GUN1 integrates retrograde signals in the chloroplast but the underlying mechanism is elusive. FUG1, a chloroplast translation initiation factor, and GUN1 are co-expressed at the transcript level, and FUG1 co-immunoprecipitates with GUN1. We used mutants of GUN1 (gun1-103) and FUG1 (fug1-3) to analyse their functional relationship at the physiological and systems-wide level, the latter including transcriptome and proteome analyses. Absence of GUN1 aggravates the effects of decreased FUG1 levels on chloroplast protein translation, resulting in transient additive phenotypes with respect to photosynthesis, leaf coloration, growth and cold acclimation. Variegation of the var2 mutant is enhanced by gun1-103 in terms of increasing the fraction of white sectors, in contrast to fug1-3 that acts as suppressor. The transcriptomes of fug1-3 and gun1-103 are very similar, but absence of GUN1 alone has almost no effects on protein levels, whereas chloroplast protein accumulation is markedly decreased in fug1-3. In gun1 fug1 double mutants, effects on transcriptomes and particularly proteomes are enhanced. Our results show that GUN1 function becomes critical when chloroplast proteostasis is perturbed by decreased translation (fug1) or degradation (var2) of chloroplast proteins. The functions of FUG1 and GUN1 appear to be related, corroborating the view that GUN1 operates in chloroplast proteostasis. Overall design: Examination of differential gene expression in the Arabdidopsis thaliana gun1, fug1 and gun1 fug1 mutants compared to wild type in three replicates
Relationship of GUN1 to FUG1 in chloroplast protein homeostasis.
Subject
View SamplesExpression of DREAM in dorsal root ganglia and spinal cord is related to endogenous control mechanisms of acute and chronic pain. In primary sensory trigeminal neurons high levels of endogenous DREAM protein are preferentially localized in the nucleus, suggesting a major transcriptional role. Here, we show that DREAM participates in the control of trigeminal pain perception through the regulation of prodynorphin and BDNF. Furthermore, genome-wide analysis of trigeminal neurons in daDREAM transgenic mice revealed that cathepsin L (CTSL) and the monoglyceride lipase (MGLL) are new DREAM downstream targets and have a role in the regulation of trigeminal nociception.
Transcriptional repressor DREAM regulates trigeminal noxious perception.
Specimen part
View SamplesSelenoproteins mediate the cancer-preventive properties of the essential nutrient selenium, but also have cancer-promoting effects. We examined the contributions of the 15-kDa selenoprotein (Sep15) and thioredoxin reductase 1 (TR1) to cancer development. Targeted down-regulation of either gene inhibited anchorage-dependent and anchorage-independent growth and cancer metastasis of mouse colon carcinoma CT26 cells. Surprisingly, combined deficiency of Sep15 and TR1 reversed the anti-cancer effects observed with down-regulation of each single gene. We found that inflammation-related genes regulated by Stat-1, especially the interferon-gamma-regulated guanylate-binding proteins, were highly elevated in Sep15-deficient cells. In contrast, the Wnt/Beta-catenin pathway was up-regulated in cells that lacked both TR1 and Sep15. These results suggest that Sep15 and TR1 participate in interfering regulatory pathways in colon cancer cells. Considering the variable expression levels of Sep15 and TR1 found within the human population, and controversial results of recent human clinical trials involving dietary selenium, our results are important to general public health.
The 15kDa selenoprotein and thioredoxin reductase 1 promote colon cancer by different pathways.
Specimen part, Cell line
View SamplesWe have investigated the p53-dependent stress response in medium spiny neurons (MSNs) that degenerate in Huntingtons disease. To induce p53 signaling cascade, we have genetically inactivated by the Cre/loxP system the essential RNA polymerase I (Pol I) transcription factor TIF-IA, leading to stabilization of p53 and induction of p53-dependent apoptosis.
A neuroprotective phase precedes striatal degeneration upon nucleolar stress.
Age, Specimen part
View SamplesDREAM (downstream regulatory element antagonist modulator) is a Ca2+-binding protein that binds DNA and represses transcription in a Ca2+-dependent manner. Previous studies have shown a role for DREAM in cerebellar function regulating the expression of the sodium/calcium exchanger3 (NCX3) in cerebellar granules to control Ca2+ homeostasis and survival of these neurons. To achieve a more global view of the genes regulated by DREAM in the cerebellum, we performed a genome-wide analysis in transgenic cerebellum expressing a Ca2+-insensitive/CREB-independent dominant active mutant DREAM (daDREAM). Our results indicate that DREAM is a major transcription factor in the cerebellum that regulates genes important for cerebellar development.
Reduced Mid1 Expression and Delayed Neuromotor Development in daDREAM Transgenic Mice.
