Project description:THO/TREX is a conserved nuclear complex that functions in mRNP biogenesis and prevents transcription-associated recombination. Whether or not it has a ubiquitous role in the genome is an open question. ChIP-chip studies reveal that the Hpr1 component of THO and the Sub2 RNA-dependent ATPase have genome wide-distributions at active ORFs in yeast. In contrast to RNAPII, evenly distributed from promoter to termination regions, THO and Sub2 are absent at promoters and distributed in a sharp 5M-bM-^@M-^YM-bM-^FM-^R3M-bM-^@M-^Y gradient. Importantly, ChIP-chips reveal an over-recruitment of Rrm3 in active genes in THO mutants that is reduced by overexpression of RNase H1. Our work establishes a genome-wide function for THO-Sub2 in transcription elongation and mRNP biogenesis that function to prevent the accumulation of transcription-mediated replication obstacles, including R-loops. ChIP-chip studies were perfomed with tagged forms of the Hpr1 component of THO (Hpr1-FLAG), the Sub2 RNA-dependent ATPase of TREX (Sub2-FLAG), the Rpb3 subunit of RNA polymerase II (Rpb3-PK) and the Rrm3 protein (Rrm3-FLAG) in the yeast S. cerevisiae.
Project description:As controversy remains as to the exact mechanisms by which the thymidine-analogue nucleoside reverse transcriptase inhibitors, zidovudine (AZT) and stavudine (d4T) induce subcutaneous adipose tissue toxicity, we used microarrays to dentify patterns of gene expression in human subcutaneous adipose tissue that change as a result of exposure to these drugs for 2 weeks. Paired RNA samples (baseline and week 2), isolated from the adipose tissue of HIV-uninfected healthy adults randomized to 6 weeks of either AZT/ lamivudine (3TC) or d4T/ 3TC were analysed by microarray.
Project description:We report a new protein complex with a role in transcription elongation that is formed by Ypr045c (Thp3) and the Csn12 component of the COP9-signalosome. Thp3-Csn12 is recruited to transcribed genes. Their mutations suppress the gene expression defects of mutants of the THO complex involved in mRNP biogenesis and export and show defects in mRNA accumulation. In vivo transcription elongation impairment of thp3M-bM-^HM-^F mutants is shown by reduction of RNAPII recruitment throughout an active gene and in transcript run on analysis performed in G-less systems. This new complex establishes a novel link between transcription and mRNA processing. Tthree repeats of the wild type control and three of the ypr045cM-bM-^HM-^F mutant (BY4741 background).
Project description:A limited number of growth factors are capable of regulating numerous developmental processes, but how they accomplish this is unclear. In the gustatory system, brain-derived neurotrophic factor (BDNF) and neurotrophin-4 (NT4) have different developmental roles but exert their effects through the same receptors (TrkB and p75). Using genome wide expression analysis, we determined that BDNF and NT4 also regulate the expression of different sets of genes downstream of receptor signaling in geniculate ganglion. These differences in gene expression likely determine their different roles. BDNF and NT4 could function differently because of temporal or spatial differences of expression or the activation of different signaling pathways. BDNF and NT4 regulate cell death, axonal growth and axonal guidance by altering gene expression. Because many of these functions of the two neurotrophins differ in taste development, each likely alters gene expression in a unique way. To determine if removal of BDNF and NT4 alters gene expression in different ways, I will compare microarray gene expression profiles in the geniculate ganglion among BDNF knockout, Nt4 knockout, and wild type mice during development.
