P16INK4a mediated supperssion of telomerase in normal and malignant human breast cells
Ontology highlight
ABSTRACT: The cyclin-dependent kinase inhibitor p16INK4a (CDKN2A) is an important tumor-suppressor gene frequently inactivated in human tumors. p16 suppresses the development of cancer by triggering an irreversible arrest of cell proliferation termed cellular senescence. Here, we describe another anti-oncogenic function of p16 in addition to its ability to halt cell cycle progression. We show that transient expression of p16 stably represses the hTERT gene, encoding the catalytic subunit of telomerase, in both normal and malignant breast epithelial cells. Short-term p16 expression increases the amount of histone H3 trimethylated on lysine 27 (H3K27) bound to the hTERT promoter, resulting in transcriptional silencing, likely mediated by polycomb complexes. Our results indicate that transient p16 exposure may prevent malignant progression in dividing cells by irreversible repression of genes, such as hTERT, whose activity is necessary for extensive self-renewal. 27 samples were analyzed to study three histone modifications (H3K4me3, H3K9me3, H3K27me3) in three different cell lines. Each combination of histone modification and cell line had three biological replicates (A,B,C).
Project description:The readout of genome information is controlled by transcriptional regulatory elements, but a comprehensive view of the combinatorial control by these DNA sequences, which bind regulatory protein and/or the modified histones in regulating gene transcription, is clearly preliminary. We have developed an experimental strategy for comprehensive determination of such functional elements in human DNA. This strategy involves the application of genome-wide location analysis, also known as ChIP-chip, to a panel of well-characterized regulatory proteins and histones with specific modifications, known to generally associate with transcriptional regulatory elements in vivo. Identification of their genomic binding sites will allow us to determine the sequence features in the human genome that carry out transcriptional regulatory function. We have designed and produced DNA microarrays to represent all the non-repetitive sequences in the 30 million basepair ENCODE regions of the human genome to map various types of transcriptional regulatory elements in three model cell types. We have identified promoters by mapping the genomic sequences associated with RNA polymerase II and the general transcription factor TFIID in cells, enhancer elements by mapping the genomic sequences associated with transcriptional co-activators and enhancer-specific chromatin modifications, and insulators by mapping the genomic sequences associated with the insulator binding protein CTCF. The raw microarray results are released periodically prior to publication. Keywords: ChIP-chip ENCODE ChIP-chip analyses were performed for various transcription factors and chromatin modifications in various cell types. Details to be described in publications. Ren B, Glass CK, Rosenfeld MG, Webster N, Ching KA, Harp L, Ye Z, Stuart RK, Calcar SV, Kim TH, Hawkins RD, Hon G, Barrera LO, Luna R, Wang K
Project description:Genome-wide location analysis of transcription factor of c-Myc and Max was conducted using RenLab Hu6K array in Daudi cells. In comparison, the GWLA was also done for general transcription factor RNA polymerase II and TAF1, and sequence specific transcription factor E2F1 in the same cell line. Keywords = GWLA Keywords = RenLab Keywords = Hu6K Keywords = Myc Keywords = Max
Project description:Aneuploidy and the evolution of aneuploid karyotypes of Candida albicans strains was identified using aCGH. Whole chromosome and segmental aneuploidies, (specifically on the left arm of chromosome 5 - shown to be due to isochromosome formation) are associated with the appearance of resistance to the antifungal drug fluconazole. Keywords: Comparative Genomic Hybridization Hybridization of all strains was compared to the hybridization of SC5314, the sequenced laboratory strain.
Project description:Trichophyton rubrum, an anthropophilic and cosmopolitan fungus, is the most common agent of superficial mycoses, causing rarely deep dermatophytosis in immunocompromised hosts. In this study, an infection condition of T. rubrum was modeled by adding human skin sections into a limited medium containing glucose to monitor T. rubrum gene expression patterns using cDNA microarrays on a global level. We found that exposure to human skin resulted in up-regulation of the expression levels of T. rubrum genes related to many cellular and biological processes, including transcription and translation, metabolism and secondary transport, stress response, and signaling pathways. These results provide a reference set of T. rubrum genes whose expression patterns change upon infection and reveal previously unknown genes that probably corresponding to proteins that should be considered as virulence factor candidates and potential new drug targets for T. rubrum infections.
