Helios represses megakaryocyte priming in hematopoietic stem and progenitor cells.

Our understanding of cell fate decisions in hematopoietic stem cells is incomplete. Here, we show that the transcription factor Helios is highly expressed in murine hematopoietic stem and progenitor cells (HSPCs), where it is required to suppress the separation of the platelet/megakaryocyte lineage from the HSPC pool. Helios acts mainly in quiescent cells, where it directly represses the megakaryocyte gene expression program in cells as early as the stem cell stage.

Salt Sensing by Serum/Glucocorticoid-Regulated Kinase 1 Promotes Th17-like Inflammatory Adaptation of Foxp3 Regulatory T Cells.

Regulatory T (Treg) cells integrate diverse environmental signals to modulate their function for optimal suppression. Translational regulation represents a favorable mechanism for Treg cell environmental sensing and adaptation. In this study, we carry out an unbiased screen of the Treg cell translatome and identify serum/glucocorticoid-regulated kinase 1 (SGK1), a known salt sensor in T cells, as being preferentially translated in activated Treg cells.

Helios: still behind the clouds.

Regulatory T (Treg) cells are a subset of CD4 T cells that are critical for the maintenance of self-tolerance. The forkhead box transcription factor Foxp3 is a master regulator for the Treg phenotype and function and its expression is essential in Treg cells, as the loss of Foxp3 results in lethal autoimmunity. Two major subsets of Treg cells have been described in vivo; thymus-derived Treg (tTreg) cells that develop in the thymus and peripherally induced Treg (pTreg) cells that are derived from conventional CD4  Foxp3 T cells and are converted in peripheral tissues to cells that express Foxp3 and acquire suppressive ability.

Selective deletion of Eos (Ikzf4) in T-regulatory cells leads to loss of suppressive function and development of systemic autoimmunity.

Eos (lkzf4) is a member of the Ikaros family of transcription factors and is preferentially expressed in T-regulatory (Treg) cells. However, the role of Eos in Treg function is controversial. One study using siRNA knock down of Eos demonstrated that it was critical for Treg suppressor function.

Helios Deficiency Predisposes the Differentiation of CD4Foxp3 T Cells into Peripherally Derived Regulatory T Cells.

The transcription factor Helios is expressed in a large percentage of Foxp3 regulatory T (Treg) cells and is required for the maintenance of their suppressive phenotype, as mice with a selective deficiency of Helios in Treg cells spontaneously develop autoimmunity. However, mice with a deficiency of Helios in all T cells do not exhibit autoimmunity, despite the defect in the suppressor function of their Treg cell population, suggesting that Helios also functions in non-Treg cells. Although Helios is expressed in a small subset of CD4Foxp3 and CD8 T cells and its expression is upregulated upon T cell activation, its function in non-Treg cells remains unknown.

Overview and Preparation Guide for Academic Careers in Pediatric Pharmacy, Part 1: Career as a Pediatric Pharmacy Practice Faculty Member.

Pediatric clinical pharmacy is a growing and evolving field with an increasing number of pediatric clinical pharmacists in academia. In 2017, pediatric practice faculty members represented approximately 7.6% of all pharmacy practice faculty in the United States.

Helios and Helios Treg subpopulations are phenotypically and functionally distinct and express dissimilar TCR repertoires.

The transcription factor Helios is expressed in a large subset of Foxp3 Tregs. We previously proposed that Helios is a marker of thymic derived Treg (tTreg), while Helios Treg were induced from Foxp3 T conventional (Tconv) cells in the periphery (pTreg). To compare the two Treg subpopulations, we generated Helios-GFP reporter mice and crossed them to Foxp3-RFP reporter mice.

IKZF2 Drives Leukemia Stem Cell Self-Renewal and Inhibits Myeloid Differentiation.

Leukemias exhibit a dysregulated developmental program mediated through both genetic and epigenetic mechanisms. Although IKZF2 is expressed in hematopoietic stem cells (HSCs), we found that it is dispensable for mouse and human HSC function. In contrast to its role as a tumor suppressor in hypodiploid B-acute lymphoblastic leukemia, we found that IKZF2 is required for myeloid leukemia.

NAFLD causes selective CD4(+) T lymphocyte loss and promotes hepatocarcinogenesis.

Hepatocellular carcinoma (HCC) is the second most common cause of cancer-related death. Non-alcoholic fatty liver disease (NAFLD) affects a large proportion of the US population and is considered to be a metabolic predisposition to liver cancer. However, the role of adaptive immune responses in NAFLD-promoted HCC is largely unknown.

Helios Controls a Limited Subset of Regulatory T Cell Functions.

A subpopulation (60-70%) of Foxp3(+) regulatory T cells (Tregs) in both mouse and man expresses the transcription factor Helios, but its role in Treg function is still unknown. We generated Treg-specific Helios-deficient mice to examine the function of Helios in Tregs. We show that the selective deletion of Helios in Tregs leads to slow, progressive systemic immune activation, hypergammaglobulinemia, and enhanced germinal center formation in the absence of organ-specific autoimmunity.

Eos Is Redundant for Regulatory T Cell Function but Plays an Important Role in IL-2 and Th17 Production by CD4+ Conventional T Cells.

Eos belongs to the Ikaros family of transcription factors. It was reported to be a regulatory T cell (Treg) signature gene, to play a critical role in Treg suppressor functions, and to maintain Treg stability. We used mice with a global deficiency in Eos to re-examine the role of Eos expression in both Tregs and conventional T cells (Tconvs).

