RESUMEN
The unfolded protein response (UPR) is an adaptive signaling pathway activated in response to endoplasmic reticulum (ER) stress. The effectors of the UPR are potent transcription activators; however, some genes are suppressed by ER stress at the mRNA level. The mechanisms underlying UPR-mediated gene suppression are less known. Exploration of the effect of UPR on NK cells ligand expression found that the transcription of NK group 2 member D (NKG2D) ligand major histocompatibility complex class I polypeptide-related sequence A/B (MICA/B) is suppressed by the inositol-requiring enzyme 1 (IRE1)/X-box binding protein 1 (XBP1) pathway of the UPR. Deletion of IRE1 or XBP1 was sufficient to promote mRNA and surface levels of MICA. Accordingly, NKG2D played a greater role in the killing of IRE1/XBP1 knockout target cells. Analysis of effectors downstream to XBP1s identified E2F transcription factor 1 (E2F1) as linking UPR and MICA transcription. The inverse correlation between XBP1 and E2F1 or MICA expression was corroborated in RNA-Seq analysis of 470 primary melanoma tumors. While mechanisms that connect XBP1 to E2F1 are not fully understood, we implicate a few microRNA molecules that are modulated by ER stress and possess dual suppression of E2F1 and MICA. Because of the importance of E2F1 and MICA in cancer progression and recognition, these observations could be exploited for cancer therapy by manipulating the UPR in tumor cells.-Obiedat, A., Seidel, E., Mahameed, M., Berhani, O., Tsukerman, P., Voutetakis, K., Chatziioannou, A., McMahon, M., Avril, T., Chevet, E., Mandelboim, O., Tirosh, B. Transcription of the NKG2D ligand MICA is suppressed by the IRE1/XBP1 pathway of the unfolded protein response through the regulation of E2F1.
Asunto(s)
Factor de Transcripción E2F1/genética , Endorribonucleasas/genética , Antígenos de Histocompatibilidad Clase I/genética , Subfamilia K de Receptores Similares a Lectina de Células NK/genética , Proteínas Serina-Treonina Quinasas/genética , Respuesta de Proteína Desplegada/genética , Proteína 1 de Unión a la X-Box/genética , Línea Celular Tumoral , Retículo Endoplásmico/genética , Estrés del Retículo Endoplásmico/genética , Humanos , Ligandos , ARN Mensajero/genética , Transducción de Señal/genética , Factores de Transcripción/genética , Transcripción Genética/genéticaRESUMEN
The recent approval of oncolytic virus for therapy of melanoma patients has increased the need for precise evaluation of the mechanisms by which oncolytic viruses affect tumor growth. Here we show that the human NK cell-activating receptor NKp46 and the orthologous mouse protein NCR1 recognize the reovirus sigma1 protein in a sialic-acid-dependent manner. We identify sites of NKp46/NCR1 binding to sigma1 and show that sigma1 binding by NKp46/NCR1 leads to NK cell activation in vitro Finally, we demonstrate that NCR1 activation is essential for reovirus-based therapy in vivo Collectively, we have identified sigma1 as a novel ligand for NKp46/NCR1 and demonstrated that NKp46/NCR1 is needed both for clearance of reovirus infection and for reovirus-based tumor therapy.IMPORTANCE Reovirus infects much of the population during childhood, causing mild disease, and hence is considered to be efficiently controlled by the immune system. Reovirus also specifically infects tumor cells, leading to tumor death, and is currently being tested in human clinical trials for cancer therapy. The mechanisms by which our immune system controls reovirus infection and tumor killing are not well understood. We report here that natural killer (NK) cells recognize a viral protein named sigma1 through the NK cell-activating receptor NKp46. Using several mouse tumor models, we demonstrate the importance of NK cells in protection from reovirus infection and in reovirus killing of tumors in vivo Collectively, we identify a new ligand for the NKp46 receptor and provide evidence for the importance of NKp46 in the control of reovirus infections and in reovirus-based cancer therapy.