Project description:The readout of genome information is controlled by transcriptional regulatory elements, but a comprehensive view of the combinatorial control by these DNA sequences, which bind regulatory protein and/or the modified histones in regulating gene transcription, is clearly preliminary. We have developed an experimental strategy for comprehensive determination of such functional elements in human DNA. This strategy involves the application of genome-wide location analysis, also known as ChIP-chip, to a panel of well-characterized regulatory proteins and histones with specific modifications, known to generally associate with transcriptional regulatory elements in vivo. Identification of their genomic binding sites will allow us to determine the sequence features in the human genome that carry out transcriptional regulatory function. We have designed and produced DNA microarrays to represent all the non-repetitive sequences in the 30 million basepair ENCODE regions of the human genome to map various types of transcriptional regulatory elements in three model cell types. We have identified promoters by mapping the genomic sequences associated with RNA polymerase II and the general transcription factor TFIID in cells, enhancer elements by mapping the genomic sequences associated with transcriptional co-activators and enhancer-specific chromatin modifications, and insulators by mapping the genomic sequences associated with the insulator binding protein CTCF. The raw microarray results are released periodically prior to publication. Keywords: ChIP-chip ENCODE ChIP-chip analyses were performed for various transcription factors and chromatin modifications in various cell types. Details to be described in publications. Ren B, Glass CK, Rosenfeld MG, Webster N, Ching KA, Harp L, Ye Z, Stuart RK, Calcar SV, Kim TH, Hawkins RD, Hon G, Barrera LO, Luna R, Wang K
Project description:The readout of genome information is controlled by transcriptional regulatory elements, but a comprehensive view of the combinatorial control by these DNA sequences, which bind regulatory protein and/or the modified histones in regulating gene transcription, is clearly preliminary. We have developed an experimental strategy for comprehensive determination of such functional elements in human DNA. This strategy involves the application of genome-wide location analysis, also known as ChIP-chip, to a panel of well-characterized regulatory proteins and histones with specific modifications, known to generally associate with transcriptional regulatory elements in vivo. Identification of their genomic binding sites will allow us to determine the sequence features in the human genome that carry out transcriptional regulatory function. We have designed and produced DNA microarrays to represent all the non-repetitive sequences in the 30 million basepair ENCODE regions of the human genome to map various types of transcriptional regulatory elements in three model cell types. We have identified promoters by mapping the genomic sequences associated with RNA polymerase II and the general transcription factor TFIID in cells, enhancer elements by mapping the genomic sequences associated with transcriptional co-activators and enhancer-specific chromatin modifications, and insulators by mapping the genomic sequences associated with the insulator binding protein CTCF. The raw microarray results are released periodically prior to publication. Keywords: ChIP-chip ENCODE ChIP-chip analyses were performed for various transcription factors and chromatin modifications in various cell types. Details to be described in publications.
Project description:The existence of two separate lineages of Escherichia coli O157:H7 has previously been reported, and research indicates that one of these lineages (lineage I) might be more pathogenic towards human hosts. We have previously shown that the more pathogenic lineage expresses higher levels of Shiga toxin 2 (Stx2) than the non-pathogenic lineage II. To evaluate why lineage 2 isolates do not express appreciable levels of toxin, two lineage 2 isolates (FRIK966 and FRIK2000) were chosen as representatives of lineage 2 and whole genome microarrays were performed using Agilent microarrays using the E. coli O157:H7 EDL933 lineage I clinical type isolate as a reference. Microarray results were utilized to evaluate what genes and pathways might be missing or differentially expressed. Quantitative RT-PCR was utilized to validate the microarray data. Based upon the transcriptome of Escherichia coli O157:H7 EDL933 an oligonucleotide microarray, made up of 60 mers was designed. A total of 4873 genes in an 8 x 15K Agilent microarray design. Designed using a custom script, specifications for gene specific oligos were based upon various design characteristics such as temperature of melting, 3’ location, specificity, lack of repeat nucleotides, etc. (Charbonnier et al., 2005). Arrays were manufactured using Agilent Sure-print technology. Each array consisted of duplicate elements for each gene randomly distributed with Agilent control elements included. All procedures were performed according to respective manufacturer protocols. Lineage I and lineage II strains were grown overnight as described, a total of 10e7 cells were washed twice in fresh media, normalized based upon optical density, inoculated into fresh media, incubated at 37oC shaking 120 x g for 3 hours and then suspended in RNAprotect bacteria reagent (Qiagen Inc., Valencia, CA.). Total RNA was extracted using RNeasy Bacteria Mini Kit (Qiagen Inc., Valencia, CA.) and trace amounts of DNA were removed using RNase-Free DNase Set (Qiagen Inc., Valencia, CA.). RNA was quantified using Nanodrop system (NanoDrop Technologies, Wilmington, DE) and quality confirmed by electrophoresis on a Bio-rad Experion system (BioRad XXX). For each sample, 10 ug of RNA were labeled with either CyDye3-dCTP or CyDye5-dCTP (Perkin Elmer) using the LabelStar kit (Qiagen Inc., Valencia, CA.) and Random nonamers (Integrated DNA Technologies ). Labeled cDNA were hybridized to the microarray using Agilent Hi-RPM hybridization solution in an Agilent Hybridization chamber (Agilent.). A total of 8 arrays, each with duplicate elements for each gene, alternating dye swap for each replicate (4 biological replicates), were analyzed to obtain genes that were consistently and differentially regulated in comparison to EDL933, while limiting false discover rate (FDR) below a stringent 5% (Benjamini and Hochberg, 1995).
