RESUMO
Specification of the T helper 17 (Th17) cell lineage requires a well-defined set of transcription factors, but how these integrate with posttranscriptional and epigenetic programs to regulate gene expression is poorly understood. Here we found defective Th17 cell cytokine expression in miR-155-deficient CD4+ T cells in vitro and in vivo. Mir155 was bound by Th17 cell transcription factors and was highly expressed during Th17 cell differentiation. miR-155-deficient Th17 and T regulatory (Treg) cells expressed increased amounts of Jarid2, a DNA-binding protein that recruits the Polycomb Repressive Complex 2 (PRC2) to chromatin. PRC2 binding to chromatin and H3K27 histone methylation was increased in miR-155-deficient cells, coinciding with failure to express Il22, Il10, Il9, and Atf3. Defects in Th17 cell cytokine expression and Treg cell homeostasis in the absence of Mir155 could be partially suppressed by Jarid2 deletion. Thus, miR-155 contributes to Th17 cell function by suppressing the inhibitory effects of Jarid2.
Assuntos
Citocinas/genética , Regulação da Expressão Gênica , MicroRNAs/metabolismo , Complexo Repressor Polycomb 2/imunologia , Células Th17/imunologia , Fator 3 Ativador da Transcrição/genética , Fator 3 Ativador da Transcrição/metabolismo , Animais , Diferenciação Celular/imunologia , Células Cultivadas , Cromatina/genética , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , MicroRNAs/genética , Complexo Repressor Polycomb 2/genética , Complexo Repressor Polycomb 2/metabolismo , Ligação Proteica , Transdução de Sinais/genética , Transdução de Sinais/imunologia , Linfócitos T Reguladores/imunologia , Células Th1/imunologiaRESUMO
The major goal of this study was to perform an in depth characterization of the "gene signature" of human FoxP3(+) T regulatory cells (Tregs). Highly purified Tregs and T conventional cells (Tconvs) from multiple healthy donors (HD), either freshly explanted or activated in vitro, were analyzed via RNA sequencing (RNA-seq) and gene expression changes validated using the nCounter system. Additionally, we analyzed microRNA (miRNA) expression using TaqMan low-density arrays. Our results confirm previous studies demonstrating selective gene expression of FoxP3, IKZF2, and CTLA4 in Tregs. Notably, a number of yet uncharacterized genes (RTKN2, LAYN, UTS2, CSF2RB, TRIB1, F5, CECAM4, CD70, ENC1 and NKG7) were identified and validated as being differentially expressed in human Tregs. We further characterize the functional roles of RTKN2 and LAYN by analyzing their roles in vitro human Treg suppression assays by knocking them down in Tregs and overexpressing them in Tconvs. In order to facilitate a better understanding of the human Treg gene expression signature, we have generated from our results a hypothetical interactome of genes and miRNAs in Tregs and Tconvs.