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Antígenos Ly/metabolismo , Células Asesinas Naturales/inmunología , Orthoreovirus Mamífero 3/metabolismo , Receptor 1 Gatillante de la Citotoxidad Natural/metabolismo , Viroterapia Oncolítica/métodos , Virus Oncolíticos/metabolismo , Proteínas Virales/metabolismo , Animales , Sitios de Unión , Chlorocebus aethiops , Modelos Animales de Enfermedad , Ensayo de Inmunoadsorción Enzimática , Humanos , Activación de Linfocitos/inmunología , Melanoma/terapia , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Noqueados , Ácido N-Acetilneuramínico/metabolismo , Células Vero , Proteínas Virales/genéticaRESUMEN
PML-RARA and AML1-ETO are important oncogenic fusion proteins that play a central role in transformation to acute myeloid leukemia (AML). Whether these fusion proteins render the tumor cells with immune evasion properties is unknown. Here we show that both oncogenic proteins specifically downregulate the expression of CD48, a ligand of the natural killer (NK) cell activating receptor 2B4, thereby leading to decreased killing by NK cells. We demonstrate that this process is histone deacetylase (HDAC)-dependent, that it is mediated through the downregulation of CD48 messenger RNA, and that treatment with HDAC inhibitors (HDACi) restores the expression of CD48. Furthermore, by using chromatin immunoprecepitation (ChIP) experiments, we show that AML1-ETO directly interacts with CD48. Finally, we show that AML patients who are carrying these specific translocations have low expression of CD48.
Asunto(s)
Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/inmunología , Proteínas de Fusión Oncogénica/genética , Proteínas de Fusión Oncogénica/inmunología , Escape del Tumor/genética , Escape del Tumor/inmunología , Antígenos CD/química , Antígenos CD/genética , Antígenos CD/metabolismo , Secuencia de Bases , Antígeno CD48 , Línea Celular Tumoral , Subunidad alfa 2 del Factor de Unión al Sitio Principal/genética , Subunidad alfa 2 del Factor de Unión al Sitio Principal/inmunología , Citotoxicidad Inmunológica , Expresión Génica , Regulación de la Expresión Génica , Histona Desacetilasas/metabolismo , Humanos , Células Asesinas Naturales/inmunología , Células Asesinas Naturales/metabolismo , Leucemia Mieloide Aguda/metabolismo , Datos de Secuencia Molecular , Proteínas de Fusión Oncogénica/metabolismo , Proteína 1 Compañera de Translocación de RUNX1RESUMEN
NK cells are innate immune lymphocytes that express a vast repertoire of germ-line encoded receptors for target recognition. These receptors include inhibitory and activating proteins, among the latter of which is CD16, a low affinity binding Fc receptor. Here, we show that human NK cells expand in response to stimulation with various tumor cell lines. We further demonstrate that the tumor-derived expansion of NK cells is accompanied by rapid, cell-dependent, changes in CD16 expression levels. We show that in NK cells expanded in response to the EBV-transformed cell line 721.221, CD16 is shed and therefore approximately half of the expanded 721.221-derived NK-cell population does not express CD16. We also show, in contrast, that in response to 1106mel cells, CD16 expression is maintained on the cell surface of the expanded NK cells due to an antibody-dependent mechanism. Our results may provide a basis for the selective expansion of NK cells that may be used for tumor immunotherapy.