Project description:Sister chromatid cohesion is mediated by cohesin but the process of cohesion establishment during S phase is still enigmatic. Recent data indicate that in mammalian cells, cohesin binding to chromatin is dynamic in G1 but becomes stabilized during S phase. Whether the regulation of chromosomal cohesin turn-over is integral to the process of cohesion establishment is unknown. Here, we provide evidence that fission yeast cohesin also displays dynamic behaviour. Cohesin association with G1 chromosomes requires continued activity of the cohesin loader Mis4/Ssl3, implying that repeated loading cycles maintain cohesin binding. Cohesin retention on G1 chromosomes was improved by deletion of wpl, the fission yeast ortholog of mammalian WAPL, suggestive of a conserved mechanism that controls cohesin stability on chromosomes. wpl is non-essential, indicating that a change in wpl-dependent cohesin turnover is not integral to the mechanism of cohesion establishment. Instead we find that cohesin instability is down-regulated during S phase in a reaction independent of DNA replication. Hence, cohesin stabilization might be a pre-requisite for cohesion establishment rather than its consequence. Keywords: ChIP-chip Experiments in budding and fission yeast have shown that the cohesin loading factors are dispensable for viability in G2, when cohesion has been established (Bernard et al., 2006; Ciosk et al., 2000). In fission yeast, inactivation of the loading machinery at that time no longer affects cohesin binding to chromosomes (Bernard et al., 2006). In mammalian cells, about one-third of nuclear cohesin becomes stably bound to chromatin in G2 (Gerlich et al., 2006). Since the binding of cohesin to chromosomes appears labile in G1, but stabilized in G2, we asked how cohesin becomes stable during the intervening S phase. Spreads showed that Rad21 was only slightly decreased in HU arrested cells after inactivation of the cohesin loading factors Mis4 or Ssl3. In this series we analyzed whether cohesin association was equally stabilised at all its association sites along chromosome arms. Rad21 binding was therefore analyzed on a chromosome-wide scale by ChIP followed by hybridization to an oligonucleotide tiling array covering chromosomes 2 and 3. We compared the Rad21 binding pattern in HU arrested wild-type versus ssl3-29 cells after the shift to the restrictive temperature. Four 50 kb regions from chromosome 2 are shown in Figure 5, and the complete chromosome 2 in Supplemental Fig.2 (based on samples GSM209708 & GSM209722 compared to the SUP sample GSM209740, provisional accession numbers). This showed that cohesin peaks remained indistinguishable in their relative height and positions whether or not Ssl3 was inactivated. We conclude that, unlike in G1, the loading machinery is dispensable for the stable binding of cohesin to chromosomes in S phase cells. The experiment was repeated twice with slightly changed parameters (16B12 vs 12CA5 anti-HA antibody, 8.5h vs 9h HU arrest at 20C, 3h at 36C vs 3h at 37C inactivation in HU, see samples for details).
Project description:Transcription is a major obstacle for replication fork progression and a cause of genome instability. Such instability increases in mutants with a suboptimal assembly of the nascent messenger ribonucleo-protein particle (mRNP), as THO/TREX and the NPC-associated THSC/TREX-2 complex. We used microarrays to analyze the global impact of THSC/TREX-2 in gene expression and found that Thp1 and Sac3 depletion has a functional impact in highly-expressed, long and G+C-rich genes regardless of their function S. cerevisiae strains were grown in YPD liquid culture, total RNA was isolated and hybridized on Affymetrix microarrays
Project description:Transcription is a major obstacle for replication fork progression and a cause of genome instability. Such instability increases in mutants with a suboptimal assembly of the nascent messenger ribonucleo-protein particle (mRNP), as THO/TREX and the NPC-associated THSC/TREX-2 complex. Here we show that yeast sac3M-bM-^HM-^F and thp1M-bM-^HM-^F cells accumulate genome-wide replication obstacles as determined by the distribution of the Rrm3 helicase. Such obstacles preferentially occur at long and highly expressed genes, to which Sac3 and its interacting partner Thp1 are preferentially bound in wild-type cells. ChIP-chip studies were perfomed with antibodies against Flag-tagged Thp1 and Sac3 proteins in wild-type cells of the yeast S. Cerevisiae, as well as Flag-tagged Rrm3 protein in sac3M-bM-^HM-^F and thp1M-bM-^HM-^F cells that were compared with Rrm3 in wild-type cells from Santos-Pereira et al., 2013 (accession number GSE50185).
Project description:Transcription is a major obstacle for replication fork progression and a cause of genome instability. Such instability increases in mutants with a suboptimal assembly of the nascent messenger ribonucleo-protein particle (mRNP), as THO/TREX and some heterogeneous nuclear ribonucleoproteins (hnRNPs) mutants. Here we show that yeast npl3M-bM-^HM-^F cells show genome-wide replication obstacles as determined by accumulation of the Rrm3 helicase. Such obstacles preferentially occur at long and highly expressed genes, to which Npl3 is preferentially bound in wild-type cells. ChIP-chip studies were perfomed with antibodies against Myc-tagged Npl3 protein in wild-type cells of the yeast S. Cerevisiae, as well as Flag-tagged Rrm3 protein in both wild-type and npl3M-bM-^HM-^F cells.