While the long noncoding RNAs (ncRNAs) constitute a large portion of the mammalian transcriptome, their biological functions has remained elusive. A few long ncRNAs that have been studied in any detail silence gene expression in processes such as X-inactivation and imprinting. We used a GENCODE annotation of the human genome to characterize over a thousand long ncRNAs that are expressed in multiple cell lines. Unexpectedly, we found an enhancer-like function for a set of these long ncRNAs in hum ...[more]
Project description:Snai1 or ncRNA-a7 were knocked down in A549 cells using siRNA and the changes in mRNA levels were determined. Comparative analysis of duplicate microarray experiments compared to control transfected cells.
Project description:Human primary keratinocytes were left untreated or treated for 48 hr with 12-O-tetradecanoylphorbol-13-acetate (TPA) and expression profiles were compared to find long ncRNAs expressed and differentially regulated upon differentiation. 4 replicates of minus TPA and 3 of plus TPA with dye-swap. Custom-made microarray from Agilent.
Project description:To identify miRNAs participating in SNAI1-orchestrated regulatory pathways, we analysed time-resolved microarray data of SNAI1-induced EMT, obtained during conditional expression of SNAI1 in a “Tet-Off” MCF7-SNAI1 breast carcinoma cell model (Vetter et al, 2009). miRNA time series study for 7 times points (4h, 8h, 12h, 24h, 48h, 72h, 96h) in 3 replicates. For each time point, we compared induced and non-induced samples. Overall, we have 42 samples (21 hybridizations).
Project description:We perform polyA independent deep sequencing of chromatin associated primary transcripts across three different cell lines to obtain a global view on in vivo microRNA processing. We use these data to define a MicroProcessing Index (MPI), to quantify the cleavage efficiency of the Microprocessor complex. Hallmarks of efficient Drosha-mediated processing are confirmed by means of deep sequencing of chromatin-associated transcripts upon Drosha knockdown. Our results suggest that both sequence features and thermodynamic properties, e.g. secondary structure of the regions flanking the pre-miRNA hairpins are determinants for efficient processing. Our data furthermore enables us to observe endogenous microprocessor cleavage sites at nucleotide resolution. This analysis reveals the presence of non-canonical processing events occurring one helical turn distal of most efficiently cleaved miRNA precursors. We performed polyA independent deep sequencing of the chromatin-isolated RNA fraction for 5 samples: 2 replicates in HeLa cells, 1 Drosha knock down in HeLa cells, 1 sample for A549 cells and 1 sample for HEK293 cells. We also performed deep sequencing of the small RNA fraction in the same cell lines.
Project description:Stem and progenitor cells maintain the tissue they reside in for life by regulating the balance between proliferation and differentiation. How this is done is not well understood. Here, we report that the human exosome maintains progenitor cell function. The expression of several subunits of the exosome were found to be enriched in epidermal progenitor cells, which were required to retain proliferative capacity and to prevent premature differentiation. Loss of PM/Scl-75 also known as EXOSC9, a key subunit of the exosome complex, resulted in loss of cells from the progenitor cell compartment, premature differentiation, and loss of epidermal tissue. EXOSC9 promotes self-renewal and prevents premature differentiation by maintaining transcript levels of a transcription factor necessary for epidermal differentiation, GRHL3, at low levels through mRNA degradation. These data demonstrate that control of differentiation specific transcription factors through mRNA degradation is required for progenitor cell maintenance in mammalian tissue. Refer to publication (Mistry et. Cell Stem Cell 2012) for more detail For gene expression profiling, cultured primary human keratinocytes were knocked down for EXOSC9, EXOSC9 and GRHL3, or control. RNA was harvested from the cells 5 days after knockdown. Microarray analysis using Affymetrix HG-U133 2.0 plus arrays was performed on duplicate samples. Significantly changed genes were identified as previously described(Sen et al., 2010).
Project description:To ensure cell survival and growth during temperature increase, eukaryotic organisms respond with transcriptional activation that results in accumulation of proteins that protect against damage, and facilitate recovery. To define the global cellular adaptation response to heat stress, we performed a systematic genetic screen that yielded 277 yeast genes required for growth at high temperature. Of these, the Rpd3 histone deacetylase complex was enriched. Global gene expression analysis showed that Rpd3 partially regulated gene expression upon heat shock. The Hsf1 and Msn2/4 transcription factors are the main regulators of gene activation in response to heat stress. RPD3-deficient cells had impaired activation of Msn2/4-dependent genes, while activation of genes controlled by Hsf1 was deacetylase independent. Rpd3 bound to heat stress-dependent promoters through the Msn2/4 transcription factors, allowing entry of RNA Pol II and activation of transcription upon stress. Finally, we found that the large, but not the small Rpd3 complex regulated cell adaptation in response to heat stress. Three independent 200 ml cultures of wild-type and rpd3Δ mutant strains were grown to mid-log phase in YPD rich medium at 25ºC (control) or at 39 ºC for 20 min (heat stressed). Results were analyzed comparing thermo-responsive gene expression respect to the control in each individual strain.
Project description:Proliferating tumor cells use aerobic glycolysis to support their high metabolic demands. Paradoxically, increased glycolysis is often accompanied by expression of the lower activity PKM isoform, effectively constraining lower glycolysis. Here, we report the discovery of novel PKM activators with a unique allosteric binding mode. Characterization of how these compounds impact cancer cells revealed an unanticipated link between glucose and amino acid metabolism. PKM activation resulted in a metabolic rewiring of cancer cells manifested by a profound dependency on the non-essential amino acid serine for continued cell proliferation. Induction of serine auxotrophy by PKM activation was accompanied by reduced carbon flow into the serine biosynthetic pathway and increased expression of high affinity serine transporters. These data support the hypothesis that PKM expression confers metabolic flexibility to cancer cells that allows adaptation to nutrient stress. A549 cancer cells were treated with compound-16 for up to 24 hours in the presence and absence of serine in the media.
Project description:We used microarrays to analyse expression profiles of zebrafish retina after optic nerve crush to identify potential regulatory mechanisms that underpin central nerve regeneration Total RNA extracted from 4 samples (pooling 4 animals) of Zebrafish retinae after performing optic nerve crush (at day 3 post crush) vs 4 samples (pooling 4 animals) of control (unoperated) Zebrafish retinae
Project description:Hog1 bypasses stress-mediated downregulation of transcription by PolII redistribution and chromatin remodeling Keyword: genetic modification Three independent 200 ml cultures of wild-type strain were grown to mid-log phase in YPD rich medium at 30ºC