Protein SUMOylation is required for regulatory T cell expansion and function
Ontology highlight
ABSTRACT: Foxp3-expressing regulatory T (Treg) cells are essential regulators in the immune system; molecular mechanisms underlying Treg cell expansion and function are still not well understood. SUMOylation is an important post-translational modification characterized by covalent attachment of SUMO moieties to lysine within proteins. UBC9 is the only E2 conjugation enzyme involved in this process and loss of UBC9 completely impairs the SUMOylation pathway. Here we report that selective deletion of Ubc9 within the Treg cell lineage resulted in fatal early-onset autoimmunity as the Foxp3 mutant mice. Ubc9-deficient Treg cells exhibited severe defects in TCR-driven homeostatic proliferation, accompanied by impaired activation and compromised suppressor function. Importantly, TCR-enhanced SUMOylation of IRF4, a critical regulator of Treg cell function downstream of TCR signals, regulates its stability in Treg cells. Our data thus have demonstrated an essential role of SUMOylation in the expansion and function of Treg cells. RNA-seq library was generated using mRNA of CD4+ YFP+ Treg cells sorted from lymph nodes and spleen of Foxp3cre/wtUbc9fl/wt or Foxp3cre/wtUbc9fl/fl mice, each sample contained pooled Treg cells from 5~10 mice.
Project description:Foxp3-expressing regulatory T (Treg) cells are essential regulators in the immune system; molecular mechanisms underlying Treg cell expansion and function are still not well understood. SUMOylation is an important post-translational modification characterized by covalent attachment of SUMO moieties to lysine within proteins. UBC9 is the only E2 conjugation enzyme involved in this process and loss of UBC9 completely impairs the SUMOylation pathway. Here we report that selective deletion of Ubc9 within the Treg cell lineage resulted in fatal early-onset autoimmunity as the Foxp3 mutant mice. Ubc9-deficient Treg cells exhibited severe defects in TCR-driven homeostatic proliferation, accompanied by impaired activation and compromised suppressor function. Importantly, TCR-enhanced SUMOylation of IRF4, a critical regulator of Treg cell function downstream of TCR signals, regulates its stability in Treg cells. Our data thus have demonstrated an essential role of SUMOylation in the expansion and function of Treg cells.
Project description:Foxp3+ T-regulatory (Treg) cells maintain immune homeostasis and limit autoimmunity, but can also curtail host responses to cancers. Tregs are therefore promising targets to enhance anti-tumor immunity. Histone/protein acetyltransferases (HATs) promote chromatin accessibility, gene transcription and the function of multiple transcription factors and non-histone proteins. We found that conditional deletion or pharmacologic inhibition of one specific HAT, p300, in Foxp3+ Tregs, increased TCR-induced apoptosis in Tregs, impaired Treg suppressive function and iTreg peripheral conversion, and limited tumor growth in immunocompetent, but not in immunodeficient, hosts. Our data demonstrate that p300 is important for Foxp3+ Treg function and homeostasis in vivo and in vitro, and identify a novel mechanism to diminish Treg function without overtly impairing effector Tcell responses or inducing autoimmunity. Collectively, these data suggest a new approach for cancer immunotherapy. RNA from three independent samples from magnetically separated CD4+CD25+ Treg of fl-p300/Foxp3cre mice, compared to wild type (Foxp3cre) control (all C57Bl/6 background).
Project description:expression profile in Bcl11b-deficient Treg cells versus wild type Treg cells Treg cells sorted from Bcl11bF/F/Cd4Cre/Foxp3-GFP+ mice and wild type Foxp3-GFP+ mice Treg cells sorted from Bcl11bF/F/Foxp3Cre mice and wild type mice RNA extracted from sorted Bcl11b-deficient Foxp3-GFP Treg cells form Bcl11bF/F/Cd4Cre/Foxp3-GFP+ mice and wild type Foxp3-GFP Treg cells; expression profile by microarray analysis RNA extracted from sorted Bcl11b-deficient Treg cells form Bcl11bF/F/Foxp3Cre mice and wild type Treg cells; expression profile by microarray analysis
Project description:T-regulatory (Treg) cells are important to immune homeostasis, and Treg cell deficiency or dysfunction leads to autoimmune disease. An histone/protein acetyltransferase (HAT), p300, was recently found important for Treg function and stability, but further insights into the mechanisms by which p300 or other HATs affect Treg biology are needed. Here we show that CBP, a p300 paralog, is also important in controlling Treg function and stability. Thus, while mice with Treg-specific deletion of CBP or p300 developed minimal autoimmune disease, the combined deletion of CBP and p300 led to fatal autoimmunity by 3-4 weeks of age. The effects of CBP and p300 deletion on Treg development are dose-dependent, and involve multiple mechanisms. CBP and p300 cooperate with several key Treg transcription factors that act on the Foxp3 promoter to promote Foxp3 production. CBP and p300 also act on the Foxp3 CNS2 region to maintain Treg stability in inflammatory environments by regulating pCREB function and GATA3 expression, respectively. Lastly, CBP and p300 regulate the epigenetic status and function of Foxp3. Our findings provide insights into how HATs orchestrate multiple aspects of Treg development and function, and identify overlapping but also discrete activities for p300 and CBP in control of Treg cells. RNA from three independent samples from magnetically separated CD4+CD25+ Treg of fl-p300/Foxp3cre mice and fl-CBP/Foxp3cre, compared to wild type (Foxp3cre) control (all C57Bl/6 background).
