We devised a novel insertional mutagenesis approach based on lentiviral vectors to induce hepatocellular carcinoma in three mouse models and identified four novel cancer initiating genes. Two genes are the well characterized Braf and Sos1, while the other two are Fign, encoding an AAA ATPase whose functions are poorly understood, and the complex Dlk1-Dio3 imprinted region which has been recently implicated in cancer and stemness. Activation of Fign or Braf and upregulation of the Dlk1-Dio3 imprinted region are functionally interconnected and may altogether control cell transformation, stemness and energy metabolism. Moreover, all the genes identified play a relevant role in human hepatocarcinogenesis as their expression levels and/or transcriptional signatures induced by their deregulation predict a different clinical outcome in hepatocellular carcinoma patients. These series consists of mRNA expression microarray data (The GeneChip Mouse Gene 1.0 ST Array, Affymetrix) from 8 non-tumoral liver and 21 hepatocellular carcinoma induced by insertional mutagenesis.
Lentiviral vector-based insertional mutagenesis identifies genes associated with liver cancer.
Specimen part
View SamplesAntitoxins are becoming recognized as proteins that regulate more than their own synthesis; for example, we found previously that antitoxin MqsA represses the gene encoding the stationary phase sigma factor RpoS. Here, we investigated the physiological role of antitoxin DinJ of the DinJ/YafQ toxin/antitoxin system and found DinJ also affects the general stress response by decreasing RpoS levels. Corroborating the reduced RpoS levels upon producing DinJ, catalase activity, cell adhesins, and cyclic diguanylate decreased while swimming increased. Using a transcriptome search and DNA-binding assays, we determined that the mechanism by which DinJ reduces RpoS is by repressing cspE which encodes cold-shock protein CspE that inhibits translation of rpoS mRNA. Hence, DinJ influences the general stress response indirectly by regulating cspE.
Antitoxin DinJ influences the general stress response through transcript stabilizer CspE.
Time
View SamplesExposure to high irradiance results in dramatic changes in nuclear gene expression in plants. However, little is known about the mechanisms by which changes in irradiance are sensed and how the information is transduced to the nucleus to initiate the genetic response. To investigate whether the photoreceptors are involved in the response to high irradiance, we analyzed expression of ELIP1, ELIP2, APX2 and LHCB2.4 in the phyA, phyB, cry1 and cry2 photoreceptor mutants and hy5 and hyh transcription factor mutants. Following exposure to high intensity white light for 3 h (HL, 1000 micro mol quanta m-2 s-1) expression of ELIP1/2 and APX2 was strongly induced and LHCB2.4 expression repressed in wild type. The cry1 and hy5 mutants showed specific mis-regulation of ELIP1/2 and we show that the induction of ELIP1/2 expression is mediated via CRY1 in a blue light intensity-dependent manner. Furthermore, using the Affymetrix Arabidopsis 24K Gene-Chip we showed that 77 of the HL responsive genes are regulated via CRY1, and 26 of those genes were also HY5 dependent. As a consequence of the mis-regulation of these genes the cry1 mutant displayed a high irradiance-sensitive phenotype with significant photoinactivation of PSII, indicated by reduced Fv/Fm. Thus, we describe a novel function of CRY1 in mediating plant responses to high irradiances that is essential to the induction of photoprotective mechanisms. This indicates that high irradiance can be sensed in a chloroplast-independent manner by a cytosolic/nucleic component.
Genome-wide gene expression analysis reveals a critical role for CRYPTOCHROME1 in the response of Arabidopsis to high irradiance.
No sample metadata fields
View SamplesWe have used the citrus GeneChip array (GPL5731) to survey the transcription profiles of sweet orange in response to the bacterial pathogens Xanthomonas axonopodis pv. citri (Xac) and Xanthomonas axonopodis pv. aurantifolii (Xaa). Xac is the causal agent of the citrus canker disease on a wide range of citrus species, including sweet oranges (Citrus sinensis). On the other hand, Xaa is pathogenic to Mexican lime (Citrus aurantifolia) only, and in sweet orange it triggers a defense response. In order to identify the genes induced during the defense response (Xaa-responsive genes) or citrus canker development (Xac-responsive genes), we conducted microarrays hybridization experiments at 6 and 48 hours after bacterial infiltration (habi). The analysis revealed that genes commonly modulated by Xac and Xaa are associated with basal defenses normally triggered by pathogen-associated molecular patterns, including those involved in reactive oxygen species production and lignification. Significantly, Xac-infected leaves showed considerable changes in the transcriptional profiles of defense-, cell wall-, vesicle trafficking- and cell growth-related genes between 6 and 48 habi. This is consistent with the notion that Xac suppresses host defenses near the beginning of the infection and simultaneously changes the physiological status of the host to promote cell enlargement and division. Finally, Xaa triggered a MAP kinase signaling pathway involving WRKY and ethylene-responsive transcriptional factors known to activate downstream defense genes.
Transcriptional analysis of the sweet orange interaction with the citrus canker pathogens Xanthomonas axonopodis pv. citri and Xanthomonas axonopodis pv. aurantifolii.
