RESUMO
Natural killer (NK) cells are critical to the innate immune system, as they recognize antigens without prior sensitization, and contribute to the control and clearance of viral infections and cancer. However, a significant proportion of NK cells in mice and humans do not express classical inhibitory receptors during their education process and are rendered naturally "anergic", i.e., exhibiting reduced effector functions. The molecular events leading to NK cell anergy as well as their relation to those underlying NK cell exhaustion that arises from overstimulation in chronic conditions, remain unknown. Here, we characterize the "anergic" phenotype and demonstrate functional, transcriptional, and phenotypic similarities to the "exhausted" state in tumor-infiltrating NK cells. Furthermore, we identify zinc finger transcription factor Egr2 and diacylglycerol kinase DGKα as common negative regulators controlling NK cell dysfunction. Finally, experiments in a 3D organotypic spheroid culture model and an in vivo tumor model suggest that a nanoparticle-based delivery platform can reprogram these dysfunctional natural killer cell populations in their native microenvironment. This approach may become clinically relevant for the development of novel anti-tumor immunotherapeutic strategies.
Assuntos
Células Matadoras Naturais , Células Matadoras Naturais/imunologia , Células Matadoras Naturais/metabolismo , Animais , Camundongos , Humanos , Proteína 2 de Resposta de Crescimento Precoce/metabolismo , Proteína 2 de Resposta de Crescimento Precoce/genética , Proteína 2 de Resposta de Crescimento Precoce/imunologia , Anergia Clonal/imunologia , Neoplasias/imunologia , Neoplasias/terapia , Neoplasias/patologia , Camundongos Endogâmicos C57BLRESUMO
Natural killer (NK) cells are a powerful weapon against viral infections and tumor growth. Although the actin-myosin (actomyosin) cytoskeleton is crucial for a variety of cellular processes, the role of mechanotransduction, the conversion of actomyosin mechanical forces into signaling cascades, was never explored in NK cells. Here, we demonstrate that actomyosin retrograde flow (ARF) controls the immune response of primary human NK cells through a novel interaction between ß-actin and the SH2-domain-containing protein tyrosine phosphatase-1 (SHP-1), converting its conformation state, and thereby regulating NK cell cytotoxicity. Our results identify ARF as a master regulator of the NK cell immune response. Since actin dynamics occur in multiple cellular processes, this mechanism might also regulate the activity of SHP-1 in additional cellular systems.
Assuntos
Citoesqueleto de Actina/fisiologia , Actinas/metabolismo , Células Matadoras Naturais/imunologia , Mecanotransdução Celular/fisiologia , Proteína Tirosina Fosfatase não Receptora Tipo 6/metabolismo , Actomiosina/metabolismo , Células Cultivadas , Humanos , Conformação Proteica , Transdução de Sinais/imunologiaRESUMO
The actin cytoskeleton network forms a key link between T-cell antigen receptor (TCR) stimulation and T-cell effector functions, providing a structural basis for T-cell morphological changes and signal transduction. Accumulating evidence positions the Wiskott-Aldrich syndrome protein (WASp), a scaffolding protein that promotes actin polymerization, at the center of actin cytoskeleton-dependent T-cell function. During the past decade, we and others have utilized multidisciplinary technologies, including live-cell imaging, biochemical, and biophysical analyses, to gain insight into the mechanisms by which WASp and other cytoskeletal proteins control actin homeostasis. Following TCR engagement, WASp is rapidly activated and recruited to TCR microclusters, as part of multiprotein complexes, where it promotes actin remodeling. Late in the activation process, WASp is internalized and eventually degraded. In this review, we describe the dynamic interactions of WASp with signaling proteins, which regulate its activation and recruitment to the TCR and to actin-rich sites. Finally, we present the molecular mechanism of WASp downregulation. Some of the signaling proteins that mediate WASp activation eventually lead to its degradation. Thus, we focus here on the regulation of WASp expression and function and the mechanisms whereby they control actin machinery and T-cell effector functions.
