Margot Thome | University of Lausanne (original) (raw)

Papers by Margot Thome

Research paper thumbnail of Evidence for a TCR Affinity Threshold Delimiting Maximal CD8 T Cell Function

The Journal of Immunology, 2010

Protective adaptive immune responses rely on TCR-mediated recognition of Ag-derived peptides pres... more Protective adaptive immune responses rely on TCR-mediated recognition of Ag-derived peptides presented by self-MHC molecules. However, self-Ag (tumor)-specific TCRs are often of too low affinity to achieve best functionality. To precisely assess the relationship between TCR-peptide-MHC binding parameters and T cell function, we tested a panel of sequence-optimized HLA-A(*)0201/NY-ESO-1(157-165)-specific TCR variants with affinities lying within physiological boundaries to preserve antigenic specificity and avoid cross-reactivity, as well as two outliers (i.e., a very high- and a low-affinity TCR). Primary human CD8 T cells transduced with these TCRs demonstrated robust correlations between binding measurements of TCR affinity and avidity and the biological response of the T cells, such as TCR cell-surface clustering, intracellular signaling, proliferation, and target cell lysis. Strikingly, above a defined TCR-peptide-MHC affinity threshold (K(D) < approximately 5 muM), T cell function could not be further enhanced, revealing a plateau of maximal T cell function, compatible with the notion that multiple TCRs with slightly different affinities participate equally (codominantly) in immune responses. We propose that rational design of improved self-specific TCRs may not need to be optimized beyond a given affinity threshold to achieve both optimal T cell function and avoidance of the unpredictable risk of cross-reactivity.

Research paper thumbnail of The paracaspase MALT1: biological function and potential for therapeutic inhibition

Cellular and Molecular Life Sciences, 2015

The paracaspase MALT1 has a central role in the activation of lymphocytes and other immune cells ... more The paracaspase MALT1 has a central role in the activation of lymphocytes and other immune cells including myeloid cells, mast cells and NK cells. MALT1 activity is required not only for the immune response, but also for the development of natural Treg cells that keep the immune response in check. Exaggerated MALT1 activity has been associated with the development of lymphoid malignancies, and recently developed MALT1 inhibitors show promising anti-tumor effects in xenograft models of diffuse large B cell lymphoma. In this review, we provide an overview of the present understanding of MALT1's function, and discuss possibilities for its therapeutic targeting based on recently developed inhibitors and animal models.

Research paper thumbnail of TCR-induced NF-kappaB activation: a crucial role for Carma1, Bcl10 and MALT1

Trends in immunology, 2003

Research paper thumbnail of PKCθ/β and CYLD Are Antagonistic Partners in the NFκB and NFAT Transactivation Pathways in Primary Mouse CD3+ T Lymphocytes

PLoS ONE, 2013

In T cells PKCθ mediates the activation of critical signals downstream of TCR/CD28 stimulation. W... more In T cells PKCθ mediates the activation of critical signals downstream of TCR/CD28 stimulation. We investigated the molecular mechanisms by which PKCθ regulates NFκB transactivation by examining PKCθ/β single and double knockout mice and observed a redundant involvement of PKCθ and PKCβ in this signaling pathway. Mechanistically, we define a PKCθ-CYLD protein complex and an interaction between the positive PKCθ/β and the negative CYLD signaling pathways that both converge at the level of TAK1/IKK/I-κBα/NFκB and NFAT transactivation. In Jurkat leukemic T cells, CYLD is endoproteolytically processed in the initial minutes of stimulation by the paracaspase MALT1 in a PKC-dependent fashion, which is required for robust IL-2 transcription. However, in primary T cells, CYLD processing occurs with different kinetics and an altered dependence on PKC. The formation of a direct PKCθ/CYLD complex appears to regulate the short-term spatial distribution of CYLD, subsequently affecting NFκB and NFAT repressional activity of CYLD prior to its MALT1-dependent inactivation. Taken together, our study establishes CYLD as a new and critical PKCθ interactor in T cells and reveals that antagonistic PKCθ/β-CYLD crosstalk is crucial for the adjustment of immune thresholds in primary mouse CD3(+) T cells.

