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Souaid, C.

Publications and source records attributed to Souaid, C..

2 recordsLinked to original sources

Epromoters bind key stress-related transcription factors to regulate clusters of stress response genes

Stress insults trigger the rapid and global reprogramming of gene transcription by coordinated recruitment of a limited number of key inducible transcription factors to cis-regulatory elements. Here, we performed a comprehensive analysis of different stress models and observed that co-induced genes are generally located in close genomic proximity. By integrating gene expression and transcription factor binding resources in different stress models, we found an enrichment for clusters whereby only one of the promoters of the cluster recruits the key transcription factors, reminiscent of Epromoters, a type of cis-regulatory elements displaying both promoter and enhancer function. Epromoter-regulated clusters were frequently found irrespectively of the stress or inflammatory response. Predicted Epromoters displayed enhancer activity and regulated clusters of stress-response genes independently of their genomic location. These findings have significant implications for understanding complex gene regulation following the response to acute perturbations. TeaserWhen cells face stress, they undergo rapid changes in gene expression, orchestrated by a handful of key transcription factors. But how do these factors coordinate such a complex response? Our study reveals that "Epromoters"--cis-regulatory elements that combine the functions of both promoters and enhancers help organize stress-response genes into tightly regulated clusters. This discovery not only deepens our understanding of gene regulation in the face of stress but also offers exciting implications for studying inflammation and other acute cellular responses.

genomics↗

Loss of Polycomb Protein EZH2 causes major depletion of H3K27 and H3K9 tri-methylation and developmental defects in the fungus Podospora anserina

Selective gene silencing is key to development. The H3K27me3 enriched heterochromatin maintains transcription repression established during early development and regulates cell fate. Conversely, H3K9me3 enriched heterochromatin prevents differentiation but constitutes a permanent protection against transposable element. We exploited the fungus Podospora anserina, a valuable alternative to higher eukaryote models to question the biological relevance and interplay of these two distinct heterochromatin conformations. We found that H3K27me3 and H3K9me3 modifications are mutually exclusive within gene-rich regions but not within repeats. Lack of PaKmt6 EZH2-like enzyme resulted in loss of H3K27me3 and in significant H3K9me3 reduction, whereas lack of PaKmt1 SU(VAR)3-9-like enzyme caused loss of H3K9me3 only. We established that P. anserina developmental programs require H3K27me3 mediated silencing unlike most fungi studied to date. Our findings provide new insight into roles of these histone marks and into the relationship between chromatin modifications and development.

genetics↗