Ordered progression of stage-specific miRNA profiles in the mouse B2 B-cell lineage

Abstract Micro-RNAs (miRNAs) have been recognized as critical regulators of gene expression, and deregulation of miRNA expression has been implicated in a wide spectrum of diseases. To provide a framework for the role of miRNAs in B-cell development and malignancy, we deep-sequenced miRNAs from B1 cells and 10 developmental stages that can be identified within the mouse B2 B-cell lineage. The expression profiles of the 232 known miRNAs that are expressed during B-cell development display stage-specific induction patterns, yet hierarchical clustering analysis showed relationships that are in full agreement with the model of the B2 B-cell developmental pathway. Analysis of exemplary miRNA expression profiles (miR-150, miR-146a, miR-155, miR-181) confirmed that our data are in agreement with previous results. The high resolution of the expression data allowed for the identification of the sequential expression of oncomir-1/miR-17-92 and its paralogs miR-106a-363 and miR-106b-25 in subsequent developmental stages in the BM. Further, we have identified and validated 45 novel miRNAs and 6 novel miRNA candidates expressed in developing B cells.

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bcl-x exhibits regulated expression during B cell development and activation and modulates lymphocyte survival in transgenic mice.

Journal of Experimental Medicine ◽

10.1084/jem.183.2.381 ◽

1996 ◽

Vol 183 (2) ◽

pp. 381-391 ◽

Cited By ~ 140

Author(s):

D A Grillot ◽

R Merino ◽

J C Pena ◽

W C Fanslow ◽

F D Finkelman ◽

...

Keyword(s):

B Cells ◽

Transgenic Mice ◽

B Cell ◽

Cell Lineage ◽

Cell Development ◽

B Cell Development ◽

Immunoglobulin M ◽

Protective Mechanism ◽

And Function ◽

Peripheral B Cells

We have assessed during B cell development, the regulation and function of bcl-x, a member of the bcl-2 family of apoptosis regulatory genes. Here we show that Bcl-xL, a product of bcl-x, is expressed in pre-B cells but downregulated at the immature and mature stages of B cell development. Bcl-xL but not Bcl-2 is rapidly induced in peripheral B cells upon surface immunoglobulin M (IgM) cross-linking, CD40 signaling, or LPS stimulation. Transgenic mice that overexpressed Bcl-xL within the B cell lineage exhibited marked accumulation of peripheral B cells in lymphoid organs and enhanced survival of developing and mature B cells. B cell survival was further increased by simultaneous expression of bcl-xL and bcl-2 transgenes. These studies demonstrate that Bcl-2 and Bcl-xL are regulated differentially during B cell development and activation of mature B cells. Induction of Bcl-xL after signaling through surface IgM and CD40 appears to provide mature B cells with an additional protective mechanism against apoptotic signals associated with antigen-induced activation and proliferation.

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Long noncoding RNAs in B-cell development and activation

Blood ◽

10.1182/blood-2015-11-680843 ◽

2016 ◽

Vol 128 (7) ◽

pp. e10-e19 ◽

Cited By ~ 48

Author(s):

Tiago F. Brazão ◽

Jethro S. Johnson ◽

Jennifer Müller ◽

Andreas Heger ◽

Chris P. Ponting ◽

...

Keyword(s):

B Cells ◽

B Cell ◽

De Novo ◽

Lymphoblastic Leukemia ◽

Cell Lineage ◽

Noncoding Rnas ◽

Cell Development ◽

B Cell Development ◽

Long Noncoding Rnas ◽

Human B Cells

AbstractLong noncoding RNAs (lncRNAs) are potentially important regulators of cell differentiation and development, but little is known about their roles in B lymphocytes. Using RNA-seq and de novo transcript assembly, we identified 4516 lncRNAs expressed in 11 stages of B-cell development and activation. Most of these lncRNAs have not been previously detected, even in the closely related T-cell lineage. Comparison with lncRNAs previously described in human B cells identified 185 mouse lncRNAs that have human orthologs. Using chromatin immunoprecipitation-seq, we classified 20% of the lncRNAs as either enhancer-associated (eRNA) or promoter-associated RNAs. We identified 126 eRNAs whose expression closely correlated with the nearest coding gene, thereby indicating the likely location of numerous enhancers active in the B-cell lineage. Furthermore, using this catalog of newly discovered lncRNAs, we show that PAX5, a transcription factor required to specify the B-cell lineage, bound to and regulated the expression of 109 lncRNAs in pro-B and mature B cells and 184 lncRNAs in acute lymphoblastic leukemia.

