The inhibitory receptor Siglec-G controls the severity of chronic lymphocytic leukemia
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE227678 | GEO | 2023/05/03
REPOSITORIES: GEO
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Project description:Siglec-6 is a glycoprotein overexpressed on chronic lymphocytic leukemia (CLL) cell. We have shown that Siglec-6 promotes migration and adhesion of CLL cells towards CLL bone marrow stromal cells. To elucidate the mechanistic pathway involved in Siglec-6 dependent migration, we performed mass spectrometry proteomics analysis on MEC1-002 CLL cell line pulled down with a Siglec-6 targeted antibody, which revealed that Siglec-6 interacts with DOCK8, a guanine nucleotide exchange factor. Interaction of Siglec-6 with its ligand promotes DOCK8 dependent Cdc42 activation, WASP protein recruitment and F-actin polymerization. Therapeutically, Siglec-6 leukemic cells can be eliminated with a Siglec-6 targeted bispecific antibody in vitro and in vivo.
2024-05-08 | PXD039892 | Pride
Project description:Despite numerous therapeutic options, safe and curative therapy is out of reach for most chronic lymphocytic leukemia (CLL) patients. We previously reported the identification of a patient-derived CLL-binding antibody, JML-1, and identified Siglec-6 as the target of JML-1. Siglec-6 is an attractive target for cancer immunotherapy due to its absence on healthy tissues and potential role in immune signaling. In this work, we identify additional patient-derived anti-Siglec-6 antibodies, RC-1 and RC-2, that bind with higher affinity than JML-1, yet exhibit similar specificity and overlapping conformational epitopes. Both JML-1 and RC-1 were employed to generate anti-Siglec-6 x anti-CD3 T cell-recruiting bispecific antibodies (T-biAbs) which were effective in vitro at activating T cells and lysing target cells. Upon engineering RC-1 into more compact and rigid T-biAb formats, we achieved sub-pM EC50 values for cell lysis in vitro. In addition, the T-biAbs mediated the killing of primary CLL cells by autologous T cells at natural effector-to-target cell ratios ex vivo. The increased potency of this T-biAb format appears to be due to the reduction in the length and/or flexibility of the cytolytic synapse. Furthermore, the anti-Siglec-6 x anti-CD3 T-biAb was effective at curing mice in a systemic in vivo model of CLL.
2022-12-19 | PXD029601 | Pride
Project description:Siglec-7 is a member of Siglec family of glycan recognition proteins involved in the regulation of natural killer (NK) cell activities. We found Siglec-7 ligand is highly expressed on JVM-3, a B cell chronic lymphocytic leukemia (B-CLL) cell line. In this experiment, we attempted at identifying the ligands of Siglec-7 on JVM-3 by applying the proximity labeling method we developed (Chang L et al., J Proteome Res. 2017, 16:3929-41).
2022-05-31 | PXD024690 | Pride
Project description:Type I interferons are critical anti-viral cytokines during virus infections and have also been implicated in the pathogenesis of systemic lupus erythematosus (SLE). The secretion of type I interferon of pDCs is modulated by Siglec-H, a DAP12 associated receptor on pDCs. We showed that Siglec-H deficient pDCs produce more of the type I interferon IFN-α in vitro and that Siglec-H ko mice produce more IFN-α after murine cytomegalovirus (mCMV) infection in vivo, leading to efficient clearance of the virus. Furthermore, ageing Siglec-H ko mice showed a mild form of systemic autoimmunity. In contrast, Siglec-H ko mice developed a severe form of systemic lupus-like autoimmune disease with strong kidney nephritis several weeks after a single mCMV infection. This induction of systemic autoimmune disease after virus infection in Siglec-H ko mice was accompanied by a type I interferon signature and fully dependent on type I interferon signaling. These results show that Siglec-H normally serves as modulator of type I interferon responses after infection with a persistent virus and thereby prevents induction of autoimmune disease. For microarray experiments gene expression profiles of total splenic cells from two wt and Siglec-H ko mice 26 weeks after infection with luciferase expressing murine Cytomegalovirus (5x105 pfu) or from two uninfected wt and Siglec-H ko control mice were analyzed
2016-03-16 | E-GEOD-79248 | biostudies-arrayexpress
Project description:The cellular origin of chronic lymphocytic leukemia (CLL) is debated. Transcriptome analysis of CLL and normal peripheral blood and splenic B cell subsets displayed highest similarity of CLL to mature CD5+ B cells. We identified a distinct CD5+CD27+ post-germinal center B cell subset, and revealed that immunoglobulin V gene mutated CLL are more similar to mutated CD5+ B cells, whereas unmutated CLL are more related to unmutated CD5+ B cells. Stereotyped immunoglobulin V gene rearrangements were significantly enriched among CD5+ B cells, providing further genetic evidence for a derivation of CLL from CD5+ B cells. Moreover, we identified deregulated expression patterns providing novel insights into the pathophysiology of CLL, including downregulation of EBF1 and KLF family members. Transcriptome profiling of CLL and healthy human blood and splenic mature B cell subsets. Identification of deregulated transcription patterns with implications on CLL pathobiology.
