Dermatan Sulfate Is a Potential Regulator of IgH via Interactions With Pre-BCR, GTF2I, and BiP ER Complex in Pre-B Lymphoblasts

Dermatan sulfate (DS) and autoantigen (autoAg) complexes are capable of stimulating autoreactive CD5+ B1 cells. We examined the activity of DS on CD5+ pre-B lymphoblast NFS-25 cells. CD19, CD5, CD72, PI3K, and Fas possess varying degrees of DS affinity. The three pre-BCR components, Ig heavy chain mu (IgH), VpreB, and lambda 5, display differential DS affinities, with IgH having the strongest affinity. DS attaches to NFS-25 cells, gradually accumulates in the ER, and eventually localizes to the nucleus. DS and IgH co-localize on the cell surface and in the ER. DS associates strongly with 17 ER proteins (e.g., BiP/Grp78, Grp94, Hsp90ab1, Ganab, Vcp, Canx, Kpnb1, Prkcsh, Pdia3), which points to an IgH-associated multiprotein complex in the ER. In addition, DS interacts with nuclear proteins (Ncl, Xrcc6, Prmt5, Eftud2, Supt16h) and Lck. We also discovered that DS binds GTF2I, a required gene transcription factor at the IgH locus. These findings support DS as a potential regulator of IgH in pre-B cells at protein and gene levels. We propose a (DS•autoAg)-autoBCR dual signal model in which an autoBCR is engaged by both autoAg and DS, and, once internalized, DS recruits a cascade of molecules that may help avert apoptosis and steer autoreactive B cell fate. Through its affinity with autoAgs and its control of IgH, DS emerges as a potential key player in the development of autoreactive B cells and autoimmunity.

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Dermatan Sulfate Is a Potential Master Regulator of IgH via Interactions with Pre-BCR, GTF2I, and BiP ER Complex in Pre-B Lymphoblasts

10.1101/2021.01.18.427153 ◽

2021 ◽

Cited By ~ 1

Author(s):

Jongmin Lee ◽

Jung-hyun Rho ◽

Michael H. Roehrl ◽

Julia Y. Wang

Keyword(s):

Transcription Factor ◽

B Cells ◽

Cell Fate ◽

Dermatan Sulfate ◽

Nuclear Proteins ◽

Multiprotein Complex ◽

Signal Model ◽

Master Regulator ◽

Autoreactive B Cells ◽

Ig Heavy Chain

AbstractDermatan sulfate (DS) and autoantigen (autoAg) complexes are capable of stimulating autoreactive CD5+ B-1 cells. We examined the activity of DS on CD5+ pre-B lymphoblast NFS-25 cells. CD19, CD5, CD72, PI3K, and Fas possess varying degrees of DS affinity. The three pre-BCR components, Ig heavy chain mu (IgH), VpreB, and lambda 5, display differential DS affinities, with IgH having the strongest affinity. DS attaches to NFS-25 cells, gradually accumulates in the ER, and eventually localizes to the nucleus. DS and IgH co-localize on the cell surface and in the ER. DS associates strongly with 17 ER proteins (e.g., BiP/Grp78, Grp94, Hsp90ab1, Ganab, Vcp, Canx, Kpnb1, Prkcsh, Pdia3), which points to an IgH-associated multiprotein complex in the ER. In addition, DS interacts with nuclear proteins (Ncl, Xrcc6, Prmt5, Eftud2, Supt16h) and Lck. We also discovered that DS binds GTF2I, a required gene transcription factor at the IgH locus. These findings support DS as a potential master regulator of IgH in pre-B cells at protein and gene levels. We propose a (DS•autoAg)-autoBCR dual signal model in which an autoBCR is engaged by both autoAg and DS, and, once internalized, DS recruits a cascade of molecules that may help avert apoptosis and steer autoreactive B cell fate. Through its affinity with autoAgs and its control of IgH, DS emerges as a potential key player in the development of autoreactive B cells and autoimmunity.

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IgM and IgD B cell receptors differentially respond to endogenous antigens and control B cell fate

eLife ◽

10.7554/elife.35074 ◽

2018 ◽

Vol 7 ◽

Cited By ~ 23

Author(s):

Mark Noviski ◽

James L Mueller ◽

Anne Satterthwaite ◽

Lee Ann Garrett-Sinha ◽

Frank Brombacher ◽

...

Keyword(s):

B Cells ◽

B Cell ◽

Cell Fate ◽

Plasma Cells ◽

Autoreactive B Cells ◽

Binding Domains ◽

Bcr Signaling ◽

And Control

Naive B cells co-express two BCR isotypes, IgM and IgD, with identical antigen-binding domains but distinct constant regions. IgM but not IgD is downregulated on autoreactive B cells. Because these isotypes are presumed to be redundant, it is unknown how this could impose tolerance. We introduced the Nur77-eGFP reporter of BCR signaling into mice that express each BCR isotype alone. Despite signaling strongly in vitro, IgD is less sensitive than IgM to endogenous antigen in vivo and developmental fate decisions are skewed accordingly. IgD-only Lyn−/− B cells cannot generate autoantibodies and short-lived plasma cells (SLPCs) in vivo, a fate thought to be driven by intense BCR signaling induced by endogenous antigens. Similarly, IgD-only B cells generate normal germinal center, but impaired IgG1+ SLPC responses to T-dependent immunization. We propose a role for IgD in maintaining the quiescence of autoreactive B cells and restricting their differentiation into autoantibody secreting cells.