Asunto(s)
Anticuerpos Antineoplásicos/inmunología , Regulación de la Expresión Génica/inmunología , Neoplasias/inmunología , Receptores de IgG/inmunología , Línea Celular Transformada , Línea Celular Tumoral , Técnicas de Cocultivo , Femenino , Proteínas Ligadas a GPI/biosíntesis , Proteínas Ligadas a GPI/genética , Proteínas Ligadas a GPI/inmunología , Regulación de la Expresión Génica/genética , Humanos , Inmunoterapia , Células Asesinas Naturales , Masculino , Neoplasias/genética , Neoplasias/metabolismo , Receptores de IgG/biosíntesis , Receptores de IgG/genéticaRESUMEN
Natural killer (NK) cells are innate immune cells able to rapidly kill virus-infected and tumor cells. Two NK cell populations are found in the blood; the majority (90%) expresses the CD16 receptor and also express the CD56 protein in intermediate levels (CD56(Dim) CD16(Pos)) while the remaining 10% are CD16 negative and express CD56 in high levels (CD56(Bright) CD16(Neg)). NK cells also reside in some tissues and traffic to various infected organs through the usage of different chemokines and chemokine receptors. Kaposi's sarcoma-associated herpesvirus (KSHV) is a human virus that has developed numerous sophisticated and versatile strategies to escape the attack of immune cells such as NK cells. Here, we investigate whether the KSHV derived cytokine (vIL-6) and chemokines (vMIP-I, vMIP-II, vMIP-III) affect NK cell activity. Using transwell migration assays, KSHV infected cells, as well as fusion and recombinant proteins, we show that out of the four cytokine/chemokines encoded by KSHV, vMIP-II is the only one that binds to the majority of NK cells, affecting their migration. We demonstrate that vMIP-II binds to two different receptors, CX3CR1 and CCR5, expressed by naïve CD56(Dim) CD16(Pos) NK cells and activated NK cells, respectively. Furthermore, we show that the binding of vMIP-II to CX3CR1 and CCR5 blocks the binding of the natural ligands of these receptors, Fractalkine (Fck) and RANTES, respectively. Finally, we show that vMIP-II inhibits the migration of naïve and activated NK cells towards Fck and RANTES. Thus, we present here a novel mechanism in which KSHV uses a unique protein that antagonizes the activity of two distinct chemokine receptors to inhibit the migration of naïve and activated NK cells.
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Fármacos Anti-VIH/farmacología , Antagonistas de los Receptores CCR5 , Movimiento Celular/efectos de los fármacos , Quimiocinas/farmacología , Herpesvirus Humano 8/química , Células Asesinas Naturales/efectos de los fármacos , Receptores de Quimiocina/antagonistas & inhibidores , Receptor 1 de Quimiocinas CX3C , Células Cultivadas , Quimiocina CCL5/metabolismo , Quimiocina CX3CL1/metabolismo , Citocinas/genética , Citocinas/metabolismo , Humanos , Immunoblotting , Interleucina-6 , Células Asesinas Naturales/citología , Células Asesinas Naturales/metabolismo , Reacción en Cadena de la Polimerasa , Receptores CCR5/genética , Receptores CCR5/metabolismo , Receptores de Quimiocina/genética , Receptores de Quimiocina/metabolismoRESUMEN
Natural Killer (NK) cells play a central role in the defense against viral infections and in the elimination of transformed cells. The recognition of pathogen-infected and tumor cells is controlled by inhibitory and activating receptors. We have previously shown that among the activating (killer) NK cell receptors the natural cytotoxicity receptors, NKp44 and NKp46, interact with the viral hemagglutinin (HA) protein expressed on the cell surface of influenza-virus-infected cells. We further showed that the interaction between NKp44/NKp46 and viral HA is sialic-acid dependent and that the recognition of HA by NKp44 and NKp46 leads to the elimination of the infected cells. Here we demonstrate that the influenza virus developed a counter-attack mechanism and that the virus uses its neuraminidase (NA) protein to prevent the recognition of HA by both the NKp44 and NKp46 receptors, resulting in reduced elimination of the infected cells by NK cells.
Asunto(s)
Virus de la Influenza A/fisiología , Neuraminidasa/metabolismo , Receptores de Células Asesinas Naturales/metabolismo , Animales , Línea Celular Tumoral , Hemaglutininas/metabolismo , Humanos , Ratones , Neuraminidasa/genéticaRESUMEN
The activity of natural killer (NK) cells is controlled by a balance of signals derived from inhibitory and activating receptors. TIGIT is a novel inhibitory receptor, recently shown in humans to interact with two ligands: PVR and Nectin2 and to inhibit human NK-cell cytotoxicity. Whether mouse TIGIT (mTIGIT) inhibits mouse NK-cell cytotoxicity is unknown. Here we show that mTIGIT is expressed by mouse NK cells and interacts with mouse PVR. Using mouse and human Ig fusion proteins we show that while the human TIGIT (hTIGIT) cross-reacts with mouse PVR (mPVR), the binding of mTIGIT is restricted to mPVR. We further demonstrate using surface plasmon resonance (SPR) and staining with Ig fusion proteins that mTIGIT binds to mPVR with higher affinity than the co-stimulatory PVR-binding receptor mouse DNAM1 (mDNAM1). Functionally, we show that triggering of mTIGIT leads to the inhibition of NK-cell cytotoxicity, that IFN-γ secretion is enhanced when mTIGIT is blocked and that the TIGIT-mediated inhibition is dominant over the signals delivered by the PVR-binding co-stimulatory receptors. Additionally, we identify the inhibitory motif responsible for mTIGIT inhibition. In conclusion, we show that TIGIT is a powerful inhibitory receptor for mouse NK cells.