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PON2 Exemplifies a Unique Dependency of B Cell Lineage ALL Cells on Detoxifying Lactonases

Blood ◽

10.1182/blood.v130.suppl_1.882.882 ◽

2017 ◽

Vol 130 (Suppl_1) ◽

pp. 882-882

Author(s):

Gang Xiao ◽

Chao Hong ◽

Huimin Geng ◽

Markus Muschen

Keyword(s):

B Cell ◽

Conflicts Of Interest ◽

Therapeutic Potential ◽

Cell Lineage ◽

Specific Treatment ◽

Cell Development ◽

B Cell Development ◽

Mrna Levels ◽

Expression Levels ◽

B Lineage

Abstract Background and significance : Paraoxonase 2 (PON2) is a member of mammalian detoxifying enzymes that are located to the mitochondrial membrane, hydrolyze lactone metabolites and interact with coenzyme Q10 to diminish oxidative stress. While PON2 is highly expressed in the CNS and multiple fetal tissues, expression levels in normal hematopoietic cells are low. We began to study the function of PON2 in B cell lineage ALL, because microarray analyses suggested high mRNA levels of PON2 in B cell lineage ALL cells. In addition, PON2 is used as a diagnostic marker on a 15 gene diagnostic LDA panel (e.g. in AALL1131; NCT02883049) that is used for the identification of Ph-like ALL, a subgroup with particularly poor outcome and specific treatment requirements. Results: Analyzing data from pediatric and adult clinical trials, we found that greater than median PON2 mRNA levels at the time of diagnosis predicted poor clinical outcomes for both children (COG P9906; n=207; P=1.09e-05) and adults (ECOG; n=215; P=0.003) with B-lineage ALL. Studying expression levels of PON2 by quantitative RT-PCR and Western blot in normal bone marrow B cell precursors from healthy donors and patient-derived pre-B ALL cells including Ph+ and Ph -like ALL, we found 3-10-fold increased mRNA and protein levels of PON2 throughout multiple pre-B ALL samples. To elucidate potential functions of PON2 in normal B cells and B-lineage ALL, we studied normal B cell development and ALL-models in Pon2-/- mice. While B cell development was unperturbed in Pon2 -deficient mice, deletion of Pon2 had profound effects on both BCR-ABL1- and N RASG12D-driven leukemogenesis. Compared to wildtype, Pon2-/- pre-B ALL cells failed to form colonies in semisolid agar. Pon2-/-ALL cells were arrested in G0/G1 phase and expressed 2-5-fold increased levels of Arf and p21, compared to Pon2+/+ ALL cells. Strikingly, >50% of Pon2-/-ALL cells spontaneously underwent cellular senescence, as shown by b-galactosidase staining in conjunction with increased Arf expression levels. These in vitro findings suggest an important role of PON2 in B-lymphoid leukemogenesis, which was confirmed in transplant experiments based on BCR-ABL1 and N RASG12D ALL models. While Pon2 -deficiency substantially prolonged survival of recipient mice of BCR-ABL1 ALL cells (P=0.0001), mice transplanted with Pon2 -deficient N RASG12D ALL cells survived for indefinite periods of time. Targeting PON2 expression in relapse ALL: Given that PON2 is expressed at very high levels in relapse ALL samples, we tested the concept of targeting PON2 lactonase activity in a prodrug-approach. While PON2 activity typically results in detoxification of lactone-metabolites, lactone-hydrolysis of the N-(3-oxododecanoyl)-homoserine lactone (3OC12) prodrug results in cytotoxic byproducts (Guoping et al., 2016). We therefore tested the therapeutic potential of 3OC12. For genetic validation, we treated wildtype and Pon2-/- ALL cells with 3OC12 and found strong cytotoxic effects in wildtype but not Pon2-/- ALL cells. Likewise, inducible overexpression of Pon2 in patient-derived pre-B ALL cells exacerbated toxicity of 3OC12 compared to empty vector controls. Likewise, CRISPR-Cas9 mediated ablation of PON2 in human ALL PDX reversed sensitivity of the pre-B ALL cells to 3OC12. Conclusion: Here we describe the previously unknown function of the detoxifying PON2 lactonase as an essential prerequisite for pre-B cell transformation and leukemogenesis. PON2 expression is specific for leukemia cells, an outcome predictor for patients with pre-B ALL and a biomarker of Ph-like ALL. While PON2 protects ALL cells and enables malignant growth, we demonstrate that its lactonase-activity can be leveraged for pharmacological targeting as exemplified by the lactone-prodrug 3OC12. Disclosures No relevant conflicts of interest to declare.

