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 SamplesThe germinal center (GC) is a microanatomical compartment wherein high-affinity antibody-producing B cells are selectively expanded. B cells proliferate and mutate their antibody genes in the dark zone (DZ) of the GC and are then selected by T cells in the light zone (LZ) on the basis of affinity. Here, we show that T cell help regulates the speed of cell cycle phase transitions and DNA replication of GC B cells. Genome sequencing and single-molecule analyses revealed that T cell help shortens S phase by regulating replication fork progression while preserving the relative order of replication origin activation. Thus, high-affinity GC B cells are selected by a mechanism that involves prolonged dwell time in the DZ where selected cells undergo accelerated cell cycles. Overall design: To determine whether GC B cells receiving high levels of T cell help show a specific change in gene expression, we compared DZ cells in the G1 phase of the cell cycle from aDEC-OVA and control aDEC-CS treated GCs using a fluorescent ubiquitination-based cell cycle indicator (Fucci-tg). RNA sequencing revealed that T cell-mediated selection produced an increase in gene expression programs associated with the cell cycle, metabolism, including the metabolism of nucleotides, and genes downstream of c-Myc and the E2F transcription factors.
HUMORAL IMMUNITY. T cell help controls the speed of the cell cycle in germinal center B cells.
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View SamplesTissue-resident mononuclear phagocytes (MNPs) in metabolic organs contribute to the regulation of whole body metabolism. CD301b+ MNPs are a subset of MNPs that are found in most peripheral organs including metabolic organs. In a mouse model in which CD301b+ MNPs can be selectively and transiently depleted, we examined the impact of the depletion on gene expression in the white adipose tissue and the liver.
CD301b(+) Mononuclear Phagocytes Maintain Positive Energy Balance through Secretion of Resistin-like Molecule Alpha.
Specimen part
View SamplesCellular function is strongly dependent on surrounding cells and environmental factors. Current technologies are limited in characterizing the spatial location and unique gene-programs of cells in less structured and dynamic niches. Here we developed a method (NICHE-seq) that combines photoactivatable fluorescent reporters, two-photon microscopy and single-cell RNA-seq to infer the cellular and molecular composition of niches. We applied NICHE-seq to examine the high-order assembly of immune cell networks. NICHE-seq is highly reproducible in spatial tissue reconstruction, enabling identification of rare niche-specific immune subpopulations and unique gene-programs, including natural killer cells within infected B cell follicles and distinct myeloid states in the marginal zone. This study establishes NICHE-seq as a broadly applicable method for elucidating high-order spatial organization of cell types and their molecular pathways. Overall design: Transcriptional profiling of single cells from the specific immune niches in the lymph node and spleen, generated from deep sequencing of tens of thousands of cells, sequenced in several batches on illumina Nextseq500
Spatial reconstruction of immune niches by combining photoactivatable reporters and scRNA-seq.
Specimen part, Cell line, Treatment, Subject
View SamplesBackground: Kawasaki Disease (KD) is a childhood illness of suspected infectious etiology that causes medium-sized muscular arteritis, most critically affecting the coronary arteries. No single diagnostic test exists, hampering early diagnosis and treatment. Approximately 25% of untreated patients develop coronary artery disease, and children who are treated with intravenous gammaglobulin but do not respond are also at high risk. Subacute/chronic arteritis and luminal myofibroblastic proliferation are the pathologic processes occurring in KD CA after the second week of illness, when neutrophilic necrotizing arteritis has subsided. The specific dysregulated immune pathways contributing to subacute/chronic arteritis have been unknown, hampering the development of effective immunomodulatory therapies for patients not responding to intravenous gammaglobulin therapy. Methods and Results: Deep RNA sequencing was performed on KD (n=8) and childhood control (n=7) coronary artery tissues, revealing 1074 differentially expressed mRNAs. Molecular pathways involving T helper cell, cytotoxic T lymphocyte, dendritic cells, and antigen presentation were the most significantly dysregulated. There was significant upregulation of immunoglobulin and type I interferon-stimulated genes. 80 upregulated extracellular genes encoding secreted proteins are candidate biomarkers of KD arteritis. Conclusions: The immune transcriptional profile in KD coronary artery tissues is primarily T helper and cytotoxic lymphocyte-mediated, and has features of an antiviral immune response such as type I interferon-stimulated gene expression. This first report of the KD coronary artery transcriptome identifies specific dysregulated immune response pathways that can inform the development of new therapies for and biomarkers of KD arteritis, and provide direction for future etiologic studies. Overall design: Primary analysis: 8 KD coronary arteries versus 7 childhood control coronary arteries. Subanalysis 1: 4 untreated KD coronary arteries versus 7 childhood control coronary arteries and subanalysis 2: 4 treated KD coronary arteries versus 7 childhood control coronary arteries
The transcriptional profile of coronary arteritis in Kawasaki disease.
