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1.
Mol Cell ; 73(1): 48-60.e5, 2019 01 03.
Artículo en Inglés | MEDLINE | ID: mdl-30449725

RESUMEN

The genome is organized into topologically associated domains (TADs) that enclose smaller subTADs. Here, we identify and characterize an enhancer that is located in the middle of the V gene region of the immunoglobulin kappa light chain (Igκ) locus that becomes active preceding the stage at which this locus undergoes V(D)J recombination. This enhancer is a hub of long-range chromatin interactions connecting subTADs in the V gene region with the recombination center at the J genes. Deletion of this element results in a highly altered long-range chromatin interaction pattern across the locus and, importantly, affects individual V gene utilization locus-wide. These results indicate the existence of an enhancer-dependent framework in the Igκ locus and further suggest that the composition of the diverse antibody repertoire is regulated in a subTAD-specific manner. This enhancer thus plays a structural role in orchestrating the proper folding of the Igκ locus in preparation for V(D)J recombination.


Asunto(s)
Diversidad de Anticuerpos , Núcleo Celular/inmunología , Elementos de Facilitación Genéticos , Reordenamiento Génico de Linfocito B , Cadenas kappa de Inmunoglobulina/inmunología , Células Precursoras de Linfocitos B/inmunología , Receptores de Antígenos de Linfocitos B/inmunología , Animales , Línea Celular Tumoral , Núcleo Celular/genética , Núcleo Celular/metabolismo , Forma del Núcleo Celular , Ensamble y Desensamble de Cromatina , Genotipo , Células HEK293 , Humanos , Cadenas kappa de Inmunoglobulina/química , Cadenas kappa de Inmunoglobulina/genética , Cadenas kappa de Inmunoglobulina/metabolismo , Ratones Endogámicos C57BL , Ratones Transgénicos , Fenotipo , Células Precursoras de Linfocitos B/metabolismo , Conformación Proteica , Receptores de Antígenos de Linfocitos B/química , Receptores de Antígenos de Linfocitos B/genética , Receptores de Antígenos de Linfocitos B/metabolismo , Relación Estructura-Actividad
2.
J Immunol ; 201(6): 1633-1638, 2018 09 15.
Artículo en Inglés | MEDLINE | ID: mdl-30076197

RESUMEN

Igκ locus contraction and Vκ gene usage are controlled by Cer, a cis-acting sequence in the Vκ-Jκ intervening region. This effect is attributed to two CTCF-binding sites within Cer that are oriented toward the Vκ gene region. However, the importance of Cer CTCF orientation in regulating VκJκ rearrangement is unknown. We used CRISPR/Cas9 editing to delete and invert Cer in murine Abl pro-B cell lines. This revealed that Cer orientation is critical because clones with either an inverted or deleted Cer element show skewing toward Jκ-proximal Vκ gene usage. However, only Cer deletion increased Jκ-proximal Vκ germline transcription, suggesting an insulating function of Cer. Lastly, circularized chromosome conformation capture interaction data show that Cer CTCF orientation regulates long-range interactions with inversion clones displaying fewer interactions with regions in the middle and distal parts of the Vκ locus and more interactions to downstream regions compared with wild-type or deletion clones.


Asunto(s)
Linfocitos B/inmunología , Factor de Unión a CCCTC , Región de Unión de la Inmunoglobulina , Cadenas kappa de Inmunoglobulina , Elementos de Respuesta/inmunología , Transcripción Genética/inmunología , Animales , Factor de Unión a CCCTC/genética , Factor de Unión a CCCTC/inmunología , Región de Unión de la Inmunoglobulina/genética , Región de Unión de la Inmunoglobulina/inmunología , Cadenas kappa de Inmunoglobulina/genética , Cadenas kappa de Inmunoglobulina/inmunología , Ratones , Ratones Noqueados
3.
Proc Natl Acad Sci U S A ; 113(27): E3911-20, 2016 07 05.
Artículo en Inglés | MEDLINE | ID: mdl-27335461

