Expression of meningioma 1 (MN1) has been proposed to be a negative prognostic molecular marker in adult AML with normal cytogenetics, however its role in pediatric leukemia is unknown. We found elevated MN1 expression in 53 of 88 pediatric leukemia cases: significant amounts of MN1 were found in immature B-cell ALL and most cases of infant leukemia but no MN1 expression was detected in T-cell acute lymphoblastic leukemia (T-ALL). Interestingly 17 of 19 cases harboring MLL-X fusions showed also elevated MN1 expression. Lentiviral siRNA mediated MN1 knock-down resulted in cell cycle arrest and impaired clonogenic growth of 3 MLL-X-positive human leukemia cell lines overexpressing MN1 (THP-1, RS4;11, MOLM13). In a mouse MLL/ENL-induced leukemia MN1 overexpression resulted from retroviral provirus insertion. Strikingly co-expression of MN1 with MLL/ENL resulted in significantly reduced latency for induction of an AML phenotype in mice suggesting functional cooperation. MN1 overexpression in MLL/ENL-carrying cells resulted in expansion of the L-GMP population and facilitated disease induction in secondary recipients. Gene expression profiling allowed to define a number of potential MN1 hematopoietic targets. Up-regulation of CD34, FLT3, HLF, or DLK1 was validated in bone marrow transiently overexpressing MN1, in MN1-induced mouse leukemias, as well as in some cases of pediatric leukemias overexpressing MN1. Taken together, our work suggests that MN1 overexpression is essential for growth of leukemic cells, and that MN1 can act as a cooperating oncogene with MLL-X fusion genes most probably through modification of a distinct gene expression program that leads to expansion of a leukemia initiating cell population.
Functional characterization of high levels of meningioma 1 as collaborating oncogene in acute leukemia.
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View SamplesUbiquitination is a post-translational mechanism of control of diverse cellular processes. We focus here on the ubiquitin ligase Fbw7, a recently identified hematopoietic tumor suppressor that can target for degradation several important oncogenes including Notch1, c-Myc and cyclin E. We have generated conditional Fbw7 knock-out animals and inactivated the gene in hematopoietic stem cells (HSC) and their differentiated progeny. Deletion of Fbw7 specifically and rapidly affects the HSC compartment in a cell-autonomous manner. Fbw7-/- HSCs show defective maintenance of quiescence, leading to impaired self-renewal and a severe loss of competitive repopulating capacity. Furthermore, Fbw7-/- HSC are unable to colonize the thymus leading to a profound depletion of T cell progenitors. Deletion of Fbw7 in bone marrow stem cells and progenitors leads to the stabilization of c-Myc, a transcription factor previously implicated in HSC self-renewal. On the other hand, neither Notch1 nor cyclin E are stabilized in the bone marrow of Fbw7 deficient mice. Genome-wide transcriptome studies of Fbw7-/- HSC and hematopoietic progenitors indicate that Fbw7 controls, through the regulation of HSC cell cycle entry, the global transcriptional signature that is associated with the quiescent, self-renewing HSC phenotype.
Control of hematopoietic stem cell quiescence by the E3 ubiquitin ligase Fbw7.
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View SamplesMost human B cell lymphomas (B-NHL) are derived from germinal centers (GCs), the structure where B-cells undergo class switch recombination (CSR) and somatic hypermutation (SHM) and are selected for high-affinity antibody production. The pathogenesis of B-NHL is associated with distinct genetic lesions, including chromosomal translocations and aberrant somatic hypermutation, which appear to arise from mistakes occurring during CSR and SHM. To ascertain the role of CSR and SHM in lymphomagenesis, we crossed three oncogene-driven (MYC, BCL6, MYC/BCL6) mouse models of B cell lymphoma with mice lacking activation-induced cytidine deaminase (AID), the enzyme required for both processes.
AID is required for germinal center-derived lymphomagenesis.
Specimen part
View SamplesSurface expression of the viral Envelope protein (Env) was used to enrich reactivated latent T cells producing HIV-RNA, and single cell RNASeq was performed to study gene expression differences between latent cells and controls. Overall design: Latent CD4+ T cells from virologically suppressed patients were reactivated in vitro and isolated using antibodies against HIV-1 Env. Single cell RNASeq was performed comparing reactivated latent cells with control, unpurified cells from the same donor and with cells actively infected in vitro using HIV-1(YU2).
Clonal CD4<sup>+</sup> T cells in the HIV-1 latent reservoir display a distinct gene profile upon reactivation.
Subject
View SamplesWe have cloned and characterized a fusion gene NUP98/HHEX1 resulting from t(7;10) from a patient with acute myeloid leukemia (AML). As NUP98/HHEX acts as an aberrant transcriptional activator, putative targets were searched upon transient expression of the fusion in primary murine bone marrow cells.