Research paper thumbnail of Faculty of 1000 evaluation for DDX5 and its associated lncRNA Rmrp modulate TH17 cell effector functions

F1000 - Post-publication peer review of the biomedical literature, 2000

Research paper thumbnail of Faculty of 1000 evaluation for A Cytoplasmic NF-κB Interacting Long Noncoding RNA Blocks IκB Phosphorylation and Suppresses Breast Cancer Metastasis

F1000 - Post-publication peer review of the biomedical literature, 2015

Research paper thumbnail of Faculty of 1000 evaluation for Expression of MALT1 oncogene in hematopoietic stem/progenitor cells recapitulates the pathogenesis of human lymphoma in mice

F1000 - Post-publication peer review of the biomedical literature, 2012

Research paper thumbnail of Faculty of 1000 evaluation for NEMO ensures signaling specificity of the pleiotropic IKKβ by directing its kinase activity toward IκBα

F1000 - Post-publication peer review of the biomedical literature, 2012

Research paper thumbnail of Faculty of 1000 evaluation for Crucial role for human Toll-like receptor 4 in the development of contact allergy to nickel

F1000 - Post-publication peer review of the biomedical literature, 2011

Research paper thumbnail of Faculty of 1000 evaluation for IkappaBbeta is an essential co-activator for LPS-induced IL-1beta transcription in vivo

F1000 - Post-publication peer review of the biomedical literature, 2011

Research paper thumbnail of Faculty of 1000 evaluation for Malt1-Induced Cleavage of Regnase-1 in CD4(+) Helper T Cells Regulates Immune Activation

F1000 - Post-publication peer review of the biomedical literature, 2013

Research paper thumbnail of Faculty of 1000 evaluation for Chronic lymphocytic leukaemia is driven by antigen-independent cell-autonomous signalling

F1000 - Post-publication peer review of the biomedical literature, 2012

Research paper thumbnail of Faculty of 1000 evaluation for OTUD7B controls non-canonical NF-κB activation through deubiquitination of TRAF3

F1000 - Post-publication peer review of the biomedical literature, 2013

Research paper thumbnail of Faculty of 1000 evaluation for The Shigella flexneri effector OspI deamidates UBC13 to dampen the inflammatory response

F1000 - Post-publication peer review of the biomedical literature, 2000

Research paper thumbnail of Faculty of 1000 evaluation for RORgammaT drives production of the cytokine GM-CSF in helper T cells, which is essential for the effector phase of autoimmune neuroinflammation

F1000 - Post-publication peer review of the biomedical literature, 2000

Research paper thumbnail of Phosphorylation of CARMA1 by HPK1 is critical for NF-B activation in T cells

Pnas, 2009

Activation of the NF-kappaB pathway in T cells is required for induction of an adaptive immune re... more Activation of the NF-kappaB pathway in T cells is required for induction of an adaptive immune response. Hematopoietic progenitor kinase (HPK1) is an important proximal mediator of T-cell receptor (TCR)-induced NF-kappaB activation. Knock-down of HPK1 abrogates TCR-induced IKKbeta and NF-kappaB activation, whereas active HPK1 leads to increased IKKbeta activity in T cells. Yet, the precise molecular mechanism of this process remains elusive. Here, we show that HPK1-mediated NF-kappaB activation is dependent on the adaptor protein CARMA1. HPK1 interacts with CARMA1 in a TCR stimulation-dependent manner and phosphorylates the linker region of CARMA1. Interestingly, the putative HPK1 phosphorylation sites in CARMA1 are different from known PKC consensus sites. Mutations of residues S549, S551, and S552 in CARMA1 abrogated phosphorylation of a CARMA1-linker construct by HPK1 in vitro. In addition, CARMA1 S551A or S5549A/S551A point mutants failed to restore HPK1-mediated and TCR-mediated NF-kappaB activation and IL-2 expression in CARMA1-deficient T cells. Thus, we identify HPK1 as a kinase specific for CARMA1 and suggest HPK1-mediated phosphorylation of CARMA1 as an additional regulatory mechanism tuning the NF-kappaB response upon TCR stimulation.

Research paper thumbnail of Inhibition of death receptor signals bycellular FLIP

Research paper thumbnail of FLIP Prevents Apoptosis Induced by Death Receptors But Not by Perforin/Granzyme B, Chemotherapeutic Drugs, and Gamma Irradiation

The Journal of Immunology, Oct 15, 1998

FLICE-inhibitory protein, FLIP (Casper/I-FLICE/FLAME-1/CASH/CLARP/MRIT), which contains two death... more FLICE-inhibitory protein, FLIP (Casper/I-FLICE/FLAME-1/CASH/CLARP/MRIT), which contains two death effector domains and an inactive caspase domain, binds to FADD and caspase-8, and thereby inhibits death receptor-mediated apoptosis. Here, we characterize the inhibitory effect of FLIP on a variety of apoptotic pathways. Human Jurkat T cells undergoing Fas ligandmediated apoptosis in response to CD3 activation were completely resistant when transfected with FLIP. In contrast, the presence of FLIP did not affect apoptosis induced by granzyme B in combination with adenovirus or perforin. Moreover, the Fas ligand, but not the perforin/granzyme B-dependent lytic pathway of CTL, was inhibited by FLIP. Apoptosis mediated by chemotherapeutic drugs (i.e., doxorubicin, etoposide, and vincristine) and gamma irradiation was not affected by FLIP or the absence of Fas, indicating that these treatments can induce cell death in a Fas-independent and FLIP-insensitive manner.

