Project description:Two regulatory elements in chr8 (chr8:579137-581436) and chr20 (chr20:62115827-62119284) were deleted using CRISPR and the effects of their deletion were assessed using RNA-seq
Project description:Salmonella enterica is a Gram-negative bacterium that causes gastroenteritis, bacteremia and typhoid fever in several animal species including humans. Its virulence is greatly dependent on two type III secretion systems (T3SSs), encoded in pathogenicity islands 1 (SPI1) and 2 (SPI2), respectively. These systems translocate proteins called effectors into eukaryotic host cell. Effectors interfere with certain host signal transduction pathways to allow the internalization of pathogens and their survival and proliferation inside vacuoles. SteA is one of the few Salmonella effectors that are substrates of both T3SSs. Nothing is known about the function of this protein inside the host cells. Here, we used gene arrays and bioinformatics analysis to study the genetic response of human epithelial cells to SteA. We found that constitutive synthesis of SteA in epithelial cells leads to induction of genes related to extracellular matrix organization and regulation of cell proliferation and serine/threonine kinase signaling pathways. SteA also represses genes related to immune processes and regulation of purine nucleotide synthesis and pathway-restricted SMAD protein phosphorylation. Consisted with this analysis a cell biology approach revealed that epithelial cells expressing steA show altered cell morphology, reduction of cytotoxicity, cell-cell adhesion and migration capability, and increase in endocytosis. Three experiments. Each experiment replicated three times. Control: HeLa cell transfected with plasmid pBABE without steA, Experiment 1:HeLa line 2 transfected with plasmid pBABE with steA. Experiment 2: HeLa line 4 transfected with plasmid pBABE with steA
Project description:Transcription profiling from young and pre-senescent IMR90 cells, transfected either with hTERT (pBabe-puro-hTERT) or vector control (pBabe-puro). Population doubling values are contained in Characteristics[generation] column.
Project description:Mutations in the NRAS oncogene are present in up to 20% of melanoma. Here, we show that interferon alpha-inducible protein 6 (IFI6) is necessary for NRASQ61K-induced transformation and melanoma growth. IFI6 was transcriptionally upregulated by NRASQ61K, and knockdown of IFI6 resulted in DNA replication stress due to dysregulated DNA replication via E2F2. This stress consequentially inhibited cellular transformation and melanoma growth via senescence or apoptosis induction depending on the RB and p53 pathway status of the cells. NRAS-mutant melanoma were significantly more resistant to the cytotoxic effects of DNA replication stress-inducing drugs, and knockdown of IFI6 increased sensitivity to these drugs. Pharmacological inhibition of IFI6 expression by the MEK inhibitor trametinib, when combined with DNA replication stress-inducing drugs, blocked NRAS-mutant melanoma growth. Collectively, we demonstrate that IFI6, via E2F2 regulates DNA replication and melanoma development and growth, and this pathway can be pharmacologically targeted to inhibit NRAS-mutant melanoma. MEL-ST cells expressing either empty vector or mutant oncogenic RAS genes (HRAS v12, KRAS v12, NRAS Q61K) were used to isolate total RNA. The RNA was then used to perform gene expression analyses using the Illumina HumanHT-12 V4.0 Expression BeadChip array.
Project description:During canonical Wnt signalling the activity of nuclear beta-catenin is largely mediated by the TCF/LEF family of transcription factors. To challenge this view we used the CRISPR/Cas9 genome editing approach to generate HEK 293T cell clones simultaneously carrying loss-of-function alleles of all four TCF/LEF genes. Exploiting unbiased whole transcriptome sequencing studies, we found that a subset of beta-catenin transcriptional targets did not require TCF/LEF factors for their regulation. Consistent with this finding, we observed in a genome-wide analysis that beta-catenin occupied specific genomic regions in the absence of TCF/LEF. Finally, we revealed the existence of a transcriptional activity of beta-catenin that specifically appears when TCF/LEF factors are absent, and refer to this as beta-catenin-GHOST response. Collectively, this study uncovers a previously neglected modus operandi of beta-catenin that bypasses the TCF/LEF transcription factors.
