scholarly journals VH replacement in primary immunoglobulin repertoire diversification

2015 ◽  
Vol 112 (5) ◽  
pp. E458-E466 ◽  
Author(s):  
Amy Sun ◽  
Tatiana I. Novobrantseva ◽  
Maryaline Coffre ◽  
Susannah L. Hewitt ◽  
Kari Jensen ◽  
...  
Keyword(s):  
Mouse Model ◽  
Base Pairs ◽  
Vh Replacement ◽  
Recombination Signal Sequences ◽  
Nucleotide Addition ◽  
Genes Encoding ◽  
V Region ◽  
Immunoglobulin Repertoire ◽  
The Individual ◽  
Cryptic Rss

The genes encoding the variable (V) region of the B-cell antigen receptor (BCR) are assembled from V, D (diversity), and J (joining) elements through a RAG-mediated recombination process that relies on the recognition of recombination signal sequences (RSSs) flanking the individual elements. Secondary V(D)J rearrangement modifies the original Ig rearrangement if a nonproductive original joint is formed, as a response to inappropriate signaling from a self-reactive BCR, or as part of a stochastic mechanism to further diversify the Ig repertoire. VH replacement represents a RAG-mediated secondary rearrangement in which an upstream VH element recombines with a rearranged VHDHJH joint to generate a new BCR specificity. The rearrangement occurs between the cryptic RSS of the original VH element and the conventional RSS of the invading VH gene, leaving behind a footprint of up to five base pairs (bps) of the original VH gene that is often further obscured by exonuclease activity and N-nucleotide addition. We have previously demonstrated that VH replacement can efficiently rescue the development of B cells that have acquired two nonproductive heavy chain (IgH) rearrangements. Here we describe a novel knock-in mouse model in which the prerearranged IgH locus resembles an endogenously rearranged productive VHDHJH allele. Using this mouse model, we characterized the role of VH replacement in the diversification of the primary Ig repertoire through the modification of productive VHDHJH rearrangements. Our results indicate that VH replacement occurs before Ig light chain rearrangement and thus is not involved in the editing of self-reactive antibodies.

scholarly journals Longitudinal Microbiome Analysis in a Dextran Sulfate Sodium-Induced Colitis Mouse Model

2021 ◽  
Vol 9 (2) ◽  
pp. 370
Author(s):  
Hyunjoon Park ◽  
Soyoung Yeo ◽  
Seokwon Kang ◽  
Chul Sung Huh
Keyword(s):  
Mouse Model ◽  
Dextran Sulfate ◽  
Dextran Sulfate Sodium ◽  
Intestinal Bleeding ◽  
Cross Sectional ◽  
Microbiome Analysis ◽  
Inflammatory Bowel ◽  
Factor Design ◽  
The Individual

The role of the gut microbiota in the pathogenesis of inflammatory bowel disease (IBD) has been in focus for decades. Although metagenomic observations in patients/animal colitis models have been attempted, the microbiome results were still indefinite and broad taxonomic presumptions were made due to the cross-sectional studies. Herein, we conducted a longitudinal microbiome analysis in a dextran sulfate sodium (DSS)-induced colitis mouse model with a two-factor design based on serial DSS dose (0, 1, 2, and 3%) and duration for 12 days, and four mice from each group were sacrificed at two-day intervals. During the colitis development, a transition of the cecal microbial diversity from the normal state to dysbiosis and dynamic changes of the populations were observed. We identified genera that significantly induced or depleted depending on DSS exposure, and confirmed the correlations of the individual taxa to the colitis severity indicated by inflammatory biomarkers (intestinal bleeding and neutrophil-derived indicators). Of note, each taxonomic population showed its own susceptibility to the changing colitis status. Our findings suggest that an understanding of the individual susceptibility to colitis conditions may contribute to identifying the role of the gut microbes in the pathogenesis of IBD.

scholarly journals Molecular characterization of a beta zero-thalassemia resulting from a 1.4 kilobase deletion

Blood ◽  
1988 ◽  
Vol 72 (2) ◽  
pp. 636-641 ◽  
Author(s):  
R Anand ◽  
CD Boehm ◽  
HH Jr Kazazian ◽  
EF Vanin
Keyword(s):  
Transcriptional Start Site ◽  
Globin Gene ◽  
Event Analysis ◽  
Beta Globin ◽  
Base Pairs ◽  
Dna Polymerase Alpha ◽  
Beta Globin Gene ◽  
American Black ◽  
The Individual