Research paper thumbnail of CARMA1- and MyD88-dependent activation of Jun/ATF-type AP-1 complexes is a hallmark of ABC diffuse large B-cell lymphomas

Blood, Jan 8, 2016

A hallmark of the diffuse large B-cell lymphoma (DLBCL) of the activated B-cell (ABC) type, a mol... more A hallmark of the diffuse large B-cell lymphoma (DLBCL) of the activated B-cell (ABC) type, a molecular subtype characterized by adverse outcome, is constitutive activation of the transcription factor NF-κB, which controls expression of genes promoting cellular survival and proliferation. Much less, however, is known about the role of the transcription factor AP-1 in ABC DLBCL. Here we show that AP-1, like NF-κB, was controlled by constitutive activation of the B-cell receptor and/or toll-like receptor signaling pathways in ABC DLBCL cell lines. In contrast to germinal center B-cell (GCB) DLBCL, ABC DLBCL cell lines expressed high levels of the AP-1 family members c-Jun, JunB and JunD, which formed heterodimeric complexes with the AP-1 family members ATF2, ATF3 and ATF7. Inhibition of these complexes by a dominant negative approach led to impaired growth of a majority of ABC DLBCL cell lines. Individual silencing of c-Jun, ATF2 or ATF3 decreased cellular survival, and revealed a c-J...

Research paper thumbnail of Fas triggers an alternative, caspase-8–independent cell death pathway using the kinase RIP as effector molecule

Nature Immunology, 2000

Cell death is achieved by two fundamentally different mechanisms: apoptosis and necrosis. Apoptos... more Cell death is achieved by two fundamentally different mechanisms: apoptosis and necrosis. Apoptosis is dependent on caspase activation, whereas the caspase-independent necrotic signaling pathway remains largely uncharacterized. We show here that Fas kills activated primary T cells efficiently in the absence of active caspases, which results in necrotic morphological changes and late mitochondrial damage but no cytochrome c release.

Research paper thumbnail of Evidence for a TCR Affinity Threshold Delimiting Maximal CD8 T Cell Function

The Journal of Immunology, 2010

Protective adaptive immune responses rely on TCR-mediated recognition of Ag-derived peptides pres... more Protective adaptive immune responses rely on TCR-mediated recognition of Ag-derived peptides presented by self-MHC molecules. However, self-Ag (tumor)-specific TCRs are often of too low affinity to achieve best functionality. To precisely assess the relationship between TCR-peptide-MHC binding parameters and T cell function, we tested a panel of sequence-optimized HLA-A(*)0201/NY-ESO-1(157-165)-specific TCR variants with affinities lying within physiological boundaries to preserve antigenic specificity and avoid cross-reactivity, as well as two outliers (i.e., a very high- and a low-affinity TCR). Primary human CD8 T cells transduced with these TCRs demonstrated robust correlations between binding measurements of TCR affinity and avidity and the biological response of the T cells, such as TCR cell-surface clustering, intracellular signaling, proliferation, and target cell lysis. Strikingly, above a defined TCR-peptide-MHC affinity threshold (K(D) < approximately 5 muM), T cell function could not be further enhanced, revealing a plateau of maximal T cell function, compatible with the notion that multiple TCRs with slightly different affinities participate equally (codominantly) in immune responses. We propose that rational design of improved self-specific TCRs may not need to be optimized beyond a given affinity threshold to achieve both optimal T cell function and avoidance of the unpredictable risk of cross-reactivity.

Research paper thumbnail of The paracaspase MALT1: biological function and potential for therapeutic inhibition

Cellular and Molecular Life Sciences, 2015

The paracaspase MALT1 has a central role in the activation of lymphocytes and other immune cells ... more The paracaspase MALT1 has a central role in the activation of lymphocytes and other immune cells including myeloid cells, mast cells and NK cells. MALT1 activity is required not only for the immune response, but also for the development of natural Treg cells that keep the immune response in check. Exaggerated MALT1 activity has been associated with the development of lymphoid malignancies, and recently developed MALT1 inhibitors show promising anti-tumor effects in xenograft models of diffuse large B cell lymphoma. In this review, we provide an overview of the present understanding of MALT1's function, and discuss possibilities for its therapeutic targeting based on recently developed inhibitors and animal models.