Assuntos
Linfócitos T/imunologia , Linfócitos T/metabolismo , Proteína da Síndrome de Wiskott-Aldrich/metabolismo , Actinas/metabolismo , Animais , Homeostase , Humanos , Sinapses Imunológicas/imunologia , Sinapses Imunológicas/metabolismo , Ligação Proteica , Transporte Proteico , Proteína da Síndrome de Wiskott-Aldrich/químicaRESUMO
T cell antigen receptor (TCR) engagement has been shown to activate pathways leading to actin cytoskeletal polymerization and reorganization, which are essential for lymphocyte activation and function. Several actin regulatory proteins were implicated in regulating the actin machinery, such as members of the Wiskott-Aldrich syndrome protein (WASp) family. These include WASp and the WASp family verprolin-homologous protein-2 (WAVE2). Although WASp and WAVE2 share several structural features, the precise regulatory mechanisms and potential redundancy between them have not been fully characterized. Specifically, unlike WASp, the dynamic molecular interactions that regulate WAVE2 recruitment to the cell membrane and specifically to the TCR signaling complex are largely unknown. Here, we identify the molecular mechanism that controls the recruitment of WAVE2 in comparison with WASp. Using fluorescence resonance energy transfer (FRET) and novel triple-color FRET (3FRET) technology, we demonstrate how WAVE2 signaling complexes are dynamically regulated during lymphocyte activation in vivo. We show that, similar to WASp, WAVE2 recruitment to the TCR site depends on protein-tyrosine kinase, ZAP-70, and the adaptors LAT, SLP-76, and Nck. However, in contrast to WASp, WAVE2 leaves this signaling complex and migrates peripherally together with vinculin to the membrane leading edge. Our experiments demonstrate that WASp and WAVE2 differ in their dynamics and their associated proteins. Thus, this study reveals the differential mechanisms regulating the function of these cytoskeletal proteins.
Assuntos
Receptores de Antígenos de Linfócitos T/metabolismo , Transdução de Sinais , Família de Proteínas da Síndrome de Wiskott-Aldrich/metabolismo , Proteína da Síndrome de Wiskott-Aldrich/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Humanos , Sinapses Imunológicas/metabolismo , Proteínas de Membrana/metabolismo , Proteínas Oncogênicas/metabolismo , Fosfoproteínas/metabolismo , Ligação Proteica , Transporte Proteico , Linfócitos T/citologia , Linfócitos T/imunologia , Linfócitos T/metabolismoRESUMO
During T cell activation, the engagement of a T cell with an antigen-presenting cell (APC) results in rapid cytoskeletal rearrangements and a dramatic increase of intracellular calcium (Ca(2+)) concentration, downstream to T cell antigen receptor (TCR) ligation. These events facilitate the organization of an immunological synapse (IS), which supports the redistribution of receptors, signaling molecules and organelles towards the T cell-APC interface to induce downstream signaling events, ultimately supporting T cell effector functions. Thus, Ca(2+) signaling and cytoskeleton rearrangements are essential for T cell activation and T cell-dependent immune response. Rapid release of Ca(2+) from intracellular stores, e.g. the endoplasmic reticulum (ER), triggers the opening of Ca(2+) release-activated Ca(2+) (CRAC) channels, residing in the plasma membrane. These channels facilitate a sustained influx of extracellular Ca(2+) across the plasma membrane in a process termed store-operated Ca(2+) entry (SOCE). Because CRAC channels are themselves inhibited by Ca(2+) ions, additional factors are suggested to enable the sustained Ca(2+) influx required for T cell function. Among these factors, we focus here on the contribution of the actin and microtubule cytoskeleton. The TCR-mediated increase in intracellular Ca(2+) evokes a rapid cytoskeleton-dependent polarization, which involves actin cytoskeleton rearrangements and microtubule-organizing center (MTOC) reorientation. Here, we review the molecular mechanisms of Ca(2+) flux and cytoskeletal rearrangements, and further describe the way by which the cytoskeletal networks feedback to Ca(2+) signaling by controlling the spatial and temporal distribution of Ca(2+) sources and sinks, modulating TCR-dependent Ca(2+) signals, which are required for an appropriate T cell response. This article is part of a Special Issue entitled: Reciprocal influences between cell cytoskeleton and membrane channels, receptors and transporters. Guest Editor: Jean Claude Hervé.