Project description:The complete genome sequence of the P. vivax Sal-1 strain allowed the design of a first version array representing 1 oligo/2 kb of coding sequences (http://zblab.sbs.ntu.edu.sg/vivax/index.html). Here, proof-of-principle experiments using total RNA of parasites obtained from the Sal-1 strain, from P. falciparum and from parasites obtained directly from two human patients are presented. To determine the extent of cross-hybridization of P. falciparum with P. vivax, and to determine overlaps in expression profiles of the P. vivax Sal1 monkey-adapted strain vs wild isolates, single dual hybridization analyses were performed.
Project description:Tissue from mammary, liver, and three adipose depots (mesenteric, omental, and subcutaneous) was collected at slaughter from a cow at peak lactation to examine gene expression profiles of 7872 sequences using a bovine cDNA microarray. RNA (20 ug) from tissues and a reference standard derived from a mixture of tissues were used to make aminoallyl-labeled cDNA followed by incorporation of Cy3-ester and Cy5-ester (Amersham, Piscataway, NJ). Each experimental sample was co-hybridized with the reference standard, which allowed the treatment of fluorescence ratios as measurements of relative expression across all samples and time points. Probes were hybridized to the array for 2 days at 42 C. All samples were hybridized to duplicate slides for a total of 4 spots per cDNA element. The microarray platform has already been described [Everts et al. (2005) Vet. Immunol. Immunopathol. 105:235-245]. Slides were scanned for both dye channels with a Scanarray 4000 (GSI-Lumonics, Billerica, MA) dual-laser confocal scanner and images were processed using GenePix 4.0 (Axon Instruments, Inc., CA).
Project description:cDNA microarrays have been shown to be useful for monitoring global gene expression patterns in normal and disease states and in response to various environmental stimuli. In this study we have used a cattle cDNA microarray containing 7653 elements to analyze expression profiles in 19 different cattle tissues. Signal intensities from all tissue sample RNAs were compared to a reference standard RNA created from different tissues and cell lines. Data analysis identified a subset of genes significantly differentially expressed between tissues and the reference standard that were further subdivided according to fold change. Log transformed ratios were normalized using the intensity-based regional Lowess algorithm. A global error model, to account for the dependence of variation on signal intensities, was used to identify lists of genes for effect of tissue on gene expression taking into account an experiment-wise significance of 0.05, using either a Bonferroni correction (663 genes) or Benjamini and Hochbergâ??s False Discovery Rate (3350 genes). Non-supervised cluster analysis revealed groups of genes common to nerve, muscle, immune or digestive tissues. Discriminant analysis was used to support physiological functional categories and embryonic origin of tissues. Unique profiles were constructed with genes preferentially expressed in specific tissues or tissue groups in order to define gene expression for individual tissues. Global expression along a large collection of tissues revealed tissue specific expression of enzyme isomers and utilization in specific metabolic pathways. A comprehensive matrix of all possible pair-wise comparisons for individual genes among tissues was constructed to further identify genes with tissue-specific behavior and possibly unique function. A reference design was used to compare 19 cattle tissues. All tissues were compared to a universal control consisting of a mix of cattle cell lines. All samples were duplicated with a dye swap.