Project description:Purpose: B-1a cells have a distinct BCR repertoire compared with that of B-2 cells. To examine whether CIC loss affects the BCR repertoire in B-1a cells, we analyzed mRNA sequences of immunoglobulin heavy (Igh) and light (Igk and Igl) chain genes in B-1a cells from 12-week-old control and Cicf/f;Cd19-Cre mice. Methods: Peritoneal cavity B-1a cells (IgM+, CD19+, CD5+, CD43+) were sorted by a MoFlo-XDP (Beckman Coulter). Total RNA was extracted using TRIzol Reagent (GeneAll), according to the manufacturer’s instructions. Long Read iR-Profile Reagent System (iRepertoire) was used to generate NGS libraries covering BCR chains including Igh, Igk, and Igl. Briefly, nested inside and outside primers selectively amplified all V- and C- regions and incorporated communal adaptors. Following clean up, only target amplicons, which contain 5’ and 3’ communal adaptors, were exponentially amplified. Amplified libraries were multiplexed for sequencing on the Illumina Miseq platform. Sequence reads were de-multiplexed according to the barcode sequences. Results: Trimmed reads were mapped to germline V, D and J reference sequences downloaded from the IMGT database. IgH diversity and the usage of variable (V) segments in heavy (Ighv) chain and light (Igkv and Iglv) chain genes were comparable between control and Cic-null B-1a cells. Analysis of non-templated (N)-nucleotide addition at V(D)J junctions revealed that Cic-null B-1a cells have a higher proportion of zero to two N-nucleotides-containing-BCRs than control cells. Conclusions: Our study presents the first comparative BCR repertoire analysis of wild-type and Cic-null B-1a cells. We concluded that CIC deficiency does not dramatically alter the BCR repertoire in B-1a cells.
Project description:Purpose: The goal of this study is to compare and examine the transcriptional profiles in control versus Cic-deficient B cells, specifically splenic B-1a and Fo B cells, by mRNA sequencing. Methods: Splenic B-1a (IgM+, CD19+, CD5+, CD43+) and Fo B (B220+, CD93-, CD23+, CD21lo-mid) cells were sorted by a MoFlo-XDP (Beckman Coulter). Total RNA was extracted using TRIzol Reagent (GeneAll), according to the manufacturer’s instructions. The DNA library for mRNA sequencing was generated using SMART-seq v4 Ultra Input RNA Kit (Clontech, for B-1a cells) and TruSeq RNA Sample Prep Kit v2 (Illumina, for Fo B cells). DNA libraries were multiplexed and pooled for sequencing on the Illumina Hiseq 4000 platform. Results: Trimmed reads were mapped to mouse reference genome (mm10 RefSeq) with HISAT2, a splice-aware aligner, and transcripts were assembled by StringTie with aligned reads, for known transcripts, novel transcripts, and alternatively spliced transcripts. A total of 712 genes were differentially expressed in Cic-null B-1a cells (325 upregulated and 387 downregulated), while 357 genes were differentially expressed in Cic-deficient Fo B cells (180 upregulated and 178 downregulated) when compared with their respective control cells (fold change >1.2 and P < 0.05). Several known CIC target genes, including Etv1, Etv4, Etv5, Spry4, Spred1, Spred2, Dusp4, Dusp6, and Per2, were included in the list of the upregulated differentially expressed genes (DEGs) in either Cic-null B-1a or Fo B cells or both, validating the reliability of RNA sequencing results. Conclusions: Our study presents the first comparative gene expression analysis of B-1a and Fo B cells from control and B cell-specific Cic-deficient mice. We concluded that CIC deficiency promotes B-1a cell development through enhancing the BCR signaling pathway. The data reported here also provide references for the gene expression profiles of murine B-1a and Fo B cells.