Asunto(s)
Moléculas de Adhesión Celular/metabolismo , Citotoxicidad Inmunológica , Células Asesinas Naturales/inmunología , Células Asesinas Naturales/metabolismo , Receptores Inmunológicos/metabolismo , Receptores Virales/metabolismo , Secuencia de Aminoácidos , Animales , Antígenos CD/metabolismo , Antígenos de Diferenciación de Linfocitos T/metabolismo , Antígenos de Histocompatibilidad Clase I/inmunología , Interferón gamma/biosíntesis , Ratones , Ratones Endogámicos C57BL , Nectinas , Receptores Inmunológicos/química , Proteínas Recombinantes de Fusión/metabolismo , Alineación de Secuencia , Transducción de Señal , Resonancia por Plasmón de SuperficieRESUMEN
NK cells employ a variety of activating receptors to kill virally infected and tumor cells. Prominent among these receptors are the natural cytotoxicity receptors (NCRs) (NKp30, NKp44, and NKp46), of which only NKp46 has a mouse ortholog (NCR1). The tumor ligand(s) of NKp46/NCR1 is still unknown, but it was shown that the human NKp46 and the mouse NCR1 are involved in tumor eradication both in vitro and in vivo. Whether any of the NK activating receptors is involved in the prevention of tumor metastasis is unknown. To address this question, we studied the activity of the NK cell receptor NKp46/NCR1 in two spontaneous metastasis models, the B16F10.9 melanoma (B16) and the Lewis lung carcinoma (D122) in the NCR1 knockout mouse that was generated by our group, in various in vitro and in vivo assays. We demonstrated that all B16 and D122 tumors, including those generated in vivo, express an unknown ligand(s) for NKp46/NCR1. We have characterized the properties of the NKp46/NCR1 ligand(s) and demonstrated that NKp46/NCR1 is directly involved in the killing of B16 and D122 cells. Importantly, we showed in vivo that NKp46/NCR1 plays an important role in controlling B16 and D122 metastasis. Thus, to our knowledge, in this study we provide the first evidence for the direct involvement of a specific NK killer receptor in preventing tumor metastasis.
Asunto(s)
Antígenos Ly/inmunología , Receptor 1 Gatillante de la Citotoxidad Natural/inmunología , Animales , Antígenos Ly/genética , Antígenos Ly/metabolismo , Carcinoma Pulmonar de Lewis , Separación Celular , Citotoxicidad Inmunológica/inmunología , Citometría de Flujo , Células Asesinas Naturales/inmunología , Células Asesinas Naturales/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Receptor 1 Gatillante de la Citotoxidad Natural/genética , Receptor 1 Gatillante de la Citotoxidad Natural/metabolismo , Invasividad Neoplásica/genética , Metástasis de la Neoplasia/prevención & controlRESUMEN
BACKGROUND: The use of checkpoint inhibitors has revolutionized cancer therapy. Unfortunately, these therapies often cause immune-related adverse effects, largely due to a lack of tumor specificity. METHODS: We stained human natural killer cells using fusion proteins composed of the extracellular portion of various tumor markers fused to the Fc portion of human IgG1, and identified Nectin4 as a novel TIGIT ligand. Next, we generated a novel Nectin4 blocking antibody and demonstrated its efficacy as a checkpoint inhibitor in killing assays and in vivo. RESULTS: We identify Nectin4 to be a novel ligand of TIGIT. We showed that, as opposed to all other known TIGIT ligands, which bind also additional receptors, Nectin4 interacts only with TIGIT. We show that the TIGIT-Nectin4 interaction inhibits natural killer cell activity, a critical part of the innate immune response. Finally, we developed blocking Nectin4 antibodies and demonstrated that they enhance tumor killing in vitro and in vivo. CONCLUSION: We discovered that Nectin4 is a novel ligand for TIGIT and demonstrated that specific antibodies against it enhance tumor cell killing in vitro and in vivo. Since Nectin4 is expressed almost exclusively on tumor cells, our Nectin4-blocking antibodies represent a combination of cancer specificity and immune checkpoint activity, which may prove more effective and safe for cancer immunotherapy.
