Graft-versus-host disease (GVHD) remains the major barrier to the success of allogeneic hematopoietic stem cell transplantation (HSCT). GVHD is caused by donor T cells that mediate host tissue injury through multiple inflammatory mechanisms. Blockade of individual effector molecules has limited efficacy in controlling GVHD. Here, we report that Notch signaling is a potent regulator of T-cell activation, differentiation, and function during acute GVHD. Inhibition of canonical Notch signaling in donor T cells markedly reduced GVHD severity and mortality in mouse models of allogeneic HSCT. Although Notch-deprived T cells proliferated and expanded in response to alloantigens in vivo, their ability to produce interleukin-2 and inflammatory cytokines was defective, and both CD4+ and CD8+ T cells failed to up-regulate selected effector molecules. Notch inhibition decreased the accumulation of alloreactive T cells in the intestine, a key GVHD target organ. However, Notch-deprived alloreactive CD4+ T cells retained significant cytotoxic potential and antileukemic activity, leading to improved overall survival of the recipients. These results identify Notch as a novel essential regulator of pathogenic CD4+ T-cell responses during acute GVHD and suggest that Notch signaling in T cells should be investigated as a therapeutic target after allogeneic HSCT.
Enhanced fetal γ-globin synthesis alleviates symptoms of β-globinopathies such as sickle cell disease and β-thalassemia, but current γ-globin–inducing drugs offer limited beneficial effects. We show here that lysine-specific demethylase 1 (LSD1) inhibition by RNAi in human erythroid cells or by the monoamine oxidase inhibitor tranylcypromine in human erythroid cells or β-type globin–transgenic mice enhances γ-globin expression. LSD1 is thus a promising therapeutic target for γ-globin induction, and tranylcypromine may serve as a lead compound for the development of a new γ-globin inducer.
Nuclear receptors TR2 and TR4 (TR2/TR4) were previously shown to bind in vitro to direct repeat elements in the mouse and human embryonic and fetal -type globin gene promoters and to play critical roles in the silencing of these genes. By chromatin immunoprecipitation (ChIP) we show that, in adult erythroid cells, TR2/TR4 bind to the embryonic -type globin promoters but not to the adult -globin promoter. We purified protein complexes containing biotin-tagged TR2/TR4 from adult erythroid cells and identified DNMT1, NuRD, and LSD1/CoREST repressor complexes, as well as HDAC3 and TIF1, all known to confer epigenetic gene silencing, as potential corepressors of TR2/TR4. Coimmunoprecipitation assays of endogenous abundance proteins indicated that TR2/TR4 complexes consist of at least four distinct molecular species. In ChIP assays we found that, in undifferentiated murine adult erythroid cells, many of these corepressors associate with both the embryonic and the adult -type globin promoters but, upon terminal differentiation, they specifically dissociate only from the adult -globin promoter concomitant with its activation but remain bound to the silenced embryonic globin gene promoters. These data suggest that TR2/TR4 recruit an array of transcriptional corepressors to elicit adult stage-specific silencing of the embryonic -type globin genes through coordinated epigenetic chromatin modifications.Regulatory pathways that control development through temporally specified gene activation and repression mechanisms have been recognized as "epigenetic" (i.e., heritable changes not involving alterations in the primary DNA code) for decades, although the molecules that elicit those developmental programs through epigenetic means have only been elucidated during the past several years. It is currently widely accepted that metazoan transcription factors (both activators and repressors) elicit their specific transcriptional responses through an enormous variety of cofactor molecules whose major purpose is to modulate chromatin structure (8, 31). Many such cofactors have been shown to chemically modify histones, transcription factors, and cofactors, as well as DNA, in order to elicit the required transcriptional responses.The -globin locus has been extensively studied as a paradigm for epigenetic regulation of lineage-specific and developmentally specific gene expression (29), as well as for its clinical relevance to -globin disorders such as sickle cell disease and -thalassemia. The human -globin locus is composed of ε-(embryonic), G␥-and A␥-(fetal), and ␦-and -globin (adult) genes, which are spatially arranged from 5Ј to 3Ј and developmentally expressed in the same order (72). The elucidation of the molecular basis for ␥-globin silencing in the adult stage in particular has been the focus of intense investigation, since it has been observed that coinheritance of genetic conditions that confer elevated ␥-globin synthesis can significantly alleviate the symptoms of -globin disorders (44, 56). Previously, several adul...
Background:Obesity is a risk factor for metabolic diseases, while preadipocyte differentiation or adipogenesis is closely related to obesity occurrence. Long noncoding RNAs (lncRNAs) are a unique class of transcripts in regulation of a variety of biological processes. Using cDNA microarray, we found lncRNA U90926 is negatively correlated with 3T3-L1 preadipocyte differentiation.Objective:The aim of this study was to explore the role of lncRNA U90926 (lnc-U90926) in adipogenesis and the underlying mechanisms.Methods:Quantitative real-time PCR (qPCR) was performed to determine lnc-U90926 expression in 3T3-L1 preadipocytes, differentiated adipocytes, and in adipose tissues form mice. RNA fluorescent in situ hybridization (FISH) was performed to determine the localization of lnc-U90926 in 3T3-L1 preadipocytes. The effects of lnc-U90926 on 3T3-L1 adipogenesis were analyzed with lentivirus-mediated gain- and loss-of-function experiments. Lipid accumulation was evaluated by oil red O staining; several adipogenesis makers were analyzed by qPCR and western blotting. Dual luciferase assay was applied to explore the transactivation of target genes modulated by lnc-U90926. All measurements were performed at least for three times.Results:Lnc-U90926 expression decreased along the differentiation of 3T3-L1 preadipocytes. In mice, lnc-U90926 is predominantly expressed in adipose tissue. Obese mice have lower lnc-U90926 expression in subcutaneous and visceral adipose tissue than non-obese mice. FISH results showed that lnc-U90926 was mainly located in the cytoplasm. Overexpression lnc-U90926 attenuated 3T3-L1 adipocyte differentiation as evidenced by its ability to inhibit lipid accumulation, to decrease the mRNA levels of peroxisome proliferator-activated receptor gamma 2 (PPARγ2), fatty acid binding protein 4 (FABP4) and adiponectin (AdipoQ) as well as to reduce the protein levels of PPARγ and FABP4 (P<0.05). Knockdown of lnc-U90926 showed opposite effects, which increased mRNA expression of PPARγ2, FABP4, CCAAT/enhancer-binding proteinα (C/EBPα) and AdipoQ.Conclusion:Lnc-U90926 attenuates 3T3-L1 adipocyte differentiation via inhibiting the transactivation of PPARγ2 or PPARγ.
Key Points RN-1 treatment of SCD mice results in increased human fetal γ-globin induction and fetal hemoglobin synthesis. RN-1 treatment of SCD mice significantly reduces sickling, hemolysis, and tissue injury with no obvious adverse side effects.
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