Project description:We report the application of DHS-Seq and digital genomic footprinting to study chromatin changes and transcription factor-DNA binding upon long-term Hsp90 depletion utilizing the temperature-sensitive allele G170D. By generating about 86 and 85.6 million reads for wild type and mutant, we were able to reconstitute the chromatin accessibility and the transcription factor-DNA binding maps under regular conditions and under conditions where Hsp90 was long-term inactivated. We find that there is a global reduction of transcription factor binding sites with concurrent loss of open chromatin upon Hsp90 inactivation. This data was used in conjunction with our previous work involving DHS-Seq studies and short-term Hsp90 depletion (GEO GSE88875) to distinguish the affected transcription factor networks and the chromatin changes upon short- and long-term Hsp90 depletion. We identified two different modes of Hsp90 operation on transcription factor activities – short-term inactivation of Hsp90 altered transcription factor DNA binding activities, whereas long-term Hsp90 inactivation affected the steady-state levels of transcription factors. Overall, this study shows that Hsp90 regulates multiple transcription factor protein families and modulates chromatin architecture on a genome-wide scale.
Project description:Nonylphenol (NP), is a bioaccumulative environmental estrogen that is widely used as a nonionic surfactant. We have previously examined short-term effects of NP on yeast cells using microarray technology. In the present study, we investigated the long-term impacts of NP on Saccharomyces cerevisiae BY4742 cells by analyzing genome-wide transcriptional profiles using RNA-sequencing. We used 2 mg/L NP concentration exposure for 40 days. Gene expression analysis showed that a total of 948 genes were differentially expressed. Of these, 834 genes were downregulated, while 114 genes were significantly upregulated. GO enrichment analysis revealed that 369 GO terms were significantly affected by NP exposure. Further analysis showed that many of the differentially expressed genes were associated with oxidative phosphorylation, iron and copper acquisition, autophagy, pleiotropic drug resistance and cell cycle progression and related processes such as DNA and mismatch repair, chromosome segregation, spindle checkpoint activity, and kinetochore organization. Overall, these results provide considerable information and a comprehensive understanding of the long-term effects of NP at the gene expression level.
Project description:Whole-genome transcriptional response of S. cerevisiae to an increase in temperature from 28°C to 41°C under well-controlled conditions. Two subsequent phases of response with very different dynamics: a short term response for the first hour after the temperature increase and a long term one for up to six hours. The initial response was strongest with almost half of the ORFs being induced or repressed to a statistically significant level (here 1.5 fold). The data was grouped based on the function of the encoded proteins. Analysis showed that the cells overexpressed genes involved in energy conservation processes. Genes encoding molecular chaperones were overexpressed as well, presumably to counteract the effect of the temperature increase on protein denaturation. Furthermore, genes encoding parts of the translation and transcription systems were repressed temporarily, in line with the observed lag in growth. More detailed analysis of certain small groups of genes involved in energy metabolism supported the notion that, although the expression level of genes represent a part of the stress response, they cannot be directly linked to the level of activity of their products.
Project description:Whole-genome transcriptional response of S. cerevisiae to an increase in temperature from 28M-BM-0C to 41M-BM-0C under well-controlled conditions. Two subsequent phases of response with very different dynamics: a short term response for the first hour after the temperature increase and a long term one for up to six hours. The initial response was strongest with almost half of the ORFs being induced or repressed to a statistically significant level (here 1.5 fold). The data was grouped based on the function of the encoded proteins. Analysis showed that the cells overexpressed genes involved in energy conservation processes. Genes encoding molecular chaperones were overexpressed as well, presumably to counteract the effect of the temperature increase on protein denaturation. Furthermore, genes encoding parts of the translation and transcription systems were repressed temporarily, in line with the observed lag in growth. More detailed analysis of certain small groups of genes involved in energy metabolism supported the notion that, although the expression level of genes represent a part of the stress response, they cannot be directly linked to the level of activity of their products. Samples were taken from three replicate control cultures at 28M-BM-0C at three timepoints and from three replicate stressed cultures at six timepoints