Asunto(s)
Moléculas de Adhesión Celular/metabolismo , Inmunoterapia/métodos , Receptores Inmunológicos/metabolismo , Animales , Femenino , Humanos , Ligandos , RatonesRESUMEN
Long, non-coding RNAs (lncRNAs) are involved in the regulation of many cellular processes. The lncRNA IFNG-AS1 was found to strongly influence the responses to several pathogens in mice by increasing interferon gamma (IFNγ) secretion. Studies have looked at IFNG-AS1 in T cells, yet IFNG-AS1 function in natural killer cells (NKs), an important source of IFNγ, remains unknown. Here, we show a previously undescribed sequence of IFNG-AS1 and report that it may be more abundant in cells than previously thought. Using primary human NKs and an NK line with IFNG-AS1 overexpression, we show that IFNG-AS1 is quickly induced upon NK cell activation, and that IFNG-AS1 overexpression leads to increased IFNγ secretion. Taken together, our work expands IFNG-AS1's activity to the innate arm of the type I immune response, helping to explain its notable effect in animal models of disease.
RESUMEN
One of the most exciting fields in modern medicine is immunotherapy, treatment which looks to harness the power of the immune system to fight disease. A particularly effective strategy uses antibodies designed to influence the activity levels of the immune system. Here we look at two receptors - TIGIT and DNAM-1 - which bind the same ligands but have opposite effects on immune cells, earning them the label `paired receptors'. Importantly, natural killer cells and cytotoxic T cells express both of these receptors, and in certain cases their effector functions are dictated by TIGIT or DNAM-1 signaling. Agonist and antagonist antibodies targeting either TIGIT or DNAM-1 present many therapeutic options for diseases spanning from cancer to auto-immunity. In this review we present cases in which the modulation of these receptors holds potential for the development of novel therapies.
Asunto(s)
Antígenos de Diferenciación de Linfocitos T/inmunología , Antineoplásicos Inmunológicos/uso terapéutico , Enfermedades Autoinmunes/tratamiento farmacológico , Inmunoterapia/métodos , Neoplasias/tratamiento farmacológico , Receptores Inmunológicos/inmunología , Antígenos de Diferenciación de Linfocitos T/genética , Enfermedades Autoinmunes/genética , Enfermedades Autoinmunes/inmunología , Enfermedades Autoinmunes/patología , Regulación de la Expresión Génica , Humanos , Células Asesinas Naturales/efectos de los fármacos , Células Asesinas Naturales/inmunología , Células Asesinas Naturales/patología , Neoplasias/genética , Neoplasias/inmunología , Neoplasias/patología , Unión Proteica , Receptor Cross-Talk/inmunología , Receptores Inmunológicos/agonistas , Receptores Inmunológicos/antagonistas & inhibidores , Receptores Inmunológicos/genética , Transducción de Señal , Linfocitos T Citotóxicos/efectos de los fármacos , Linfocitos T Citotóxicos/inmunología , Linfocitos T Citotóxicos/patologíaRESUMEN
The poliovirus receptor (PVR) is a ubiquitously expressed glycoprotein involved in cellular adhesion and immune response. It engages the activating receptor DNAX accessory molecule (DNAM)-1, the inhibitory receptor TIGIT, and the CD96 receptor with both activating and inhibitory functions. Human cytomegalovirus (HCMV) down-regulates PVR expression, but the significance of this viral function in vivo remains unknown. Here, we demonstrate that mouse CMV (MCMV) also down-regulates the surface PVR. The m20.1 protein of MCMV retains PVR in the endoplasmic reticulum and promotes its degradation. A MCMV mutant lacking the PVR inhibitor was attenuated in normal mice but not in mice lacking DNAM-1. This attenuation was partially reversed by NK cell depletion, whereas the simultaneous depletion of mononuclear phagocytes abolished the virus control. This effect was associated with the increased expression of DNAM-1, whereas TIGIT and CD96 were absent on these cells. An increased level of proinflammatory cytokines in sera of mice infected with the virus lacking the m20.1 and an increased production of iNOS by inflammatory monocytes was observed. Blocking of CCL2 or the inhibition of iNOS significantly increased titer of the virus lacking m20.1. In this study, we have demonstrated that inflammatory monocytes, together with NK cells, are essential in the early control of CMV through the DNAM-1-PVR pathway.
