Somatic hypermutation (SHM) and class switch recombination (CSR) increase the affinity and diversify the effector functions of antibodies during immune responses. Although SHM and CSR are fundamentally different, their independent roles in regulating B cell fate have been difficult to uncouple because a single enzyme, activation-induced cytidine deaminase (encoded by Aicda), initiates both reactions. Here, we used a combination of Aicda and antibody mutant alleles that separate the effects of CSR and SHM on polyclonal immune responses. We found that class-switching to IgG1 biased the fate choice made by B cells, favoring the plasma cell over memory cell fate without significantly affecting clonal expansion in the germinal center (GC). In contrast, SHM reduced the longevity of memory B cells by creating polyreactive specificities that were selected against over time. Our data define the independent contributions of SHM and CSR to the generation and persistence of memory in the antibody system. Overall design: IgG1 and IgM light zone (LZ) and dark zone (DZ) germinal center (GC) B cells were compared in immunized AIDcre/- IgH-96K/+ R26-LSL-YFP mice.
Independent Roles of Switching and Hypermutation in the Development and Persistence of B Lymphocyte Memory.
Specimen part, Cell line, Subject
View SamplesSomatic hypermutation (SHM) and class switch recombination (CSR) increase the affinity and diversify the effector functions of antibodies during immune responses. Although SHM and CSR are fundamentally different, their independent roles in regulating B cell fate have been difficult to uncouple because a single enzyme, activation-induced cytidine deaminase (encoded by Aicda), initiates both reactions. Here, we used a combination of Aicda and antibody mutant alleles that separate the effects of CSR and SHM on polyclonal immune responses. We found that class-switching to IgG1 biased the fate choice made by B cells, favoring the plasma cell over memory cell fate without significantly affecting clonal expansion in the germinal center (GC). In contrast, SHM reduced the longevity of memory B cells by creating polyreactive specificities that were selected against over time. Our data define the independent contributions of SHM and CSR to the generation and persistence of memory in the antibody system. Overall design: IgG1 and IgM light zone (LZ) germinal center (GC) B cells that were Nurr77-GFP+ or Nurr77-GFP- were compared in immunized AIDcre/- IgH-96K/+ Nurr77-GFP mice.
Independent Roles of Switching and Hypermutation in the Development and Persistence of B Lymphocyte Memory.
Specimen part, Cell line, Subject
View SamplesCultured keratinocytes treated with TNFa in the presence or absence of NFkB inhibitor; time course 1, 4, 24 & 48 hrs.
Pathway-specific profiling identifies the NF-kappa B-dependent tumor necrosis factor alpha-regulated genes in epidermal keratinocytes.
No sample metadata fields
View SamplesCultured epidermal keratinocytes treated with OsM 1, 4, 24 & 48hrs, and Skinethic epidermal substitutes treated 1, 4, 24, 48h & 7days, each with untreated control
Transcriptional responses of human epidermal keratinocytes to Oncostatin-M.
No sample metadata fields
View SamplesEpidermal keratinocytes respond to extracellular influences by activating cytoplasmic signal transduction pathways that change the transcriptional profiles of affected cells. To define responses to two such pathways, p38 and ERK, we used SB203580 and PD98059 as specific inhibitors, and identified the regulated genes after 1, 4, 24 and 48 hrs, using Affymetrix Hu133Av2 microarrays. Additionally, we compared genes specifically regulated by p38 and ERKs with those regulated by JNK and by all three pathways simultaneously. We find that the p38 pathway induces the expression of extracellular matrix and proliferation-associated genes, while suppressing microtubule-associated genes; the ERK pathway induces the expression of nuclear envelope and mRNA splicing proteins, while suppressing steroid synthesis and mitochondrial energy production enzymes. Both pathways promote epidermal differentiation and induce feedback inactivation of MAPK signaling. c-FOS, SRY and N-Myc appear to be the principal targets of the p38 pathway, Elk-1 SAP1 and HLH2 of ERK, while FREAC-4, ARNT and USF are common to both. The results for the first time comprehensively define the genes regulated by the p38 and ERK pathways in epidermal keratinocytes and suggest a list of targets potentially useful in therapeutic interventions.
Transcriptional profiling defines the roles of ERK and p38 kinases in epidermal keratinocytes.
Specimen part, Treatment
View SamplesIn epidermal differentiation basal keratinocytes detach from the basement membrane, stop proliferating, and express a new set of structural proteins and enzymes, which results in an impermeable protein/lipid barrier that protects us. To define the transcriptional changes essential for this process, we purified large quantities of basal and suprabasal cells from human epidermis, using the expression of b4 integrin as the discriminating factor. The expected expression differences in cytoskeletal, cell cycle and adhesion genes confirmed the effective separation of the cell populations. Using DNA microarray chips, we comprehensively identify the differences in genes expressed in basal and differentiating layers of the epidermis, including the ECM components produced by the basal cells, the proteases in both the basal and suprabasal cells, and the lipid and steroid metabolism enzymes in suprabasal cells responsible for the permeability barrier. We identified the signaling pathways specific for the two populations, and found two previously unknown paracrine and one juxtacrine signaling pathway operating between the basal and suprabasal cells. Furthermore, using specific expression signatures, we identified a new set of late differentiation markers and mapped their chromosomal loci, as well as a new set of melanocyte-specific markers. The data represent a quantum jump in understanding the mechanisms of epidermal differentiation. Basal keratinocytes are defined as integrin b4-positive. Suprabasal sample contains all melanocytes as well.
Transcriptional profiling of epidermal differentiation.
Specimen part, Subject
View SamplesTranscriptome profile of highly purified multipotential (P), erythroid (E), and myeloid (M) bone marrow progenitors from three RPS19 mutated Diamond-Blackfan anemia and six control human subjects.
Defective ribosomal protein gene expression alters transcription, translation, apoptosis, and oncogenic pathways in Diamond-Blackfan anemia.
Sex, Age, Specimen part, Disease, Subject
View SamplesWe utilized our transgenic Fgd5-mCherry mouse to sort and RNAseq for HSCs under acute immune activation (with pIC) to reveal a complex cell cycle gene expression and an upregulated IFN I/II signature Overall design: RNAseq of bone marrow Lineage-Sca1+cKit+CD150+mCherry+ cells (1000) 24hrs after pIC was administered and control (PBS treated)
Identification of immune-activated hematopoietic stem cells.
Specimen part, Cell line, Treatment, Subject
View SamplesDuring malaria infection is observed a robust immune response culminating on release of inflammatory mediators. This exacerbated immune response is involved in malaria symptoms and mortality. There are evidences that this response is mediated by innate immunity where pattern recognition receptors have a key role. We used microarrays to elucidate some pro-inflammatory genes that are differential expressed during P. chabaudi infection, a malarial murine model
Daily Rhythms of TNFα Expression and Food Intake Regulate Synchrony of Plasmodium Stages with the Host Circadian Cycle.
Sex, Age, Specimen part
View SamplesThese arrays are used for various projects
DNA amplification is a ubiquitous mechanism of oncogene activation in lung and other cancers.
Sex, Age, Race
View Samples