Assuntos
Sinalização do Cálcio , Cálcio/metabolismo , Citoesqueleto/metabolismo , Ativação Linfocitária , Linfócitos T/metabolismo , Animais , Humanos , Transdução de SinaisRESUMO
TCR-mediated activation induces receptor microclusters that evolve to a defined immune synapse (IS). Many studies showed that actin polymerization and remodeling, which create a scaffold critical to IS formation and stabilization, are TCR mediated. However, the mechanisms controlling simultaneous TCR and actin dynamic rearrangement in the IS are yet not fully understood. Herein, we identify two novel TCR ζ-chain motifs, mediating the TCR's direct interaction with actin and inducing actin bundling. While T cells expressing the ζ-chain mutated in these motifs lack cytoskeleton (actin) associated (cska)-TCRs, they express normal levels of non-cska and surface TCRs as cells expressing wild-type ζ-chain. However, such mutant cells are unable to display activation-dependent TCR clustering, IS formation, expression of CD25/CD69 activation markers, or produce/secrete cytokine, effects also seen in the corresponding APCs. We are the first to show a direct TCR-actin linkage, providing the missing gap linking between TCR-mediated Ag recognition, specific cytoskeleton orientation toward the T-cell-APC interacting pole and long-lived IS maintenance.
Assuntos
Citoesqueleto/metabolismo , Sinapses Imunológicas/metabolismo , Receptores de Antígenos de Linfócitos T/metabolismo , Linfócitos T/imunologia , Actinas/metabolismo , Motivos de Aminoácidos/genética , Animais , Células Cultivadas , Citocinas/metabolismo , Feminino , Sinapses Imunológicas/imunologia , Ativação Linfocitária/genética , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Knockout , Camundongos Mutantes , Mutação/genética , Agregação de Receptores/genética , Receptores de Antígenos de Linfócitos T/genéticaRESUMO
T-cell antigen receptor (TCR) engagement induces formation of multi-protein signalling complexes essential for regulating T-cell functions. Generation of a complex of SLP-76, Nck and VAV1 is crucial for regulation of the actin machinery. We define the composition, stoichiometry and specificity of interactions in the SLP-76, Nck and VAV1 complex. Our data reveal that this complex can contain one SLP-76 molecule, two Nck and two VAV1 molecules. A direct interaction between Nck and VAV1 is mediated by binding between the C-terminal SH3 domain of Nck and the VAV1 N-terminal SH3 domain. Disruption of the VAV1:Nck interaction deleteriously affected actin polymerization. These novel findings shed new light on the mechanism of actin polymerization after T-cell activation.
Assuntos
Actinas/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas Oncogênicas/metabolismo , Fosfoproteínas/metabolismo , Proteínas Proto-Oncogênicas c-vav/metabolismo , Transdução de Sinais/fisiologia , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Humanos , Células Jurkat , Ativação Linfocitária , Proteínas Oncogênicas/genética , Fosfoproteínas/genética , Ligação Proteica , Proteínas Proto-Oncogênicas c-vav/genética , Receptores de Antígenos de Linfócitos T/metabolismo , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Linfócitos T/citologia , Linfócitos T/metabolismo , Domínios de Homologia de srcRESUMO
WASp-interacting protein (WIP) is a 503-residue proline-rich polypeptide expressed in human T cells. The WIP C-terminal domain binds to Wiskott-Aldrich syndrome protein (WASp) and regulates its activation and degradation, and the WIP-WASp interaction has been shown to be critical for actin polymerization and implicated in the onset of WAS and X-linked thrombocytopenia. WIP is predicted to be an intrinsically disordered protein, a class of polypeptides that are of great interest because they violate the traditional structure-function paradigm. In this first (to our knowledge) study of WIP in its unbound state, we used NMR to investigate the biophysical behavior of WIP(C), a C-terminal domain fragment of WIP that includes residues 407-503 and contains the WASp-binding site. In light of the poor spectral dispersion exhibited by WIP(C) and the high occurrence (25%) of proline residues, we employed 5D-NMR(13)C-detected NMR experiments with nonuniform sampling to accomplish full resonance assignment. Secondary chemical-shift analysis, (15)N relaxation rates, and protection from solvent exchange all concurred in detecting transient structure located in motifs that span the WASp-binding site. Residues 446-456 exhibited a propensity for helical conformation, and an extended conformation followed by a short, capped helix was observed for residues 468-478. The (13)C-detected approach allows chemical-shift assignment in the WIP(C) polyproline stretches and thus sheds light on their conformation and dynamics. The effects of temperature on chemical shifts referenced to a denatured sample of the polypeptide demonstrate that heating reduces the structural character of WIP(C). Thus, we conclude that the disordered WIP(C) fragment is comprised of regions with latent structure connected by flexible loops, an architecture with implications for binding affinity and function.
