Project description:MicroRNAs (miRNAs) are tightly regulated in the immune system, as aberrant expression of miRNAs often results in hematopoietic malignancies and autoimmune diseases. Previously, elevated levels of miR-27 in T cells isolated from multiple sclerosis patients has been suggested to facilitate disease progression through inhibiting Th2 immunity and promoting pathogenic Th1 responses. Here we demonstrate that while mice with T cell-specific overexpression of miR-27 harbor dysregulated Th1 responses and develop autoimmune pathology, these disease phenotypes are not driven by miR-27 in effector T cells in a cell-autonomous manner but rather resulted from a perturbed regulatory T (Treg) cell compartment. Excessive miR-27 expression in T cells severely impairs Treg cell differentiation. Moreover, Treg cells with exaggerated miR-27-mediated gene regulation exhibit diminished homeostasis and suppressor function in vivo. Mechanistically, miR-27 represses several known as well as previously uncharacterized targets that play critical roles in controlling multiple aspects of Treg cell biology. Collectively, our data show miR-27 functions as a key regulator in Treg cell development and function and suggest that proper regulation of miR-27 is pivotal to safeguard Treg cell-mediated immunological tolerance.
Project description:MicroRNAs (miRNAs) are tightly regulated in the immune system, as aberrant expression of miRNAs often results in hematopoietic malignancies and autoimmune diseases. Previously, elevated levels of miR-27 in T cells isolated from multiple sclerosis patients has been suggested to facilitate disease progression through inhibiting Th2 immunity and promoting pathogenic Th1 responses. Here we demonstrate that while mice with T cell-specific overexpression of miR-27 harbor dysregulated Th1 responses and develop autoimmune pathology, these disease phenotypes are not driven by miR-27 in effector T cells in a cell-autonomous manner but rather resulted from a perturbed regulatory T (Treg) cell compartment. Excessive miR-27 expression in T cells severely impairs Treg cell differentiation. Moreover, Treg cells with exaggerated miR-27-mediated gene regulation exhibit diminished homeostasis and suppressor function in vivo. Mechanistically, miR-27 represses several known as well as previously uncharacterized targets that play critical roles in controlling multiple aspects of Treg cell biology. Collectively, our data show miR-27 functions as a key regulator in Treg cell development and function and suggest that proper regulation of miR-27 is pivotal to safeguard Treg cell-mediated immunological tolerance.
Project description:Coordinated repression of gene expression by evolutionarily conserved microRNA (miRNA) clusters and paralogs ensures that miRNAs efficiently exert their biological impact. Combining both loss- and gain-of-function genetic approaches, here we show that the miR-23~27~24 clusters regulate multiple aspects of T cell biology, particularly Th2 immunity. Low expression of this miRNA family confers proper effector T cell function at both physiological and pathological settings. Further studies in T cells with exaggerated regulation by individual members of the miR-23~27~24 clusters revealed miR-24 and miR-27 collaboratively limit Th2 responses through targeting IL-4 and GATA3 in both direct and indirect manners. Intriguingly, while overexpression of the entire miR-23 cluster also negatively impacts other Th lineages, enforced expression of miR-24, in contrast to miR-23 and miR-27, actually promotes the differentiation of Th1, Th17 and iTreg cells, implying that under certain conditions, miRNA families can fine tune the biological effects of their regulation by having individual members antagonize rather than cooperate with each other. Together, our results identify a miRNA family with important immunological roles and suggest tight regulation of miR-23~27~24 clusters in T cells is required to maintain optimal effector function and to prevent aberrant immune responses.