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Single cell expression analysis uncouples transdifferentiation and reprogramming

10.1101/351957 ◽

2018 ◽

Author(s):

Mirko Francesconi ◽

Bruno Di Stefano ◽

Clara Berenguer ◽

Marisa de Andres ◽

Maria Mendez Lago ◽

...

Keyword(s):

Transcription Factor ◽

B Cells ◽

Single Cell ◽

Cell Fate ◽

Expression Analysis ◽

High Efficiency ◽

Cell Types ◽

Direct Conversion ◽

Small Cells ◽

Cell Conversion

AbstractMany somatic cell types are plastic, having the capacity to convert into other specialized cells (transdifferentiation)(1) or into induced pluripotent stem cells (iPSCs, reprogramming)(2) in response to transcription factor over-expression. To explore what makes a cell plastic and whether these different cell conversion processes are coupled, we exposed bone marrow derived pre-B cells to two different transcription factor overexpression protocols that efficiently convert them either into macrophages or iPSCs and monitored the two processes over time using single cell gene expression analysis. We found that even in these highly efficient cell fate conversion systems, cells differ in both their speed and path of transdifferentiation and reprogramming. This heterogeneity originatesin two starting pre-B cell subpopulations,large pre-BII and the small pre-BII cells they normally differentiate into. The large cells transdifferentiate slowly but exhibit a high efficiency of iPSC reprogramming. In contrast, the small cells transdifferentiate rapidly but are highly resistant to reprogramming. Moreover, the large B cells induce a stronger transient granulocyte/macrophage progenitor (GMP)-like state, while the small B cells undergo a more direct conversion to the macrophage fate. The large cells are cycling and exhibit high Myc activity whereas the small cells are Myc low and mostly quiescent. The observed heterogeneity of the two cell conversion processes can therefore be traced to two closely related cell types in the starting population that exhibit different types of plasticity. These data show that a somatic cell’s propensity for either transdifferentiation and reprogramming can be uncoupled.One sentence summarySingle cell transcriptomics of cell conversions

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The cytoskeletal regulator HEM1 governs B cell development and prevents autoimmunity

Science Immunology ◽

10.1126/sciimmunol.abc3979 ◽

2020 ◽

Vol 5 (49) ◽

pp. eabc3979 ◽

Cited By ~ 2

Author(s):

Elisabeth Salzer ◽

Samaneh Zoghi ◽

Máté G. Kiss ◽

Frieda Kage ◽

Christina Rashkova ◽

...

Keyword(s):

B Cells ◽

B Cell ◽

Cell Fate ◽

Immune Cell ◽

Cell Receptor ◽

Eukaryotic Cell ◽

Cell Development ◽

Filamentous Actin ◽

Autoreactive B Cells ◽

Systemic Autoimmunity

The WAVE regulatory complex (WRC) is crucial for assembly of the peripheral branched actin network constituting one of the main drivers of eukaryotic cell migration. Here, we uncover an essential role of the hematopoietic-specific WRC component HEM1 for immune cell development. Germline-encoded HEM1 deficiency underlies an inborn error of immunity with systemic autoimmunity, at cellular level marked by WRC destabilization, reduced filamentous actin, and failure to assemble lamellipodia. Hem1−/− mice display systemic autoimmunity, phenocopying the human disease. In the absence of Hem1, B cells become deprived of extracellular stimuli necessary to maintain the strength of B cell receptor signaling at a level permissive for survival of non-autoreactive B cells. This shifts the balance of B cell fate choices toward autoreactive B cells and thus autoimmunity.

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The BCL11A Transcription Factor Directly Activates RAG Gene Expression and V(D)J Recombination

Molecular and Cellular Biology ◽

10.1128/mcb.00987-12 ◽

2013 ◽

Vol 33 (9) ◽

pp. 1768-1781 ◽

Cited By ~ 9

Author(s):

Baeck-seung Lee ◽

Joseph D. Dekker ◽

Bum-kyu Lee ◽

Vishwanath R. Iyer ◽

Barry P. Sleckman ◽

...

Keyword(s):

Transcription Factor ◽

B Cells ◽

B Cell ◽

Cell Fate ◽

B Cell Development ◽

Receptor Expression ◽

Molecular Function ◽

Cell Fate Specification ◽

Fate Specification ◽

Recombination Activating Gene

Recombination-activating gene 1 protein (RAG1) and RAG2 are critical enzymes for initiating variable-diversity-joining (VDJ) segment recombination, an essential process for antigen receptor expression and lymphocyte development. The transcription factor BCL11A is required for B cell development, but its molecular function(s) in B cell fate specification and commitment is unknown. We show here that the major B cell isoform, BCL11A-XL, binds the RAG1 promoter and Erag enhancer to activate RAG1 and RAG2 transcription in pre-B cells. We employed BCL11A overexpression with recombination substrates in a cultured pre-B cell line as well as Cre recombinase-mediated Bcl11a lox/lox deletion in explanted murine pre-B cells to demonstrate direct consequences of BCL11A/RAG modulation on V(D)J recombination. We conclude that BCL11A is a critical component of a transcriptional network that regulates B cell fate by controlling V(D)J recombination.

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