Assuntos
Proteínas do Citoesqueleto/química , Peptídeos e Proteínas de Sinalização Intracelular/química , Motivos de Aminoácidos , Sequência de Aminoácidos , Sítios de Ligação , Humanos , Espectroscopia de Ressonância Magnética , Dados de Sequência Molecular , Peptídeos/química , Estrutura Terciária de ProteínaRESUMO
Actin polymerization is a fundamental cellular process regulating immune cell functions and the immune response. The Wiskott-Aldrich syndrome protein (WASp) is an actin nucleation promoting factor, which is exclusively expressed in hematopoietic cells, where it plays a key regulatory role in cytoskeletal dynamics. WASp interacting protein (WIP) was first discovered as the binding partner of WASp, through the use of the yeast two hybrid system. WIP was later identified as a chaperone of WASp, necessary for its stability. Mutations occurring at the WASp homology 1 domain (WH1), which serves as the WIP binding site, were found to cause the Wiskott-Aldrich syndrome (WAS) and X-linked thrombocytopenia (XLT). WAS manifests as an immune deficiency characterized by eczema, thrombocytopenia, recurrent infections, and hematopoietic malignancies, demonstrating the importance of WIP for WASp complex formation and for a proper immune response. WIP deficiency was found to lead to different abnormalities in the activity of various lymphocytes, suggesting differential cell-dependent roles for WIP. Additionally, WIP deficiency causes cellular abnormalities not found in WASp-deficient cells, indicating that WIP fulfills roles beyond stabilizing WASp. Indeed, WIP was shown to interact with various binding partners, including the signaling proteins Nck, CrkL and cortactin. Recent studies have demonstrated that WIP also takes part in non immune cellular processes such as cancer invasion and metastasis, in addition to cell subversion by intracellular pathogens. Understanding of numerous functions of WIP can enhance our current understanding of activation and function of immune and other cell types.
Assuntos
Actinas/imunologia , Proteínas do Citoesqueleto/imunologia , Peptídeos e Proteínas de Sinalização Intracelular/imunologia , Transdução de Sinais/imunologia , Actinas/genética , Proteínas Adaptadoras de Transdução de Sinal/genética , Proteínas Adaptadoras de Transdução de Sinal/imunologia , Animais , Cortactina/genética , Cortactina/imunologia , Proteínas do Citoesqueleto/genética , Doenças Genéticas Ligadas ao Cromossomo X/genética , Doenças Genéticas Ligadas ao Cromossomo X/imunologia , Neoplasias Hematológicas/genética , Neoplasias Hematológicas/imunologia , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Proteínas Nucleares/genética , Proteínas Nucleares/imunologia , Proteínas Oncogênicas/genética , Proteínas Oncogênicas/imunologia , Transdução de Sinais/genética , Trombocitopenia/genética , Trombocitopenia/imunologia , Síndrome de Wiskott-Aldrich/genética , Síndrome de Wiskott-Aldrich/imunologia , Proteína da Síndrome de Wiskott-Aldrich/genética , Proteína da Síndrome de Wiskott-Aldrich/imunologiaRESUMO
Understanding the crosstalk between natural killer (NK) cells and the tumor microenvironment (TME) has enhanced the potential of exploiting the interplay between activation and inhibition of NK cells for immunotherapy. This interaction is crucial for understanding how tumor cells escape NK cell immune surveillance. NK cell dysfunction is regulated by two molecular mechanisms, downregulated activating receptor ligand expression on the tumor cells, and upregulated inhibitory signals delivered to NK cells. Recent studies demonstrated the role of mechanotransduction in modulating NK cell responses in the TME. The immunological synapse represents a functional interface between the NK cell and its target, regulated by Actin Retrograde Flow (ARF), which drives the adhesion molecules and receptors toward the central zone of the immunological synapse (IS). Here, we further characterize the role of ARF in controlling the immune response of NK cells, using CRISPR/cas9-mediated Wiskott-Aldrich Syndrome protein (WASp) gene silencing of NK cells. We demonstrate that WASp regulates ARF velocity, affecting the conformation and function of the key NK inhibitory regulator, SH2-domain containing protein tyrosine phosphatase-1 (SHP-1), and consequently, the NK cell response. Our results demonstrate the potential of modulating the biophysical and intracellular regulation of NK activation as a promising approach for improving immunotherapy.