Abstract We report the characterization of a beta zero-thalassemia in an American Black with unusually high HbA2 and HbF levels. Genomic southern analysis indicated that the individual was heterozygous for a deletion that began within the second intervening sequence of the beta- globin gene and extended approximately 1.4 kb in the 5′ direction. A clone spanning the breakpoint on the abnormal chromosome was isolated and further mapped, and the deletion joint was sequenced. Comparison of the normal beta-globin gene and its 5′ flanking region with the deletion joint sequence indicated that the 5′ breakpoint for this deletion was 484 base pairs (bp) 5′ to the transcriptional start site for the beta-globin gene and the 3′ breakpoint was 908 bp into the beta- globin gene; the deletion removed a total of 1,393 bp. Comparison of the normal 5′ and 3′ breakpoint sequences indicated that this deletion was the result of a “clean” nonhomologous breakage and reunion event; ie, no spurious bases were added during the recombinational event. Analysis of the breakpoints of this deletion together with the breakpoints of two other small deletions involving the beta-globin gene suggests that the breakpoints may occur at DNA polymerase alpha pause sites.

GlcNAc is a mast-cell chromatin-remodeling oncometabolite that promotes systemic mastocytosis aggressiveness

Blood ◽  
2021 ◽  
Author(s):  
Julie Agopian ◽  
Quentin Da Costa ◽  
Quang Vo Nguyen ◽  
Giulia Scorrano ◽  
Paraskevi Kousteridou ◽  
...  
Keyword(s):  
Mouse Model ◽  
Tyrosine Kinases ◽  
Inflammatory Responses ◽  
Immunoglobulin E ◽  
Therapeutic Potential ◽  
Systemic Mastocytosis ◽  
High Plasma ◽  
Humanized Mouse Model ◽  
Acute Response ◽  
Genes Encoding

Systemic mastocytosis (SM) is a KIT-driven hematopoietic neoplasm characterized by the excessive accumulation of neoplastic mast cells (MCs) in various organs and, mainly, the bone marrow (BM). Multiple genetic and epigenetic mechanisms contribute to the onset and severity of SM. However, little is known to date about the metabolic underpinnings underlying SM aggressiveness, which has thus far impeded the development of strategies to leverage metabolic dependencies when existing KIT-targeted treatments fail. Here, we show that plasma metabolomic profiles were able to discriminate indolent from advanced forms of the disease. We identified N-acetyl-D-glucosamine (GlcNAc) as the most predictive metabolite of SM severity. High plasma levels of GlcNAc in patients with advanced SM correlated with the activation of the GlcNAc-fed hexosamine biosynthesis pathway (HBP) in patients BM aspirates and purified BM MCs. At the functional level, GlcNAc enhanced human neoplastic MCs proliferation and promoted rapid health deterioration in a humanized mouse model of SM. In addition, in the presence of GlcNAc, immunoglobulin E-stimulated MCs triggered enhanced release of proinflammatory cytokines and a stronger acute response in a mouse model of passive cutaneous anaphylaxis. Mechanistically, elevated GlcNAc levels promoted the transcriptional accessibility of chromatin regions that contain genes encoding mediators of receptor tyrosine kinases cascades and inflammatory responses, thus leading to a more aggressive phenotype. Therefore, GlcNAc is an oncometabolite driver of SM aggressiveness. This study suggests the therapeutic potential for targeting metabolic pathways in MC-related diseases to manipulate MCs effector functions.

The heart in neuromuscular disease: primary mitochondrial diseases

ESC CardioMed ◽  
2018 ◽  
pp. 1528-1530
Author(s):  
Denis Duboc
Keyword(s):  
Neuromuscular Disease ◽  
Nuclear Dna ◽  
Single Cells ◽  
Mitochondrial Diseases ◽  
Respiratory Chain Complexes ◽  
Base Pairs ◽  
Daughter Cells ◽  
Dna Molecule ◽  
Chain Complexes ◽  
Genes Encoding

Mitochondria are responsible for energy production in most eukaryotic cells. Each cell contains at least one mitochondrion and every mitochondrion contains two to ten copies of a circular DNA molecule (mitochondrial DNA or mtDNA). Cardiomyocytes contain approximately 10,000 mtDNA copies. MtDNA is composed of around 16,500 base pairs and 37 genes encoding 13 subunits of the respiratory chain complexes I, III, IV, and V, 22 mitochondrial tRNAs and 2 rRNAs. With each cell division, mitochondria and mtDNA are randomly distributed to daughter cells. In humans, mitochondria are inherited exclusively from the mother. In healthy people mtDNA copies are usually identical at birth (homoplasmy) but with ageing, mtDNA is particularly prone to somatic mutation because, unlike nuclear DNA, it is continuously replicated, even in non-dividing tissues such as myocardium. This can lead to the propagation of somatic mutations within single cells by a process called clonal expansion. In addition, mtDNA lacks an extensive DNA repair mechanism.

