Foxo transcription factors have a conserved role in the adaptation of cells and organisms to nutrient and growth factor availability. Here we show that Foxo1 has a crucial, nonredundant role in T cells. In naive T cells, Foxo1 controlled the expression of the adhesion molecule L-selectin, the chemokine receptor CCR7 and the transcription factor Klf2, and its deletion was sufficient to alter lymphocyte trafficking. Furthermore, Foxo1 deficiency resulted in a severe defect in interleukin 7 receptor α-chain (IL-7Rα) expression associated with its ability to bind an Il7r enhancer. Finally, growth factor withdrawal induced a Foxo1-dependent increase in Sell, Klf2 and Il7r expression. These data suggest that Foxo1 regulates the homeostasis and life span of naive T cells by sensing growth factor availability and regulating homing and survival signals.Throughout adult life, the number and diversity of peripheral T cells depends on de novo cell development and cell division, balanced against programmed cell death. A growing number of studies show that this 'homeostasis' of T cells is controlled by cytokines, such as interleukin 7 (IL-7), as well as by interactions between T cell antigen receptor (TCR) and major histocompatibility complex (MHC) 1, 2. However, the cell-intrinsic factors responsible for the integration of environmental signals and the manner in which they manifest changes in cell populations remain poorly defined.The Foxo subfamily of transcription factors has a highly conserved role in the regulation of life span, cell cycle progression, apoptosis, glucose metabolism and stress resistance by integrating information pertaining to the abundance of nutrients, growth factors and stress signals 3 . In mammals, the Foxo subfamily consists of four members: Foxo1 (A000944),

MicroRNA (miRNAs) are negative regulators of gene expression and can function as tumor suppressors or oncogenes. Expression patterns of miRNAs and their role in the pathogenesis of hepatocellular carcinoma (HCC) are still poorly understood. We profiled miRNA expression in tissue samples (104 HCC, 90 adjacent cirrhotic livers, 21 normal livers) as well as in 35 HCC cell lines. A set of 12 miRNAs (including miR-21, miR-221/222, miR-34a, miR-519a, miR-93, miR-96, and let-7c) was linked to disease progression from normal liver through cirrhosis to full-blown HCC. miR-221/222, the most upregulated miRNAs in tumor samples, are shown to target the CDK inhibitor p27 and to enhance cell growth in vitro. Conversely, these activities can be efficiently inhibited by an antagomiR specific for miR-221. In addition, we show, using a mouse model of liver cancer, that miR-221 overexpression stimulates growth of tumorigenic murine hepatic progenitor cells. Finally, we identified DNA damage-inducible transcript 4 (DDIT4), a modulator of mTOR pathway, as a bona fide target of miR-221. Taken together, these data reveal an important contribution for miR-221 in hepatocarcinogenesis and suggest a role for DDIT4 dysregulation in this process. Thus, the use of synthetic inhibitors of miR-221 may prove to be a promising approach to liver cancer treatment.hepatocarcinogenesis | microRNA | antagomiRs | mouse model | DDIT4

We have previously described a human complementary DNA that encodes a novel protein which is homologous to members of the steroid/thyroid nuclear receptor multigene family. This novel protein (hap for hepatoma) exhibits strong homology with the human retinoic acid receptor (RAR) which has been recently characterized. To test the possibility that the hap protein might also be a retinoid receptor, a chimaeric receptor was created by replacing the putative DNA binding domain of hap with that of the human oestrogen receptor (ER). The resulting hap-ER chimaera was then tested for its ability to trans-activate an oestrogen-responsive reporter gene (vit-tk-CAT) in the presence of possible receptor ligands. Here we show that retinoic acid (RA) at physiological concentrations is effective in inducing the expression of this reporter gene by the hap-ER chimaeric receptor. This demonstrates the existence of two human retinoic acid receptors designated RAR-alpha and RAR-beta.