Project description:Cellular senescence is a stable proliferation arrest associated with an altered secretory pathway, the Senescence-Associated Secretory Phenotype (SASP). However, cellular senescence is initiated by diverse molecular triggers, such as activated oncogenes and shortened telomeres, and is associated with varied and complex physiological endpoints, such as tumor suppression and tissue aging. The extent to which distinct triggers activate divergent modes of senescence that might be associated with different physiological endpoints is largely unknown. To begin to address this, we performed gene expression profiling to compare the senescence programs associated with two different modes of senescence, oncogene-induced senescence (OIS) and replicative senescence (RS [in part caused by shortened telomeres]). While both OIS and RS are associated with many common changes in gene expression compared to control proliferating cells, they also exhibit substantial differences. These results are discussed in light of potential physiological consequences, tumor suppression and aging. We used microarrays to detail the global programme of gene expression after oncogene induced senescence.
Project description:With the advent of advanced sequencing technology, studies of RNA viruses have shown that genetic diversity contribute to both attenuation and virulence. The differences in genetic diversity of wild-type Asibi virus and 17D-204 vaccine provides an unique opportunity to investigate RNA population theory in the context of a well described live attenuated vaccine. Utilizing infectious clone-derived viruses containing some of the amino acid substitutions that differentiate yellow fever wild-type Asibi strain from 17D vaccine and recovered in a controlled experiment, establishes that the genetic diversity differences that exist between wild-type Asibi and 17D-204 vaccine viruses are not influenced by either different passage history or source of samples, but rather resulted from the attenuation of wild-type Asibi virus to yield the 17D vaccine sub-strains.
Project description:Skeletal muscle is composed of both slow-twich oxidative myofibers and fast-twitch glycolytic myofibers that differentially impact muscle metabolism, function, and eventually whole-body physiology. In the present study, we find that the mesodermal transcription factor T-box 15 (Tbx15) is highly and specifically expressed in glycolytic myofibers. Ablation of Tbx15 in vivo leads to a decrease in muscle size due to a decrease in the number of glycolytic fibers, associated with a small increase in the number of oxidative fibers. This shift in fiber composition results in muscles with slower myofiber contraction and relaxation, and also results in decreased whole-body oxygen consumption, decreased spontaneous activity, increased adiposity, and glucose intolerance. In order to identify genes regulated by Tbx15, we utilized C2C12 myoblasts with either a stable retroviral over-expression or stable lentiviral knockdown of Tbx15. RNA was extracted and biotin labelled complementary RNA (cRNA) was prepared from three independent transfections of the four stable C2C12 myoblast cell lines: shTbx15, shGFP, pBABE-Empty-puro, pBABE-Tbx15-puro. Cells were collected at 90% confluency, and subjected to microarray analysis. Affymetrix M430 2.0 Chips were used.
Project description:Here we performed DNAse-seq experiments on samples of adherent cultures of mouse neural stem cells (NS5 cell line) under normal growth conditions and upon differentiation by expression of an inducible version of the proneural factor Mash1/Ascl1 (Ascl1-ERT2). This resulted in the generation of genome-wide maps of regions of chromatin accessibility in both conditions.
Project description:Zika virus (ZIKV) is a mosquito-transmitted positive-sense RNA virus in the family Flaviviridae. Candidate live-attenuated vaccine (LAV) viruses with engineered deletions in the 3’UTR provide immunity and protection in animal models of ZIKV infection, and phenotypic studies show that LAVs retain protective abilities following in vitro passage. The present study investigates the genetic diversity of wild-type (WT) parent ZIKV and its candidate LAVs using next generation sequencing analysis of five sequential in vitro passages. ZIKV RNA from was transfected into Vero cells, incubated for nine days, harvested, and clarified by centrifugation to generate passage 0 (P0) ZIKV infectious clones. Subsequently, P0 ZIKVs were blind-passaged into fresh cultures to generate P1, then serially through P5. P1-P5 stocks were harvested from cell media at 4-5 days post-infection. ZIKV RNA from 3’UTR deletion mutants were transfected into Vero cells, incubated for nine days, harvested, and clarified by centrifugation to generate passage 0 (P0) ZIKV infectious clones. Subsequently, P0 ZIKVs were blind-passaged into fresh cultures to generate P1, then serially through P5. P1-P5 stocks were harvested from cell media at 4-5 days post-infection. Genetic diversity of the viruses were assessed by evaluating both the variability (or uncertainty) at each nucleotide position was determined using Shannon entropy calculations and identified single nucleotide variants (SNVs). The results showed both the parental WT and LAV derivatives increase in genetic diversity with evidence of adaptation following passage.