Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Transcriptome profiling reveals a novel role for Trichostatin A in antagonizing histone chaperone Chz1 mediated telomere anti-silencing.

ABSTRACT: The histone chaperones play an important role in chromatin assembly and disassembly during replication and transcription. We assessed the global roles of histone chaperones in Saccharomyces cerevisiae. Microarray transcriptional analyses indicate that histone chaperones have their own specific target genes, and various histone chaperones have partially overlapping functions during transcriptional regulation. Histone deacetylase inhibitor TSA and histone chaperones Asf1, Vps75 and Rtt106 can function in parallel pathways to regulate transcription. Moreover, TSA can specifically antagonize histone chaperone Chz1-mediated telomere anti-silencing. This study demonstrates that a mutual cross-talk mechanism exists between histone chaperones and histone deacetylation in transcriptional regulation. All yeast strains used in this study are listed in the paper (Table S1). CHZ1, NAP1, ASF1, VPS75 and RTT106 genes were deleted individually by homologous recombination in BY4742 (WT) by using a previously described in (Wan, Y. et al. MCB, 2009) PCR-based procedure. The strains were cultured at 30°C in YPD (1% yeast extract, 2% peptone, 2% glucose) media. For TSA treatments, WT and deletion mutants were grown to mid-log phase (OD600=0.5), TSA (Sigma-Aldrich) was then added to the yeast cultures at a final concentration of 10 ?M and cells were cultured for additional hour.Total RNA was isolated by hot acid phenol extraction protocol as previously described in Wan, Y. et al. MCB, 2009. Microarray labeling and hybridization reactions were performed as previously described in Wan, Y. et al. MCB, 2009 and Wan, Y. et al. NAR, 2010. Two color microarrays, comparing RNA from the experimental conditions (deletion mutations grown in YPD, WT and deletion mutations grown in YPD with TSA treatment) to RNA from the control WT cells grown in glucose-containing medium (YPD), were performed using Agilent whole-genome S. cerevisiae arrays.

ORGANISM(S): Saccharomyces cerevisiae

SUBMITTER: Yakun Wan

PROVIDER: E-GEOD-30228 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Histones are the protein components of the basic unit of chromatin, the core particle of the nucleosome. They play a central role in defining chromatin states associated with distinct cell fates and are classified into replicative and non-replicative/replacement histone variants. While the latter do not exhibit S phase regulation in their expression, the replicative histone variants show a major peak in expression early during S phase to support chromatin assembly during replication of the genome. Their expression is tightly regulated during the cell-cycle both transcriptionally and post-transcriptionally and involves a number of actors. During replication in human cells, two main chaperones ensure the deposition of H3-H4 onto DNA: Chromatin assembly factor 1 (CAF-1) and Anti-silencing factor 1 (ASF1). Interestingly, on the one hand, ASF1 binds the newly synthesized replicative histones H3.1/H3.2-H4 to hand them off to the downstream chaperone, CAF-1, for deposition onto the duplicated DNA strands in a DNA synthesis-coupled (DSC) manner. On the other hand, ASF1 also promotes the recycling of parental histones during replication. In addition, ASF1 binds the non-replicative variant H3.3 and hands it off to the downstream chaperone Histone regulator A (HIRA) for deposition of H3.3 in a DNA synthesis independent (DSI) manner. Finally, in human cells, ASF1 but not CAF-1, also provides a buffering system for histone excess generated in response to stalled replication, indicating yet another role for ASF1 in regulating the flow of replicative histones in higher eukaryotes. However, to date, roles of these chaperones in histone RNA metabolism in mammals had remained unexplored. This is particularly interesting to consider given that in budding yeast, where there are no distinct replicative and non-replicative H3 variants, the single ASF1 ortholog participates in activating transcription of histone genes in S phase and transcriptional repression outside S phase in combination with Hir1, the budding yeast counterpart of HIRA. We thus decided to explore how the key histone chaperones involved in DNA synthesis-coupled chromatin assembly could contribute to the critical regulation of expression of replicative histone genes in human cells during S phase. From total RNA extracted from asynchronous and synchronized human cells, we performed RNA-seq and found that most of the annotated replicative histone genes decreased in expression upon ASF1 depletion by siRNA during S phase compared to the control condition with siRNA againt GFP. However, by 4sU-labeled RNA-seq we detected an increase in newly synthesized replicative histone transcripts. These findings indicate that the decrease in expression of replicative histone genes in ASF1-depleted cells cannot be due to a decrease at the level of transcription. We then inspected closely the sequences at the 3’ end of the replicative histone transcripts in our RNA-seq data and detected a defect of their 3’ processing. Thus, we propose that in mammals ASF1 plays a role in the unique regulation of replicative histone RNA metabolism.

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Transcriptome profiling reveals a novel role for Trichostatin A in antagonizing histone chaperone Chz1 mediated telomere anti-silencing.

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