No sample metadata fields
View SamplesPGC1beta is a transcriptional coactivator that potently stimulates mitochondrial biogenesis and respiration of cells. Here, we have generated mice lacking exons 3 to 4 of the Pgc1beta gene (PGC1beta E3,4-/E3,4- mice). These mice express a mutant protein that has reduced coactivation activity on a subset of transcription factors, including ERRalpha, a major target of PGC1beta in the induction of mitochondrial gene expression. The mutant mice have reduced expression of OXPHOS genes and mitochondrial dysfunction in liver and skeletal muscle as well as elevated liver triglycerides. Euglycemic-hyperinsulinemic clamp and insulin signaling studies show that PGC1beta mutant mice have normal skeletal muscle response to insulin, but have hepatic insulin resistance. These results demonstrate that PGC1beta is required for normal expression of OXPHOS genes and mitochondrial function in liver and skeletal muscle. Importantly, these abnormalities do not cause insulin resistance in skeletal muscle but cause substantially reduced insulin action in the liver.
Hypomorphic mutation of PGC-1beta causes mitochondrial dysfunction and liver insulin resistance.
No sample metadata fields
View SamplesThe quantitative deep bulk MARS-seq analysis demonstrated that DCs from ICAM-1/2 double knockout (DKO) chimeric LNs display similar transcriptomes to those of WT DCs in both their resting and CD40 mAb activated states. Overall design: Transciptome analysis of activated and resting classical DCs from either WT or ICAM-1/2 DKO chimeric mice was performed. DC cells were isolated from popliteal lymph nodes and sorted according to the following markers: CD45, CD11c and MHC-II
ICAMs Are Not Obligatory for Functional Immune Synapses between Naive CD4 T Cells and Lymph Node DCs.
Specimen part, Cell line, Treatment, Subject
View SamplesWe used high throughput sequencing to compare the differential gene expression of HepG2 cells with and without H19 knockdown. We found critical genes involved in glucose production changed significantly after H19 konckdown compared to control. Overall design: HepG2 cells were transfected with either control siRNA or siH19. 48h after transfection, total RNA was extracted for library preparation and RNA-seq analysis to compare trancript profiles between siCon and siH19 cells.
Elevated hepatic expression of H19 long noncoding RNA contributes to diabetic hyperglycemia.
Cell line, Subject
View SamplesInsulin action in adipocytes affects whole-body insulin sensitivity. Studies of adipose-specific Glut4 knockout mice have established that adipose Glut4 contributes to the control of systemic glucose homeostasis. Presumably, this reflects a role for Glut4-mediated glucose transport in the regulation of secreted adipokines. In cultured 3T3-L1 adipocytes, Rab10 GTPase is required for insulin-stimulated translocation of Glut4 (Sano et al., 2007). The physiological importance of adipose Rab10 and the significance of its role in the control of Glut4 vesicle trafficking in vivo are unknown. Here we report that adipocytes from adipose-specific Rab10 knockout mice have a ~50% reduction in glucose uptake and Glut4 translocation to the cell surface in response to insulin, demonstrating a role for Rab10 in Glut4 trafficking. Moreover, hyperinsulinemic-euglycemic clamp shows decreased whole-body glucose uptake as well as impaired suppression of hepatic glucose production in adipose Rab10 knockout mice. Thus, fully functional Glut4 vesicle trafficking in adipocytes is critical for maintaining insulin sensitivity. Comparative transcriptome analysis of perigonadal adipose tissue demonstrates significant transcriptional similarities between adipose Rab10 knockout mice and adipose Glut4 knockout mice, consistent with the notion that the phenotypic similarities between the two models are mediated by reduced insulin-stimulated glucose transport into adipocytes. Overall design: Transcriptome sequencing of perigonadal white adipose tissue
Disruption of Adipose Rab10-Dependent Insulin Signaling Causes Hepatic Insulin Resistance.
No sample metadata fields
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