Research paper thumbnail of TCR-induced NF-kappaB activation: a crucial role for Carma1, Bcl10 and MALT1

Trends in immunology, 2003

Research paper thumbnail of PKCθ/β and CYLD Are Antagonistic Partners in the NFκB and NFAT Transactivation Pathways in Primary Mouse CD3+ T Lymphocytes

PLoS ONE, 2013

In T cells PKCθ mediates the activation of critical signals downstream of TCR/CD28 stimulation. W... more In T cells PKCθ mediates the activation of critical signals downstream of TCR/CD28 stimulation. We investigated the molecular mechanisms by which PKCθ regulates NFκB transactivation by examining PKCθ/β single and double knockout mice and observed a redundant involvement of PKCθ and PKCβ in this signaling pathway. Mechanistically, we define a PKCθ-CYLD protein complex and an interaction between the positive PKCθ/β and the negative CYLD signaling pathways that both converge at the level of TAK1/IKK/I-κBα/NFκB and NFAT transactivation. In Jurkat leukemic T cells, CYLD is endoproteolytically processed in the initial minutes of stimulation by the paracaspase MALT1 in a PKC-dependent fashion, which is required for robust IL-2 transcription. However, in primary T cells, CYLD processing occurs with different kinetics and an altered dependence on PKC. The formation of a direct PKCθ/CYLD complex appears to regulate the short-term spatial distribution of CYLD, subsequently affecting NFκB and NFAT repressional activity of CYLD prior to its MALT1-dependent inactivation. Taken together, our study establishes CYLD as a new and critical PKCθ interactor in T cells and reveals that antagonistic PKCθ/β-CYLD crosstalk is crucial for the adjustment of immune thresholds in primary mouse CD3(+) T cells.

Research paper thumbnail of Faculty of 1000 evaluation for DDX5 and its associated lncRNA Rmrp modulate TH17 cell effector functions

F1000 - Post-publication peer review of the biomedical literature, 2000

Research paper thumbnail of Faculty of 1000 evaluation for A Cytoplasmic NF-κB Interacting Long Noncoding RNA Blocks IκB Phosphorylation and Suppresses Breast Cancer Metastasis

F1000 - Post-publication peer review of the biomedical literature, 2015

Research paper thumbnail of Faculty of 1000 evaluation for Expression of MALT1 oncogene in hematopoietic stem/progenitor cells recapitulates the pathogenesis of human lymphoma in mice

F1000 - Post-publication peer review of the biomedical literature, 2012

Research paper thumbnail of Faculty of 1000 evaluation for NEMO ensures signaling specificity of the pleiotropic IKKβ by directing its kinase activity toward IκBα

F1000 - Post-publication peer review of the biomedical literature, 2012

Research paper thumbnail of Faculty of 1000 evaluation for Crucial role for human Toll-like receptor 4 in the development of contact allergy to nickel

F1000 - Post-publication peer review of the biomedical literature, 2011

Research paper thumbnail of Faculty of 1000 evaluation for IkappaBbeta is an essential co-activator for LPS-induced IL-1beta transcription in vivo

F1000 - Post-publication peer review of the biomedical literature, 2011

Research paper thumbnail of Faculty of 1000 evaluation for Malt1-Induced Cleavage of Regnase-1 in CD4(+) Helper T Cells Regulates Immune Activation

F1000 - Post-publication peer review of the biomedical literature, 2013

Research paper thumbnail of Faculty of 1000 evaluation for Chronic lymphocytic leukaemia is driven by antigen-independent cell-autonomous signalling

F1000 - Post-publication peer review of the biomedical literature, 2012

Research paper thumbnail of Faculty of 1000 evaluation for OTUD7B controls non-canonical NF-κB activation through deubiquitination of TRAF3

F1000 - Post-publication peer review of the biomedical literature, 2013

Research paper thumbnail of Faculty of 1000 evaluation for The Shigella flexneri effector OspI deamidates UBC13 to dampen the inflammatory response

F1000 - Post-publication peer review of the biomedical literature, 2000

Research paper thumbnail of Faculty of 1000 evaluation for RORgammaT drives production of the cytokine GM-CSF in helper T cells, which is essential for the effector phase of autoimmune neuroinflammation

F1000 - Post-publication peer review of the biomedical literature, 2000

Research paper thumbnail of Phosphorylation of CARMA1 by HPK1 is critical for NF-B activation in T cells