RESUMEN

Ying Yang 1 (YY1) is a ubiquitously expressed transcription factor shown to be essential for pro-B-cell development. However, the role of YY1 in other B-cell populations has never been investigated. Recent bioinformatics analysis data have implicated YY1 in the germinal center (GC) B-cell transcriptional program. In accord with this prediction, we demonstrated that deletion of YY1 by Cγ1-Cre completely prevented differentiation of GC B cells and plasma cells. To determine if YY1 was also required for the differentiation of other B-cell populations, we deleted YY1 with CD19-Cre and found that all peripheral B-cell subsets, including B1 B cells, require YY1 for their differentiation. Transitional 1 (T1) B cells were the most dependent upon YY1, being sensitive to even a half-dosage of YY1 and also to short-term YY1 deletion by tamoxifen-induced Cre. We show that YY1 exerts its effects, in part, by promoting B-cell survival and proliferation. ChIP-sequencing shows that YY1 predominantly binds to promoters, and pathway analysis of the genes that bind YY1 show enrichment in ribosomal functions, mitochondrial functions such as bioenergetics, and functions related to transcription such as mRNA splicing. By RNA-sequencing analysis of differentially expressed genes, we demonstrated that YY1 normally activates genes involved in mitochondrial bioenergetics, whereas it normally down-regulates genes involved in transcription, mRNA splicing, NF-κB signaling pathways, the AP-1 transcription factor network, chromatin remodeling, cytokine signaling pathways, cell adhesion, and cell proliferation. Our results show the crucial role that YY1 plays in regulating broad general processes throughout all stages of B-cell differentiation.


Asunto(s)
Linfocitos B/fisiología , Diferenciación Celular , Regulación de la Expresión Génica , Centro Germinal/fisiología , Factor de Transcripción YY1/fisiología , Animales , Linaje de la Célula , ADN Helicasas/metabolismo , Femenino , Centro Germinal/citología , Histona Demetilasas con Dominio de Jumonji/metabolismo , Masculino , Ratones Endogámicos C57BL
4.
J Immunol ; 189(11): 5185-93, 2012 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-23087406

RESUMEN

Anergy is a key physiological mechanism for restraining self-reactive B cells. A marked portion of peripheral B cells are anergic B cells that largely depend on BAFF for survival. BAFF activates the canonical and noncanonical NF-κB pathways, both of which are required for B cell survival. In this study we report that deficiency of the adaptor protein B cell lymphoma 10 (Bcl10) impaired the ability of BAFF to support B cell survival in vitro, and it specifically increased apoptosis in anergic B cells in vivo, dramatically reducing anergic B cells in mice. Bcl10-dependent survival of self-reactive anergic B cells was confirmed in the Ig hen egg lysozyme/soluble hen egg lysozyme double-transgenic mouse model of B cell anergy. Furthermore, we found that BAFF stimulation induced Bcl10 association with IκB kinase ß, a key component of the canonical NF-κB pathway. Consistently, Bcl10-deficient B cells were impaired in BAFF-induced IκBα phosphorylation and formation of nuclear p50/c-Rel complexes. Bcl10-deficient B cells also displayed reduced expression of NF-κB2/p100, severely reducing BAFF-induced nuclear accumulation of noncanonical p52/RelB complexes. Consequently, Bcl10-deficient B cells failed to express Bcl-x(L), a BAFF-induced NF-κB target gene. Taken together, these data demonstrate that Bcl10 controls BAFF-induced canonical NF-κB activation directly and noncanonical NF-κB activation indirectly. The BAFF-R/Bcl10/NF-κB signaling axis plays a critical role in peripheral B cell tolerance by regulating the survival of self-reactive anergic B cells.


Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/inmunología , Factor Activador de Células B/inmunología , Supervivencia Celular/inmunología , FN-kappa B/inmunología , Transducción de Señal , Proteínas Adaptadoras Transductoras de Señales/deficiencia , Proteínas Adaptadoras Transductoras de Señales/genética , Animales , Apoptosis , Factor Activador de Células B/genética , Proteína 10 de la LLC-Linfoma de Células B , Linfocitos B/citología , Linfocitos B/inmunología , Linfocitos B/metabolismo , Supervivencia Celular/genética , Anergia Clonal , Regulación de la Expresión Génica/inmunología , Quinasa I-kappa B/genética , Quinasa I-kappa B/inmunología , Ratones , Ratones Transgénicos , Muramidasa/inmunología , FN-kappa B/genética , Subunidad p52 de NF-kappa B/genética , Subunidad p52 de NF-kappa B/inmunología , Fosforilación , Proteínas Proto-Oncogénicas c-rel/genética , Proteínas Proto-Oncogénicas c-rel/inmunología , Bazo/citología , Bazo/inmunología , Bazo/metabolismo , Factor de Transcripción ReIB/genética , Factor de Transcripción ReIB/inmunología , Proteína bcl-X/genética , Proteína bcl-X/inmunología
5.
Nat Commun ; 14(1): 1225, 2023 03 03.
Artículo en Inglés | MEDLINE | ID: mdl-36869028