2012-09-27 | GSE36907 | GEO
Project description:Immunomodulation of mast cell (MC) activity is warranted in allergic and inflammatory diseases where MCs have a central role in pathogenesis. Targeting Siglec-8, an inhibitory receptor on MCs and eosinophils, has shown promising activity in preclinical and clinical studies. While the intracellular pathways that regulate Siglec-8 activity in eosinophils have been well studied, the signaling mechanisms that lead to MC inhibition have not been fully elucidated. Here, we evaluate the intracellular signaling pathways of Siglec‐8‐mediated inhibition in primary MCs using an anti‐Siglec‐8 monoclonal antibody (mAb). Phospho‐proteomic profiling of FcεRI‐activated MCs revealed Siglec-8 mAb-treatment globally inhibited proximal and downstream kinases, leading to attenuated MC activation and degranulation. In fact, Siglec‐8 was found to directly interact with FcεRI signaling molecules. Siglec‐8 inhibition was dependent on both cytoplasmic immunoreceptor tyrosine-based inhibitory motifs (ITIMs) that interact with the SH2 containing protein phosphatase Shp-2 upon Siglec-8 phosphorylation. Taken together, these data support a model in which Siglec-8 regulates proximal FcεRI‐induced phosphorylation events through phosphatase recruitment and interaction with FcεRI, resulting in global inhibition of MCs upon Siglec-8 mAb engagement.
2022-01-21 | PXD030820 | Pride
Project description:Chronic Lymphocytic Leukaemia (CLL) is the most common leukemia in adults in the Western world. B cell receptor (BCR) signalling is known to be crucial for the pathogenesis and maintenance of CLL cells which develop from mature CD5+ B cells. BCR signalling is regulated by the inhibitory co-receptor Siglec-G and Siglec-G-deficient mice have an enlarged CD5+ B1a cell population. Here, we determine how Siglec-G expression influences the severity of CLL. Our results show that Siglec-G deficiency leads to earlier onset and more severe course of the CLL-like disease in the murine Eµ-TCL1 model. In contrast, mice overexpressing Siglec-G on the B cell surface are almost completely protected from developing CLL-like disease. Furthermore, we observe a downmodulation of the human orthologue Siglec-10 from the surface of human CLL cells. These results demonstrate a critical role for Siglec-G in disease progression in mice, and suggest that a similar mechanism for Siglec-10 in human CLL may exist.
| S-SCDT-10_15252-EMBR_202256420 | biostudies-other
Project description:Influence of soluble Siglec-14 on macrophage poloarization was examined by analyzing the transcripts from human macrophages cultured in the presence or absence of recombinant soluble Siglec-14 protein
2018-10-29 | GSE121311 | GEO
Project description:The cellular origin of chronic lymphocytic leukemia (CLL) is debated. Transcriptome analysis of CLL and normal peripheral blood and splenic B cell subsets displayed highest similarity of CLL to mature CD5+ B cells. We identified a distinct CD5+CD27+ post-germinal center B cell subset, and revealed that immunoglobulin V gene mutated CLL are more similar to mutated CD5+ B cells, whereas unmutated CLL are more related to unmutated CD5+ B cells. Stereotyped immunoglobulin V gene rearrangements were significantly enriched among CD5+ B cells, providing further genetic evidence for a derivation of CLL from CD5+ B cells. Moreover, we identified deregulated expression patterns providing novel insights into the pathophysiology of CLL, including downregulation of EBF1 and KLF family members. Transcriptome profiling of CLL and healthy human blood and splenic mature B cell subsets. Identification of deregulated transcription patterns with implications on CLL pathobiology. Human mature B cell subsets and CLL with mutated (mCLL) and unmutated V gene status (uCLL) were purified from peripheral blood and spleen. Samples of 5 to 7 donors each were collected and processed in three batches in a two rounded in vitro transcription protocol. Retrieved data were batch corrected and subjected to analysis. Human mature CD5+ B cell subsets and CLL with mutated (mCLL) and unmutated V gene status (uCLL) were purified from peripheral blood.
2012-09-27 | E-GEOD-36907 | biostudies-arrayexpress
Project description:Siglec-E is a murine CD33-related siglec that functions as an inhibitory receptor and is expressed mainly on neutrophils and macrophage populations. Recent studies have suggested that siglec-E is an important negative regulator of LPS-TLR4 signalling and one report (Wu et al 2016) claimed that siglec-E is required for TLR4 endocytosis following uptake of Escherichia coli by macrophages and dendritic cells (DCs). Our attempts to reproduce these observations using cells from wildtype (WT) and siglec E deficient mice were unsuccessful. We used a variety of assays to determine if siglec-E expressed by different macrophage populations can regulate TLR-4 signalling in response to LPS, but found no consistent differences in cytokine secretion in vitro and in vivo, comparing 3 different strains of siglec-E-deficient mice with matched WT controls. No evidence was found that the siglec-E deficiency was compensated by expression of siglecs-F and –G, the other murine inhibitory CD33-related siglecs. Quantitative proteomics was used as an unbiased approach and provided additional evidence that siglec-E does not suppress inflammatory TLR4 signaling. Interestingly, proteomics revealed a siglec E dependent alteration in macrophage phenotype that could be relevant to functional responses in host defence. In support of this, siglec-E-deficient mice exhibited enhanced growth of Salmonella enterica serovar Typhimurium in the liver following intravenous infection, but macrophages lacking siglec-E did not show altered uptake or killing of bacteria in vitro. Using various cell types including bone marrow derived DCs (BMDC), splenic DCs and macrophages from WT and siglec-E-deficient mice, we showed that siglec-E is not required for TLR4 endocytosis following E.coli uptake or LPS challenge. We failed to see expression of siglec-E by BMDC even after LPS-induced maturation, but confirmed previous studies that splenic DCs express low levels of siglec-E. Taken together, our findings do not support a major role of siglec-E in regulation of TLR4 signalling functions or TLR4 endocytosis in macrophages or DCs. Instead, they reveal that induction of siglec-E by LPS can modulate the phenotype of macrophages, the functional significance of which is currently unclear.
2018-02-09 | PXD008406 | Pride