RESUMO
Natural killer (NK) cells provide a powerful weapon mediating immune defense against viral infections, tumor growth, and metastatic spread. NK cells demonstrate great potential for cancer immunotherapy; they can rapidly and directly kill cancer cells in the absence of MHC-dependent antigen presentation and can initiate a robust immune response in the tumor microenvironment (TME). Nevertheless, current NK cell-based immunotherapies have several drawbacks, such as the requirement for ex vivo expansion of modified NK cells, and low transduction efficiency. Furthermore, to date, no clinical trial has demonstrated a significant benefit for NK-based therapies in patients with advanced solid tumors, mainly due to the suppressive TME. To overcome current obstacles in NK cell-based immunotherapies, we describe here a non-viral lipid nanoparticle-based delivery system that encapsulates small interfering RNAs (siRNAs) to gene silence the key intrinsic inhibitory NK cell molecules, SHP-1, Cbl-b, and c-Cbl. The nanoparticles (NPs) target NK cells in vivo, silence inhibitory checkpoint signaling molecules, and unleash NK cell activity to eliminate tumors. Thus, the novel NP-based system developed here may serve as a powerful tool for future NK cell-based therapeutic approaches.
Assuntos
Imunoterapia , Neoplasias , Humanos , Células Matadoras Naturais , Lipossomos , Nanopartículas , Neoplasias/patologia , Microambiente TumoralRESUMO
Natural killer (NK) cells play a crucial role in immunity, killing virally infected and cancerous cells. The balance of signals initiated upon engagement of activating and inhibitory NK receptors with cognate ligands determines killing or tolerance. Nevertheless, the molecular mechanisms regulating rapid NK cell discrimination between healthy and malignant cells in a heterogeneous tissue environment are incompletely understood. The SHP-1 tyrosine phosphatase is the central negative NK cell regulator that dephosphorylates key activating signaling proteins. Though the mechanism by which SHP-1 mediates NK cell inhibition has been partially elucidated, the pathways by which SHP-1 is itself regulated remain unclear. Here, we show that phosphorylation of SHP-1 in NK cells on the S591 residue by PKC-θ promotes the inhibited SHP-1 'folded' state. Silencing PKC-θ maintains SHP-1 in the active conformation, reduces NK cell activation and cytotoxicity, and promotes tumor progression in vivo. This study reveals a molecular pathway that sustains the NK cell activation threshold through suppression of SHP-1 activity.