RESUMEN

The mouse Igh locus is organized into a developmentally regulated topologically associated domain (TAD) that is divided into subTADs. Here we identify a series of distal VH enhancers (EVHs) that collaborate to configure the locus. EVHs engage in a network of long-range interactions that interconnect the subTADs and the recombination center at the DHJH gene cluster. Deletion of EVH1 reduces V gene rearrangement in its vicinity and alters discrete chromatin loops and higher order locus conformation. Reduction in the rearrangement of the VH11 gene used in anti-PtC responses is a likely cause of the observed reduced splenic B1 B cell compartment. EVH1 appears to block long-range loop extrusion that in turn contributes to locus contraction and determines the proximity of distant VH genes to the recombination center. EVH1 is a critical architectural and regulatory element that coordinates chromatin conformational states that favor V(D)J rearrangement.


Asunto(s)
Linfocitos B , Cadenas Pesadas de Inmunoglobulina , Secuencias Reguladoras de Ácidos Nucleicos , Animales , Ratones , Cromatina , Aberraciones Cromosómicas , Receptores de Antígenos , Cadenas Pesadas de Inmunoglobulina/genética
6.
Sci Rep ; 11(1): 9561, 2021 05 05.
Artículo en Inglés | MEDLINE | ID: mdl-33953256

RESUMEN

Extracellular adenosine suppresses T cell immunity in the tumor microenvironment and in vitro treatment of memory T cells with adenosine can suppress antigen-mediated memory T cell expansion. We describe utilizing the recall antigen assay platform to screen small molecule drug off-target effects on memory T cell expansion/function using a dosing regimen based on adenosine treatment. As a proof of principle, we show low dose GS-5734, a monophosphoramidate prodrug of an adenosine analog, does not alter memory T cell recall at lower doses whereas toxicity observed at high dose favors antigen-specific memory T cell survival/proliferation over non-specific CD8+ T cells. Conversely, parent nucleoside GS-441524 at high dosage does not result in cellular toxicity and reduces antigen-specific T cell recall in most donors. Despite similar chemical structure, these drugs displayed opposing effects on memory T cell expansion and viability highlighting the sensitivity of this assay setup in screening compounds for off-target effects.


Asunto(s)
Adenosina Monofosfato/análogos & derivados , Adenosina/análogos & derivados , Adenosina/farmacología , Alanina/análogos & derivados , Memoria Inmunológica/efectos de los fármacos , Linfocitos T/efectos de los fármacos , Adenosina Monofosfato/farmacología , Alanina/farmacología , Linfocitos T CD8-positivos/efectos de los fármacos , Linfocitos T CD8-positivos/inmunología , Proliferación Celular/efectos de los fármacos , Humanos , Memoria Inmunológica/inmunología , Linfocitos T/inmunología
7.
Front Immunol ; 12: 705307, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34512628

RESUMEN

While apoptosis plays a role in B-cell self-tolerance, its significance in preventing autoimmunity remains unclear. Here, we report that dysregulated B cell apoptosis leads to delayed onset autoimmune phenotype in mice. Our longitudinal studies revealed that mice with B cell-specific deletion of pro-apoptotic Bim (BBimfl/fl ) have an expanded B cell compartment with a notable increase in transitional, antibody secreting and recently described double negative (DN) B cells. They develop greater hypergammaglobulinemia than mice lacking Bim in all cells and accumulate several autoantibodies characteristic of Systemic Lupus Erythematosus (SLE) and related Sjögren's Syndrome (SS) including anti-nuclear, anti-Ro/SSA and anti-La/SSB at a level comparable to NODH2h4 autoimmune mouse model. Furthermore, lymphocytes infiltrated the tissues including submandibular glands and formed follicle-like structures populated with B cells, plasma cells and T follicular helper cells indicative of ongoing immune reaction. This autoimmunity was ameliorated upon deletion of Bruton's tyrosine kinase (Btk) gene, which encodes a key B cell signaling protein. These studies suggest that Bim-mediated apoptosis suppresses and B cell tyrosine kinase signaling promotes B cell-mediated autoimmunity.


