scholarly journals SRPK3 regulates alternative pre-mRNA splicing required for B lymphocyte development and humoral responsiveness

2019 ◽  
Author(s):  
Tessa Arends ◽  
J. Matthew Taliaferro ◽  
Eric Peterman ◽  
Jennifer R. Knapp ◽  
Brian P. O’Connor ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
B Cells ◽  
B Lymphocyte ◽  
Mrna Splicing ◽  
Conditional Knockout ◽  
Lymphocyte Development ◽  
Linked Gene ◽  
B Lymphocyte Development

AbstractAlternative splicing (AS) of pre-mRNA is a critical component of transcriptional regulation that diversifies the cellular proteome. The Serine-Arginine Protein Kinases (SRPK) initiate early events in AS. Using conditional knockout mice (cKO), we demonstrated the importance of the X-linked gene Srpk3 in B lymphocyte development and in response to immunization in vivo. Significantly decreased numbers of immature and mature B cells were observed in Srpk3-cKO BM relative to wild-type (WT). Immunization of Srpk3-cKO mice with a T lymphocyte-independent type-2 antigen elicited greatly reduced amounts of specific IgG3. Srpk3 deletion resulted in hundreds of differentially spliced mRNAs in B cells, including mRNAs encoding proteins associated with signaling pathways and mitochondrial function. Several alternative splicing outcomes in Srpk3-cKO cells are due to altered splicing regulation of SR proteins. We conclude that Srpk3 is an immunomodulatory kinase that controls humoral immunity via its regulation of pre-mRNA splicing, antibody production, and metabolism in B cells.One Sentence SummarySRPK3 regulates alternative splicing of pre-mRNA that is crucial for B cell development, activation and antibody responses.

scholarly journals Regulation of B Lymphocyte Development by Histone H2A Deubiquitinase BAP1

2021 ◽  
Vol 12 ◽  
Author(s):  
Yun Hsiao Lin ◽  
Yue Liang ◽  
HanChen Wang ◽  
Lin Tze Tung ◽  
Michael Förster ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Cycle Progression ◽  
B Lymphocyte ◽  
Cell Development ◽  
B Cell Development ◽  
Lymphocyte Development ◽  
A Cell ◽  
B Lymphocyte Development

BAP1 is a deubiquitinase (DUB) of the Ubiquitin C-terminal Hydrolase (UCH) family that regulates gene expression and other cellular processes, via deubiquitination of histone H2AK119ub and other substrates. BAP1 is an important tumor suppressor in human, expressed and functional across many cell-types and tissues, including those of the immune system. B lymphocytes are the mediators of humoral immune response, however the role of BAP1 in B cell development and physiology remains poorly understood. Here we characterize a mouse line with a selective deletion of BAP1 within the B cell lineage (Bap1fl/fl mb1-Cre) and establish a cell intrinsic role of BAP1 in the regulation of B cell development. We demonstrate a depletion of large pre-B cells, transitional B cells, and mature B cells in Bap1fl/fl mb1-Cre mice. We characterize broad transcriptional changes in BAP1-deficient pre-B cells, map BAP1 binding across the genome, and analyze the effects of BAP1-loss on histone H2AK119ub levels and distribution. Overall, our work establishes a cell intrinsic role of BAP1 in B lymphocyte development, and suggests its contribution to the regulation of the transcriptional programs of cell cycle progression, via the deubiquitination of histone H2AK119ub.

Role of class IA phosphoinositide 3-kinase in B lymphocyte development and functions

2004 ◽  
Vol 32 (2) ◽  
pp. 320-325 ◽  
Author(s):  
S. Koyasu
Keyword(s):  
B Lymphocyte ◽  
Cell Types ◽  
Lymphocyte Development ◽  
Regulatory Subunits ◽  
B Lymphocyte Development ◽  
Intracellular Organelles ◽  
B Lineage ◽  
Phosphoinositide 3 Kinase

PI3K (phosphoinositide 3-kinase) family members control a variety of cellular responses, such as cell growth, survival, cytoskeletal remodelling and the trafficking of intracellular organelles, in many cell types, including lymphocytes. It has been difficult to evaluate the roles of distinct PI3Ks in immune responses, because specific inhibitors for each PI3K are lacking and most stimuli activate multiple PI3Ks. The development of gene-targeted mice has now allowed the elucidation of roles played in vivo by PI3K species in the immune system. Studies on mice deficient in catalytic as well as regulatory subunits of class IA PI3Ks have shown the importance of this class of PI3K in B lineage cells. Here I discuss the role of class IA PI3Ks in B lymphocyte development and B cell antigen receptor-mediated signal transduction.