Assuntos
Citotoxicidade Imunológica , Proteínas Tirosina Fosfatases , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Células Matadoras Naturais , Fosforilação , Proteína Quinase C-theta/metabolismo , Proteína Tirosina Fosfatase não Receptora Tipo 6 , Proteínas Tirosina Fosfatases/metabolismoRESUMO
The default pathway of cell-surface T-cell receptor (TCR) complex formation, and the subsequent transport to the membrane, is thought to entail endoplasmic reticulum (ER) localization followed by proteasome degradation of the unassembled chains. We show herein an alternative pathway: short, incomplete peptide versions of TCRbeta naturally occur in the thymus. Such peptides, which have minimally lost the leader sequence or have been massively truncated, leaving only the very C terminus intact, are sorted preferentially to the mitochondrion. As a consequence of the mitochondrial localization, apoptotic cell death is induced. Structure function analysis showed that both the specific localization and induction of apoptosis depend on the transmembrane domain (TMD) and associated residues at the COOH-terminus of TCR. Truncated forms of TCR, such as the short peptides that we detected in the thymus, may be products of protein degradation within thymocytes. Alternatively, they may occur through the translation of truncated mRNAs resulting from unfruitful rearrangement or from germline transcription. It is proposed that mitochondria serve as a subcellular sequestration site for incomplete TCR molecules.
Assuntos
Apoptose/imunologia , Mitocôndrias/metabolismo , Transporte Proteico/imunologia , Receptores de Antígenos de Linfócitos T alfa-beta/metabolismo , Linfócitos T/citologia , Linfócitos T/metabolismo , Animais , Células COS , Sobrevivência Celular/imunologia , Chlorocebus aethiops , Rearranjo Gênico do Linfócito T , Proteínas de Fluorescência Verde/genética , Região Variável de Imunoglobulina/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Mutantes , Estrutura Terciária de Proteína , RNA Mensageiro/metabolismo , Receptores de Antígenos de Linfócitos T alfa-beta/química , Receptores de Antígenos de Linfócitos T alfa-beta/genética , Transdução de Sinais/imunologia , Timo/citologiaRESUMO
Receptor oligomerization is vital for activating intracellular signaling, in part by initiating events that recruit effector and adaptor proteins to sites of active signaling. Whether these distal molecules themselves oligomerize is not well appreciated. In this study, we examined the molecular interactions of the adaptor protein GRB2. In T cells, the SH2 domain of GRB2 binds phosphorylated tyrosines on the adaptor protein LAT and the GRB2 SH3 domains associate with the proline-rich regions of SOS1 and CBL. Using biochemical and biophysical techniques in conjunction with confocal microscopy, we observed that the simultaneous association of GRB2, via its SH2 and SH3 domains, with multivalent ligands led to the oligomerization of these ligands, which affected signaling. These data suggest that multipoint binding of distal adaptor proteins mediates the formation of oligomeric signaling clusters vital for intracellular signaling.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteína Adaptadora GRB2/metabolismo , Proteínas de Membrana/metabolismo , Estrutura Quaternária de Proteína , Proteína SOS1/metabolismo , Transdução de Sinais , Proteínas Adaptadoras de Transdução de Sinal/química , Sequência de Aminoácidos , Proteína Adaptadora GRB2/química , Humanos , Células Jurkat , Ligantes , Proteínas de Membrana/química , Modelos Biológicos , Dados de Sequência Molecular , Fosfopeptídeos/metabolismo , Prolina/metabolismo , Ligação Proteica , Receptores de Antígenos de Linfócitos T/metabolismo , Proteína SOS1/química , Domínios de Homologia de srcRESUMO
Natural killer (NK) cells are innate lymphoid cells, which play key roles in elimination of virally infected and malignant cells. The balance between activating and inhibitory signals derived from NK surface receptors govern the NK cell immune response. The cytoskeleton facilitates most NK cell effector functions, such as motility, infiltration, conjugation with target cells, immunological synapse assembly, and cytotoxicity. Though many studies have characterized signaling pathways that promote actin reorganization in immune cells, it is not completely clear how particular cytoskeletal architectures at the immunological synapse promote effector functions, and how cytoskeletal dynamics impact downstream signaling pathways and activation. Moreover, pioneering studies employing advanced imaging techniques have only begun to uncover the architectural complexity dictating the NK cell activation threshold; it is becoming clear that a distinct organization of the cytoskeleton and signaling receptors at the NK immunological synapse plays a decisive role in activation and tolerance. Here, we review the roles of the actin cytoskeleton in NK cells. We focus on how actin dynamics impact cytolytic granule secretion, NK cell motility, and NK cell infiltration through tissues into inflammatory sites. We will also describe the additional cytoskeletal components, non-muscle Myosin II and microtubules that play pivotal roles in NK cell activity. Furthermore, special emphasis will be placed on the role of the cytoskeleton in assembly of immunological synapses, and how mutations or downregulation of cytoskeletal accessory proteins impact NK cell function in health and disease.