No sample metadata fields
View SamplesPersister cells are a sub-population of all bacterial cultures which exhibit a non-inheritable, multi-drug tolerance when subjected to lethal antibiotic challenge. These persisters arise as a result of metabolic dormancy, and can resume growth subsequent to antibiotic challenge, leading to recalcitrance of bacterial infections.
Phosphodiesterase DosP increases persistence by reducing cAMP which reduces the signal indole.
No sample metadata fields
View SamplesMultipotent progenitor cells (MPs) have been observed in human kidneys and particularly in Bowman's capsule and proximal tubules. The kidney owns the ability to repair local damage and renal MPs may play a role in the regenerative processes. Microarray technology was applied to identify differentially expressed genes among resident MPs isolated from glomeruli and tubules of normal renal tissue, renal proximal tubular epithelial cells (RPTECs) and mesenchymal stem cells (MSCs).
TLR2 plays a role in the activation of human resident renal stem/progenitor cells.
Subject
View SamplesE. coli K-12 BW25113 persister cells generated via H202 pre-treatment and deletion of rpoS, relative to BW25113 wild-type stationary phase gene expression. Persister cells were generated following exposure to ampicillin 20 ug/mL.
Bacterial persistence increases as environmental fitness decreases.
Specimen part, Disease, Treatment, Time
View SamplesPersisters are a subpopulation of metabolically-dormant cells in biofilms that are resistant to antibiotics; hence, understanding persister cell formation is important for controlling bacterial infections. Previously we discerned that MqsR and MqsA of Escherichia coli are a toxin/antitoxin pair that influence persister cell production via their regulation of Hha, CspD, and HokA. Here, to gain more insights into the origin of persisters, we used protein engineering to increase the toxicity of toxin MqsR by reasoning it would be easier to understand the effect of this toxin if it were more toxic. We found that two mutations (K3N and N31Y) increase the toxicity four fold and increase persistence 73 fold compared to native MqsR by making the protein less labile. A whole transcriptome study revealed that the MqsR variant represses acid resistance genes (gadABCEWX and hdeABD), multidrug resistance genes (mdtEF), and osmotic resistance genes (osmEY). Corroborating these microarray results, deletion of rpoS as well as the genes that the master stress response regulator RpoS controls, gadB, gadX, mdtF, and osmY, increased persister formation dramatically to the extent that nearly the whole population became persistent. Therefore, the more toxic MqsR increases persistence by decreasing the ability of the cell to respond to antibiotic stress through its RpoS-based regulation of acid resistance, multidrug resistance, and osmotic resistance systems.
Bacterial persistence increases as environmental fitness decreases.
Specimen part, Time
View SamplesThough it is well established that immunological functions of CD4+ T cells are time of day-dependent, the underlying molecular mechanisms remain largely obscure. To address the question whether T cells themselves harbor a functional clock driving circadian rhythms of immune function, we analyzed clock gene expression and immune responses of CD4+ T cells purified from blood of healthy subjects at different time points throughout the day. Circadian clock function as well as immune function was further analyzed in cultivated T cells and circadian clock reporter systems. We found robust rhythms of clock gene expression as well as, after stimulation, of IFN-g production and CD40L expression in both freshly isolated and in cultured CD4+ T cells. Moreover, circadian luciferase reporter activities in CD4+ T cells and in thymic sections from PER2::LUCIFERASE reporter mice suggest that endogenous T cell clock rhythms are self-sustained under constant culture conditions. Microarray analysis of stimulated CD4+ T cell cultures revealed a rhythmic regulation of the NF-kB pathway as a candidate mechanism regulating circadian immune responses. Collectively, these data demonstrate for the first time that CD4+ T cell responses are regulated by an intrinsic cellular circadian oscillator capable of driving rhythmic adaptive immune responses in vitro and in vivo.
Circadian clocks in mouse and human CD4+ T cells.
Specimen part, Time
View SamplesStatins and bisphosponates (BPs) are two distinct classes of isoprenoid pathway inhibitors targeting HMG-CoA reductase (upstream enzyme) and Farnesyl-pyrophospate synthase (downstream enzyme) respectively. Here we conducted a comparative study of two representatives of these classes, fluvastatin (Fluva) and Zoledronate (Zol), to assess the differences in their in vivo metastatic potentials and pharmacogenomic profiles. Both drugs, being administered after emergence of detectable metastases, appeared to be potent metastasis inhibitors in MDA-MB-231 breast cancer metastasis model. We observed a reduced number of metastatic sites under Fluva, but not Zol treatment. Combinatorial in vivo treatment by Fluva and Zol showed no synergy for these drugs, as reported earlier on the basis of in vitro studies (Budman DR, Oncology 2006), staying in line with similarity of their transcriptomic profiles. Comparison of Zol and Fluva transcriptomic profiles revealed similar patterns of affected genes (describe involved genes functions) through different kinetics (when treated with IC50 determined for 72h treatment, the majority of changes were observed after 24h incubation with Fluva , and only after 48h incubation with Zol at 72h-IC50 or after 24h treatment with its 3 times higher dose). We demonstrated here that targeting different enzymes of the same pathway neither necessarily leads to distinct changes in gene profiles, nor to synergy for in vivo anti-metastatic potential.
Transcriptome analysis and in vivo activity of fluvastatin versus zoledronic acid in a murine breast cancer metastasis model.
Cell line, Time
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