Retinoic acid receptors (RARs) are hormone-regulated transcription factors that control key aspects of normal differentiation. Aberrant RAR activity may be a causal factor in neoplasia. Human acute promyelocytic leukemia, for example, is tightly linked to chromosomal translocations that fuse novel amino acid sequences (denoted PML, PLZF, and NPM) to the DNA-binding and hormone-binding domains of RAR␣. The resulting chimeric receptors have unique transcriptional properties that may contribute to leukemogenesis. Normal RARs repress gene transcription by associating with ancillary factors denoted corepressors (also referred to as SMRT, N-CoR, TRAC, or RIP13). We report here that the PML-RAR␣ and PLZF-RAR␣ oncoproteins retain the ability of RAR␣ to associate with corepressors, and that this corepressor association correlates with certain aspects of the leukemic phenotype. Unexpectedly, the PLZF moiety itself can interact with SMRT corepressor. This interaction with corepressor is mediated, in part, by a POZ motif within PLZF. Given the presence of POZ motifs in a number of known transcriptional repressors, similar interactions with SMRT may play a role in transcriptional silencing by a variety of both receptor and nonreceptor transcription factors.Retinoids regulate many aspects of vertebrate cell proliferation and differentiation through receptors that function as hormone-regulated transcription factors (1-6). Two major classes of retinoid receptors have been identified: retinoic acid receptors (RARs) and retinoid X receptors (RXRs) (3-6). Both RARs and RXRs bind to specific sites on the DNA, and they can activate or repress expression of adjacent target genes (1-6). Aberrant RARs appear to play a crucial role in human acute promyelocytic leukemia (APL) (7-15). In over 95% of all APL patients, specific chromosomal translocations create abnormal RARs by replacing the N terminus of RAR␣ with novel ORFs. The breakpoint in RAR␣ is identical in all cases, whereas the nature of the novel N-terminal sequences can vary. In the common t(15;17) translocation, the RAR␣ N terminus is replaced with an ORF denoted PML (for promyelocytic leukemia) (7-12). Alternatively, t(11;17) and t(5;17) translocations result in chimeric proteins denoted PLZF (promyelocytic leukemia zinc finger)-RAR␣ and NPM (nucleophosmin)-RAR␣, respectively (13-15). Although possessing a number of recognizable structural motifs, including several prevalent in transcription factors, the PML, PLZF, and NPMderived sequences exhibit little structural interrelatedness, and the functions of these proteins in the normal cell are not fully understood (reviewed in refs. 16-18).The near-invariant association of acute promyelocytic leukemia with the expression of chimeric RAR␣ proteins, and the ability of retinoids to drive leukemias bearing the PML-RAR␣ translocation into differentiation and clinical remission (16-18), suggest an active role for these chimeras in conferring the leukemogenic phenotype. Furthermore, ectopic expression of PML-RAR␣ in murine or av...

Foxo transcription factors regulate cell cycle progression, survival, and DNA repair pathways. Here, we demonstrate that a deficiency in Foxo3 resulted in increased expansion of T cell populations after viral infection. This exaggerated expansion was not T cell intrinsic. Rather, it was caused by the enhanced capacity of Foxo3-deficient dendritic cells to sustain T cell viability by producing increased amounts of interleukin 6 (IL-6). CTLA-4-mediated stimulation of dendritic cells induced nuclear localization of Foxo3, which in turn inhibited IL-6 and tumor necrosis factor production. Thus, Foxo3 acts to constrain dendritic cell production of key inflammatory cytokines and control T cell survival.

