RESUMEN
Regulatory factor X 7 (Rfx7) is an uncharacterized transcription factor belonging to a family involved in ciliogenesis and immunity. Here, we found that deletion of Rfx7 leads to a decrease in natural killer (NK) cell maintenance and immunity in vivo. Genomic approaches showed that Rfx7 coordinated a transcriptional network controlling cell metabolism. Rfx7-/- NK lymphocytes presented increased size, granularity, proliferation, and energetic state, whereas genetic reduction of mTOR activity mitigated those defects. Notably, Rfx7-deficient NK lymphocytes were rescued by interleukin 15 through engagement of the Janus kinase (Jak) pathway, thus revealing the importance of this signaling for maintenance of such spontaneously activated NK cells. Rfx7 therefore emerges as a novel transcriptional regulator of NK cell homeostasis and metabolic quiescence.
Asunto(s)
Interleucina-15/metabolismo , Células Asesinas Naturales/metabolismo , Factor Regulador X1/metabolismo , Animales , Proliferación Celular , Supervivencia Celular , Células Cultivadas , Quimera , Metabolismo Energético , Redes Reguladoras de Genes , Inmunidad Celular/genética , Inmunidad Innata/genética , Quinasas Janus/metabolismo , Células Asesinas Naturales/inmunología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Factor Regulador X1/genética , Transducción de Señal , Serina-Treonina Quinasas TOR/genética , Serina-Treonina Quinasas TOR/metabolismoRESUMEN
MYC is a pleiotropic transcription factor involved in cancer, cell proliferation, and metabolism. Its regulation and function in NK cells, which are innate cytotoxic lymphocytes important to control viral infections and cancer, remain poorly defined. Here, we show that mice deficient for Myc in NK cells presented a severe reduction in these lymphocytes. Myc was required for NK cell development and expansion in response to the key cytokine IL-15, which induced Myc through transcriptional and posttranslational mechanisms. Mechanistically, Myc ablation in vivo largely impacted NK cells' ribosomagenesis, reducing their translation and expansion capacities. Similar results were obtained by inhibiting MYC in human NK cells. Impairing translation by pharmacological intervention phenocopied the consequences of deleting or blocking MYC in vitro. Notably, mice lacking Myc in NK cells exhibited defective anticancer immunity, which reflected their decreased numbers of mature NK cells exerting suboptimal cytotoxic functions. These results indicate that MYC is a central node in NK cells, connecting IL-15 to translational fitness, expansion, and anticancer immunity.
Asunto(s)
Interleucina-15 , Células Asesinas Naturales , Animales , Humanos , Ratones , Citocinas/metabolismo , Regulación de la Expresión Génica , Interleucina-15/genética , Interleucina-15/metabolismo , Transducción de SeñalRESUMEN
Somewhat counterintuitively, the tyrosine phosphatase SHP-2 (SH2 domain-containing protein tyrosine phosphatase-2) is crucial for the activation of extracellular signal-regulated kinase (ERK) downstream of various growth factor receptors, thereby exerting essential developmental functions. This phosphatase also deploys proto-oncogenic functions and specific inhibitors have recently been developed. With respect to the immune system, the role of SHP-2 in the signaling of cytokines relevant for myelopoiesis and myeloid malignancies has been intensively studied. The function of this phosphatase downstream of cytokines important for lymphocytes is less understood, though multiple lines of evidence suggest its importance. In addition, SHP-2 has been proposed to mediate the suppressive effects of inhibitory receptors (IRs) that sustain a dysfunctional state in anticancer T cells. Molecules involved in IR signaling are of potential pharmaceutical interest as blockade of these inhibitory circuits leads to remarkable clinical benefit. Here, we discuss the dichotomy in the functions ascribed to SHP-2 downstream of cytokine receptors and IRs, with a focus on T and NK lymphocytes. Further, we highlight the importance of broadening our understanding of SHP-2's relevance in lymphocytes, an essential step to inform on side effects and unanticipated benefits of its therapeutic blockade.