Release of active TGF-β1 from the latent TGF-β1/GARP complex on T regulatory cells is mediated by integrin β8.

Activated T regulatory cells (Tregs) express latent TGF-β1 on their cell surface bound to GARP. Although integrins have been implicated in mediating the release of active TGF-β1 from the complex of latent TGF-β1 and latent TGF-β1 binding protein, their role in processing latent TGF-β1 from the latent TGF-β1/GARP complex is unclear. Mouse CD4(+)Foxp3(+) Treg, but not CD4(+)Foxp3(-) T cells, expressed integrin β8 (Itgb8) as detected by quantitative RT-PCR.

tTregs, pTregs, and iTregs: similarities and differences.

Foxp3(+) T-regulatory cells (Tregs) are primarily generated in the thymus (tTreg), but also may be generated extrathymically at peripheral sites (pTreg), or induced in cell culture (iTreg) in the presence of transforming growth factor β (TGFβ). A major unresolved issue is how these different populations of Tregs exert their suppressive function in vivo. We have developed novel systems in which the function of Tregs can be evaluated in vivo in normal mice.

Modulation of Treg cells/T effector function by GITR signaling is context-dependent.

Treg cells express high levels of the glucocorticoid-induced tumor necrosis factor-related receptor (GITR), while resting conventional T (Tconv) cells express low levels that are increased upon activation. Manipulation of GITR/GITR-Ligand (GITR-L) interactions results in enhancement of immune responses, but it remains unclear whether this enhancement is secondary to costimulation of Tconv cells or to reversal of Treg-cell-mediated suppression. Here, we used a nondepleting Fc-GITR-L and combinations of WT and GITR KO Treg cells and Tconv cells to reexamine the effects of GITR stimulation on each subpopulation in both unmanipulated mice and mice with inflammatory bowel disease.

Oligodeoxynucleotides stabilize Helios-expressing Foxp3+ human T regulatory cells during in vitro expansion.

Foxp3(+) regulatory T cells (Tregs) maintain self-tolerance and adoptive therapy, and using Foxp3(+) Tregs has been proposed as treatment for autoimmune diseases. The clinical use of Tregs will require large numbers of cells and methods for in vitro expansion of Tregs are being developed. Foxp3(+) Tregs can be divided into 2 subpopulations based on expression of the transcription factor, Helios.

The deubiquitinase CYLD targets Smad7 protein to regulate transforming growth factor β (TGF-β) signaling and the development of regulatory T cells.

CYLD is a lysine 63-deubiquitinating enzyme that inhibits NF-κB and JNK signaling. Here, we show that CYLD knock-out mice have markedly increased numbers of regulatory T cells (Tregs) in peripheral lymphoid organs but not in the thymus. In vitro stimulation of CYLD-deficient naive T cells with anti-CD3/28 in the presence of TGF-β led to a marked increase in the number of Foxp3-expressing T cells when compared with stimulated naive control CD4(+) cells.

A self-reactive TCR drives the development of Foxp3+ regulatory T cells that prevent autoimmune disease.

Although Foxp3(+) regulatory T cells (Tregs) are thought to express autoreactive TCRs, it is not clear how individual TCRs influence Treg development, phenotype, and function in vivo. We have generated TCR transgenic mice (termed SFZ70 mice) using Tcra and Tcrb genes cloned from an autoreactive CD4(+) T cell isolated from a Treg-deficient scurfy mouse. The SFZ70 TCR recognizes a cutaneous autoantigen and drives development of both conventional CD4(+) Foxp3(-) T cells (T(conv)) and Foxp3(+) Tregs.

Store-operated Ca(2+) entry (SOCE) contributes to normal skeletal muscle contractility in young but not in aged skeletal muscle.

Muscle atrophy alone is insufficient to explain the significant decline in contractile force of skeletal muscle during normal aging. One contributing factor to decreased contractile force in aging skeletal muscle could be compromised excitation-contraction (E-C) coupling, without sufficient available Ca(2+) to allow for repetitive muscle contractility, skeletal muscles naturally become weaker. Using biophysical approaches, we previously showed that store-operated Ca(2+) entry (SOCE) is compromised in aged skeletal muscle but not in young ones.

Expression of Helios, an Ikaros transcription factor family member, differentiates thymic-derived from peripherally induced Foxp3+ T regulatory cells.

Helios, a member of the Ikaros transcription factor family, is preferentially expressed at the mRNA level by regulatory T cells (Treg cells). We evaluated Helios protein expression using a newly generated mAb and demonstrated that it is expressed in all thymocytes at the double negative 2 stage of thymic development. Although Helios was expressed by 100% of CD4(+)CD8(-)Foxp3(+) thymocytes, its expression in peripheral lymphoid tissues was restricted to a subpopulation ( approximately 70%) of Foxp3(+) T cells in mice and humans.

CD4+CD25+ T regulatory cells limit effector T cells and favor the progression of brucellosis in BALB/c mice.

Brucellosis is one of the most common bacterial zoonoses worldwide. Infection is usually chronic and sometimes lifelong. Different mechanisms can be postulated as to the basis for the induction of the chronic status of brucellosis, but a comprehensive knowledge is still lacking.

Proliferative assays for T cell function.

This addition to UNIT 3.12 will describe the assays needed to evaluate CD4.CD25.

Fractionation of T and B cells using magnetic beads.

This unit describes the purification of mouse T cells, B cells, and T cell subsets using magnetic bead separation. Isolation of cell subsets using magnetic beads is quick, simple, and reliable and can result in high yields of very pure cells.