Asunto(s)
Antígenos de Diferenciación de Linfocitos T/fisiología , Infecciones por Citomegalovirus/etiología , Células Asesinas Naturales/fisiología , Monocitos/fisiología , Animales , Infecciones por Citomegalovirus/inmunología , Interleucina-12/biosíntesis , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Óxido Nítrico Sintasa de Tipo II/fisiología , Receptores Virales/antagonistas & inhibidores , Receptores Virales/fisiologíaRESUMEN
Cells in our body can induce hundreds of antiviral genes following virus sensing, many of which remain largely uncharacterized. CEACAM1 has been previously shown to be induced by various innate systems; however, the reason for such tight integration to innate sensing systems was not apparent. Here, we show that CEACAM1 is induced following detection of HCMV and influenza viruses by their respective DNA and RNA innate sensors, IFI16 and RIG-I. This induction is mediated by IRF3, which bound to an ISRE element present in the human, but not mouse, CEACAM1 promoter. Furthermore, we demonstrate that, upon induction, CEACAM1 suppresses both HCMV and influenza viruses in an SHP2-dependent process and achieves this broad antiviral efficacy by suppressing mTOR-mediated protein biosynthesis. Finally, we show that CEACAM1 also inhibits viral spread in ex vivo human decidua organ culture.
Asunto(s)
Antígenos CD/metabolismo , Moléculas de Adhesión Celular/metabolismo , Citomegalovirus/fisiología , Orthomyxoviridae/fisiología , Animales , Infecciones por Citomegalovirus/metabolismo , Infecciones por Citomegalovirus/virología , Proteína 58 DEAD Box/metabolismo , ADN Viral/metabolismo , Humanos , Gripe Humana/metabolismo , Gripe Humana/virología , Factor 3 Regulador del Interferón/metabolismo , Ratones , Técnicas de Cultivo de Órganos , Biosíntesis de Proteínas , Receptores Inmunológicos , Serina-Treonina Quinasas TOR/metabolismo , Replicación ViralRESUMEN
Genetic deficiencies provide insights into gene function in humans. Here we describe a patient with a very rare genetic deficiency of ADAM17. We show that the patient's PBMCs had impaired cytokine secretion in response to LPS stimulation, correlating with the clinical picture of severe bacteremia from which the patient suffered. ADAM17 was shown to cleave CD16, a major NK killer receptor. Functional analysis of patient's NK cells demonstrated that his NK cells express normal levels of activating receptors and maintain high surface levels of CD16 following mAb stimulation. Activation of individual NK cell receptors showed that the patient's NK cells are more potent when activated directly by CD16, albeit no difference was observed in Antibody Depedent Cytotoxicity (ADCC) assays. Our data suggest that ADAM17 inhibitors currently considered for clinical use to boost CD16 activity should be cautiously applied, as they might have severe side effects resulting from impaired cytokine secretion.