Asunto(s)
Proteína Tirosina Fosfatasa no Receptora Tipo 11/fisiología , Receptores de Citocinas/fisiología , Receptores KIR/fisiología , Linfocitos T/inmunología , Quinasas MAP Reguladas por Señal Extracelular/fisiología , Humanos , Células Asesinas Naturales/inmunología , Neoplasias/tratamiento farmacológico , Fosfatidilinositol 3-Quinasas/fisiología , Fosforilación , Proteína Tirosina Fosfatasa no Receptora Tipo 11/antagonistas & inhibidores , Transducción de Señal/fisiologíaRESUMEN
The phosphatase Shp-2 was implicated in NK cell development and functions due to its interaction with NK inhibitory receptors, but its exact role in NK cells is still unclear. Here we show, using mice conditionally deficient for Shp-2 in the NK lineage, that NK cell development and responsiveness are largely unaffected. Instead, we find that Shp-2 serves mainly to enforce NK cell responses to activation by IL-15 and IL-2. Shp-2-deficient NK cells have reduced proliferation and survival when treated with high dose IL-15 or IL-2. Mechanistically, Shp-2 deficiency hampers acute IL-15 stimulation-induced raise in glycolytic and respiration rates, and causes a dramatic defect in ERK activation. Moreover, inhibition of the ERK and mTOR cascades largely phenocopies the defect observed in the absence of Shp-2. Together, our data reveal a critical function of Shp-2 as a molecular nexus bridging acute IL-15 signaling with downstream metabolic burst and NK cell expansion.
Asunto(s)
Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Células Asesinas Naturales/metabolismo , Proteína Tirosina Fosfatasa no Receptora Tipo 11/metabolismo , Receptores de Interleucina-15/metabolismo , Animales , Antígenos Ly/metabolismo , Recuento de Células , Proliferación Celular/efectos de los fármacos , Tamaño de la Célula/efectos de los fármacos , Activación Enzimática/efectos de los fármacos , Integrasas/metabolismo , Interleucina-15/farmacología , Células Asesinas Naturales/efectos de los fármacos , Ratones Endogámicos C57BL , Ratones Noqueados , Muromegalovirus/fisiología , Receptor 1 Gatillante de la Citotoxidad Natural/metabolismo , Proteína Tirosina Fosfatasa no Receptora Tipo 11/deficiencia , Serina-Treonina Quinasas TOR/metabolismoRESUMEN
In chronic infection and cancer, T cells acquire a dysfunctional state characterized by the expression of inhibitory receptors. In vitro studies implicated the phosphatase Shp-2 downstream of these receptors, including PD-1. However, whether Shp-2 is responsible in vivo for such dysfunctional responses remains elusive. To address this, we generated T cell-specific Shp-2-deficient mice. These mice did not show differences in controlling chronic viral infections. In this context, Shp-2-deleted CD8+ T lymphocytes expanded moderately better but were less polyfunctional than control cells. Mice with Shp-2-deficient T cells also showed no significant improvement in controlling immunogenic tumors and responded similarly to controls to α-PD-1 treatment. We therefore showed that Shp-2 is dispensable in T cells for globally establishing exhaustion and for PD-1 signaling in vivo. These results reveal the existence of redundant mechanisms downstream of inhibitory receptors and represent the foundation for defining these relevant molecular events.
Asunto(s)
Linfocitos T CD8-positivos/inmunología , Neoplasias Experimentales/inmunología , Proteína Tirosina Fosfatasa no Receptora Tipo 11/genética , Transducción de Señal , Virosis/inmunología , Animales , Línea Celular Tumoral , Femenino , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Receptor de Muerte Celular Programada 1/inmunología , Proteína Tirosina Fosfatasa no Receptora Tipo 11/inmunologíaRESUMEN
GA101, also known as obinutuzumab or Gazyva (Gazyvaro), is a glycoengineered type II humanized antibody that targets the CD20 antigen expressed at the surface of B-cells. This novel anti-CD20 antibody is currently assessed in clinical trials with promising results as a single agent or as part of therapeutic combinations for the treatment of B-cell malignancies. Detailed understanding of the mechanisms of GA101-induced cell death is needed to get insight into possible resistance mechanisms occurring in patients. Although multiple in vitro and in vivo mechanisms have been suggested to describe the effects of GA101 on B-cells, currently available data are ambiguous. The aim of our study was to clarify the cellular mechanisms involved in GA101-induced cell death in vitro, and more particularly the respective roles played by lysosomal and mitochondrial membrane permeabilization. Our results confirm previous reports suggesting that GA101 triggers homotypic adhesion and caspase-independent cell death, two processes that are dependent on actin remodeling and involve the production of reactive oxygen species. With respect to lysosomal membrane permeabilization (LMP), our data suggest that lack of specificity of available antibodies directed against cathepsin B may have confounded previously published results, possibly challenging current LMP-driven model of GA101 action mode.