Project description:LatY136F mice in which tyrosine 136 of the LAT adaptor is mutate accumulate CD4+ T cells that trigger a fast-onset autoimmune and inflammatory condition called LAT signaling pathology (LSP). Its histopathological manifestations resemble those of human IgG4-related disease (IgG4-RD), an inflammatory condition unifying a constellation of clinical entities leading to multi-organ damage. LatY136F mice deprived of STAT6 transcription factor develop a lymphoproliferative disorder with a kinetics and magnitude identical to that of LatY136F mice. Consistent with a role of STAT6 in Th2 differentiation, the LatY136F x Stat6KO lymphoproliferative disorder is characterize by a lymphoproliferation of both CD4 and CD8 Tc producing high levels of IFN-g. This Tc proliferation is associated with massive B cell proliferation and hyperglobulinemia G2a and G2b. Using single-cell RNA sequencing, we analyzed 48287 CD4 and CD8 T cells isolated from the spleen of LatY136F and LatY136F x Stat6KO mice over the period that leads to LSP installation. In this study, LatY136F lymphoproliferative disorder is also analyze in Grab2KO mice. Unexpectedly, LatY136F x Grap2KO mice present a lymphoproliferative disorder similar to the one observed in LatY136F mice but this time TCRgd Tc.
Project description:LatY136F mice in which tyrosine 136 of the LAT adaptor is mutated accumulate CD4+ T cells that trigger a fast-onset autoimmune and inflammatory condition called LAT signaling pathology (LSP). Its histopathological manifestations resemble those of human IgG4-related disease (IgG4-RD), an inflammatory condition unifying a constellation of clinical entities leading to multi-organ damage. Using single-cell RNA sequencing, we analyzed 5,030 CD4+ T cells isolated from the spleen of LatY136F mice over the period that leads to LSP installation. It charted the trajectory leading to full-fledged LSP and demonstrated that LSP involved T follicular helper (Tfh) cells, CD4+ cytotoxic T cells, and IgG1+ plasma cells. These cell types were also identified in the massive infiltrates found in LatY136F lung. Therefore, the LatY136F LSP entails all the cell types postulated to trigger human IgG4-RD. It offers the unique possibility to disentangle their pathological cross-talk as illustrated here using B cell-deficient LatY136F mice.
Project description:Single-cell RNA-seq analysis of the lymphoproliferative disorders triggered by defective LAT signalosome. Modulation of the pathology in the context of two additional mutations, Stat6KO or Grap2KO
Project description:The aim of the dataset was to study on a genome-wide level the impact of Lat deficiency on gene expression in resting and activated CD4+ T cells Lat+ and Lat? CD4+ T cells were isolated from lymph nodes and spleen of Latfl-dtr Tmat-Cre mice using a Dynabeads untouched mouse CD4 cells kit (Life Technology) and further purified by cell sorting. Lat+ CD4+ T cells were defined as: CD5+, hDTR+, CD8?, TCR???, CD25?, CD69?, CD62L+, lineage (CD11c, CD11b, CD19, CD45R, CD161)? and Lat? CD4+ Tcells were defined as: CD5+, hDTR?, CD8?, TCR???, CD25?, CD69?, CD62L+, lineage (CD11c, CD11b, CD19, CD45R, CD161)?. Sorted Lat+ or Lat? CD4+ T cells were then kept in vitro for 4 hours without stimulation or activated for 4 hours using anti-CD3 antibody and anti-CD28 antibody. Cell samples corresponding to three biological replicates were analyzed and gene expression profiles were obtained from total RNA.
Project description:Immune cells transduce environmental stimuli into responses essential for host health via complex signaling cascades. T cells, in particular, leverage their unique T cell receptors (TCRs) to detect specific Human Leukocyte Antigen (HLA)-presented peptides. TCR activation is then relayed via linker for activation of T cells (LAT), a TCR-proximal disordered adapter protein, which organizes protein partners and mediates the propagation of signals down diverse pathways including NFAT and AP-1. Here, we studied how balanced downstream pathway activation is encoded in the amino acid sequence of LAT. To comprehensively profile the sequence-function relationship of LAT, we developed a pooled, single-cell, high-content screening approach in which a large series of mutants in the LAT protein were analyzed to characterize their effects on T cell activation. Measuring epigenetic, transcriptomic, and cell surface protein dynamics of single cells harboring distinct LAT mutants, we found functional regions spanning over 40% of the LAT amino acid sequence. Conserved sequence motifs for protein interactions, along with charge distribution, are critical sequence features, and contribute to interpretation of human genetic variation in LAT. While mutant defect severity spans from moderate to complete loss of function, nearly all defective mutants, irrespective of their position in LAT, confer balanced defects across the NFAT and AP-1 pathways. To understand the molecular basis for this observation, we performed proximal protein labeling, which demonstrated that disruption of LAT interaction with a single partner protein indirectly disrupts other partner interactions, likely through the dual roles of these proteins as effectors of downstream pathways and bridging factors between LAT molecules. Overall, we report widely distributed functional regions throughout a disordered adapter and a precise physical organization of LAT and interacting molecules which constrains signaling outputs. More broadly, we describe an approach for interrogating sequence-function relationships for proteins with complex activities across regulatory layers of the cell.
