RESUMO
Diverse gene regulatory mechanisms impact on immune homeostasis, and a new model now emerges as fundamental in light of recent genome-wide studies. In this picture, transcriptional networks drive functional changes during immune activation, whereas autoregulatory feedback loops of post-transcriptional programs ensure the original cell lineage identity and subsequent immune resolution.
Assuntos
Redes Reguladoras de Genes/imunologia , Imunidade/genética , Transcrição Gênica/imunologia , Animais , Redes Reguladoras de Genes/genética , Humanos , Transcrição Gênica/genéticaRESUMO
Post-transcriptional gene regulation in T cells is dynamic and complex as targeted transcripts respond to various factors. This is evident for the Icos mRNA encoding an essential costimulatory receptor that is regulated by several RNA-binding proteins (RBP), including Roquin-1 and Roquin-2. Here, we identify a core RBPome of 798 mouse and 801 human T cell proteins by utilizing global RNA interactome capture (RNA-IC) and orthogonal organic phase separation (OOPS). The RBPome includes Stat1, Stat4 and Vav1 proteins suggesting unexpected functions for these transcription factors and signal transducers. Based on proximity to Roquin-1, we select ~50 RBPs for testing coregulation of Roquin-1/2 targets by induced expression in wild-type or Roquin-1/2-deficient T cells. Besides Roquin-independent contributions from Rbms1 and Cpeb4 we also show Roquin-1/2-dependent and target-specific coregulation of Icos by Celf1 and Igf2bp3. Connecting the cellular RBPome in a post-transcriptional context, we find contributions from multiple RBPs to the prototypic regulation of mRNA targets by individual trans-acting factors.
Assuntos
RNA Mensageiro/metabolismo , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , Linfócitos T Auxiliares-Indutores/metabolismo , Animais , Proteínas de Ligação a DNA , Regulação da Expressão Gênica , Células HEK293 , Humanos , Proteína Coestimuladora de Linfócitos T Induzíveis/genética , Camundongos , Proteínas Proto-Oncogênicas c-vav , Fator de Transcrição STAT1 , Fator de Transcrição STAT4 , Transdução de Sinais , Transativadores/metabolismo , Ubiquitina-Proteína Ligases/genéticaRESUMO
Activation of immune cells results in rapid functional changes, but how such fast changes are accomplished remains enigmatic. By combining time courses of 4sU-seq, RNA-seq, ribosome profiling (RP), and RNA polymerase II (RNA Pol II) ChIP-seq during T cell activation, we illustrate genome-wide temporal dynamics for â¼10,000 genes. This approach reveals not only immediate-early and posttranscriptionally regulated genes but also coupled changes in transcription and translation for >90% of genes. Recruitment, rather than release of paused RNA Pol II, primarily mediates transcriptional changes. This coincides with a genome-wide temporary slowdown in cotranscriptional splicing, even for polyadenylated mRNAs that are localized at the chromatin. Subsequent splicing optimization correlates with increasing Ser-2 phosphorylation of the RNA Pol II carboxy-terminal domain (CTD) and activation of the positive transcription elongation factor (pTEFb). Thus, rapid de novo recruitment of RNA Pol II dictates the course of events during T cell activation, particularly transcription, splicing, and consequently translation.
Assuntos
Genoma , Biossíntese de Proteínas , RNA Polimerase II/metabolismo , Splicing de RNA/genética , Linfócitos T/metabolismo , Transcrição Gênica , Animais , Sistemas Computacionais , Camundongos Transgênicos , Fosforilação , Domínios Proteicos , RNA Polimerase II/químicaRESUMO
Bcl-3 is an atypical NF-κB family member that regulates NF-κB-dependent gene expression in effector T cells, but a cell-intrinsic function in regulatory T (Treg) cells and colitis is not clear. Here we show that Bcl-3 expression levels in colonic T cells correlate with disease manifestation in patients with inflammatory bowel disease. Mice with T-cell-specific overexpression of Bcl-3 develop severe colitis that can be attributed to defective Treg cell development and function, leading to the infiltration of immune cells such as pro-inflammatory γδT cells, but not αß T cells. In Treg cells, Bcl-3 associates directly with NF-κB p50 to inhibit DNA binding of p50/p50 and p50/p65 NF-κB dimers, thereby regulating NF-κB-mediated gene expression. This study thus reveals intrinsic functions of Bcl-3 in Treg cells, identifies Bcl-3 as a potential prognostic marker for colitis and illustrates the mechanism by which Bcl-3 regulates NF-κB activity in Tregs to prevent colitis.