The immune system contains natural regulatory T cells that control the magnitude of the immune response during physiologic and pathologic conditions. Although this suppressive function was historically attributed to CD8 T cells, most recent reports have focused on natural regulatory CD4 T cells. In the present study, we describe a new subset of natural CD8 regulatory T cells in normal healthy animals. This subset expresses low levels of CD45RC at its surface (CD45RC low ); produces mainly interleukin-4 (IL-4), IL-10, and IL-13 cytokines upon in vitro stimulation; expresses Foxp3 and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4); and is not cytotoxic against allogeneic targets. This subset suppresses the proliferation and differentiation of autologous CD4 T cells into type-1 cytokines producing T cells after stimulation with allogeneic accessory cells. We also provide evidence that this regulatory subset mediates its suppression by cell-to-cell contact and not through secretion of suppressive cytokines. Finally, the regulatory activity of CD8 CD45RC low cells is also demonstrated in vivo in a rat model of CD4-dependent graft-versus-host disease. Collectively, these data demonstrate for the first time that freshly isolated rat CD8 CD45RC low T cells contain T cells with regulatory properties, a result that enlarges the general picture of T-cell-mediated regulation. ( IntroductionThe delicate balance between pathogen-induced effector immunologic functions and natural self-tolerance mechanisms is of vital importance for preserving the integrity of a host in the course of an immune response. In different species of rodents and in humans, there is compelling evidence that the regulation of the magnitude of protective immunity to foreign antigens as well as the control of autoaggressive immune reactions are ensured by regulatory CD4 and CD8 T lymphocytes that display anti-inflammatory and antiproliferative functions. Convergent evidence indicates that multiple subtypes of regulatory T cells exist and that their regulatory activities are mediated either by immunosuppressive cytokines or by contact-dependent mechanisms. [1][2][3][4][5][6][7][8] CD45 is a transmembrane tyrosine phosphatase expressed as isoforms of different molecular weight, which result in the differential splicing of 3 exons (A, B, and C) encoding part of the N-terminal extracellular domain. In the rat, CD45RC expression levels define 2 subpopulations of CD4 T cells with different cytokine profiles and functions. 3,[9][10][11][12] Functional analyses of CD45RC high and CD45RC low CD4 T cells have demonstrated that important regulatory interactions occur between these subsets in vivo. 11,13,14 For example, the adoptive transfer of CD45RC high CD4 T cells from congenic euthymic donors to nude rats induces a fatal wasting disease, while the transfer of both subpopulations, or of the CD45RC low cells alone, has no effect. 11 Similar results were obtained using mouse CD4 T cells fractionated on the basis of CD45RB expression. 15 It has also been demo...

Objectives To report early experience with treatment of intrauterine cytomegalovirus (CMV) infection using maternal oral administration of valaciclovir (VACV).Design Observational study of fetuses infected with CMV with or without treatment with valaciclovir.Population Pregnancies with confirmed fetal CMV infection were treated with oral VACV (8 g/day).Main outcome measures Fetal viral load and drug concentration were monitored in amniotic fluid and in fetal blood. Data on the course and outcome of a group of untreated symptomatic fetuses infected with CMV are also reported.Results Therapeutic concentrations were achieved in maternal and fetal bloods. The viral load in the fetal blood (VLFB) decreased significantly after 1-12 weeks of treatment (Wilcoxon paired test P = 0.02). Twenty pregnancies including 21 fetuses were treated at 28 weeks (median, range: 22-34) for 7 weeks (median, range: 1-12). Ten infants were developing normally at between 1 and 5 years of age. Two infants (both aged 2 years) had severe isolated unilateral deafness. One neonate presented with microcephaly and severe deafness but was also diagnosed with incontinentia pigmenti. Six out of seven cases that eventually required termination of pregnancy (TOP) had evidence of in utero progression of the disease with worsening cerebral lesions. One fetus died in utero. The outcome of 14/24 (58.3%) untreated symptomatic infected fetuses was poor with either TOP, intrauterine fetal demise or severe congenital infection disease of the neonate; the remaining ten infants were healthy at follow up.Conclusion Maternal oral administration of VACV leads to therapeutic concentrations in the maternal and fetal compartments, with a decrease in VLFB. Our results suggest that in cases where TOP is declined, a randomised controlled trial to study this treatment option further is indicated.

Risk assessment of infected fetuses for being symptomatic at birth is possible as early as the time of diagnosis by using a combination of targeted ultrasound examination along with viral load in amniotic fluid and in fetal blood together with platelet count. The advantage of using amniotic fluid is that it is available at prenatal diagnosis. One may wonder if increasing the negative predictive value of the overall assessment of an infected fetus from 95-100% is worth the additional risk of cordocentesis for fetal blood sampling. This can only be an individual decision made by well-informed women and it seems therefore appropriate to use the figures presented here and their confidence intervals for counseling.