Project description:Immune cells transduce environmental stimuli into responses essential for host health via complex signaling cascades. T cells, in particular, leverage their unique T cell receptors (TCRs) to detect specific Human Leukocyte Antigen (HLA)-presented peptides. TCR activation is then relayed via linker for activation of T cells (LAT), a TCR-proximal disordered adapter protein, which organizes protein partners and mediates the propagation of signals down diverse pathways including NFAT and AP-1. Here, we studied how balanced downstream pathway activation is encoded in the amino acid sequence of LAT. To comprehensively profile the sequence-function relationship of LAT, we developed a pooled, single-cell, high-content screening approach in which a large series of mutants in the LAT protein were analyzed to characterize their effects on T cell activation. Measuring epigenetic, transcriptomic, and cell surface protein dynamics of single cells harboring distinct LAT mutants, we found functional regions spanning over 40% of the LAT amino acid sequence. Conserved sequence motifs for protein interactions, along with charge distribution, are critical sequence features, and contribute to interpretation of human genetic variation in LAT. While mutant defect severity spans from moderate to complete loss of function, nearly all defective mutants, irrespective of their position in LAT, confer balanced defects across the NFAT and AP-1 pathways. To understand the molecular basis for this observation, we performed proximal protein labeling, which demonstrated that disruption of LAT interaction with a single partner protein indirectly disrupts other partner interactions, likely through the dual roles of these proteins as effectors of downstream pathways and bridging factors between LAT molecules. Overall, we report widely distributed functional regions throughout a disordered adapter and a precise physical organization of LAT and interacting molecules which constrains signaling outputs. More broadly, we describe an approach for interrogating sequence-function relationships for proteins with complex activities across regulatory layers of the cell.
Project description:Immune cells transduce environmental stimuli into responses essential for host health via complex signaling cascades. T cells, in particular, leverage their unique T cell receptors (TCRs) to detect specific Human Leukocyte Antigen (HLA)-presented peptides. TCR activation is then relayed via linker for activation of T cells (LAT), a TCR-proximal disordered adapter protein, which organizes protein partners and mediates the propagation of signals down diverse pathways including NFAT and AP-1. Here, we studied how balanced downstream pathway activation is encoded in the amino acid sequence of LAT. To comprehensively profile the sequence-function relationship of LAT, we developed a pooled, single-cell, high-content screening approach in which a large series of mutants in the LAT protein were analyzed to characterize their effects on T cell activation. Measuring epigenetic, transcriptomic, and cell surface protein dynamics of single cells harboring distinct LAT mutants, we found functional regions spanning over 40% of the LAT amino acid sequence. Conserved sequence motifs for protein interactions, along with charge distribution, are critical sequence features, and contribute to interpretation of human genetic variation in LAT. While mutant defect severity spans from moderate to complete loss of function, nearly all defective mutants, irrespective of their position in LAT, confer balanced defects across the NFAT and AP-1 pathways. To understand the molecular basis for this observation, we performed proximal protein labeling, which demonstrated that disruption of LAT interaction with a single partner protein indirectly disrupts other partner interactions, likely through the dual roles of these proteins as effectors of downstream pathways and bridging factors between LAT molecules. Overall, we report widely distributed functional regions throughout a disordered adapter and a precise physical organization of LAT and interacting molecules which constrains signaling outputs. More broadly, we describe an approach for interrogating sequence-function relationships for proteins with complex activities across regulatory layers of the cell.
Project description:The aim of the dataset was to study on a genome-wide level the impact of Lat deficiency on gene expression in resting and activated CD4+ T cells
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.