Project description:Even though SYK and ZAP70 kinases share high sequence homology and serve analogous functions, their expression in B and T cells is strictly segregated throughout evolution. Here, we identified aberrant ZAP70 expression as a common feature in a broad range of B cell malignancies. We validated SYK as the kinase that sets the thresholds for negative selection of autoreactive and premalignant clones. When aberrantly expressed in B cells, ZAP70 competes with SYK at the BCR signalosome and redirects SYK from negative selection to tonic PI3K signaling, thereby promoting B cell survival. In genetic mouse models for B-ALL and B-CLL, conditional expression of Zap70 accelerated disease onset, while genetic deletion impaired malignant transformation. Inducible activation of Zap70 during B cell development compromised negative selection of autoreactive B cells, resulting in pervasive autoantibody production. Strict segregation of the two kinases is critical for normal B cell selection and represents a central safeguard against the development of autoimmune disease and B cell malignancies.
Project description:Even though SYK and ZAP70 kinases share high sequence homology and serve analogous functions, their expression in B and T cells is strictly segregated throughout evolution. Here, we identified aberrant ZAP70 expression as a common feature in a broad range of B cell malignancies. We validated SYK as the kinase that sets the thresholds for negative selection of autoreactive and premalignant clones. When aberrantly expressed in B cells, ZAP70 competes with SYK at the BCR signalosome and redirects SYK from negative selection to tonic PI3K signaling, thereby promoting B cell survival. In genetic mouse models for B-ALL and B-CLL, conditional expression of Zap70 accelerated disease onset, while genetic deletion impaired malignant transformation. Inducible activation of Zap70 during B cell development compromised negative selection of autoreactive B cells, resulting in pervasive autoantibody production. Strict segregation of the two kinases is critical for normal B cell selection and represents a central safeguard against the development of autoimmune disease and B cell malignancies.
Project description:T cell antigen receptor (TCR) signaling depends upon the kinases Lck and Zap70. Lck phosphorylates the TCR, facilitating Zap70 recruitment to the stimulated TCR. Lck also phosphorylates Zap70, relieving its auto-inhibition and activating its catalytic domain. Zap70 then phosphorylates the critical adaptors LAT and SLP76 which serve to nucleate key effector molecules required for downstream responses. However, mechanisms facilitating the interaction of Zap70 with its substrates have not been described. We report an evolutionarily conserved proline-rich motif in LAT is important for Zap70-induced phosphorylation of LAT and downstream signaling. This LAT proline-rich motif associated with the Lck SH3 domain, thereby facilitating Zap70-mediated phosphorylation of LAT and downstream functions. Our results suggest Lck orchestrates multiple steps in TCR signaling including the newly described facilitation of the interaction of Zap70 with its substrate LAT. This previously unrecognized feature of TCR proximal signaling may contribute to the development of more immunomodulatory therapies.
Project description:The ?v?3 integrin stimulates the resorptive capacity of the differentiated osteoclast (OC) by organizing its cytoskeleton via the tyrosine kinase, Syk. Thus, Syk-deficient OCs fails to spread or form actin rings, in vitro and in vivo. The Syk family of tyrosine kinases consists of Syk itself and Zap70 which are expressed by different cell types. Because of their structural similarity, and its compensatory properties in other cells, we asked if Zap70 can substitute for absence of Syk in OCs. While expression of Syk, as expected, normalizes the cytoskeletal abnormalities of Syk(-/-) OCs, Zap70 fails do so. In keeping with this observation, Syk, but not Zap70, rescues ?v?3 integrin-induced SLP76 phosphorylation in Syk(-/-) OCs. Furthermore the kinase sequence of Syk partially rescues the Syk(-/-) phenotype but full normalization also requires its SH2 domains. Surprisingly, expression of Zap70 inhibits WT OC spreading, actin ring formation and bone resorptive activity, but not differentiation. In keeping with arrested cytoskeletal organization, Zap70 blocks integrin-activated endogenous Syk and Vav3, SLP76 phosphorylation. Such inhibition requires Zap70 kinase activity, as it is abolished by mutation of the Zap70 kinase domain. Thus, while the kinase domain of Syk is uniquely required for OC function that of Zap70 inhibits it.
