate that the transcription factors of the alternative NF-κB pathway control distinct stages of late B-cell development, which may have implications for B-cell malignancies that aberrantly activate this pathway.

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