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Role of mTORC1 and mTORC2 during Chronic Lymphocytic Leukaemia (CLL) Initiation and Progression

Blood ◽

10.1182/blood-2018-99-116614 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 3123-3123

Author(s):

Natasha Malik ◽

Karen Dunn ◽

Owen Sansom ◽

Alison M Michie

Keyword(s):

B Cell ◽

Colony Formation ◽

Conflicts Of Interest ◽

Cell Lineage ◽

Cell Development ◽

B Cell Development ◽

Cell Cycling ◽

And Migration

Abstract Mechanistic target of rapamycin (mTOR) functions within a complex signalling cascade, through its activity in two unique complexes mTORC1 and mTORC2, to promote a multitude of different cellular functions including autophagy, protein synthesis and survival. The exact role of these complexes during leukaemia initiation/maintenance remains to be elucidated. Here, using transgenic knockout (KO) mouse models, we determine the individual roles of mTORC1 (targeting raptor) and mTORC2 (targeting rictor) in normal haemopoiesis and in CLL initiation/maintenance. Our results demonstrate that mice carrying a targeted KO of raptor at the haemopoietic stem cell (HSC) stage (Vav-cre+Raptorfl/fl ) do not survive post birth. This is due to anaemia resulting from a significant decrease in Ter119+ population, a significant decrease in KLF1 and KLF2 gene expression, and a significant increase in the megakaryocyte-erythroid population (MEP), suggesting a block at the MEP stage in Vav-cre+Raptorfl/fl foetal liver. While mTORC1 plays a fundamental role in RBC development, we show that mTORC2 plays a role in RBC regulation, as Rictor-deficient HSPCs exhibit an increase in RBC colony formation ex vivo. Conditional KO (cKO) of Raptor (Mx1-cre+Raptorfl/fl) in adult mice results in splenomegaly accompanied by increased spleen organ cellularity. There is a significant decrease in the B cell lineage, with a block in B cell development at the Lin-Sca-1+CD117+ (LSK) stage in the BM. mTORC2, on the other hand regulates late B cell maintenance as indicated by a significant decrease in transitional B cells (T1/T2), marginal zone progenitor (MZP), and follicular 1 (Fol1) cells in Vav-cre+Rictorfl/fl mice compared to controls. To address the role of mTORC1 and mTORC2 in CLL initiation/maintenance in vitro, BM-derived haemopoietic progenitors isolated from control (Cre-), Raptor-deficient (Mx1-cre+Raptorfl/fl) or Rictor-deficient (Vav-cre+Rictorfl/fl) mice were retrovirally-transduced with a kinase dead PKCα (PKCα-KR) construct to induce an aggressive CLL-like disease. Raptor-deficient BM progenitors exhibited reduced proliferation and failed to generate a CLL-like disease, due to a block in B cell lineage commitment. However, there was an increase in cell cycling and migration in PKCα-KR CLL-like cells with Rictor- deficiency suggesting a role of mTORC2 in disease maintenance. To determine a role for mTORC1 in disease maintenance in vivo, NSG mice were transplanted with PKCα-KR-transduced BM-isolated from either Mx1-cre-Raptorfl/fl or Mx1-cre+Raptorfl/fl. Once disease was established in vivo, cKO was induced and disease load and progression was monitored. Our data indicate a significant decrease in disease load with Raptor cKO, together with a trend towards increased survival. Ongoing experiments with Mx1-cre+Rictorfl/fl mice will give us an insight into the role of mTORC2 in CLL. Taken together, mTORC1 plays an essential role in haemopoiesis, with Raptor-deficiency causing a block in RBC and B cell development at the MEP and LSK stage respectively. In comparison, Rictor-deficiency regulates later B cell lineages and promotes RBC colony formation, potentially through mTORC1 activation. Importantly, CLL-like cells lacking mTORC2 have increased cell cycling and migration whereas mTORC1 deficiency causes a decrease in disease load. Therefore, mTORC1 and mTORC2 play complementary roles in haemopoietic development and leukaemia initiation/progression. These studies provide a strong foundation for further studies testing clinical mTOR inhibitors for CLL in our models. Disclosures No relevant conflicts of interest to declare.