STAT5 Has Tumor Suppressor-Like Activity in a Murine Model of Myc-Initiated Acute B-Lymphoblastic Leukemia/Lymphoma

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 919-919 ◽  
Author(s):  
Zhengqi Wang ◽  
Geqiang Li ◽  
Zizhen Kang ◽  
Silvia T Bunting ◽  
William Tse ◽  
...  
Keyword(s):  
Bone Marrow ◽  
B Cell ◽  
B Lymphocyte ◽  
Fetal Liver ◽  
Lymphoblastic Leukemia ◽  
Conditional Knockout ◽  
Lymphocyte Development ◽  
Wild Type ◽  
B Lymphocyte Development ◽  
B Lymphoid

Abstract Abstract 919 Signal transducer and activator of transcription 5 (STAT5) is a critical regulator of normal and leukemic lympho-myeloid hematopoiesis through activation downstream of early-acting cytokines, their receptors, and janus kinases (JAKs). Despite upstream activating mutations driving JAK-STAT phosphorylation in precursor-B acute lymphoblastic leukemia (B-ALL), activated JAK-STAT is absent from the aggressive “double hit” lymphomas expressing myc and bcl-2. Using C57BL/6 background transgenic mouse models for myc and bcl-2, we set out to determine whether endogenous STAT5 functions in guarding against B-ALL induced by combined myc/bcl-2 or myc alone. We first determined whether constitutive expression of bcl-2 driven from the H2K promoter and Moloney murine leukemia virus enhancer in C57BL/6 background STAT5-deficient hematopoietic cells could bypass blocks in B-lymphocyte development. Transgenic H2K/bcl-2 expression in hypomorphic STAT5abDN/DN mice, which are leaky and still produce some mature B-lymphocytes, largely rescued peripheral B-lymphocyte survival to near normal levels but could only rescue about 10% of the multilineage hematopoietic stem cell (HSC) competitive repopulating defect. Complete deletion of the entire STAT5ab locus resulted in the expected severe block of B-cell development at the pre-pro-B-cell stage following transplantation of STAT5ab null/null fetal liver cells into irradiated wild type or common γC−/− recipients. Peripheral B-lymphocyte development could not be restored by transgenic bcl-2 alone in the absence of STAT5. However, transgenic myc driven from an immunoglobulin H chain enhancer (Emu/myc) combined with H2K/bcl-2 induced B-ALL peripheral counts as high as 1.1 × 105 B-cells/ul and reduced latency (a median survival of 44 days) compared to wild-type control (a median survival of 91 days) in either lethally-irradiated (P<0.001; N range from 8–14 mice/group) or sub-lethally-irradiated cohorts of fetal liver transplanted mice (P=0.007; N range 10–20 mice/group). B-ALL in mice with or without STAT5 was a mix of Pro-B and Pre-B ALL (IgM-CD43+B220+CD19+/−CD4+/−) and morphologically similar in the spleen and bone marrow. Multi-parameter flow cytometry analysis of bone marrow cells from STAT5ab null/null fetal liver transplanted mice (N=4) showed that deletion of STAT5 significantly reduced by 11.5-fold (P=0.004) the fraction of long-term repopulating HSC (CD150+CD48-) c-Kit+Lin-Sca-1+ (KLS). In an independent adult Mx1-Cre conditional knockout of STAT5 by pI:pC treatment, lymphomas induced by Myc alone were also accelerated (P=0.05; N range 14–15 mice/group) with STAT5 maintained deleted in sorted B-cells. These mice also had reduced CD150+CD48- KLS cells (5.6-fold; N=4; P=0.006). Interestingly, several phenotypes recently reported as associated with increased HSC cycling and lymphoid-biased differentiation were observed. The mean fluorescence intensity of slamf1 (CD150) was reduced 2.2-fold (P<0.001; N=4) in conditional knockout mice and the B-lymphoid biased CD48+CD150+ or CD48-CD150- KLS cells representing short-term HSC/multipotent progenitors were not significantly reduced. Microarray analyses of the KLS fraction provided evidence that STAT5 promotes HSC maintenance and myeloid potential (limiting lymphoid commitment, cycling) in the KLS compartment. The deletion of STAT5 reduced expression of HSC self-renewal and quiescence promoting genes and increased immunoglobulin and B-lymphoid transcripts. Combined with the pre-pro-B-cell block, loss of STAT5 promotes accumulation of B-lineage committed progenitors as potential ALL initiating cells. The effects of bcl-2 and myc hits on STAT5 null/null hematopoietic cells are currently being further characterized with respect to B-cell developmental blocks and molecular heterogeneity. B-ALL has a high relapse rate and is driven by clonally diverse tumor propagating populations. Our work may have important implications for ALL drug therapy. In conclusion, we demonstrate that STAT5, considered primarily as functioning like an oncogene in hematologic malignancies upon persistent activation, can play a tumor suppressor-like role in subsets of B-ALL. These data add to an emerging understanding that endogenous STAT5 can suppress some cancers and transcriptionally regulate several cell cycle inhibitors. Disclosures: No relevant conflicts of interest to declare.

