scholarly journals What Will B Will B: Identifying Molecular Determinants of Diverse B-Cell Fate Decisions Through Systems Biology

2021 ◽  
Vol 8 ◽  
Author(s):  
Simon Mitchell
Keyword(s):  
Systems Biology ◽  
B Cells ◽  
B Cell ◽  
Cell Fate ◽  
Experimental Studies ◽  
Cell Receptor ◽  
Signaling Networks ◽  
Molecular Signaling ◽  
Antigen Receptors ◽  
Cell Fate Decisions

B-cells are the poster child for cellular diversity and heterogeneity. The diverse repertoire of B lymphocytes, each expressing unique antigen receptors, provides broad protection against pathogens. However, B-cell diversity goes beyond unique antigen receptors. Side-stepping B-cell receptor (BCR) diversity through BCR-independent stimuli or engineered organisms with monoclonal BCRs still results in seemingly identical B-cells reaching a wide variety of fates in response to the same challenge. Identifying to what extent the molecular state of a B-cell determines its fate is key to gaining a predictive understanding of B-cells and consequently the ability to control them with targeted therapies. Signals received by B-cells through transmembrane receptors converge on intracellular molecular signaling networks, which control whether each B-cell divides, dies, or differentiates into a number of antibody-secreting distinct B-cell subtypes. The signaling networks that interpret these signals are well known to be susceptible to molecular variability and noise, providing a potential source of diversity in cell fate decisions. Iterative mathematical modeling and experimental studies have provided quantitative insight into how B-cells achieve distinct fates in response to pathogenic stimuli. Here, we review how systems biology modeling of B-cells, and the molecular signaling networks controlling their fates, is revealing the key determinants of cell-to-cell variability in B-cell destiny.

scholarly journals The quantity of CD40 signaling determines the differentiation of B cells into functionally distinct memory cell subsets

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Takuya Koike ◽  
Koshi Harada ◽  
Shu Horiuchi ◽  
Daisuke Kitamura
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Fate ◽  
Plasma Cells ◽  
Memory Cell ◽  
Cell Receptor ◽  
Primary Immune Response ◽  
Cell Fate Decisions ◽  
Cd40 Stimulation

In mice, memory B (Bmem) cells can be divided into two subpopulations: CD80hi Bmem cells, which preferentially differentiate into plasma cells; and CD80lo Bmem cells, which become germinal center (GC) B cells during a recall response. We demonstrate that these distinct responses can be B-cell-intrinsic and essentially independent of B-cell receptor (BCR) isotypes. Furthermore, we find that the development of CD80hi Bmem cells in the primary immune response requires follicular helper T cells, a relatively strong CD40 signal and a high-affinity BCR on B cells, whereas the development of CD80lo Bmem cells does not. Quantitative differences in CD40 stimulation were enough to recapitulate the distinct B cell fate decisions in an in vitro culture system. The quantity of CD40 signaling appears to be translated into NF-κB activation, followed by BATF upregulation that promotes Bmem cell differentiation from GC B cells.

scholarly journals The AKT isoforms 1 and 2 drive B cell fate decisions during the germinal center response

2019 ◽  
Vol 2 (6) ◽  
pp. e201900506 ◽  
Author(s):  
Zilu Zhu ◽  
Ashima Shukla ◽  
Parham Ramezani-Rad ◽  
John R Apgar ◽  
Robert C Rickert
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Fate ◽  
Germinal Center ◽  
Cytidine Deaminase ◽  
Cell Receptor ◽  
Pi3k Pathway ◽  
Affinity Maturation ◽  
Cell Fate Decisions ◽  
Antibody Class

The PI3K pathway is integral for the germinal center (GC) response. However, the contribution of protein kinase B (AKT) as a PI3K effector in GC B cells remains unknown. Here, we show that mice lacking the AKT1 and AKT2 isoforms in B cells failed to form GCs, which undermined affinity maturation and antibody production in response to immunization. Upon B-cell receptor stimulation, AKT1/2–deficient B cells showed poor survival, reduced proliferation, and impaired mitochondrial and metabolic fitness, which collectively halted GC development. By comparison, Foxo1T24A mutant, which cannot be inactivated by AKT1/2 phosphorylation and is sequestered in the nucleus, significantly enhanced antibody class switch recombination via induction of activation-induced cytidine deaminase (AID) expression. By contrast, repression of FOXO1 activity by AKT1/2 promoted IRF4-driven plasma cell differentiation. Last, we show that T-cell help via CD40, but not enforced expression of Bcl2, rescued the defective GC response in AKT1/2–deficient animals by restoring proliferative expansion and energy production. Overall, our study provides mechanistic insights into the key role of AKT and downstream pathways on B cell fate decisions during the GC response.