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Transcription factor Zfx controls BCR-induced proliferation and survival of B lymphocytes

Blood ◽

10.1182/blood-2008-11-188888 ◽

2009 ◽

Vol 113 (23) ◽

pp. 5857-5867 ◽

Cited By ~ 15

Author(s):

Teresita L. Arenzana ◽

Matthew R. Smith-Raska ◽

Boris Reizis

Keyword(s):

Transcription Factor ◽

B Cells ◽

B Cell ◽

B Lymphocytes ◽

Cell Lineage ◽

Cell Development ◽

B Cell Development ◽

Stem Cell Maintenance ◽

And Function ◽

Cell Maintenance

Abstract The development, homeostasis, and function of B lymphocytes involve multiple rounds of B-cell receptor (BCR)–controlled proliferation and prolonged maintenance. We analyzed the role of transcription factor Zfx, a recently identified regulator of hematopoietic stem cell maintenance, in B-cell development and homeostasis. Panhematopoietic or B cell–specific deletion of Zfx in the bone marrow blocked B-cell development at the pre-BCR selection checkpoint. Zfx deficiency in peripheral B cells caused accelerated B-cell turnover, depletion of mature recirculating B cells, and delayed T-dependent antibody responses. In addition, the numbers and function of B-1 cell lineage were reduced. Zfx-deficient B cells showed normal proximal BCR signaling, but impaired BCR-induced proliferation and survival in vitro. This was accompanied by aberrantly enhanced and prolonged integrated stress response and by delayed induction of cyclin D2 and Bcl-xL proteins. Thus, Zfx restrains the stress response and couples antigen receptor signaling to cell expansion and maintenance during B-cell development and peripheral homeostasis. These results identify a novel transcriptional regulator of the B-cell lineage and highlight the common genetic control of stem cell maintenance and lymphocyte homeostasis.

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B Cell Development in the Mouse: Scenarios for Defects Expressed in the B Cell Lineage

Symposium in Immunology III ◽

10.1007/978-3-642-78438-5_2 ◽

1994 ◽

pp. 5-12

Author(s):

F. Melchers ◽

U. Grawunder ◽

D. Haasner ◽

H. Karasuyama ◽

L. Reininger ◽

...

Keyword(s):

B Cell ◽

Cell Lineage ◽

Cell Development ◽

B Cell Development

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2485

Journal of Clinical and Translational Science ◽

10.1017/cts.2017.234 ◽

2017 ◽

Vol 1 (S1) ◽

pp. 65-66

Author(s):

Greg Kirkpatrick ◽

Courtney Jones ◽

Susan Fosmire ◽

Christopher Porter ◽

Jorge DiPaola

Keyword(s):

B Cell ◽

Expression Patterns ◽

Protein A ◽

Cell Lineage ◽

Cell Development ◽

B Cell Development ◽

Cell Fraction ◽

Mouse Bone Marrow ◽

Base Pairs ◽

Hematopoietic Stem

OBJECTIVES/SPECIFIC AIMS: The goal of this project is to determine the role of ETV6 in early B-cell development and define how germline ETV6 mutations result in predisposition to leukemia. METHODS/STUDY POPULATION: Gene expression commons were queried for expression levels of Etv6 and Pax5 at different stages of hematopoiesis. Mouse bone marrow was isolated and fractioned into cells committed to the B cell lineage via B220+ and CD43+ staining by flow cytometry and then separated into the following fractions: Fraction A (CD24low, CD19−), Fraction B (CD19+, CD24+, BP1−), and Fraction C (CD19+ CD24+ BP1+). Wild-type or germline mutant P214L ETV6 were cloned in an MiG vector and expressed in Ba/F3 cells. ChIP-PCR was performed by cross-linking proteins to DNA with 1% formaldehyde for 10 minute at room temperature, followed by cell lysis with RIPA buffer. Lysates were sonicated to shear DNA to a length of 200–1000 base pairs, then Protein A agarose beads were used to clean and immunoprecipitate chromatin. RESULTS/ANTICIPATED RESULTS: We observed that Etv6 is highly expressed in hematopoietic stem and lymphoid progenitor cells through the pre-pro-B stage (FrA), but its expression is significantly reduced in fraction B and thereafter (p<0.0001). Etv6 expression decreases as B cells develop and is negatively correlated with Pax5 expression (r2=0.9993; p=0.0167). We next confirmed the expression patterns of ETV6 and PAX5 during B cell development in human samples. We found that ETV6 expression was higher in the early B cell fraction (CD10+, CD34+, CD19−, and CD20−) compared to the pre-B cell fraction (CD10+, CD34−, CD19+, CD20−). Conversely, we observed that PAX5 expression was higher in the preB cell fraction compared with the early B cell fraction. In Ba/F3 cells expressing ETV6 constructs, ETV6, but not ETV6 P214L overexpression significantly decreased Pax5 expression (p≤0.05). ETV6 is associated with the proximal GGAA site 72 base pairs upstream of the Pax5 TSS, but not GGAA sites further from the TSS. In addition, the transcriptional repressors SIN3A and HDAC3 were detected on the same regions of the Pax5 locus. We detected association of ETV6, SIN3A, and HDAC3 with the proximal GGAA site upon expression of WT ETV6, but not ETV6 P214L. DISCUSSION/SIGNIFICANCE OF IMPACT: Our results provide a mechanism of interaction for ETV6 and PAX5, 2 genes often disrupted in B-cell leukemia. These findings are significant because PAX5 misregulation results in a B cell development halt, lineage infidelity, and leukemogenesis. In continuing our studies, we have generated a transgenic mouse endogenously expressing the ETV6 P214L mutation by CRISPR/Cas9 editing, and these mice appear to have a thrombocytopenic phenotype similar to that observed in patients carrying the ETV6 P214L mutation. These animals will be the focus of our continued investigation of the mechanism by which ETV6 germline mutation results in a predisposition to leukemia. Our ultimate goal is a comprehensive understanding of how this process may be targeted more efficiently in patients with both heritable and sporadic forms of leukemia involving ETV6.