scholarly journals DNA Microarray Assessment of Putative Borrelia burgdorferi Lipoprotein Genes

2002 ◽  
Vol 70 (6) ◽  
pp. 3300-3303 ◽  
Author(s):  
Fang Ting Liang ◽  
F. Kenneth Nelson ◽  
Erol Fikrig
Keyword(s):  
Lyme Disease ◽  
Borrelia Burgdorferi ◽  
Dna Microarray ◽  
Sensu Stricto ◽  
Borrelia Garinii ◽  
Borrelia Afzelii ◽  
Genes Encoding ◽  
The Individual

ABSTRACT A DNA microarray containing fragments of 137 Borrelia burgdorferi B31 putative lipoprotein genes was used to examine Lyme disease spirochetes. DNA from B. burgdorferi sensu stricto B31, 297, and N40; Borrelia garinii IP90; and Borrelia afzelii P/Gau was fluorescently labeled and hybridized to the microarray, demonstrating the degree to which the individual putative lipoprotein genes were conserved among the genospecies. These data show that a DNA microarray can globally examine the genes encoding B. burgdorferi lipoproteins.

V region genes encoding an immunocytoma-secreted anti-phospholipid autoantibody

1997 ◽  
Vol 56 ◽  
pp. 324
Author(s):  
M. Blay ◽  
C. Benito ◽  
J.C. Reverter ◽  
E. Campo ◽  
F. Bosch ◽  
...  
Keyword(s):  
Genes Encoding ◽  
V Region

Dietary L-leucine improves the anemia in a mouse model for Diamond-Blackfan anemia

Blood ◽  
2012 ◽  
Vol 120 (11) ◽  
pp. 2225-2228 ◽  
Author(s):  
Pekka Jaako ◽  
Shubhranshu Debnath ◽  
Karin Olsson ◽  
David Bryder ◽  
Johan Flygare ◽  
...  
Keyword(s):  
Mouse Model ◽  
Ribosomal Proteins ◽  
Therapeutic Agent ◽  
Hemoglobin Concentration ◽  
Response To Treatment ◽  
Diamond Blackfan Anemia ◽  
Genes Encoding ◽  
Marrow Cellularity ◽  
Deficient Mice

Abstract Diamond-Blackfan anemia (DBA) is a congenital erythroid hypoplasia caused by a functional haploinsufficiency of genes encoding for ribosomal proteins. Recently, a case study reported a patient who became transfusion-independent in response to treatment with the amino acid L-leucine. Therefore, we have validated the therapeutic effect of L-leucine using our recently generated mouse model for RPS19-deficient DBA. Administration of L-leucine significantly improved the anemia in Rps19-deficient mice (19% improvement in hemoglobin concentration; 18% increase in the number of erythrocytes), increased the bone marrow cellularity, and alleviated stress hematopoiesis. Furthermore, the therapeutic response to L-leucine appeared specific for Rps19-deficient hematopoiesis and was associated with down-regulation of p53 activity. Our study supports the rationale for clinical trials of L-leucine as a therapeutic agent for DBA.

scholarly journals Precocious Puberty and Leydig Cell Hyperplasia in Male Mice With a Gain of Function Mutation in the LH Receptor Gene

Endocrinology ◽  
2013 ◽  
Vol 154 (10) ◽  
pp. 3900-3913 ◽  
Author(s):  
Stacey R. McGee ◽  
Prema Narayan
Keyword(s):  
Mouse Model ◽  
Precocious Puberty ◽  
Leydig Cell ◽  
Receptor Gene ◽  
Fold Increase ◽  
Male Mice ◽  
Cell Hyperplasia ◽  
Lh Receptor ◽  
Genes Encoding ◽  
Leydig Cell Hyperplasia

The LH receptor (LHR) is critical for steroidogenesis and gametogenesis. Its essential role is underscored by the developmental and reproductive abnormalities that occur due to genetic mutations identified in the human LHR. In males, activating mutations are associated with precocious puberty and Leydig cell hyperplasia. To generate a mouse model for the human disease, we have introduced an aspartic acid to glycine mutation in amino acid residue 582 (D582G) of the mouse LHR gene corresponding to the most common D578G mutation found in boys with familial male-limited precocious puberty (FMPP). In transfected cells, mouse D582G mLHR exhibited constitutive activity with a 23-fold increase in basal cAMP levels compared with the wild-type receptor. A temporal study of male mice from 7 days to 24 weeks indicated that the knock-in mice with the mutated receptor (KiLHRD582G) exhibited precocious puberty with elevated testosterone levels as early as 7 days of age and through adulthood. Leydig cell-specific genes encoding LHR and several steroidogenic enzymes were up-regulated in KiLHRD582G testis. Leydig cell hyperplasia was detected at all ages, whereas Sertoli and germ cell development appeared normal. A novel finding from our studies, not previously reported in the FMPP cases, is that extensive hyperplasia is commonly found around the periphery of the testis. We further demonstrate that the hyperplasia is due to premature proliferation and precocious differentiation of adult Leydig cells in the KiLHRD582G testis. The KiLHRD582G mice provide a mouse model for FMPP, and we suggest that it is a useful model for studying pathologies associated with altered LHR signaling.

