Project description:Chip-chip from pro-B cells from Rag1KO mice for H3K27ac and RNA Pol II Identification of novel enhancers from Ig heavy and light chain loci Rag1KO pro-B epigenetic landscape at Ig heavy and light chain loci
Project description:Chip-chip from pro-B cells from Rag1KO mice for H3K27ac and RNA Pol II Identification of novel enhancers from Ig heavy and light chain loci
Project description:During B lymphopoiesis, B cell progenitors progress through alternating and mutually exclusive stages of clonal expansion and immunoglobulin (Ig) gene rearrangements. Great diversity is generated through the stochastic recombination of Ig gene segments encoding heavy and light chain variable domains. However, this commonly generates autoreactivity. Receptor editing is the predominant tolerance mechanism for self-reactive B cells in the bone marrow (BM). B cell receptor editing rescues autoreactive B cells from negative selection through renewed light chain recombination first at Igκ then Igλ loci. Receptor editing depends upon BM microenvironment cues and key transcription factors such as Nuclear factor kappa B, Forkhead box protein O and Transcription Factor 3. The specific BM factor required for receptor editing is unknown. Furthermore, how transcription factors coordinate these developmental programs to promote usage of the λ-chain remain poorly defined. Therefore, we utilized two mouse models that recapitulate pathways by which Igλ light chain positive B cells develop. The first possess deleted J kappa (Jκ) genes and, as such, models Igκ expression resulting from failed Igκ recombination (Igκdel). The second models autoreactivity by ubiquitous expression of a single-chain chimeric anti-Igκ antibody (κ-mac). Here, we demonstrated that autoreactive B cells transit asymmetric forward and reverse developmental trajectories. This imparted a unique epigenetic landscape on small pre-B cells, which opened chromatin to transcription factors essential for Igλ recombination. The consequences of this asymmetric developmental path were both amplified and complemented by CXCR4 signaling. These findings reveal how intrinsic molecular programs integrate with extrinsic signals to drive receptor editing.
Project description:We analyzed the transcriptome (RNA-seq) of mouse plasma cells (PC) expressing a human Ig light chain from a patient suffering light chain deposition disease (LCDD) as compared to control plasma cells (WT and DH-LMP2A, the latter producing no complete immunoglobulins, only free Ig light chains). Ig light chains causing LCDD present structural peculiarities leading to their aggregation and deposition into tissues and organs, mainly the kidney. We sought to determine if plasma cells producing these abnormal Ig could present specific phenotypes. The aim of the present study is to analyse the transcriptomic signature of plasma cells producing abnormal Ig free light chains.
Project description:IgCaller is a python program designed to fully characterize the immunoglobulin (IG) gene rearrangements and oncogenic translocations in lymphoid neoplasms from whole-genome sequencing (WGS) data. Using a cohort of 331 patients comprising different subtypes of B-cell neoplasms, we demonstrate that IgCaller identifies both heavy and light chain rearrangements providing additional information on their functionality, somatic mutational status, class switch recombination, and oncogenic IG translocations. We provided here IG reads of the previously unpublished WGS.
Project description:Productive rearrangement of the immunoglobulin heavy chain locus triggers a major developmental checkpoint that promotes limited clonal expansion of pre-B cells, culminating in cell cycle arrest and rearrangement of the kappa (κ) or lambda (λ) light-chain loci. B lineage cells lacking the related transcription factors IRF-4 and IRF-8 undergo a developmental arrest at the cycling pre-B cell stage and are blocked for light-chain recombination. Using Irf-4,8-/- pre-B cells we demonstrate that two pathways converge to synergistically drive light-chain rearrangement, a process that is not simply activated by cell cycle exit. One pathway is directly dependent on IRF-4, whose expression is elevated by pre-BCR signaling. IRF-4 targets the κ 3Ⲡand λ enhancers to increase locus accessibility and positions a kappa allele away from pericentromeric heterochromatin. The other pathway is triggered by attenuation of IL-7 signaling and results in activation of the κ intronic enhancer via binding of the transcription factor, E2A. Intriguingly, IRF-4 regulates the expression of CXCR4 and promotes the migration of pre-B cells in response to the chemokine CXCL12. We propose that IRF-4 coordinates the two pathways regulating light-chain recombination by positioning pre-B cells away from IL-7 expressing stromal cells. We used microarrys to identify the changes in gene expression under different levels of the cytokine IL-7 and after rescue of genetic defect. Experiment Overall Design: IRF4,8 null pre-B cells were cultures in the indicated conditions prior to RNA isolation and hybridization to Affymetrix arrays.
Project description:We analyzed the transcriptome (RNA-seq) of glomeruli in a mouse model of light chain deposition disease (LCDD) as compared to control mice (WT and DH-LMP2A, the latter producing no complete immunoglobulins, only free Ig light chains). Kidney lesions in LCDD are due to the deposition of an abnormal monoclonal free Ig light chain and comprise progressive thickening of basement membranes (tubular and glomerular) and nodular glomerulosclerosis resembling the lesions observed in diabetic nephropathy. The aim of the present study is to analyse the transcriptomic changes at early steps of glomerulosclerosis.
Project description:Recent advancements in microfluidics and high-throughput sequencing technologies have enabled recovery of paired heavy- and light- chain of immunoglobulins (Ig) and VDJ- and VJ- chains of T cell receptors (TCR) from thousands of single cells simultaneously. Due to the complexity of these polyclonal receptors, for many species single-cell immune repertoire sequencing assays are not yet commercially available. Rhesus macaques are one of the most well-studied model organisms of the human adaptive immune response; application of these new immune repertoire sequencing assays is highly relevant to vaccine and infectious disease studies. Here we use custom designed primers to target and enrich for every known Ig and TCR chain and isotype in the rhesus macaque animal model. We sequenced more than 110,000 cell barcodes from rhesus macaque repertoires using PBMC, splenocyte, and FACS-sorted T and B cell. We were able to recover every Ig and TCR isotype, measure clonal expansion in proliferating T cells, and pair repertoires with gene expression profiles of single cells. Our results establish the ability to perform single-cell based immune repertoire analysis in rhesus macaque.