Project description:Purpose: The goals of this study are to compare the transcriptome profiling of Wild Type and poh1-/- splenic foxp3+Treg cells Methods:Splenic CD4+Foxp3+ (YFP+) cells mRNA profiles of 2-week-old poh1+/+ Foxp3Cre+ wild type and poh1fl/fl Foxp3Cre+ mice were generated by deep sequencing, using Illumina HiSeq 2500. The sequence reads that passed quality filters were analyzed with edgeR. qRT–PCR validation was performed using SYBR Green assays Results:Using an optimized data analysis workflow, we mapped about 50 million sequence reads per sample to the mouse genome (build mm10). Among all genes expressed, 1067 genes were upregulated and1391 genes were downregulated in poh1−/− Foxp3+ Treg cells relative to their expression in POH1 +/+ Treg cells. The gene-expression altered in POH1-ablated cells adversely correlated with those expressed in Treg cells in TCR-dependent manner. The gene sets were downreglated in POH1-deficiency Treg cells encoding various cell-surface receptors and intracellular molecules involved in migration, suppressive function and signature of Treg cells. Conclusions:Gene expression in POH1-deficiency Treg cells was markedly diverse compared with that in POH1-sufficient Treg cells.
Project description:To explore the role of Ku70 in Treg cell biology, we isolated conventional T cells (Tconv) and regulatory T cells (Treg) from Foxp3Yfp-cre mice and performed Ku70 ChIP-seq. Furthermore, to investigate the impact of Ku70 deficiency on Foxp3 binding patterns, we sorted Treg cells from Foxp3Cre (WT) and Xrcc6fl/fl;Foxp3Cre (KO) mice and conducted Foxp3 ChIP-seq. These analyses revealed that Ku70 forms a complex with FOXP3, which supports FOXP3 transcriptional activity.
Project description:The Foxp3 transcription factor is a crucial determinant of both regulatory T (TREG) cell development and their functional maintenance. Appropriate modulation of tolerogenic immune responses therefore requires tight regulation of Foxp3 transcriptional output, and this involves both transcriptional and post-translational regulation. Here, we show that during T cell activation, phosphorylation of Foxp3 in TREG cells can be regulated by a TGFβ Activated Kinase 1 (TAK1)-Nemo Like Kinase (NLK) signaling pathway. NLK interacts with Foxp3 in TREG cells and directly phosphorylates Foxp3 on multiple serine residues. This phosphorylation results in stabilization of Foxp3 protein levels by preventing association with the STUB1 E3-ubiquitin protein ligase, resulting in both reduced ubiquitination and proteasome-mediated degradation. Conditional TREG cell NLK-knockout (NLKTREG) results in decreased TREG cell-mediated immunosuppression in vivo and NLK-deficient TREG cell animals develop more severe experimental autoimmune encephalomyelitis. Our data suggest a molecular mechanism, in which stimulation of TCR-mediated signaling can induce a TAK1-NLK pathway to sustain Foxp3 transcriptional activity through stabilization of protein levels, thereby maintaining TREG cell suppressive function. Pharmacological manipulation of this phosphorylation-ubiquitination axis may provide therapeutic opportunities for regulating TREG cell function, for example during cancer immunotherapy.
Project description:expression profile in Bcl11b-deficient Treg cells versus wild type Treg cells Treg cells sorted from Bcl11bF/F/Cd4Cre/Foxp3-GFP+ mice and wild type Foxp3-GFP+ mice Treg cells sorted from Bcl11bF/F/Foxp3Cre mice and wild type mice
Project description:Foxp3+ regulatory T cells (Treg cells) maintain immunological tolerance and their deficiency results in fatal multi-organ autoimmunity. Although heightened T cell receptor (TCR) signaling is critical for the differentiation of Treg cells, the role of TCR signaling in Treg cell function remains largely unknown. Here we demonstrate inducible ablation of the TCR results in Treg cell dysfunction which cannot be attributed to impaired Foxp3 expression, decreased expression of Treg cell signature genes or altered ability to sense and consume interleukin 2. Rather, TCR signaling was required for maintaining the expression of a limited subset of genes comprising 25% of the activated Treg cell transcriptional signature. Our results reveal a critical role for the TCR in Treg cell suppressor capacity. Array expression of Foxp3-CreERT2 CalphaFL/WT mice
Project description:During development, thymocytes bearing a moderately self-reactive T cell receptor (TCR) can be selected to become regulatory T (Treg) cells. Several observations suggest that also in the periphery mature Treg cells continuously receive self-reactive TCR signals. However, the importance of this inherent autoreactivity for Treg cell biology remains poorly defined. To address this open question, we genetically ablated the TCR of mature Treg cells in vivo. These experiments revealed that TCR-induced Treg lineage-defining FoxP3 expression and gene hypomethylation were uncoupled from TCR input in mature Treg cells. However, Treg cell homeostasis, cell-type-specific gene expression and suppressive function critically depend on continuous triggering of their TCR. TCRpos (FoxP3+ CD4+ CD25high cells from CM-NM-1F/F FoxP3 I eGFP mice) and TCRneg (FoxP3+ TCRM-bM-^@M-^S CD4+ CD25high cells from Mx-Cre CM-NM-1F/F FoxP3 I eGFP mice) Treg cells were FACS sorted 6 weeks after poly(I:C) injection. Cells from 3-5 mice were pooled for sorting, and 4 replicates for the controls (TCRpos) as well as 5 replicates for the Mx-Cre (TCRneg) mice were generated. mRNA from 3-5 x 105 cells was purified with a RNeasy Micro kit (Qiagen), amplified, labeled and hybridized to Affymetrix M430 V2 microarrays