RESUMEN

Follicular regulatory T (Tfr) cells differentiate from conventional regulatory T (Treg) cells and suppress excessive germinal center (GC) responses by acting on both GC B cells and T follicular helper (Tfh) cells. Here, we examined the impact of mTOR, a serine/threonine protein kinase that senses and integrates diverse environmental cues, on the differentiation and functional competency of Tfr cells in response to protein immunization or viral infection. By genetically deleting Rptor or Rictor, essential components for mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2), respectively, we found that mTORC1 but not mTORC2 is essential for Tfr differentiation. Mechanistically, mTORC1-mediated phosphorylation of the transcription factor STAT3 induced the expression of the transcription factor TCF-1 by promoting STAT3 binding to the Tcf7 5'-regulatory region. Subsequently, TCF-1 bound to the Bcl6 promoter to induce Bcl6 expression, which launched the Tfr cell differentiation program. Thus, mTORC1 initiates Tfr cell differentiation by activating the TCF-1-Bcl-6 axis during immunization or infection.

Asunto(s)

Inmunomodulación , Complejos Multiproteicos/metabolismo , Linfocitos T Reguladores/inmunología , Linfocitos T Reguladores/metabolismo , Serina-Treonina Quinasas TOR/metabolismo , Animales , Biomarcadores , Diferenciación Celular/inmunología , Análisis por Conglomerados , Perfilación de la Expresión Génica , Factor Nuclear 1-alfa del Hepatocito/metabolismo , Inmunización , Inmunofenotipificación , Diana Mecanicista del Complejo 1 de la Rapamicina , Ratones , Ratones Transgénicos , Complejos Multiproteicos/genética , Proteínas Proto-Oncogénicas c-bcl-6/metabolismo , Factor de Transcripción STAT3/metabolismo , Transducción de Señal , Linfocitos T Reguladores/citología , Serina-Treonina Quinasas TOR/genética

RESUMEN

The mammalian target of rapamycin (mTOR) is a serine-threonine kinase that has been shown to be essential for the differentiation and function of various immune cells. Earlier in vitro studies showed that mTOR signalling regulates B-cell biology by supporting their activation and proliferation. However, how mTOR signalling temporally regulates in vivo germinal centre B (GCB) cell development and differentiation into short-lived plasma cells, long-lived plasma cells and memory cells is still not well understood. In this study, we used a combined conditional/inducible knock-out system to investigate the temporal regulation of mTOR complex 1 (mTORC1) in the GCB cell response to acute lymphocytic choriomeningitis virus infection by deleting Raptor, a main component of mTORC1, specifically in B cells in pre- and late GC phase. Early Raptor deficiency strongly inhibited GCB cell proliferation and differentiation and plasma cell differentiation. Nevertheless, late GC Raptor deficiency caused only decreases in the size of memory B cells and long-lived plasma cells through poor maintenance of GCB cells, but it did not change their differentiation. Collectively, our data revealed that mTORC1 signalling supports GCB cell responses at both early and late GC phases during viral infection but does not regulate GCB cell differentiation into memory B cells and plasma cells at the late GC stage.

Asunto(s)

Proteínas Adaptadoras Transductoras de Señales/metabolismo , Linfocitos B/enzimología , Centro Germinal/enzimología , Coriomeningitis Linfocítica/enzimología , Virus de la Coriomeningitis Linfocítica/inmunología , Complejos Multiproteicos/metabolismo , Serina-Treonina Quinasas TOR/metabolismo , Proteínas Adaptadoras Transductoras de Señales/deficiencia , Proteínas Adaptadoras Transductoras de Señales/genética , Proteínas Adaptadoras Transductoras de Señales/inmunología , Animales , Linfocitos B/inmunología , Linfocitos B/trasplante , Linfocitos B/virología , Trasplante de Médula Ósea , Diferenciación Celular , Proliferación Celular , Modelos Animales de Enfermedad , Predisposición Genética a la Enfermedad , Centro Germinal/inmunología , Centro Germinal/virología , Interacciones Huésped-Patógeno , Inmunidad Humoral , Memoria Inmunológica , Activación de Linfocitos , Coriomeningitis Linfocítica/genética , Coriomeningitis Linfocítica/inmunología , Coriomeningitis Linfocítica/virología , Virus de la Coriomeningitis Linfocítica/patogenicidad , Diana Mecanicista del Complejo 1 de la Rapamicina , Ratones Endogámicos C57BL , Ratones Noqueados , Complejos Multiproteicos/deficiencia , Complejos Multiproteicos/genética , Complejos Multiproteicos/inmunología , Fenotipo , Células Plasmáticas/enzimología , Células Plasmáticas/inmunología , Células Plasmáticas/virología , Proteína Reguladora Asociada a mTOR , Transducción de Señal , Serina-Treonina Quinasas TOR/deficiencia , Serina-Treonina Quinasas TOR/genética , Serina-Treonina Quinasas TOR/inmunología , Factores de Tiempo , Quimera por Trasplante

RESUMEN

Accumulating evidence indicates that microRNAs function as oncogenes or tumor suppressor genes in human cancer. MiR-503 is deregulated in various human cancers and has been associated with hepatocellular carcinoma (HCC) progression. However, the underlying mechanisms of miR-503 involvement in the development and progression of HCC remains poorly understood. In the present study, we report that miR-503 suppresses cell metastasis in HCC through targeting the protein arginine methyl transferase 1 (PRMT1) mRNA. Notably, we identified that miR-503 was able to target 3'-untranslated region (3'-UTR) of PRMT1 mRNA by luciferase reporter gene assays. Then, we revealed that miR-503 was able to reduce the expression of PRMT1 at the levels of mRNA and protein using RT-PCR and Western blotting analysis. The expression levels of miR-503 were negatively related to those of PRMT1 mRNA in clinical HCC tissues. In terms of function, transwell and wound healing assays demonstrated that the miR-503 remarkably inhibited invasion and migration of HCC cells, which was reversed by overexpressed PRMT1. Furthermore, exogenous expression of miR-503 dramatically suppressed epithelial-mesenchymal transition (EMT) via PRMT1 in HCC cells. In conclusion, we denomstrated PRMT1 as a novel target gene of miR-503 and miR-503-mediated PRMT1 could also emerge as a potential important biomarker for HCC.

Asunto(s)

Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/metabolismo , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/metabolismo , MicroARNs/genética , MicroARNs/metabolismo , Proteína-Arginina N-Metiltransferasas/antagonistas & inhibidores , Proteína-Arginina N-Metiltransferasas/genética , Proteínas Represoras/antagonistas & inhibidores , Proteínas Represoras/genética , Regiones no Traducidas 3' , Biomarcadores de Tumor/genética , Biomarcadores de Tumor/metabolismo , Carcinoma Hepatocelular/secundario , Movimiento Celular , Transición Epitelial-Mesenquimal/genética , Células Hep G2 , Humanos , Neoplasias Hepáticas/terapia , Terapia Molecular Dirigida , Invasividad Neoplásica/genética , Invasividad Neoplásica/prevención & control , Metástasis de la Neoplasia/genética , Metástasis de la Neoplasia/prevención & control