Asunto(s)
Proteínas ADAM/deficiencia , Citocinas/metabolismo , Síndromes de Inmunodeficiencia/enzimología , Células Asesinas Naturales/enzimología , Leucocitos Mononucleares/enzimología , Activación de Linfocitos , Proteínas ADAM/genética , Proteínas ADAM/inmunología , Proteína ADAM17 , Citotoxicidad Celular Dependiente de Anticuerpos , Línea Celular Tumoral , Preescolar , Citocinas/inmunología , Resultado Fatal , Proteínas Ligadas a GPI/inmunología , Proteínas Ligadas a GPI/metabolismo , Predisposición Genética a la Enfermedad , Humanos , Inmunidad Innata , Síndromes de Inmunodeficiencia/diagnóstico , Síndromes de Inmunodeficiencia/genética , Síndromes de Inmunodeficiencia/inmunología , Células Asesinas Naturales/inmunología , Leucocitos Mononucleares/efectos de los fármacos , Leucocitos Mononucleares/inmunología , Lipopolisacáridos/farmacología , Masculino , Fenotipo , Receptores de IgG/inmunología , Receptores de IgG/metabolismoRESUMEN
Natural killer (NK) cells mediate innate immune responses against hazardous cells and are particularly important for the control of human cytomegalovirus (HCMV). NKG2D is a key NK activating receptor that recognizes a family of stress-induced ligands, including MICA, MICB, and ULBP1-6. Notably, most of these ligands are targeted by HCMV proteins and a miRNA to prevent the killing of infected cells by NK cells. A particular highly prevalent MICA allele, MICA∗008, is considered to be an HCMV-resistant "escape variant" that confers advantage to human NK cells in recognizing infected cells. However, here we show that HCMV uses its viral glycoprotein US9 to specifically target MICA∗008 and thus escapes NKG2D attack. The finding that HCMV evolved a protein dedicated to countering a single host allele illustrates the dynamic co-evolution of host and pathogen.
RESUMEN
MicroRNAs are key players in most biological processes. Some microRNAs are involved in the genesis of tumors and are therefore termed oncomiRs, while others, termed metastamiRs, play a significant role in the formation of cancer metastases. Previously, we identified ten different cellular microRNAs that downregulate the expression of MICB, a ligand of the activating NK receptor NKG2D. Interestingly, several of the ten MICB-targeting microRNAs, such as miR-10b, are involved in tumor formation and metastasis. In this work, we identify a complex interplay between these different microRNAs. Specifically, we demonstrate that three of the MICB-targeting microRNAs: miR-20a, miR-17-5p and miR-93, also target the same site in the 3'UTR of TWIST1, a transcription factor implicated in cancer metastasis. Additionally, we show that miR-520d-5p targets a different site in the 3'UTR of TWIST1. We next show that the miR-520d-5p-mediated decrease of TWIST1 expression results in reduced expression of one of its targets, miR-10b, and in the restoration of E-Cadherin expression, which in turn results in reduced cellular motility and invasiveness. Finally, we show that miR-520d-5p leads to reduced proliferation of tumor cells, and that high levels of miR-520d-5p correlate with higher survival rates of cancer patients.
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Regulación Neoplásica de la Expresión Génica/genética , MicroARNs/genética , Invasividad Neoplásica/genética , Neoplasias/genética , Proteínas Nucleares/biosíntesis , Proteína 1 Relacionada con Twist/biosíntesis , Secuencia de Aminoácidos , Western Blotting , Línea Celular Tumoral , Regulación hacia Abajo , Citometría de Flujo , Humanos , Datos de Secuencia Molecular , Neoplasias/mortalidad , Reacción en Cadena en Tiempo Real de la PolimerasaRESUMEN
TOP mRNAs encode components of the translational apparatus, and repression of their translation comprises one mechanism, by which cells encountering amino acid deprivation downregulate the biosynthesis of the protein synthesis machinery. This mode of regulation involves TSC as knockout of TSC1 or TSC2 rescued TOP mRNAs translation in amino acid-starved cells. The involvement of mTOR in translational control of TOP mRNAs is demonstrated by the ability of constitutively active mTOR to relieve the translational repression of TOP mRNA upon amino acid deprivation. Consistently, knockdown of this kinase as well as its inhibition by pharmacological means blocked amino acid-induced translational activation of these mRNAs. The signaling of amino acids to TOP mRNAs involves RagB, as overexpression of active RagB derepressed the translation of these mRNAs in amino acid-starved cells. Nonetheless, knockdown of raptor or rictor failed to suppress translational activation of TOP mRNAs by amino acids, suggesting that mTORC1 or mTORC2 plays a minor, if any, role in this mode of regulation. Finally, miR10a has previously been suggested to positively regulate the translation of TOP mRNAs. However, we show here that titration of this microRNA failed to downregulate the basal translation efficiency of TOP mRNAs. Moreover, Drosha knockdown or Dicer knockout, which carries out the first and second processing steps in microRNAs biosynthesis, respectively, failed to block the translational activation of TOP mRNAs by amino acid or serum stimulation. Evidently, these results are questioning the positive role of microRNAs in this mode of regulation.
