Project description:CD1d expression by thymocytes is required to select iNKT cells. When CD1d is expressed only on thymocytes (pLck-CD1d tg mice), iNKT cells are hyperresponsive to antigen stimulation suggesting that, in physiological conditions, these cells undergo functional education mediated by additional CD1d-expressing cells. Here, we investigated the mechanisms of this functional education. We find that peripheral iNKT cells from pLck-CD1d tg mice express significantly less SHP-1, a tyrosine phosphatase negatively regulating TCR signaling, than WT cells. iNKT cells from heterozygous SHP-1-mutated motheaten mice, displaying similar SHP-1 reduction as pLck-CD1d tg iNKT cells, are antigen-hyperresponsive. Restoring normal CD1d expression in pLck-CD1d tg mice normalizes SHP-1 expression and responsiveness of iNKT cells. In WT mice, iNKT cells upregulate SHP-1 and decrease responsiveness upon emigration from thymus to periphery. This depends on contacts with CD1d-expressing DCs. iNKT cell functional education is therefore controlled by DCs via tuning SHP-1 expression level in the periphery. Hepatic iNKT cells from wild-type and transgenic mice (expressing hCD1d molecule under the pLck promoter)
Project description:Anticancer T cells acquire a dysfunctional state characterized by poor effector function and expression of inhibitory receptors, such as programmed cell death protein 1 (PD-1). Blockade of PD-1 signalling leads to T cell reinvigoration and is increasingly applied as an effective anticancer treatment. Recent work challenged the commonly held view that the phosphatase Src homology 2 (SH2) domain–containing phosphatase (SHP)-2 is essential for the molecular cascade downstream PD-1, suggesting functional redundancy with the homologous phosphatase SHP-1. Therefore, we investigated the effect of concomitant SHP-1 and 2 deletion in T cells by knocking out these phosphatases under the CD4cre promoter. In vivo results not only indicate that Shp-1/2 deletion is insufficient to ameliorate tumour control, but also that it impairs the therapeutic effects of anti-PD1 treatment, affecting tumour-infiltrating CD8+ T cells. Notably, acute deletion of Shp-1/2 in effector T cells also fails to improve tumour control. In vitro results show that Shp-1/2-deleted CD8+ T cells exhibit impaired expansion due to a survival defect and proteomics analysis reveals substantial alterations in their proteome, including in apoptosis-related pathways. This data indicates that concomitant ablation of SHP-1/2 in polyclonal T cells fails to improve their anticancer properties, implying that caution shall be taken when considering their inhibition for immunotherapeutic approaches.
Project description:CD1d expression by thymocytes is required to select iNKT cells. When CD1d is expressed only on thymocytes (pLck-CD1d tg mice), iNKT cells are hyperresponsive to antigen stimulation suggesting that, in physiological conditions, these cells undergo functional education mediated by additional CD1d-expressing cells. Here, we investigated the mechanisms of this functional education. We find that peripheral iNKT cells from pLck-CD1d tg mice express significantly less SHP-1, a tyrosine phosphatase negatively regulating TCR signaling, than WT cells. iNKT cells from heterozygous SHP-1-mutated motheaten mice, displaying similar SHP-1 reduction as pLck-CD1d tg iNKT cells, are antigen-hyperresponsive. Restoring normal CD1d expression in pLck-CD1d tg mice normalizes SHP-1 expression and responsiveness of iNKT cells. In WT mice, iNKT cells upregulate SHP-1 and decrease responsiveness upon emigration from thymus to periphery. This depends on contacts with CD1d-expressing DCs. iNKT cell functional education is therefore controlled by DCs via tuning SHP-1 expression level in the periphery.
Project description:The importance of regulatory T cells (Treg) for immune tolerance is well recognized, yet the signaling molecules influencing their suppressive activity are relatively poorly understood. We identified the cytoplasmic tyrosine phosphatase SHP-1 as a novel ‘endogenous brake’ and modifier of the suppressive ability of Treg cells; consistent with this notion, loss of SHP-1 expression strongly augments the ability of Treg cells to suppress inflammation in a mouse model. Specific harmacological inhibition of SHP-1 enzymatic activity via the cancer drug sodium stibogluconate (SSG) potently augmented Treg cell suppressor activity both in vivo and ex vivo. We evaluated the gene expression profiles of sorted T reg cells (CD4+CD25+) from wild type (wt) mice and mice that were heterozygous (he) or homozygous (me) for SHP-1 knockout (motheaten phenotype). T reg (CD4+CD25+) cells were isolated form wild type (WT) mice and that were heterozygous (he) or homozygous (me) for SHP-1 knockout (motheaten phenotype); totalRNA was isolated using Arcturus reagents; aRNA was generated and amplified using Arcturus reagents; and labeled product was hybridized to Affymetrix chips to asses gene expression patterns.
Project description:Follicular T-helper (TFH) cells highly express the programmed cell death-1 (PD-1) molecule. Whereas inhibition of T cell receptor (TCR) signaling and CD28 co-stimulation is thought to be the primary mode of PD-1 functions, how PD-1 regulates TFH development and function remains unclear. Here we show that, when engaged by the ensemble of bystander B cells constitutively expressing PD-1 ligand 1 (PD-L1), PD-1 inhibits T-cell recruitment into follicles. This inhibition involves suppression of PI3K activities downstream of follicle-guidance receptor CXCR5, is independent from co-signaling with the TCR, and necessitates ICOS signaling to overcome. PD-1 further restricts CXCR3 upregulation on TFH cells, serving to concentrate these cells toward the GC territory, where PD-L1-PD-1 interactions between individual TFH and B cells optimize B-cell competition and affinity maturation. Therefore, operating in both costimulation-independent and -dependent manners, PD-1 plays an integral role in orchestrating tissue positioning and function of TFH cells.