Pnas, 2009

Activation of the NF-kappaB pathway in T cells is required for induction of an adaptive immune re... more Activation of the NF-kappaB pathway in T cells is required for induction of an adaptive immune response. Hematopoietic progenitor kinase (HPK1) is an important proximal mediator of T-cell receptor (TCR)-induced NF-kappaB activation. Knock-down of HPK1 abrogates TCR-induced IKKbeta and NF-kappaB activation, whereas active HPK1 leads to increased IKKbeta activity in T cells. Yet, the precise molecular mechanism of this process remains elusive. Here, we show that HPK1-mediated NF-kappaB activation is dependent on the adaptor protein CARMA1. HPK1 interacts with CARMA1 in a TCR stimulation-dependent manner and phosphorylates the linker region of CARMA1. Interestingly, the putative HPK1 phosphorylation sites in CARMA1 are different from known PKC consensus sites. Mutations of residues S549, S551, and S552 in CARMA1 abrogated phosphorylation of a CARMA1-linker construct by HPK1 in vitro. In addition, CARMA1 S551A or S5549A/S551A point mutants failed to restore HPK1-mediated and TCR-mediated NF-kappaB activation and IL-2 expression in CARMA1-deficient T cells. Thus, we identify HPK1 as a kinase specific for CARMA1 and suggest HPK1-mediated phosphorylation of CARMA1 as an additional regulatory mechanism tuning the NF-kappaB response upon TCR stimulation.

Research paper thumbnail of Inhibition of death receptor signals bycellular FLIP

Research paper thumbnail of FLIP Prevents Apoptosis Induced by Death Receptors But Not by Perforin/Granzyme B, Chemotherapeutic Drugs, and Gamma Irradiation

The Journal of Immunology, Oct 15, 1998

FLICE-inhibitory protein, FLIP (Casper/I-FLICE/FLAME-1/CASH/CLARP/MRIT), which contains two death... more FLICE-inhibitory protein, FLIP (Casper/I-FLICE/FLAME-1/CASH/CLARP/MRIT), which contains two death effector domains and an inactive caspase domain, binds to FADD and caspase-8, and thereby inhibits death receptor-mediated apoptosis. Here, we characterize the inhibitory effect of FLIP on a variety of apoptotic pathways. Human Jurkat T cells undergoing Fas ligandmediated apoptosis in response to CD3 activation were completely resistant when transfected with FLIP. In contrast, the presence of FLIP did not affect apoptosis induced by granzyme B in combination with adenovirus or perforin. Moreover, the Fas ligand, but not the perforin/granzyme B-dependent lytic pathway of CTL, was inhibited by FLIP. Apoptosis mediated by chemotherapeutic drugs (i.e., doxorubicin, etoposide, and vincristine) and gamma irradiation was not affected by FLIP or the absence of Fas, indicating that these treatments can induce cell death in a Fas-independent and FLIP-insensitive manner.

Research paper thumbnail of CARMA1- and MyD88-dependent activation of Jun/ATF-type AP-1 complexes is a hallmark of ABC diffuse large B-cell lymphomas

Blood, Jan 8, 2016

A hallmark of the diffuse large B-cell lymphoma (DLBCL) of the activated B-cell (ABC) type, a mol... more A hallmark of the diffuse large B-cell lymphoma (DLBCL) of the activated B-cell (ABC) type, a molecular subtype characterized by adverse outcome, is constitutive activation of the transcription factor NF-κB, which controls expression of genes promoting cellular survival and proliferation. Much less, however, is known about the role of the transcription factor AP-1 in ABC DLBCL. Here we show that AP-1, like NF-κB, was controlled by constitutive activation of the B-cell receptor and/or toll-like receptor signaling pathways in ABC DLBCL cell lines. In contrast to germinal center B-cell (GCB) DLBCL, ABC DLBCL cell lines expressed high levels of the AP-1 family members c-Jun, JunB and JunD, which formed heterodimeric complexes with the AP-1 family members ATF2, ATF3 and ATF7. Inhibition of these complexes by a dominant negative approach led to impaired growth of a majority of ABC DLBCL cell lines. Individual silencing of c-Jun, ATF2 or ATF3 decreased cellular survival, and revealed a c-J...

Research paper thumbnail of Fas triggers an alternative, caspase-8–independent cell death pathway using the kinase RIP as effector molecule

Nature Immunology, 2000

Cell death is achieved by two fundamentally different mechanisms: apoptosis and necrosis. Apoptos... more Cell death is achieved by two fundamentally different mechanisms: apoptosis and necrosis. Apoptosis is dependent on caspase activation, whereas the caspase-independent necrotic signaling pathway remains largely uncharacterized. We show here that Fas kills activated primary T cells efficiently in the absence of active caspases, which results in necrotic morphological changes and late mitochondrial damage but no cytochrome c release.