B-Lymphocyte Development Is Impaired by FLT3/ITD Signaling in Knock-in Mice Because of Defective Non-Homologous End-Joining.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 184-184
Author(s):  
Li Li ◽  
Li Zhang ◽  
Jinshui Fan ◽  
Kathleen E Greenberg ◽  
Stephen Desiderio ◽  
...  
Keyword(s):  
B Cells ◽  
B Lymphocyte ◽  
Dna Ligase ◽  
Lymphocyte Development ◽  
Wild Type ◽  
End Joining ◽  
Leukemic Transformation ◽  
Nhej Pathway ◽  
B Lymphocyte Development ◽  
Non Homologous End Joining

Abstract Abstract 184 Constitutive activation of FLT3 by internal tandem duplication (ITD) mutations is one of the most common molecular alterations found in up to 35% of acute myeloid leukemia (AML) and 3% of acute lymphoid leukemia (ALL). Its roles in leukemic transformation of normal hematopoietic stem/ progenitor cells (HSPCs) are not yet fully understood. We have generated a FLT3/ITD knock-in mouse model in which mice heterozygous for a FLT3/ITD mutation develop myeloid proliferation and a block in B-lymphocyte development at the Pro-B stage. To investigate the mechanisms for this block in lymphoid development, we studied V(D)J recombination in the B-lineage cells from the bone marrow (BM) of FLT3/ITD mice. The ligation-mediated PCR assay showed that Pro-B cells from FLT3/ITD mice accumulated high levels of signal-end recombination intermediates, generated by DNA cleavage at the DJH recombination signal sequences (RSSs), with a concomitant decrease in the frequency of completed DJH rearrangements when compared to wild-type littermate controls. These observations are consistent with decreased repair of double strand breaks (DSBs) introduced by the V(D)J recombinase in B cell progenitors from FLT3/ITD mice, resulting in impaired development beyond the Pro-B stage. The classical Ku and DNA-PK-dependent non-homologous end-joining (NHEJ) pathway is required for rejoining DSBs during V(D)J recombination. In vivo NHEJ assays demonstrate that BM cells, including Pro-B cells, with FLT3/ITD mutations have a lower efficiency and decreased accuracy of repair of DSBs, suggesting a defect in the classical NHEJ pathway. Quantitative RT-PCR and Western blotting analysis of Pro-B cells from FLT3/ITD mice demonstrate greatly reduced expression of Ku70/Ku86 and Ligase IV, key components of the the classical NHEJ pathway, confirming the idea that Classical NHEJ is defective. We and others have recently demonstrated that alternative (ALT) NHEJ pathway(s) compensate for deficiencies in classical NHEJ. Components of this pathway include DNA ligase III/XRCC1 and poly (ADP) ribose polymerase 1 (PARP1). Indeed, we show by Western blotting analysis that steady state levels of ALT NHEJ components DNA ligase III and PARP1 are increased in FLT3/ITD cells, compared with wild-type controls. These data suggest that during the process of DJH recombination in Pro-B cells from FLT3/ITD mice, impairment of the classical NHEJ pathway decreases the ability of cells to complete post-cleavage DSB ligation, resulting in failure to complete DJH recombination with a subsequent block of Pro-B cell maturation. With the classical NHEJ pathway impaired, BM cells from mice with FLT3/ITD mutations appear to repair DSBs through the highly error-prone ALT NHEJ pathway. The resultant increased genomic instability might underlie an important mechanism for the leukemic transformation of normal HSPCs by FLT3/ITD mutations and explain the poor prognosis of AML patients with this mutation. Disclosures: No relevant conflicts of interest to declare.