scholarly journals V(D)J Recombination: Modulation of RAG1 and RAG2 Cleavage Activity on 12/23 Substrates by Whole Cell Extract and DNA-bending Proteins

1997 ◽  
Vol 185 (11) ◽  
pp. 2025-2032 ◽  
Author(s):  
Dennis J. Sawchuk ◽  
Frances Weis-Garcia ◽  
Sohail Malik ◽  
Eva Besmer ◽  
Michael Bustin ◽  
...  
Keyword(s):  
Dna Cleavage ◽  
Gene Rearrangement ◽  
Receptor Gene ◽  
Cell Extract ◽  
Base Pairs ◽  
Whole Cell ◽  
Recombination Activating Genes ◽  
Cleavage Activity ◽  
Recombination Signal Sequences ◽  
Whole Cell Extract

Antigen receptor gene rearrangement is directed by DNA motifs consisting of a conserved heptamer and nonamer separated by a nonconserved spacer of either 12 or 23 base pairs (12 or 23 recombination signal sequences [RSS]). V(D)J recombination requires that the rearranging DNA segments be flanked by RSSs of different spacer lengths, a phenomenon known as the 12/23 rule. Recent studies have shown that this restriction operates at the level of DNA cleavage, which is mediated by the products of the recombination activating genes RAG1 and RAG2. Here, we show that RAG1 and RAG2 are not sufficient for 12/23 dependent cleavage, whereas RAG1 and RAG2 complemented with whole cell extract faithfully recapitulates the 12/23 rule. In addition, HMG box containing proteins HMG1 and HMG2 enhance RAG1- and RAG2-mediated cleavage of substrates containing 23 RSS but not of substrates containing only 12 RSS. These results suggest the existence of a nucleoprotein complex at the cleavage site, consisting of architectural, catalytic, and regulatory components.

scholarly journals Coordinated Zinc Homeostasis Is Essential for the Wild-Type Virulence of Brucella abortus

2015 ◽  
Vol 197 (9) ◽  
pp. 1582-1591 ◽  
Author(s):  
Lauren M. Sheehan ◽  
James A. Budnick ◽  
R. Martin Roop ◽  
Clayton C. Caswell
Keyword(s):  
Mouse Model ◽  
Brucella Abortus ◽  
Zinc Uptake ◽  
Zinc Homeostasis ◽  
Zinc Toxicity ◽  
Uptake System ◽  
Bacterial Cells ◽  
Gene Encoding ◽  
Content Type ◽  
Genes Encoding

ABSTRACTMetal homeostasis in bacterial cells is a highly regulated process requiring intricately coordinated import and export, as well as precise sensing of intracellular metal concentrations. The uptake of zinc (Zn) has been linked to the virulence ofBrucella abortus; however, the capacity ofBrucellastrains to sense Zn levels and subsequently coordinate Zn homeostasis has not been described. Here, we show that expression of the genes encoding the zinc uptake system ZnuABC is negatively regulated by the Zn-sensing Fur family transcriptional regulator, Zur, by direct interactions between Zur and the promoter region ofznuABC. Moreover, the MerR-type regulator, ZntR, controls the expression of the gene encoding the Zn exporter ZntA by binding directly to its promoter. Deletion ofzurorzntRalone did not result in increased zinc toxicity in the corresponding mutants; however, deletion ofzntAled to increased sensitivity to Zn but not to other metals, such as Cu and Ni, suggesting that ZntA is a Zn-specific exporter. Strikingly, deletion ofzntRresulted in significant attenuation ofB. abortusin a mouse model of chronic infection, and subsequent experiments revealed that overexpression ofzntAin thezntRmutant is the molecular basis for its decreased virulence.IMPORTANCEThe importance of zinc uptake forBrucellapathogenesis has been demonstrated previously, but to date, there has been no description of how overall zinc homeostasis is maintained and genetically controlled in the brucellae. The present work defines the predominant zinc export system, as well as the key genetic regulators of both zinc uptake and export inBrucella abortus. Moreover, the data show the importance of precise coordination of the zinc homeostasis systems as disregulation of some elements of these systems leads to the attenuation ofBrucellavirulence in a mouse model. Overall, this study advances our understanding of the essential role of zinc in the pathogenesis of intracellular bacteria.

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