Project description:The importance of regulatory T cells (Treg) for immune tolerance is well recognized, yet the signaling molecules influencing their suppressive activity are relatively poorly understood. We identified the cytoplasmic tyrosine phosphatase SHP-1 as a novel ‘endogenous brake’ and modifier of the suppressive ability of Treg cells; consistent with this notion, loss of SHP-1 expression strongly augments the ability of Treg cells to suppress inflammation in a mouse model. Specific harmacological inhibition of SHP-1 enzymatic activity via the cancer drug sodium stibogluconate (SSG) potently augmented Treg cell suppressor activity both in vivo and ex vivo. We evaluated the gene expression profiles of sorted T reg cells (CD4+CD25+) from wild type (wt) mice and mice that were heterozygous (he) or homozygous (me) for SHP-1 knockout (motheaten phenotype).
Project description:THEMIS is critical for conventional T cell development but its precise molecular function remains elusive. Here we show that THEMIS constitutively associates with the phosphatases SHP-1 and SHP-2. This complex requires the adapter GRB2, which bridges SHP to Themis in a Tyr-phosphorylation-independent fashion. Rather, SHP1 and THEMIS engage with the N-SH3 and C-SH3 domains of GRB2, respectively, a configuration that allows GRB2-SH2 to recruit the complex onto LAT. Coherent with THEMIS-mediated recruitment of SHP to the TCR signalosome, THEMIS knockdown increased TCR-induced TCR- phosphorylation, Erk activation and CD69 expression, however not Lck phosphorylation. This generalized TCR signalling increase led to augmented apoptosis, a phenotype mirrored by SHP-1 knockdown. Remarkably, a KI mutation of Lck Ser59, previously suggested to be key in ERK-mediated resistance towards SHP-1 negative feedback, did not affect TCR signalling nor ligand discrimination in vivo. Thus, THEMIS:SHP complex dampens early TCR signalling by a previously unknown molecular mechanism that favors T cell survival. We discuss possible implications of this mechanism in modulating TCR output signals towards conventional T cell development and differentiation.
Project description:The protein-tyrosine phosphatase SHP-1 (PTPN6) is an important glucose homeostasis modulator. Besides negatively regulating insulin signaling, the specific role of SHP-1 in metabolic control remains poorly understood. We show that SHP-1 acts as a co-activator for transcription of the phosphoenolpyruvate carboxykinase 1 (PCK1) gene, thereby modulating basal gluconeogenesis in hepatocytes. SHP-1 interacts with RNA polymerase II-subunits and signal transducer and activator of transcription 5 (STAT5), and localizes to the nucleus, where a sub-fraction of SHP-1 associates with chromatin. While SHP-1 binds to the PCK1-promoter, its loss affects RNA polymerase II-recruitment to this and other promoters of genes enriched for glucose metabolism-related functions. SHP-1-downregulation, and similarly STAT5 pharmacological inhibition reduce PCK1-transcript levels correlating with blunted gluconeogenesis. Overall, we identified a novel molecular SHP-1-function, that of a regulator of PCK1-transcription and subsequently hepatic gluconeogenesis, through physical interaction with the transcription machinery, mediated by an Akt-independent mechanism, but independent of STAT5 tyrosine-phosphorylation status.
Project description:Regulatory T cells (Tregs) expressing the transcription factor Foxp3 constitute a unique T cell lineage committed to suppressive functions and are crucial for suppressing aberrant immune responses in autoimmunity and allergy. Treg transcriptional landscape is tightly controlled by Foxp3-binding partners, including RelA. Although those DNA-binding complexes have been well characterized, the TCR signaling events that coordinate those dynamic molecular assembly are still poorly understood. Using a combination of genetic models, we show that the suppressive function of Tregs is controlled by a tri-molecular interplay between the signaling proteins Themis1, Vav1 and SHP-1. We identify the tyrosine phosphatase SHP-1 as a central component of an inhibitory circuit, which leads to the dephosphorylation of Vav1, which in turn is associated with a dramatic reduction of RelA activity and Treg suppressive function. Themis1 disconnects this circuit by blocking SHP-1 catalytic activity. Collectively, our results reveal a previously unappreciated pathway, whereby Themis1-mediated repression of SHP-1 activity promotes Tregs suppressive functions through a Vav1-RelA signaling axis.
Project description:We generated mice with conditional targeting of the Ptpn11 gene (encoding for Shp-2) in T cells (Shp-2fl/flLckCre) or myeloid cells (Shp-2fl/flLysMCre). Although no difference in tumor growth was observed between Shp-2fl/flLckCre and control mice and both groups were similarly benefitted by PD-1 blockade, Shp-2fl/flLysMCre mice had significantly diminished tumor growth that was not further decreased by anti-PD-1 treatment. As revealed by RNA-seq, myeloid-specific Shp-2 ablation was paralleled by expansion of activated myeloid cells and macrophages with molecular signatures of enhanced neutrophil and macrophage differentiation, phagocytosis, antigen-presenting function, TLR and type I IFN signaling, chemokine production, and expression of immunostimulatory molecules, which promoted T cell recruitment and activation.