In many mammals, halogenated aromatic hydrocarbon (HAH) exposure causes wasting syndrome, defined as lethal weight loss as a result of severe and persistent hypophagia. The most potent HAH in causing wasting is 2,3,7,8-tetrachlorodibenzo--dioxin (TCDD), which exerts its toxic effects through the aryl hydrocarbon receptor (AHR) a transcription factor. Because TCDD toxicity is thought to predominantly arise from dysregulation of AHR-transcribed genes, we hypothesized that wasting syndrome is due to TCDD-induced dysregulation of genes involved in regulation of food-intake. We therefore focused on the hypothalamus, as it is the regulatory center of food-intake and energy balance in the central nervous system. We profiled mRNA abundance in hypothalamic tissue from two rat strains with widely differing sensitivities to wasting syndrome: TCDD-sensitive Long-Evans rats and TCDD-resistant Han/Wistar rats, 23 hours after exposure to TCDD (100 g/kg) or corn oil vehicle. We found that TCDD exposure caused minimal transcriptional dysregulation effects in the hypothalamus, with only 6 genes changed in Long-Evans rats and 15 genes in Han/Wistar rats. Two of the most dysregulated genes were Cyp1a1 and Nqo1, which are induced by TCDD across a wide range of tissues and are considered sensitive markers of TCDD exposure. The minimal response of the hypothalamic transcriptome to a lethal dose of TCDD at an early time-point suggests that the hypothalamus is not the predominant site of initial events leading to hypophagia and associated wasting. TCDD may affect feeding behaviour via events upstream or downstream of the hypothalamus, and further work is required to evaluate this at the level of individual hypothalamic nuclei and subregions.
Transcriptional profiling of rat hypothalamus response to 2,3,7,8-tetrachlorodibenzo-ρ-dioxin.
We analyzed the genome-wide expression by RNA-seq of a yeast strain that expresses Cas9d and a guideRNA targeted to the GAL10 locus (called +116), which inhibits GAL10 ncRNA expression from the antisense strand. We compared this strain to a strain expressing a scrambled guideRNA. The goal was to examine the effects of ncRNA inhibition and to examine if CRISPR inhibition of gene expression has off-target effects. We find that CRISPR-mediated inhibtion of GAL10 ncRNA only significantly changes expression of transcripts at the GAL1-10 locus, showing that CRISPR is highly specific, and that GAL10 ncRNA only control genes at the GAL locus. Overall design: RNA-seq of 2 strains with CRISPR scrambled and 2 strains with CRISPR +116, the latter of which inhibits GAL10 ncRNA
Single-Molecule Imaging Reveals a Switch between Spurious and Functional ncRNA Transcription.
Cell line, SubjectView Samples
Rodents exposed to the environmental contaminant, TCDD, suffer from a number of acute and chronic toxicities, including lethality and a wasting syndrome. Hypothesizing that the wasting syndrome may be caused by changes in adipose tissue -- either in its hormonal regulation or in homeostatic effects -- we profiled the transcriptional response of rat white adipose to TCDD. We employed two separate rat strains: the Long-Evans strain is sensitive to TCDD toxicities while the Han/Wistar strain is over four orders of magnitude more resistant. One day after TCDD exposure few genes were altered in either strain, but after four days a modest number of transcriptional alterations were observed. Strikingly, TCDD had far fewer effects than did a feed-restriction protocol intended to mimic the wasting syndrome itself. Notably several classic TCDD-responsive genes were modulated at all time-points, including Cyp1a1, Cyp1b1, and Nqo1. We therefore concluded that rat adipose tissue is unlikely to be the primary driver of the wasting syndrome, and that another tissue is likely involved.
Transcriptional profiling of rat white adipose tissue response to 2,3,7,8-tetrachlorodibenzo-ρ-dioxin.
Treatment induced senescence (TIS) is a terminal cell cycle arrest program, increasingly recognized as a tumor suppressor mechanism complementing apoptosis in response to standard chemotherapy regimens. In particular cells with blocked apoptotic pathways rely on senescence as the only remaining failsafe mechanism to keep the neoplastic growth in check. However, little is known about biological properties, long-term fate of senescent tumor cells and their impact on the microenvironment.
Opposing roles of NF-κB in anti-cancer treatment outcome unveiled by cross-species investigations.
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Diffuse large B-cell lymphoma (DLBCL) represents a heterogeneous diagnostic category with distinct molecular subtypes that can be defined by gene expression profiling. However, even within these defined subtypes, heterogeneity prevails. To further elucidate the pathogenesis of these entities, we determined the expression of the tumor suppressor phosphatase and tensin homolog (PTEN) in 248 primary DLBCL patient samples. These analyses revealed that loss of PTEN was detectable in 55% of germinal center B-cell-like (GCB) DLBCLs, whereas this abnormality was found in only 14% of non-GCB DLBCL patient samples. In GCB DLBCL, the PTEN status was inversely correlated with activation of the oncogenic PI3K/ protein kinase B (AKT) pathway in both DLBCL cell lines and primary patient samples. Re-expression of PTEN induced cytotoxicity in PTEN-deficient GCB DLBCL cell line models by inhibiting PI3K/AKT signaling, indicating an addiction to this pathway in this subset of GCB DLBCLs. PI3K/AKT inhibition induced down-regulation of the transcription factor MYC. Re-expression of MYC rescued GCB DLBCL cells from PTEN-induced toxicity, identifying a regulatory mechanism of MYC expression in DLBCL. Finally, pharmacologic PI3K inhibition resulted in toxicity selectively in PTEN-deficient GCB DLBCL lines. Collectively, our results indicate that PTEN loss defines a PI3K/ AKT-dependent GCB DLBCL subtype that is addicted to PI3K and MYC signaling and suggest that pharmacologic inhibition of PI3K might represent a promising therapeutic approach in these lymphomas.