scholarly journals The microRNA-212/132 cluster regulates B cell development by targeting Sox4

2015 ◽  
Vol 212 (10) ◽  
pp. 1679-1692 ◽  
Author(s):  
Arnav Mehta ◽  
Mati Mann ◽  
Jimmy L. Zhao ◽  
Georgi K. Marinov ◽  
Devdoot Majumdar ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Fate ◽  
Cell Receptor ◽  
Cell Development ◽  
B Cell Development ◽  
Cell Recovery ◽  
Cell Fate Decisions ◽  
Myc Oncogene ◽  
B Cell Receptor Signaling

MicroRNAs have emerged as key regulators of B cell fate decisions and immune function. Deregulation of several microRNAs in B cells leads to the development of autoimmune disease and cancer in mice. We demonstrate that the microRNA-212/132 cluster (miR-212/132) is induced in B cells in response to B cell receptor signaling. Enforced expression of miR-132 results in a block in early B cell development at the prepro–B cell to pro–B cell transition and induces apoptosis in primary bone marrow B cells. Importantly, loss of miR-212/132 results in accelerated B cell recovery after antibody-mediated B cell depletion. We find that Sox4 is a target of miR-132 in B cells. Co-expression of SOX4 with miR-132 rescues the defect in B cell development from overexpression of miR-132 alone, thus suggesting that miR-132 may regulate B lymphopoiesis through Sox4. In addition, we show that the expression of miR-132 can inhibit cancer development in cells that are prone to B cell cancers, such as B cells expressing the c-Myc oncogene. We have thus uncovered miR-132 as a novel contributor to B cell development.

MicroRNA-directed pathway discovery elucidates an miR-221/222–mediated regulatory circuit in class switch recombination

2021 ◽  
Vol 218 (11) ◽  
Author(s):  
Eric J. Wigton ◽  
Yohei Mikami ◽  
Ryan J. McMonigle ◽  
Carlos A. Castellanos ◽  
Adam K. Wade-Vallance ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Fate ◽  
Cell Activation ◽  
Class Switch Recombination ◽  
Cell Fate Decisions ◽  
Class Switch ◽  
Mrna Targets ◽  
Regulatory Circuit ◽  
Pathway Discovery

MicroRNAs (miRNAs, miRs) regulate cell fate decisions by post-transcriptionally tuning networks of mRNA targets. We used miRNA-directed pathway discovery to reveal a regulatory circuit that influences Ig class switch recombination (CSR). We developed a system to deplete mature, activated B cells of miRNAs, and performed a rescue screen that identified the miR-221/222 family as a positive regulator of CSR. Endogenous miR-221/222 regulated B cell CSR to IgE and IgG1 in vitro, and miR-221/222–deficient mice exhibited defective IgE production in allergic airway challenge and polyclonal B cell activation models in vivo. We combined comparative Ago2-HITS-CLIP and gene expression analyses to identify mRNAs bound and regulated by miR-221/222 in primary B cells. Interrogation of these putative direct targets uncovered functionally relevant downstream genes. Genetic depletion or pharmacological inhibition of Foxp1 and Arid1a confirmed their roles as key modulators of CSR to IgE and IgG1.

scholarly journals Rapid B Cell Receptor-induced Unfolded Protein Response in Nonsecretory B Cells Correlates with Pro-VersusAntiapoptotic Cell Fate

2005 ◽  
Vol 280 (48) ◽  
pp. 39762-39771 ◽  
Author(s):  
Alison H. Skalet ◽  
Jennifer A. Isler ◽  
Leslie B. King ◽  
Heather P. Harding ◽  
David Ron ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Unfolded Protein Response ◽  
Cell Fate ◽  
Cell Receptor ◽  
B Cell Receptor ◽  
Unfolded Protein ◽  
Protein Response

scholarly journals Internalization of B Cell Receptors in Human EU12μHC+Immature B Cells Specifically Alters Downstream Signaling Events

2013 ◽  
Vol 2013 ◽  
pp. 1-9
Author(s):  
Jing Liu ◽  
Wanqin Xie ◽  
Miles D. Lange ◽  
Sang Yong Hong ◽  
Kaihong Su ◽  
...  
Keyword(s):  
B Cells ◽  
Cell Surface ◽  
B Cell ◽  
Cell Fate ◽  
Cell Activation ◽  
Underlying Mechanism ◽  
Cell Fate Decisions ◽  
Downstream Signaling ◽  
Signaling Events ◽  
Immature B Cells