RESUMO
Cancer cells depend on actin cytoskeleton rearrangement to carry out hallmark malignant functions including activation, proliferation, migration and invasiveness. Wiskott-Aldrich Syndrome protein (WASp) is an actin nucleation-promoting factor and is a key regulator of actin polymerization in hematopoietic cells. The involvement of WASp in malignancies is incompletely understood. Since WASp is exclusively expressed in hematopoietic cells, we performed in silico screening to identify small molecule compounds (SMCs) that bind WASp and promote its degradation. We describe here one such identified molecule; this WASp-targeting SMC inhibits key WASp-dependent actin processes in several types of hematopoietic malignancies in vitro and in vivo without affecting naïve healthy cells. This small molecule demonstrates limited toxicity and immunogenic effects, and thus, might serve as an effective strategy to treat specific hematopoietic malignancies in a safe and precisely targeted manner.
Assuntos
Antineoplásicos/metabolismo , Antineoplásicos/uso terapêutico , Neoplasias Hematológicas/tratamento farmacológico , Proteína da Síndrome de Wiskott-Aldrich/metabolismo , Actinas/metabolismo , Animais , Antineoplásicos/farmacocinética , Antineoplásicos/farmacologia , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Proteínas do Citoesqueleto/metabolismo , Neoplasias Hematológicas/metabolismo , Neoplasias Hematológicas/patologia , Humanos , Integrinas/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Camundongos , Invasividade Neoplásica , Ligação Proteica/efeitos dos fármacos , Bibliotecas de Moléculas Pequenas/metabolismo , Bibliotecas de Moléculas Pequenas/farmacocinética , Bibliotecas de Moléculas Pequenas/farmacologia , Bibliotecas de Moléculas Pequenas/uso terapêutico , Ubiquitinação/efeitos dos fármacos , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
The emergence of immunotherapy for cancer treatment bears considerable clinical promise. Nevertheless, many patients remain unresponsive, acquire resistance, or suffer dose-limiting toxicities. Immune-editing of tumors assists their escape from the immune system, and the tumor microenvironment (TME) induces immune suppression through multiple mechanisms. Immunotherapy aims to bolster the activity of immune cells against cancer by targeting these suppressive immunomodulatory processes. Natural Killer (NK) cells are a heterogeneous subset of immune cells, which express a diverse array of activating and inhibitory germline-encoded receptors, and are thus capable of directly targeting and killing cancer cells without the need for MHC specificity. Furthermore, they play a critical role in triggering the adaptive immune response. Enhancing the function of NK cells in the context of cancer is therefore a promising avenue for immunotherapy. Different NK-based therapies have been evaluated in clinical trials, and some have demonstrated clinical benefits, especially in the context of hematological malignancies. Solid tumors remain much more difficult to treat, and the time point and means of intervention of current NK-based treatments still require optimization to achieve long term effects. Here, we review recently described mechanisms of cancer evasion from NK cell immune surveillance, and the therapeutic approaches that aim to potentiate NK function. Specific focus is placed on the use of specialized monoclonal antibodies against moieties on the cancer cell, or on both the tumor and the NK cell. In addition, we highlight newly identified mechanisms that inhibit NK cell activity in the TME, and describe how biochemical modifications of the TME can synergize with current treatments and increase susceptibility to NK cell activity.