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Activated Notch2 Potentiates CD8 Lineage Maturation and Promotes the Selective Development of B1 B Cells

Molecular and Cellular Biology ◽

10.1128/mcb.23.23.8637-8650.2003 ◽

2003 ◽

Vol 23 (23) ◽

pp. 8637-8650 ◽

Cited By ~ 44

Author(s):

Colleen M. Witt ◽

Vincent Hurez ◽

C. Scott Swindle ◽

Yoshio Hamada ◽

Christopher A. Klug

Keyword(s):

T Cell ◽

B Cells ◽

B Cell ◽

Cell Lineage ◽

Cell Subset ◽

Cell Development ◽

B Cell Development ◽

Thymocyte Development ◽

Cell Stage ◽

B1 B Cells

ABSTRACT Although studies have shown that the Notch2 family member is critical for embryonic development, little is known concerning its role in hematopoiesis. In this study, we show that the effects of an activated form of Notch2 (N2IC) on the T-cell lineage are dosage related. High-level expression of N2IC results in the development of T-cell leukemias. In contrast, lower-level expression of N2IC does not lead to transformation but skews thymocyte development to the CD8 lineage. Underlying this skew is a dramatic enhancement in positive selection and CD8SP maturation. N2IC permits early B-cell development but blocks the maturation of conventional B2 cells at the pre-B stage, which is the limit of endogenous Notch2 protein expression in developing B cells. Most strikingly, while B2 B cell development is blocked at the pre-B-cell stage, N2IC promotes the selective development of LPS-responsive B1 B cells. This study implicates a role for Notch2 in the maturation of the CD8 lineage and suggests a novel function for Notch2 in the development of the B1 B-cell subset.

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Divergent Lineage-Specific Functions of PP2A in Chronic Phase CML and Lymphoid Blast Crisis

Blood ◽

10.1182/blood.v124.21.3128.3128 ◽

2014 ◽

Vol 124 (21) ◽

pp. 3128-3128

Author(s):

Gang Xiao ◽

Huimin Geng ◽

Lai N Chan ◽

Zhengshan Chen ◽

Markus Muschen

Keyword(s):