Project description:We report that B-1a cells develop in a surrogate light chain independent context. As a consequence, the precursor B-1a cell population avoids a pre-BCR positive selection stage. To confirm that the B-1a cells generated in this manner repersent a bonafide B-1a cell compartment, we did NGS on BCR rearrangements to assess the repertoire diversity. We find that as a whoile, B-1a cell repertoire that develop in Igll1 kncokout mice are similar compared to wild-type. This supports our findings that B-1a cells develop properly in the absence of surrogate light chain.
Project description:The innate-like B-1a cells provide a first line of defense against pathogens, and yet little is known about their transcriptional control. Here we identified an essential role of the transcription factor Bhlhe41, with a lesser contribution of Bhlhe40, in controlling late stages of B-1a cell differentiation. Bhlhe41/Bhlhe40 mutant B-1a cells were strongly reduced and had an abnormal cell-surface phenotype and altered B-cell receptor (BCR) repertoire, as exemplified by loss of the phosphatidylcholine-specific Vh12/Vk4 BCR. Expression of a pre-rearranged Vh12/Vk4 BCR failed to rescue the mutant phenotype and revealed enhanced proliferation accompanied with increased cell death, implicating Bhlhe41 in controlling the self-renewal of B-1a cells. Bhlhe41 directly repressed the expression of cell cycle regulators and inhibitors of BCR signaling, while activating pro-survival cytokine signaling.
Project description:B cells are known to have different properties and BCR repertoires depending on the time of development. Our objective is to investigate the BCR repertoire of B cells across embryonic, neonatal, and adult stages, particularly in cells with a RAG2 expression history. We focus on sequencing and analyzing the immunoglobulin heavy chain (IGH) genes of these cells to understand their BCR diversity and specificity. Additionally, we explore the relationship between B-1a cells and bone marrow IgM+ plasmablasts/plasma cells, aiming to shed light on the development and function of B-1a cells in the immune system.
Project description:Inclusion body myositis (IBM) is an autoimmune and degenerative disorder of skeletal muscle. The B cell infiltrates in IBM muscle tissue are predominantly fully differentiated antibody-secreting plasma cells, with scarce naïve or memory B cells. The role of this infiltrate in the disease pathology is not well understood. To better define the humoral response in IBM, we used adaptive immune receptor repertoire sequencing to generate large B cell receptor (BCR) repertoire libraries from IBM muscle biopsies and compared them to those generated from dermatomyositis (DM), polymyositis (PM), and circulating CD27+ memory B cells, derived from healthy controls and antibody secreting cells (ASC) collected following vaccination. The repertoire properties of the IBM infiltrate included: expanded clones that equaled or exceeded the highly clonal vaccine-associated ASC repertoire; reduced somatic mutation selection pressure in the complementary determining regions and framework regions; and enriched usage of class switched IgG and IgA isotypes, with a minor population of IgM expressing cells. These IBM IgM-expressing population revealed unique features, including an elevated somatic mutation frequency and distinct CDR3 physicochemical properties., These findings demonstrate that the IBM muscle BCR repertoire is highly distinct from DM and PM and circulating antigen-experienced subsets, suggesting that it may form through selection by a disease-specific set of antigens.
Project description:CIC encodes a transcriptional repressor inactivated by loss-of-function mutations in several cancer types, indicating that it may function as a tumor suppressor. Recent data indicate that CIC may regulate cell cycle genes in humans; however, a thorough investigation of this proposed role has not yet been reported. Here, we used single-cell RNA sequencing technology to provide evidence that inactivation of CIC in human cell lines resulted in transcriptional dysregulation of genes involved in cell cycle control. We also mapped CIC’s protein-protein and genetic interaction networks, identifying interactions between CIC and members of the Switch/Sucrose Non-Fermenting (SWI/SNF) complex, as well as novel candidate interactions between CIC and cell cycle regulators. We further showed that CIC loss was associated with an increased frequency of mitotic defects in human cell lines and a mouse model. Overall, our study positions CIC as a cell cycle regulator and indicates that CIC loss can lead to mitotic errors, consistent with CIC’s emerging role as a tumor suppressor of relevance in several cancer contexts.