Asunto(s)
Agammaglobulinemia Tirosina Quinasa/antagonistas & inhibidores , Apoptosis/fisiología , Enfermedades Autoinmunes/inmunología , Autoinmunidad/inmunología , Linfocitos B/inmunología , Proteína 11 Similar a Bcl2/fisiología , Agammaglobulinemia Tirosina Quinasa/deficiencia , Agammaglobulinemia Tirosina Quinasa/fisiología , Animales , Especificidad de Anticuerpos , Autoanticuerpos/sangre , Linfocitos B/enzimología , Linfocitos B/patología , Proteína 11 Similar a Bcl2/deficiencia , División Celular , Células Cultivadas , Hipergammaglobulinemia/inmunología , Tolerancia Inmunológica/inmunología , Lupus Eritematoso Sistémico/inmunología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Receptores de Antígenos/inmunología , Síndrome de Sjögren/inmunología , Linfocitos T/inmunología
8.
Front Immunol ; 9: 2074, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30271408

RESUMEN

To date there has not been a study directly comparing relative Igκ rearrangement frequencies obtained from genomic DNA (gDNA) and cDNA and since each approach has potential biases, this is an important issue to clarify. Here we used deep sequencing to compare the unbiased gDNA and RNA Igκ repertoire from the same pre-B cell pool. We find that ~20% of Vκ genes have rearrangement frequencies ≥2-fold up or down in RNA vs. DNA libraries, including many members of the Vκ3, Vκ4, and Vκ6 families. Regression analysis indicates Ikaros and E2A binding are associated with strong promoters. Within the pre-B cell repertoire, we observed that individual Vκ genes rearranged at very different frequencies, and also displayed very different Jκ usage. Regression analysis revealed that the greatly unequal Vκ gene rearrangement frequencies are best predicted by epigenetic marks of enhancers. In particular, the levels of newly arising H3K4me1 peaks associated with many Vκ genes in pre-B cells are most predictive of rearrangement levels. Since H3K4me1 is associated with long range chromatin interactions which are created during locus contraction, our data provides mechanistic insight into unequal rearrangement levels. Comparison of Igκ rearrangements occurring in pro-B cells and pre-B cells from the same mice reveal a pro-B cell bias toward usage of Jκ-distal Vκ genes, particularly Vκ10-96 and Vκ1-135. Regression analysis indicates that PU.1 binding is the highest predictor of Vκ gene rearrangement frequency in pro-B cells. Lastly, the repertoires of iEκ-/- pre-B cells reveal that iEκ actively influences Vκ gene usage, particularly Vκ3 family genes, overlapping with a zone of iEκ-regulated germline transcription. These represent new roles for iEκ in addition to its critical function in promoting overall Igκ rearrangement. Together, this study provides insight into many aspects of Igκ repertoire formation.


Asunto(s)
Linfocitos B/fisiología , Cadenas Ligeras de Inmunoglobulina/genética , Células Precursoras de Linfocitos B/fisiología , Animales , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/genética , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , ADN Complementario/genética , Epigénesis Genética , Reordenamiento Génico de Cadena Ligera de Linfocito B , Genoma , Factor de Transcripción Ikaros/genética , Factor de Transcripción Ikaros/metabolismo , Región Variable de Inmunoglobulina/genética , Cadenas kappa de Inmunoglobulina/genética , Ratones , Ratones Endogámicos C57BL , Regiones Promotoras Genéticas/genética , Unión Proteica , Proteínas Proto-Oncogénicas/metabolismo , Transactivadores/metabolismo
10.
Front Immunol ; 6: 30, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-25717326

RESUMEN

Splenic transitional B-cells (T1 and T2) are selected to avoid self-reactivity and to safeguard against autoimmunity, then differentiate into mature follicular (FO-I and FO-II) and marginal zone (MZ) subsets. Transcriptomic analysis by RNA-seq of the five B-cell subsets revealed T1 cell signature genes included RAG suggesting a potential for receptor revision. T1 to T2 B-cell differentiation was marked by a switch from Myb to Myc, increased expression of the PI3K adapter DAP10 and MHC class II. FO-II may be an intermediate in FO-I differentiation and may also become MZ B-cells as suggested by principle component analysis. MZ B-cells possessed the most distinct transcriptome including down-regulation of CD45 phosphatase-associated protein (CD45-AP/PTPRC-AP), as well as upregulation of IL-9R and innate molecules TLR3, TLR7, and bactericidal Perforin-2 (MPEG1). Among the endosomal TLRs, stimulation via TLR3 further enhanced Perforin-2 expression exclusively in MZ B-cells. Using gene-deleted and overexpressing transgenic mice we show that IL-9/IL-9R interaction resulted in rapid activation of STAT1, 3, and 5, primarily in MZ B-cells. Importantly, CD45-AP mutant mice had reduced transitional and increased mature MZ and FO B-cells, suggesting that it prevents premature entry of transitional B-cells to the mature B-cell pool or their survival and proliferation. Together, these findings suggest, developmental plasticity among splenic B-cell subsets, potential for receptor revision in peripheral tolerance whereas enhanced metabolism coincides with T2 to mature B-cell differentiation. Further, unique core transcriptional signatures in MZ B-cells may control their innate features.