B Cell ◽

Blast Crisis ◽

Cell Lineage ◽

Chronic Phase ◽

Cell Development ◽

B Cell Development ◽

Erk Signaling ◽

Glycolytic Flux ◽

Myeloid Lineage

Abstract Background & Hypothesis: Protein phosphatase 2A (PP2A) is a Ser/Thr phosphatase and functions as negative regulator of Akt- and Erk-signaling. PP2A attenuates downstream signaling of BCR-ABL1 and thereby functions as important tumor suppressor in chronic myeloid leukemia (CML). PP2A-activating drugs have been proposed for the treatment of CML and eradication of tyrosine kinase inhibitor resistant leukemia stem cells in CML (Neviani et al., 2013). Studying Cre-mediated ablation of PP2A in mouse models for BCR-ABL1-driven leukemia including myeloid CML in chronic phase (CML-CP), B lymphoid blast crisis (LBC) and B cell lineage Ph+ ALL, we were able to provide genetic evidence for this treatment concept in CML. Seemingly paradoxically, however, inducible ablation of PP2A in B cell lineage LBC and Ph+ ALL cells has the opposite effect and induced rapid cell death. These findings highlight fundamental differences in the regulation of Akt- and Erk-signaling in myeloid lineage and B cell lineage cells and have implications for specific therapy concepts that distinguish between chronic phase CML and lymphoid blast crisis/ Ph+ ALL. Results: Interestingly, PP2A protein levels are significantly higher in B cell lineage Ph+ ALL and CML lymphoid blast crisis (LBC) compared to chronic phase CML. To explore the function of PP2A during early B cell development, we deleted the α isoform of the PP2A subunit A in pro-B cells by introducing Mb1-Cre into Ppp2r1afl/fl mice. Analysis of bone marrow from Ppp2r1afl/flMb1-Cre (PP2A-cko) mice showed obvious B cell development block at the pre-B cell receptor checkpoint, although V(D) recombination and RAG1/2 activity were intact in PP2A-cko pre-B cells. Since high mRNA levels of PP2A subunits at the time of diagnosis predict poor outcome of children (COG P9906; n=207) and adults (ECOG 2993; n=215) with ALL, we studied the function of PP2A in mouse models for B cell lineage ALL including Ph+ ALL and CML lymphoid blast crisis (LBC). After Cre-induced deletion of Ppp2r1a, we observed reduced protein expression of both PP2A subunit A and subunit C accompanied with decreased PP2A phosphatase. The PP2A-cKO ALL cells showed normal proliferation but significantly impaired colony formation capability and increased apoptosis, both of which could be rescued by overexpression of wildtype PP2A in PP2A-cKO ALL cells. We next transplanted luciferase expressing PP2A-KO ALL cells into recipient mice and monitored cell growth and leukemia progression. Cre-mediated deletion significantly prolonged overall survival of recipient mice that were transplanted with Ppp2r1afl/fl ALL cells. Although all of those mice died eventually from leukemia, the ALL cells isolated from the mice retained Ppp2r1a floxed alleles suggesting that these mice died from clones that had escaped Cre-mediated deletion of PP2A. Cre-mediated deletion increased phosphorylation levels of Stat5 and Erk, resulted in accumulation of p53 and increased output of the PI3K-AKT signaling pathway as measured by increased phosphorylation of FoxO factors, p70S6K and S6 ribosomal protein. Based on the involvement of PI3K-AKT in glucose metabolism, we measured the effects of inducible PP2A-deletion on glycolytic function in CML and Ph+ ALL/LBC cells. Interestingly, inducible deletion of PP2A induced profound imbalances of glucose metabolism in B cell lineage Ph+ ALL/LBC but not myeloid lineage CML-like cells. Upon PP2A-deletion, ALL cells showed higher glycolytic flux shunted into lactate rather than NADPH production. Lower NADPH/NADP ratio and higher reactive oxygen species level in PP2A-KO ALL cells indicated impaired balance of glycolytic flux and may account for increased apoptosis of those cells. This notion was supported by a strong rescue effect of overexpression of the antioxidant catalase in PP2A-cKO cells. In agreement with reported tumor suppressor role of PP2A in CML cells (Neviani et al., 2005), we observed that CEBPα-driven lineage conversion of B cell lineage Ph+ ALL/LBC into not myeloid lineage. Conclusion: Here we reported the requirement of PP2A in normal B cell development and lineage-specific oncogenic role of PP2A in BCR-ABL1-driven leukemia. Divergent roles of PP2A in Ph+ ALL/LBC and myeloid lineage CML may lead to future insights into mechanisms of LBC-transformation of CML and lineage-specific requirement of BCR-ABL1-transformation. Disclosures No relevant conflicts of interest to declare.

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An Erg driven transcriptional program controls B-lymphopoiesis

10.1101/861542 ◽

2019 ◽

Author(s):

Ashley P. Ng ◽

Hannah D. Coughlan ◽

Soroor Hediyeh-zadeh ◽

Kira Behrens ◽

Timothy M. Johanson ◽

...

Keyword(s):

B Cell ◽

Regulatory Network ◽

Cell Lineage ◽

Cell Receptor ◽

Cell Development ◽

B Cell Development ◽

Immunoglobulin Gene ◽

B Cell Differentiation ◽

B Lymphopoiesis ◽

Hematopoietic Stem

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

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