scholarly journals B Lymphocyte Development in Rabbit: Progenitor B Cells and Waning of B Lymphopoiesis

2003 ◽  
Vol 171 (12) ◽  
pp. 6372-6380 ◽  
Author(s):  
Paul J. Jasper ◽  
Shi-Kang Zhai ◽  
Susan L. Kalis ◽  
Mae Kingzette ◽  
Katherine L. Knight
Keyword(s):  
B Cells ◽  
B Lymphocyte ◽  
Lymphocyte Development ◽  
B Lymphopoiesis ◽  
B Lymphocyte Development

scholarly journals B-lymphocyte development is regulated by the combined dosage of three basic helix-loop-helix genes, E2A, E2-2, and HEB.

1996 ◽  
Vol 16 (6) ◽  
pp. 2898-2905 ◽  
Author(s):  
Y Zhuang ◽  
P Cheng ◽  
H Weintraub
Keyword(s):  
B Cells ◽  
B Cell ◽  
B Lymphocyte ◽  
Cell Lineage ◽  
Lymphocyte Development ◽  
Normal Numbers ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix ◽  
B Lymphocyte Development ◽  
Essential Function

B-lymphocyte development requires the basic helix-loop-helix proteins encoded by the E2A gene. In this study, the control mechanism of E2A was further explored by disruption of the E2A-related genes, E2-2 and HEB. In contrast to E2A, E2-2 and HEB are not essential for the establishment of the B-cell lineage. However, both E2-2 and HEB are required for the generation of the normal numbers of pro-B cells in mouse embryos. Breeding tests among mice carrying different mutations revealed that E2-2 and HEB interact with E2A in many developmental processes including generation of B cells. Specifically, mice transheterozygous for any two mutations of these three genes produced fewer pro-B cells than the singly heterozygous littermates. This study indicates that B-cell development is dependent not only on an essential function provided by the E2A gene but also on a combined dosage set by E2A, E2-2, and HEB.

ERP, a new member of the ets transcription factor/oncoprotein family: cloning, characterization, and differential expression during B-lymphocyte development

1994 ◽  
Vol 14 (5) ◽  
pp. 3292-3309
Author(s):  
M Lopez ◽  
P Oettgen ◽  
Y Akbarali ◽  
U Dendorfer ◽  
T A Libermann
Keyword(s):  
Transcription Factor ◽  
Dna Binding ◽  
Gene Family ◽  
B Cell ◽  
Binding Sites ◽  
B Lymphocyte ◽  
Striking Similarity ◽  
Lymphocyte Development ◽  
B Lymphocyte Development ◽  
Ets Transcription Factor

The ets gene family encodes a group of proteins which function as transcription factors under physiological conditions and, if aberrantly expressed, can cause cellular transformation. We have recently identified two regulatory elements in the murine immunoglobulin heavy-chain (IgH) enhancer, pi and microB, which exhibit striking similarity to binding sites for ets-related proteins. To identify ets-related transcriptional regulators expressed in pre-B lymphocytes that may interact with either the pi or the microB site, we have used a PCR approach with degenerate oligonucleotides encoding conserved sequences in all members of the ets family. We have cloned the gene for a new ets-related transcription factor, ERP (ets-related protein), from the murine pre-B cell line BASC 6C2 and from mouse lung tissue. The ERP protein contains a region of high homology with the ETS DNA-binding domain common to all members of the ets transcription factor/oncoprotein family. Three additional smaller regions show homology to the ELK-1 and SAP-1 genes, a subgroup of the ets gene family that interacts with the serum response factor. Full-length ERP expresses only negligible DNA-binding activity by itself. Removal of the carboxy terminus enables ERP to interact with a variety of ets-binding sites including the E74 site, the IgH enhancer pi site, and the lck promoter ets site, suggesting a carboxy-terminal negative regulatory domain. At least three ERP-related transcripts are expressed in a variety of tissues. However, within the B-cell lineage, ERP is highly expressed primarily at early stages of B-lymphocyte development, and expression declines drastically upon B-cell maturation, correlating with the enhancer activity of the IgH pi site. These data suggest that ERP might play a role in B-cell development and in IgH gene regulation.

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