11.
Immunol Res ; 57(1-3): 335-53, 2013 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-24293007

RESUMEN

B-lymphocytes are integral to host defense against microbial pathogens and are associated with many autoimmune diseases. The B-cell receptor implements B-cell self-tolerance based on the antigen specificity, and B-cell-activating factor receptor (BAFF-R) imposes homeostatic control. While shaping the repertoire, the immune tolerance process also culls mature B cells into distinct populations. The activation response of B cells is tailored to the type of pathogen attack and is facilitated by T-cell help via CD40/CD40L interaction and/or innate cell help via toll-like receptors in conjunction with BAFF receptors and ligands. Activated effector B cells not only produce antibodies, but also produce a variety of cytokines to enhance and suppress the immune response. Not surprisingly, B cells play multiple roles in both humoral and cellular immune responses during infection and autoimmune pathogenesis. Here, we discuss how gene expression and signaling networks regulate peripheral B-cell tolerance, B-cell effector functions and emerging therapies targeting B-cell signaling in autoimmune diseases.


Asunto(s)
Autoinmunidad , Subgrupos de Linfocitos B/inmunología , Linfocitos B/inmunología , Tolerancia Inmunológica , Inmunidad , Agammaglobulinemia Tirosina Quinasa , Animales , Apoptosis/inmunología , Enfermedades Autoinmunes/inmunología , Enfermedades Autoinmunes/metabolismo , Subgrupos de Linfocitos B/metabolismo , Linfocitos B/metabolismo , Homeostasis , Humanos , Proteínas Tirosina Quinasas/metabolismo , Receptores de Antígenos de Linfocitos B/metabolismo , Transducción de Señal
12.
Endocrinology ; 150(5): 2087-97, 2009 May.
Artículo en Inglés | MEDLINE | ID: mdl-19116344

RESUMEN

Serine/arginine-rich (SR) proteins play essential roles in the constitutive and regulated splicing of precursor mRNAs. Phosphorylation of the arginine/serine dipeptide-rich (RS) domain by SR protein kinases such as Cdc2-like kinases (Clk/Sty) modulates their subcellular localization and activation. However, it remains unclear how these kinases and their target SR proteins are regulated by extracellular signals. Regulation of protein kinase C betaII (PKCbetaII) pre-mRNA alternative splicing via exon inclusion by Akt2, a central kinase in insulin action, involves phosphorylation of SR proteins. Here we showed that Akt2, in response to insulin, resulted in phosphorylation of Clk/Sty, which then altered SR protein phosphorylation in concert with Akt2. Insulin-stimulated PKCbetaII pre-mRNA splicing was blocked by Clk/Sty and phosphatidylinositol-3-kinase inhibitors, and diabetic Akt2-null mouse tissues had impaired phospho-Clk/Sty, SR protein phosphorylation, and PKCbetaII expression. Furthermore, we observed that Akt2 phosphorylated several SR proteins distinct from Clk/Sty in response to insulin. Akt2-catalyzed phosphorylation of Clk/Sty and SR proteins revealed a role for both kinases in splicing regulation indicating dual functions for Akt2 in response to insulin in this pathway.


Asunto(s)
Empalme Alternativo/efectos de los fármacos , Insulina/farmacología , Proteínas Nucleares/metabolismo , Proteína Quinasa C/genética , Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas Tirosina Quinasas/metabolismo , Proteínas Proto-Oncogénicas c-akt/fisiología , Proteínas de Unión al ARN/metabolismo , Empalme Alternativo/genética , Animales , Células COS , Células Cultivadas , Chlorocebus aethiops , Ratones , Ratones Noqueados , Modelos Biológicos , Fosforilación/genética , Proteína Quinasa C/metabolismo , Proteína Quinasa C beta , Proteínas Proto-Oncogénicas c-akt/genética , Proteínas Proto-Oncogénicas c-akt/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Ratas , Factores de Empalme Serina-Arginina
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