Assuntos
Vacinas Anticâncer/imunologia , Neoplasias Hematológicas/terapia , Imunoterapia Adotiva/métodos , Células Matadoras Naturais/imunologia , Animais , Ensaios Clínicos como Assunto , Humanos , Células Matadoras Naturais/transplante , Microambiente TumoralRESUMO
The COVID-19 pandemic is shining a spotlight on the field of immunology like never before. To appreciate the diverse ways in which immunologists have contributed, Nature Reviews Immunology invited the president of the International Union of Immunological Societies and the presidents of 15 other national immunology societies to discuss how they and their members responded following the emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).
Assuntos
COVID-19/epidemiologia , Infecções por Coronavirus/epidemiologia , Cooperação Internacional , Pandemias , Pneumonia Viral/epidemiologia , Síndrome Respiratória Aguda Grave/epidemiologia , Sociedades Científicas/organização & administração , Antivirais/síntese química , Antivirais/uso terapêutico , Betacoronavirus/efeitos dos fármacos , Betacoronavirus/imunologia , Betacoronavirus/patogenicidade , COVID-19/imunologia , COVID-19/prevenção & controle , COVID-19/terapia , Vacinas contra COVID-19 , Relações Comunidade-Instituição , Infecções por Coronavirus/imunologia , Infecções por Coronavirus/prevenção & controle , Infecções por Coronavirus/terapia , Saúde Global/tendências , Humanos , Educação de Pacientes como Assunto/organização & administração , Equipamento de Proteção Individual/provisão & distribuição , Pneumonia Viral/imunologia , Pneumonia Viral/terapia , SARS-CoV-2 , Síndrome Respiratória Aguda Grave/imunologia , Síndrome Respiratória Aguda Grave/terapia , Vacinas Virais/biossínteseRESUMO
Bam32 (B lymphocyte adapter molecule of 32 kDa) is an adapter protein expressed in some hematopoietic cells including B and T lymphocytes. It was previously shown that Bam32-deficient mice have defects in various aspects of B cell activation including B cell receptor (BCR)-induced Erk activation, BCR-induced proliferation and T-independent antibody responses. In this study, we have examined the role of Bam32 in T cell activation using Bam32-deficient mice. By comparing CD4(+) T cells from lymph nodes of wild-type and Bam32-deficient mice, we found that Bam32 was required for optimal TCR-induced Erk activation, cytokine production, proliferation and actin-mediated spreading of CD4(+) T cells. These results indicate a novel pathway to Erk activation in T cells involving the adapter protein Bam32.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Linfócitos T CD4-Positivos/metabolismo , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Lipoproteínas/metabolismo , Actinas/genética , Actinas/imunologia , Proteínas Adaptadoras de Transdução de Sinal/genética , Proteínas Adaptadoras de Transdução de Sinal/imunologia , Animais , Adesão Celular/imunologia , Proliferação de Células , Citocinas/metabolismo , Ativação Enzimática/genética , MAP Quinases Reguladas por Sinal Extracelular/imunologia , Humanos , Células Jurkat , Lipoproteínas/genética , Lipoproteínas/imunologia , Ativação Linfocitária/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptores de Antígenos de Linfócitos T/genética , Receptores de Antígenos de Linfócitos T/metabolismo , Transdução de SinaisRESUMO
The process of mechanotransduction, that is, conversion of physical forces into biochemical signaling cascades, has attracted interest as a potential mechanism for regulating immune cell activation. The cytoskeleton serves a critical role in a variety of lymphocyte functions, from cellular activation, proliferation, adhesion, and migration, to creation of stable immune synapses, and execution of functions such as directed cytotoxicity. Though traditionally considered a scaffold that enables formation of signaling complexes that maintain stable immune synapses, the cytoskeleton was additionally shown to play a dynamic role in lymphocyte signaling cascades by sensing physical cues such as substrate rigidity, and transducing these mechanical features into chemical signals that ultimately influence lymphocyte effector functions. It is thus becoming clear that cytoskeletal dynamics are essential for the lymphocyte response, beyond the role of the cytoskeleton as a stationary framework. Here, we describe the transduction of extracellular forces to activate signaling pathways and effector functions mediated through the cytoskeleton in lymphocytes. We also highlight recent discoveries of cytoskeleton-mediated mechanotransduction on intracellular signaling pathways in NK cells.