It has been recognized for a long time that engagement of B cell antigen receptors (BCRs) on immature B cells or mature B cells leads to completely opposite cell fate decisions. The underlying mechanism remains unclear. Here, we show that crosslinking of BCRs on human EU12μHC+immature B cells resulted in complete internalization of cell surface BCRs. After loss of cell surface BCRs, restimulation of EU12μHC+cells showed impaired Ca2+flux, delayed SYK phosphorylation, and decreased CD19 and FOXO1 phosphorylation, which differ from those in mature Daudi or Ramos B cells with partial internalization of BCRs. In contrast, sustained phosphorylation and reactivation of ERK upon restimulation were observed in the EU12μHC+cells after BCR internalization. Taken together, these results show that complete internalization of cell surface BCRs in EU12μHC+cells specifically alters the downstream signaling events, which may favor receptor editing versus cell activation.

scholarly journals Regulation of B cell fate by chronic activity of the IgE B cell receptor

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Zhiyong Yang ◽  
Marcus J Robinson ◽  
Xiangjun Chen ◽  
Geoffrey A Smith ◽  
Jack Taunton ◽  
...  
Keyword(s):  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Cell Fate ◽  
Plasma Cells ◽  
Cell Receptor ◽  
Culture Conditions ◽  
B Cell Receptor ◽  
Cell Cycles ◽  
T Cell Help

IgE can trigger potent allergic responses, yet the mechanisms regulating IgE production are poorly understood. Here we reveal that IgE+ B cells are constrained by chronic activity of the IgE B cell receptor (BCR). In the absence of cognate antigen, the IgE BCR promoted terminal differentiation of B cells into plasma cells (PCs) under cell culture conditions mimicking T cell help. This antigen-independent PC differentiation involved multiple IgE domains and Syk, CD19, BLNK, Btk, and IRF4. Disruption of BCR signaling in mice led to consistently exaggerated IgE+ germinal center (GC) B cell but variably increased PC responses. We were unable to confirm reports that the IgE BCR directly promoted intrinsic apoptosis. Instead, IgE+ GC B cells exhibited poor antigen presentation and prolonged cell cycles, suggesting reduced competition for T cell help. We propose that chronic BCR activity and access to T cell help play critical roles in regulating IgE responses.

scholarly journals IgH isotype-specific B cell receptor expression influences B cell fate

2017 ◽  
Vol 114 (40) ◽  
pp. E8411-E8420 ◽  
Author(s):  
Pei Tong ◽  
Alessandra Granato ◽  
Teng Zuo ◽  
Neha Chaudhary ◽  
Adam Zuiani ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Fate ◽  
Rna Splicing ◽  
Memory Function ◽  
Cell Receptor ◽  
Receptor Expression ◽  
Wild Type ◽  
Cell Stage ◽  
Membrane Bound

Ig heavy chain (IgH) isotypes (e.g., IgM, IgG, and IgE) are generated as secreted/soluble antibodies (sIg) or as membrane-bound (mIg) B cell receptors (BCRs) through alternative RNA splicing. IgH isotype dictates soluble antibody function, but how mIg isotype influences B cell behavior is not well defined. We examined IgH isotype-specific BCR function by analyzing naturally switched B cells from wild-type mice, as well as by engineering polyclonal Ighγ1/γ1 and Ighε/ε mice, which initially produce IgG1 or IgE from their respective native genomic configurations. We found that B cells from wild-type mice, as well as Ighγ1/γ1 and Ighε/ε mice, produce transcripts that generate IgM, IgG1, and IgE in an alternative splice form bias hierarchy, regardless of cell stage. In this regard, we found that mIgμ > mIgγ1 > mIgε, and that these BCR expression differences influence respective developmental fitness. Restrained B cell development from Ighγ1/γ1 and Ighε/ε mice was proportional to sIg/mIg ratios and was rescued by enforced expression of the respective mIgs. In addition, artificially enhancing BCR signal strength permitted IgE+ memory B cells—which essentially do not exist under normal conditions—to provide long-lived memory function, suggesting that quantitative BCR signal weakness contributes to restraint of IgE B cell responses. Our results indicate that IgH isotype-specific mIg/BCR dosage may play a larger role in B cell fate than previously anticipated.