PTEN loss defines a PI3K/AKT pathway-dependent germinal center subtype of diffuse large B-cell lymphoma.
Sex, Disease, Cell line, TreatmentView Samples
Pluripotency, the capacity of embryo-derived stem cells to generate all tissues in the organism, can be induced in somatic cells by nuclear transfer into oocyte, fusion with embryonic stem cells, and for male germ cells by cell culture alone. Recently, murine fibroblasts have been reprogrammed directly to pluripotency by ectopic expression of four transcription factors (Oct4, Sox2, Klf4, and Myc) to yield induced Pluripotent Stem (iPS) cells. Using the same four factors, we have derived iPS cells from human embryonic stem cell-derived fibroblasts, primary human fetal cells, and diverse cells of neonatal and adult human origin. The human iPS cells manifest the colony morphology, gene expression patterns, and epigenetic characteristics of human Embryonic Stem (hES) cells, and form well-differentiated teratomas in immune-deficient mice. These data demonstrate that defined factors can reprogram human cells to pluripotency, and establish a method whereby patient-specific cells might be established in culture.
Reprogramming of human somatic cells to pluripotency with defined factors.
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Tumor-induced immunosuppression remains a major challenge for immunotherapy of cancer patients. To further elucidate why an allogeneic gene-modified (Interleukin-7(IL-7)/CD80 co-transfected) renal cell cancer vaccine failed to induce clinically relevant TH1-polarized immune responses, peripheral blood mononuclear cells (PBMCs) from enrolled study patients were analyzed by gene expression profiling (GEP) both prior and after vaccination. At baseline before vaccination, a profound downregulation of gene signatures associated with antigen presentation, immune response/T cells, cytokines/chemokines and signaling/transcription factors was observed in renal cell cancer patients as compared to healthy controls. Vaccination led to a partial reversion of preexisting immunosuppression, however, GEP indicated that an appropriate TH1 polarization could not be achieved. Most interestingly, our results suggest that the nuclear factor kappa B (NF-B) signaling pathway might be involved in the impairment of immunological responsiveness and the observed TH2 deviation. In summary, our data suggest that GEP might be a powerful tool for the prediction of immunosuppression and the monitoring of immune responses within immunotherapy trials.
Gene expression profiling of peripheral blood mononuclear cells during treatment with a gene-modified allogeneic tumor cell vaccine in advanced renal cell cancer: tumor-induced immunosuppression and a possible role for NF-κB.
Transcription factor-mediated reprogramming yields induced pluripotent stem cells (iPSC) by erasing tissue specific methylation and re-setting DNA methylation status to an embryonic stage. We compared bona fide human iPSC derived from umbilical cord blood (CB) and neonatal keratinocytes (K). Through both incomplete erasure of tissue specific methylation and de novo tissue specific methylation, CB-iPSC and K-iPSC are distinct in genome-wide DNA methylation profiles. Functionally, CB-iPSC displayed better blood formation in vitro, whereas K-iPSC differentiated better to a keratinocyte fate, implying that the tissue of origin needs to be considered in future therapeutic applications of human iPSCs.
Donor cell type can influence the epigenome and differentiation potential of human induced pluripotent stem cells.
Specimen partView Samples
Constitutive activation of the anti-apoptotic NF-B signaling pathway is a hallmark of the activated B-cell-like (ABC) subtype of diffuse large B-cell lymphomas (DLBCL) that is characterized by adverse survival. Recurrent oncogenic mutations are found in the scaffold protein CARMA1 (CARD11) that connects B-cell receptor (BCR) signaling to the canonical NF-B pathway. We asked how far additional downstream processes are activated and contribute to the oncogenic potential of DLBCL-derived CARMA1 mutants. To this end, we expressed oncogenic CARMA1 mutants in the NF-B negative DLBCL lymphoma cell line BJAB. By a proteomic approach we identified recruitment of -Catenin and its destruction complex consisting of APC, AXIN1, CK1 and GSK3 to oncogenic CARMA1. Recruitment of the -Catenin destruction complex was independent of CARMA1-BCL10-MALT1 (CBM) complex formation or constitutive NF-B activation and promoted the stabilization of -Catenin. Elevated -Catenin expression was detected in cell lines and biopsies from ABC DLBCL that rely on chronic BCR signaling. Increased -Catenin amounts alone were not sufficient to induce classical WNT target gene signatures, but could augment TCF/LEF dependent transcriptional activation in response to WNT signaling. In conjunction with NF-B, -Catenin enhanced expression of immune suppressive IL-10 and repressed anti-tumoral CCL3, indicating that -Catenin may induce a favorable tumor microenvironment. Thus, parallel activation of NF-B and -Catenin signaling by gain-of-function mutations in CARMA1 can augment WNT stimulation and is required for maintaining high expression of distinct NF-B target genes and can thereby trigger cell intrinsic and extrinsic processes that promote DLBCL lymphomagenesis.
Oncogenic CARMA1 couples NF-κB and β-catenin signaling in diffuse large B-cell lymphomas.
Specimen part, Cell lineView Samples