Leukemogenic mechanisms and targets of a NUP98/HHEX fusion in acute myeloid leukemia.
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View SamplesThe Hedgehog (Hh) signaling pathway is a developmentally conserved regulator of stem cell function. Several reports suggested that Hh signaling is an important regulator of hematopoietic stem cell (HSC) maintenance and differentiation. Here we test this hypothesis in vivo using both gain- and loss-of-function Hh genetic models. Surprisingly, our studies demonstrate that conditional Smoothened (Smo) deletion or over-activation has no significant effects on adult HSC self-renewal and function. Moreover, they indicate a lack of synergism between the Notch and Hh pathways in HSC function, as RBPJ- and Smo-deficiency do not affect hematopoiesis. In agreement with this notion, detailed genome-wide transcriptome analysis reveals that silencing of Hh signaling does not significantly alter the HSC-specific gene expression signature. Our studies demonstrate that the Hh signaling pathway is dispensable for adult HSC function and suggest that the Hh pathway can be targeted in future clinical trials addressing the effect of Hh inhibition on leukemia-initiating cell maintenance.
Hedgehog signaling is dispensable for adult hematopoietic stem cell function.
Sex
View SamplesBlimp-1 expression in T cells extinguishes the T follicular helper cell fate and drives terminal differentiation, but also limits autoimmunity. Although various factors have been described to control Blimp-1 expression in T cells, little is known about what regulates Blimp-1 expression in Th2 cells and the molecular basis of its actions. Herein, we report that STAT3 unexpectedly played a critical role in regulating Blimp-1 in Th2 cells. Furthermore, we found that the cytokine IL-10 acted directly on Th2 cells and was necessary and sufficient to induce optimal Blimp-1 expression through STAT3. Together, Blimp-1 and STAT3 amplified IL-10 production in Th2 cells, creating a strong autoregulatory loop that enhanced Blimp-1 expression. Increased Blimp-1 in T cells antagonized STAT5-regulated cell cycle and anti-apoptotic genes to limit cell expansion. These data elucidate the signals required for Blimp-1 expression in Th2 cells and reveal an unexpected mechanism of action of IL-10 in T cells, providing insights into the molecular underpinning by which Blimp-1 constrains T cell expansion to limit autoimmunity. Overall design: RNAseq of activated undifferentiated CD4 T cells with or without exogenous expression of Blimp-1.
IL-10 induces a STAT3-dependent autoregulatory loop in T<sub>H</sub>2 cells that promotes Blimp-1 restriction of cell expansion via antagonism of STAT5 target genes.
Specimen part, Subject
View SamplesZinc is an essential micronutrient in pregnancy and zinc deficiency impairs fetal growth. We used a mouse model of moderate zinc deficiency to determine how zinc is important to placental morphogenesis.
Zinc is a critical regulator of placental morphogenesis and maternal hemodynamics during pregnancy in mice.
Specimen part
View SamplesGenome-wide analysis was performed on microRNA 155+/+ and -/- Th17 cells to determine the differentially expressed transcripts that are regulated by miR-155. We found that Jarid2 was differentially expressed in absence of miR-155 and highlight the mechanism for the silencing of IL-22 by Jarid2 and PRC2 in miR-155-/- Th17 cells. Overall design: Comparison of transcriptome of Th17 cells in presence or absence of microRNA 155
miR-155 activates cytokine gene expression in Th17 cells by regulating the DNA-binding protein Jarid2 to relieve polycomb-mediated repression.
Specimen part, Cell line, Subject
View SamplesTrisomy 21 (Ts21) or Down syndrome (DS) is the most common genetic cause of intellectual disability. To investigate the consequences of Ts21 on human brain development, we have systematically analyzed the transcriptome of dorsolateral prefrontal cortex (DFC) and cerebellar cortex (CBC) using exon array mapping in DS and matched euploid control brains spanning from prenatal development to adulthood. We identify hundreds of differentially expressed (DEX) genes in the DS brains, many of which exhibit temporal changes in expression over the lifespan. To gain insight into how these DEX genes may cause specific DS phenotypes, we identified functional modules of co-expressed genes using several different bioinformatics approaches, including WGCNA and gene ontology analysis. A module comprised of genes associated with myelination, including those dynamically expressed over the course of oligodendrocyte development, was amongst those with the great levels of differential gene expression. Using Ts65Dn mouse line, the most common rodent model of DS, w e observed significant and novel defects in oligodendrocyte maturation and myelin ultrastructure; establishing a correlative proof-of-principle implicating myelin dysgenesis in DS. Thus, examination of the spatio-temporal transcriptome predicts specific cellular and functional events in the DS brain and is an outstanding resource for determining putative mechanisms involved in the neuropathology of DS.
Down Syndrome Developmental Brain Transcriptome Reveals Defective Oligodendrocyte Differentiation and Myelination.
Sex, Disease, Race
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