Project description:The progression of periodontitis is closely associated with Th17 cells, yet the functional differences of Th17 cells under periodontitis conditions remain poorly understood. Therefore, we established an experimental periodontitis model using IL-17GFP/+ transgenic mice, isolated Th17 cells via flow cytometry, and performed RNA sequencing. Results showed that periodontitis induced significant changes in Th17 cells, including a marked increase in cell proportion, as well as upregulated expression of Th17-associated immunoinflammatory signaling pathways and inflammatory cytokines (IL-17, IL-23, and GM-CSF). Within Th17 differentiation-related pathways, Zap70 expression was significantly upregulated and exhibited a positive correlation with IL-17. Local silencing of Zap70 via AAV-sh-Zap70 significantly reduced the expression of IL-17, IL-23/IL-23r, and GM-CSF, while alleviating alveolar bone resorption. In conclusion, periodontitis significantly enhances the proinflammatory capacity of Th17 cells, and this change is associated with Zap70, which indicates that Zap70 holds promise as a potential therapeutic target for periodontitis.
Project description:Comparison of Chronic Lymphocytic Leukemia patients expressing high or low levels of ZAP70 mRNA: prognostic factors and interaction with the microenvironment. Zeta-associated protein 70 (ZAP70) is a widely recognized prognostic factor in chronic lymphocytic leukemia (CLL), but mechanisms by which its higher expression leads to a poor outcome remain to be fully explained. In an attempt to unveil unfavorable cellular properties linked to high ZAP70 expression, we used gene expression profiling to identify genes associated with disparities in B-cells from CLL patients expressing high versus low ZAP70 mRNA, measured by quantitative real-time PCR. Keywords: comparison of poor and good prognosis CLL patient transcriptome regarding ZAP70 expression
Project description:Comparison of Chronic Lymphocytic Leukemia patients expressing high or low levels of ZAP70 mRNA: prognostic factors and interaction with the microenvironment. Zeta-associated protein 70 (ZAP70) is a widely recognized prognostic factor in chronic lymphocytic leukemia (CLL), but mechanisms by which its higher expression leads to a poor outcome remain to be fully explained. In an attempt to unveil unfavorable cellular properties linked to high ZAP70 expression, we used gene expression profiling to identify genes associated with disparities in B-cells from CLL patients expressing high versus low ZAP70 mRNA, measured by quantitative real-time PCR. Experiment Overall Design: Two groups of seven CLL patients were compared, selected on the basis of either high or low ZAP70 mRNA expression. Total RNA from CD19+ purified cells was exctracted and hybidyzed on Affymetrix GeneChipî Human Genome U133 Plus 2.0 Array. Amplification, hybridization and scanning were done according to standard Affymetrix protocols (www.affymetrix.com). CEL files were ,normalized with RMA method.
Project description:Background: Among all gynecologic malignancies, epithelial ovarian cancer has the highest case-to-fatality ratio. Most patients are diagnosed at advanced stages and recurrence is common and accounts for disease-related mortality. Spleen tyrosine kinase (SYK) is an emerging cancer-associated kinase upregulated in recurrent tumors and is amenable for inhibition using small compounds that have been studied in clinical trials for autoimmune diseases. Our previous proteomic analysis identified several novel SYK substrates including EGFR and ERBB2. Here, we investigated the cross-talk between these pathways in ovarian carcinomas. Methods: Immunohistochemistry and immunoblotting were utilized to assess SYK and EGFR phosphorylation in ovarian serous carcinomas. Association with survival was determined by Kaplan-Meier analysis and the log-rank test. To study its role in EGFR signaling, SYK activity was modulated using a small molecule inhibitor, a syngeneic knockout, and an active kinase inducible system. We applied RNA-seq to investigate the SYK-regulated EGF-induced transcriptome. Results: Intense immunoreactivity of active pSYK(Y525/526) correlated with poor overall survival in two independent ovarian cancer cohorts. SYK directly phosphorylated EGFR and ERBB2, while knockout of SYK reduces their phosphorylation. Phosphorylation levels of SYK(Y525/526) positively correlated with EGFR(Y1187) and STAT3(Y705). Active SYK reduced sensitivity to the EGFR/ERBB2 inhibitor, lapatinib, and SYK non-phosphorylatable EGFR mutant was more sensitive to paclitaxel. SYK modulated the EGF-induced transcriptome, supporting its involvement in EGFR/ERBB2-regulated transcriptional activity. Conclusions: Our findings suggest an upstream role of SYK in regulating the EGFR/ERBB2 signaling, and provide a biological rationale for targeting SYK in ovarian cancer therapy.