Specimen part
View SamplesIn adult cancers, epigenetic changes and aberrant splicing of the DNMT3B is commonly observed, and the pattern of gene methylation and expression has been shown to be modified by DNMT3B7, a truncated protein of DNMT3B. Much less is known about the mechanism of epigenetic changes in the pediatric cancer neuroblastoma. To investigate if aberrant DNMT3B transcripts alter DNA methylation, gene expression and tumor phenotype in neuroblastoma, we measured DNMT3B isoform expression in primary tumors and cell lines. Higher levels of DNMT3B7 were detected in differentiated ganglioneuroblastomas compared to undifferentiated neuroblastomas, suggesting that expression of DNMT3B7 may induce a less clinically aggressive tumor phenotype. To test this hypothesis, we investigated the effects of forced DNMT3B7 in neuroblastoma cells. We found that DNMT3B7 expression significantly inhibited neuroblastoma cell proliferation in vitro, and in neuroblastoma xenografts, DNMT3B7 decreased angiogenesis and tumor growth. DNMT3B7-positive cells had higher levels of total genomic methylation, and RNA-sequencing revealed a dramatic decrease in expression of FOS and JUN family members, AP1 complex components. Consistent with the established antagonistic relationship between AP1 expression and retinoic acid receptor activity, decreased proliferation and increased differentiation was seen in the DNMT3B7-expressing neuroblastoma cells following treatment with all trans retinoic acid (ATRA) compared to controls. Our results demonstrate that high levels of DNMT3B7 modify the epigenome in neuroblastoma cells, induce changes in gene expression, inhibit tumor growth, and increase sensitivity to ATRA. Further knowledge regarding mechanisms by which DNMT3B7 regulates gene methylation may ultimately lead to the development of therapeutic strategies that reverse the epigenetic aberrations that drive neuroblastoma pathogenesis. Overall design: DNMT3B7, a truncated DNMT3B isoform, was stably transfected into an N-type neuroblastoma cell line (LA1-55n) using a Tet-off inducible system. DNMT3B7 expressing cells were compared to vector control cells after 21 days of induction.
Truncated DNMT3B isoform DNMT3B7 suppresses growth, induces differentiation, and alters DNA methylation in human neuroblastoma.
Cell line, Subject
View SamplesDeregulated intracellular Ca2+ homeostasis underlies synaptic dysfunction and is a common feature in neurodegenerative processes, including Huntington's disease (HD). DREAM/calsenilin/KChIP-3 is a multifunctional Ca2+ binding protein that controls the expression level and/or the activity of several proteins related to Ca2+ homeostasis, neuronal excitability and neuronal survival. We found that expression of endogenous DREAM (DRE antagonist modulator) is reduced in the striatum of R6 mice, in STHdh-Q111/111 knock in striatal neurons and in HD patients. DREAM down regulation in R6 striatum occurs early after birth, well before the onset of motor coordination impairment, and could be part of an endogenous mechanism of neuroprotection, since i) R6/2 mice hemizygous for the DREAM gene (R6/2xDREAM+/-) showed delayed onset of locomotor impairment and prolonged lifespan, ii) motor impairment after chronic administration of 3-NPA was reduced in DREAM knockout mice and enhanced in daDREAM transgenic mice and, iii) lentiviral-mediated DREAM expression in STHdh-Q111/111 knock in cells sensitizes them to oxidative stress. Transcriptomic analysis showed that changes in gene expression in R6/2 striatum were notably reduced in R6/2xDREAM+/- striatum. Chronic administration of repaglinide, a molecule able to bind to DREAM in vitro and to accelerate its clearance in vivo, delayed the onset of motor dysfunction, reduced striatal loss and prolonged the lifespan in R6/2 mice. Furthermore, exposure to repaglinide protected STHdh-Q111/111 knock in striatal neurons sensitized to oxidative stress by lentiviral-mediated DREAM overexpression. Thus, genetic and pharmacological evidences disclose a role for DREAM silencing in early neuroprotective mechanisms in HD.
Activating transcription factor 6 derepression mediates neuroprotection in Huntington disease.
Specimen part
View SamplesChanges in nuclear Ca2+ homeostasis activate specific gene expression programs and are central to the acquisition and the plastic storage of memories. DREAM /KChIP proteins form heterotetramers that bind DNA and repress transcription in a Ca2+-dependent manner. Single ablation of one member of the DREAM/KChIP family may result in a mild or the absence of phenotype due to partial gene compensation. To study the function of DREAM/KChIP proteins in the brain, we used transgenic mice expressing a Ca2+-insensitive/CREB-independent dominant active mutant DREAM (daDREAM). We show that daDREAM controls the expression of several activity-dependent transcription factors including Npas4, Nr4a1, Mef2C, JunB and c-Fos, as well as the chromatin modifying enzyme Mbd4 and proteins related to actin polymerization like Arc and gelsolin. Thus, directly or through these targets, expression of daDREAM in the forebrain resulted in a complex phenotype characterized by i) impaired learning and memory, ii) loss of recurrent inhibition and enhanced LTP in the dentate gyrus without affecting Kv4-mediated potassium currents, and iii) modified spine density in DG granule neurons. Our results propose DREAM as a master-switch transcription factor regulating several activity-dependent gene expression programs to control synaptic plasticity, learning and memory.
DREAM controls the on/off switch of specific activity-dependent transcription pathways.
Specimen part
View SamplesMouse glioblastomas were induced by lentiviral vector expressing HrasG12V and shRNA against p53. Tumor tissues were isolated from mice reached clinical endpoints. RNA was isolated using the RNeasy kit according to manufacturer’s protocol with the addition of DNase (Qiagen). cDNA libraries were prepared using the TruSeq RNA Sample Prep kit (Illumina). RNA sequencing was performed using a HiSeq 2500 Sequencing System (Illumina). Overall design: 3 normal mouse brain samples compared to 5 glioblastoma samples by standard RNAseq method.
Targeting NF-κB in glioblastoma: A therapeutic approach.
Specimen part, Subject
View SamplesBy using high-density DNA microarrays, we analyzed the gene-expression profile of SHSY5Y neuroblastoma cells after treatment with cobalt chloride
Investigation of Endogenous Retrovirus Sequences in the Neighborhood of Genes Up-regulated in a Neuroblastoma Model after Treatment with Hypoxia-Mimetic Cobalt Chloride.
Specimen part, Cell line
View Samples