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 3′ and 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. Keywords: growth conditions and rescue
Project description:Lyme disease (Borrelia burgdorferi infection) is increasingly recognized as a significant source of morbidity world-wide. Here, we investigated B cell responses to Lyme disease through molecular identifier-enabled antibody heavy chain sequencing of bulk B cells from PBMCs. Single-cell immunoglobulin sequencing of paired heavy- and light-chain genes from this project will also be separately deposited. Additional information regarding patient characteristics and overlap with other data from the SLICE study is available upon request.
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:Background: Systemic light chain amyloidosis is a protein misfolding disorder characterized by deposition of clonal immunoglobulin light chains in vital organs. To date, little is known about the contribution of light chain constant domain mutations in thermodynamic stability and amyloidogenicity.Methods: In 89 patients, RNA-based full-length light chain repertoire sequencing with Oxford Nanopore was performed, in addition to Illumina sequencing and mass spectrometric detection of light chain protein in serum and amyloid deposits. Computational methods for conservation, free energy calculation, and molecular dynamics simulations were applied to investigate the thermodynamic stability.Results: Monoclonal light chain detection rate was 95.4%, and sequences showed 100% identity with Illumina in all patients. Light chain protein was specifically detectable by mass spectrometry in serum and amyloid deposits. Lambda constant domain mutations were present in 10%, while no kappa constant domain mutations were detected. Fold free energy change and molecular dynamics simulations indicate potential light chain stabilizing or destabilizing effects of detected constant domain mutations.Conclusion: Current findings highlight the importance of routinely implementing full-length light chain sequencing in plasma cell dyscrasias, particularly light chain amyloidosis to account for the potential impact of constant domain mutations on light chain stability and amyloidogenicity.
Project description:Background: Hepatitis C virus (HCV) infects human liver hepatocytes, often leading to liver cirrhosis and hepatocellular carcinoma (HCC). It is believed that chronic infection alters host gene expression and favours HCC development. In particular, HCV replication in Endoplasmic Reticulum (ER) derived membranes induces chronic ER stress. How HCV replication affects host mRNA translation and transcription at a genome wide level is not yet known. Methods: We used Riboseq (Ribosome Profiling) to analyze transcriptome and translatome changes in Huh-7.5 hepatoma cells replicating HCV for 6 days. Results: Established viral replication does not cause global changes in host gene expression - only around 30 genes are differentially expressed. Upregulated genes are related to ER stress, HCV replication and HCC development. Some mRNAs (PPP1R15A/GADD34, DDIT3/CHOP, TRIB3) may be subject to uORF mediated translation control in response to stress-induced eIF2 inactivation. Transcriptional downregulation mainly affects mitochondrial respiratory chain complex genes. Conclusion: After establishing HCV replication, cellular gene expression is reprogrammed towards stress response and HCC development. Downregulation of mitochondrial respiratory chain genes indicates how a virus induces cancer cell-like metabolic reprogramming ("Warburg effect"). Thus, HCV escapes stress response pathways but induces selective gene expression changes which likely are beneficial for chronic infection and cancerogenesis.