Regulation and Function of NOTCH2 in B-CLL Cells.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 1138-1138
Author(s):  
Rainer Hubmann ◽  
Martin Hilgarth ◽  
Susanne Schnabl ◽  
Dita Demirtas ◽  
Josef D. Schwarzmeier ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Fate ◽  
Target Gene ◽  
Active Form ◽  
Lymphocytic Leukemia ◽  
B Cell Differentiation ◽  
Cell Fate Decisions ◽  
Mutational Status ◽  
And Function

Abstract B-cell chronic lymphocytic leukemia (B-CLL) represents a clonal expansion of self-reactive CD5+ B-lymphocytes which seems to be resistant to apoptosis in vivo. One of the characteristics of B-CLL lymphocytes is the high expression of the B-cell differentiation/activation marker CD23 which we recently identified as a target gene for NOTCH2 signaling. NOTCH2 is implicated in the development/homeostasis of murine CD5+ (B-1a) B-cells, suggesting a function for human NOTCH2 in B-CLL leukemogenesis. Here we show that peripheral B-CLL lymphocytes overexpress a transcriptionally active form of NOTCH2 (N2IC) irrespective of their prognostic marker profile (ie. IgVH mutational status, CD38 expression, and cytogenetics). Although the majority of unstimulated B-CLL samples downregulate their N2IC activity in vitro, DNA-bound N2IC complexes could be maintained by the protein kinase C (PKC) activator TPA (12-O-tetradecanoylphorbol 13-acetate) accompanied by an upregulation of the NOTCH2 target gene CD23 and increased B-CLL cell viability. These effects are sensitive to the PKC-δ selective inhibitor Rottlerin. In 80% of B-CLL cases, NOTCH2 signaling was found to be resistant to the γ-secretase inhibitors (GSI’s) Dapt and compound E, indicative for the expression of truncated forms of NOTCH2 which do not require γ-secretase for processing and function. Inhibition of NOTCH2 either by Dapt in GSI sensitive B-CLL cases or, more specifically, by RNA interference downregulates CD23 expression on the mRNA and protein level and sensitizes B-CLL cells for apoptosis. Since self-reactive B-cells are normally eliminated either by chronic (anergy) or apoptotic (negative selection) B-cell receptor (BCR) signaling, we asked whether NOTCH2 modulates B-cell fate decisions triggered by the BCR. For this reason, we stably transduced the human B-cell line BL41 with constitutive active forms of NOTCH2 and found that NOTCH2 inhibits BCR mediated apoptosis induced by surface-IgM cross-linking. In summary, the data demonstrate that NOTCH2 signaling is deregulated in B-CLL cells and might be critically involved in the PKC-dependent maintenance of their malignant phenotype.

scholarly journals The aryl hydrocarbon receptor controls cell-fate decisions in B cells

2016 ◽  
Vol 214 (1) ◽  
pp. 197-208 ◽  
Author(s):  
Bharat Vaidyanathan ◽  
Ashutosh Chaudhry ◽  
William T. Yewdell ◽  
Davide Angeletti ◽  
Wei-Feng Yen ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Aryl Hydrocarbon Receptor ◽  
Cell Fate ◽  
Plasma Cells ◽  
Ex Vivo ◽  
Critical Role ◽  
Cell Fate Decisions ◽  
Aryl Hydrocarbon

Generation of cellular heterogeneity is an essential feature of the adaptive immune system. This is best exemplified during humoral immune response when an expanding B cell clone assumes multiple cell fates, including class-switched B cells, antibody-secreting plasma cells, and memory B cells. Although each cell type is essential for immunity, their generation must be exquisitely controlled because a class-switched B cell cannot revert back to the parent isotype, and a terminally differentiated plasma cell cannot contribute to the memory pool. In this study, we show that an environmental sensor, the aryl hydrocarbon receptor (AhR) is highly induced upon B cell activation and serves a critical role in regulating activation-induced cell fate outcomes. We find that AhR negatively regulates class-switch recombination ex vivo by altering activation-induced cytidine deaminase expression. We further demonstrate that AhR suppresses class switching in vivo after influenza virus infection and immunization with model antigens. In addition, by regulating Blimp-1 expression via Bach2, AhR represses differentiation of B cells into plasmablasts ex vivo and antibody-secreting plasma cells in vivo. These experiments suggest that AhR serves as a molecular rheostat in B cells to brake the effector response, possibly to facilitate optimal recall responses. Thus, AhR might represent a novel molecular target for manipulation of B cell responses during vaccination.

Sign in / Sign up

Export Citation Format

Share Document