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Transcriptional reprogramming by oxidative stress occurs within a predefined chromatin accessibility landscape [RNA-seq]

ABSTRACT: Reactive oxygen species (ROS) are important signalling molecules in many physiological processes, yet excess ROS leads to cell damage and can lead to pathology. Accordingly, cells need to maintain tight regulation of ROS levels, and ROS-responsive transcriptional reprogramming is central to this process. Although it has long been recognized that oxidative stress leads to rapid, significant changes in gene expression, the impact of oxidative stress on the underlying chromatin accessibility landscape remained unclear. Here, we asked whether ROS-responsive transcriptional reprogramming is accompanied by reprogramming of the chromatin environment in MCF7 human breast cancer cells. Using a time-course exposure to multiple inducers of oxidative stress, we determined that the widespread ROS-responsive changes in gene expression induced by ROS occur with minimal changes to the chromatin environment. While we did observe changes in chromatin accessibility, these changes were: (1) far less numerous than gene expression changes after oxidative stress, and (2) occur within pre-existing regions of accessible chromatin. TF footprinting analysis identified 5 TFs or TF families with evidence for ROS-responsive changes in DNA binding: NRF2, AP-1, p53, NFY, and SP/KLF. Importantly, several of these (AP-1, NF- Y, and SP/KLF factors) have not been previously implicated as widespread regulators in the response to ROS. In summary, we have characterized genome-wide changes in gene expression and chromatin accessibility in response to ROS treatment of MCF7 cells, and we have found that regulation of the large-scale transcriptional response to excess ROS is primarily constrained by the cell’s pre-existing chromatin landscape.

ORGANISM(S): Homo sapiens

PROVIDER: GSE173662 | GEO | 2021/05/07

REPOSITORIES: GEO

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Project description:Reactive oxygen species (ROS) play a prominent role in signal transduction and cellular homeostasis in plants. However, imbalances between generation and elimination of ROS can give rise to oxidative stress in growing cells. Because ROS are important to cell growth, ROS modulation could be responsive to natural or human-mediated selection pressure in plants. To study the evolution of oxidative stress related genes in a single plant cell, we conducted comparative expression profiling analyses of the elongated seed trichomes (‘‘fibers’’) of cotton (Gossypium), using a phylogenetic approach. We measured expression changes during diploid progenitor species divergence, allopolyploid formation and parallel domestication of diploid and allopolyploid species, using a microarray platform that interrogates 42,429 unigenes. The distribution of differentially expressed genes in progenitor diploid species revealed significant up-regulation of ROS scavenging and potential signaling processes in domesticated G. arboreum. Similarly, in two independently domesticated allopolyploid species (G. barbadense and G. hirsutum) antioxidant genes were substantially up-regulated in comparison to antecedent wild forms. In contrast, analyses of three wild allopolyploid species indicate that genomic merger and ancient allopolyploid formation had no significant influences on regulation of ROS related genes. Remarkably, many of the ROS-related processes diagnosed as possible targets of selection were shared among diploid and allopolyploid cultigens, but involved different sets of antioxidant genes. Our data suggests that parallel human selection for enhanced fiber growth in several geographically widely dispersed species of domesticated cotton resulted in similar and overlapping metabolic transformations of the manner in which cellular redox levels have become modulated. We measured expression changes during diploid progenitor species divergence, allopolyploid formation and parallel domestication of diploid and allopolyploid species, using a microarray platform that interrogates 42,429 unigenes. The distribution of differentially expressed genes was studied for domesticated G. arboreum and two independently domesticated allopolyploid species (G. barbadense and G. hirsutum). These were compared to three wild allopolyploid species. Three biological replicates were performed.

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Transcriptional reprogramming by oxidative stress occurs within a predefined chromatin accessibility landscape [RNA-seq]

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