Project description:Coordinated repression of gene expression by evolutionarily conserved microRNA (miRNA) clusters and paralogs ensures that miRNAs efficiently exert their biological impact. Combining both loss- and gain-of-function genetic approaches, here we show that the miR-23~27~24 clusters regulate multiple aspects of T cell biology, particularly Th2 immunity. Low expression of this miRNA family confers proper effector T cell function at both physiological and pathological settings. Further studies in T cells with exaggerated regulation by individual members of the miR-23~27~24 clusters revealed miR-24 and miR-27 collaboratively limit Th2 responses through targeting IL-4 and GATA3 in both direct and indirect manners. Intriguingly, while overexpression of the entire miR-23 cluster also negatively impacts other Th lineages, enforced expression of miR-24, in contrast to miR-23 and miR-27, actually promotes the differentiation of Th1, Th17 and iTreg cells, implying that under certain conditions, miRNA families can fine tune the biological effects of their regulation by having individual members antagonize rather than cooperate with each other. Together, our results identify a miRNA family with important immunological roles and suggest tight regulation of miR-23~27~24 clusters in T cells is required to maintain optimal effector function and to prevent aberrant immune responses. naïve T cells isolated from mice with T cell-specific overexpression of the entire miR-23 cluster or individual miR-23 family members as well as from mice with T cell-specific deletion of both miR-23a/b clusters
Project description:Follicular helper T (Tfh) cells are essential for generating protective humoral immunity. To date, microRNAs (miRNAs) have emerged as important players in regulating Tfh cell biology. Here, we show that loss of miR-23~27~24 clusters in T cells resulted in elevated Tfh cell frequencies upon different immune challenges whereas overexpression of this miRNA family led to reduced Tfh cell responses. Mechanistically, miR-23~27~24 clusters coordinately control Tfh cells through targeting a network of genes that are crucial for Tfh cell biology. Among them, thymocyte selection-associated HMG-box protein (TOX) was identified as a central transcription regulator in Tfh cell development. TOX is highly up-regulated in both mouse and human Tfh cells in a BCL6-dependent manner. In turn, TOX promotes the expression of multiple molecules that play critical roles in Tfh cell differentiation and function. Collectively, our study on miR-23~27~24-mediated control of humoral immunity reveals a TOX-driven regulatory circuit in orchestrating Tfh cell responses.
Project description:Tumor associated CD4+ and CD8+ T cells were sorted from B16f10 OVA expressing tumors in miR-155 flox, miR-155 flox CD4Cre+, and miR-155 flox CD4Cre+ mice treated with immune checkpoint blocking (ICB) antibodies by flow sorting on CD45+CD3+CD4+ cells and CD45+ CD3+CD8+ cells. RNA was collected from these cells to perform RNA sequencing of total RNA.
Project description:A microarray study performed in iTreg of miR-31fl/fl/CD4Cre and control mice to identify genes that are regulated by the miR-31. CD4+ naïve T cells from miR-31fl/fl mice and miR-31fl/flCD4Cre mice were used to induce iTreg in vitro. Four independent experiments were performed.
Project description:The role of FoxP3+ regulatory T (Treg) cells in the maintenance of immunological tolerance is well established. Recently, genome-wide association studies (GWAS) in humans have associated polymorphisms within the BACH2 locus encoding the transcription factor BTB and CNC homology 1, basic leucine zipper transcription factor 2 (Bach2) with diverse allergic and autoimmune diseases including asthma, multiple sclerosis, Crohn's disease, celiac disease, generalized vitiligo and type 1 diabetes. Common to these diseases is a failure to adequately maintain immunological tolerance. However, a role for Bach2 in this process has not been established. Here, by assessing the phenotype of mice in which the Bach2 gene is disrupted, we demonstrate a non-redundant role for Bach2 in the prevention of a spontaneous lethal inflammatory disorder predominantly affecting the lung and gut with excessive T helper 2 (Th2) responses and formation of circulating autoantibodies. Bach2 was necessary for efficient induction of FoxP3 expression both during thymopoesis and upon stimulation of naïve peripheral CD4+ T cells under Treg polarizing conditions in vitro. Consequently, in bone marrow reconstitution experiments, Bach2 expression within the haematopoetic system was necessary for suppression of lethal autoimmunity in a manner that was FoxP3 dependent. These findings demonstrate a requirement for Bach2 in early lineage commitment of both thymic and induced Treg cells and point to shared mechanisms that underlie diverse allergic and autoimmune disorders that may serve as targets in the development of novel therapeutic strategies. Six samples were collected from separate mice: three Ly5.1+ wildtype thymocyte samples (biological replicates) and three Ly5.1- Bach2 knockout thymocyte samples (biological replicates).