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MicroARNs/genética , Complejos Multiproteicos/genética , Biosíntesis de Proteínas , Transducción de Señal/genética , Serina-Treonina Quinasas TOR/genética , Proteínas Supresoras de Tumor/genética , Aminoácidos/genética , Animales , Regulación de la Expresión Génica , Humanos , Diana Mecanicista del Complejo 1 de la Rapamicina , Diana Mecanicista del Complejo 2 de la Rapamicina , Ratones , Ratones Noqueados , Fosforilación , ARN Mensajero/genética , Proteína 1 del Complejo de la Esclerosis TuberosaRESUMEN
Metastases are responsible for more than 90% of cancer-related deaths. We have recently reported that miR-10b inhibits the expression of MICB, a stress-induced ligand of the activating natural killer (NK)-cell receptor NKG2D. Here, we discuss our findings, which link metastasis formation to immune evasion.
RESUMEN
HLA-G is a non-classical HLA class-Ib molecule expressed mainly by the extravillous cytotrophoblasts (EVT) of the placenta. The expression of HLA-G on these fetal cells protects the EVT cells from immune rejection and is therefore important for a healthy pregnancy. The mechanisms controlling HLA-G expression are largely unknown. Here we demonstrate that miR-148a and miR-152 down-regulate HLA-G expression by binding its 3'UTR and that this down-regulation of HLA-G affects LILRB1 recognition and consequently, abolishes the LILRB1-mediated inhibition of NK cell killing. We further demonstrate that the C/G polymorphism at position +3142 of HLA-G 3'UTR has no effect on the miRNA targeting of HLA-G. We show that in the placenta both miR-148a and miR-152 miRNAs are expressed at relatively low levels, compared to other healthy tissues, and that the mRNA levels of HLA-G are particularly high and we therefore suggest that this might enable the tissue specific expression of HLA-G.
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Antígenos HLA-G/genética , Antígenos HLA-G/inmunología , MicroARNs/genética , Embarazo/genética , Embarazo/inmunología , Regiones no Traducidas 3' , Antígenos CD/inmunología , Secuencia de Bases , Línea Celular , Regulación hacia Abajo , Femenino , Histocompatibilidad Materno-Fetal/genética , Histocompatibilidad Materno-Fetal/inmunología , Humanos , Células Asesinas Naturales/inmunología , Receptor Leucocitario Tipo Inmunoglobulina B1 , ARN Mensajero/genética , ARN Mensajero/metabolismo , Receptores Inmunológicos/inmunología , Distribución Tisular , Trofoblastos/inmunologíaRESUMEN
Natural killer (NK) cells are innate cytotoxic lymphocytes that specialize in the defense against viral infection and oncogenic transformation. Their action is tightly regulated by signals derived from inhibitory and activating receptors; the later include proteins such as the Natural Cytotoxicity Receptors (NCRs: NKp46, NKp44 and NKp30). Among the NCRs, NKp46 is the only receptor that has a mouse orthologue named Ncr1. NKp46/Ncr1 is also a unique marker expressed on NK and on Lymphoid tissue inducer (LTI) cells and it was implicated in the control of various viral infections, cancer and diabetes. We have previously shown that human NKp46 recognizes viral hemagglutinin (HA) in a sialic acid-dependent manner and that the O-glycosylation is essential for the NKp46 binding to viral HA. Here we studied the molecular interactions between Ncr1 and influenza viruses. We show that Ncr1 recognizes influenza virus in a sialic acid dependent manner and that N-glycosylation is important for this binding. Surprisingly we demonstrate that none of the predicted N-glycosilated residues of Ncr1 are essential for its binding to influenza virus and we thus conclude that other, yet unidentified N-glycosilated residues are responsible for its recognition. We have demonstrated that N glycosylation play little role in the recognition of mouse tumor cell lines and also showed the in-vivo importance of Ncr1 in the control of influenza virus infection by infecting C57BL/6 and BALB/c mice knockout for Ncr1 with influenza.