Pluto Bioinformatics

GSE81405: Convergent roles of ATF3 and CSL in chromatin control of CAF activation [RNA-seq]

Bulk RNA sequencing

Cancer associated fibroblasts (CAFs) play an important role in initiating and promoting epithelial cancers. The specific chromatin modifications involved in CAF activation remain to be elucidated. CSL, a constitutive transcriptional repressor and mediator of canonical Notch signaling, functions as a direct negative regulator of CAF effector genes and suppresses cancer/stromal cell expansion. We find that ATF3, a key stress responsive transcriptional repressor up-regulated in the acute UVA response of skin fibroblasts, is down-modulated in stromal cells of premalignant skin SCC lesions similarly to CSL. Increased ATF3 expression counteracts the consequences of compromised CSL, binding to a large set of overlapping target genes. At low basal levels, ATF3 converges with CSL in negative control of CAF activation, binding to a very small number of genomic loci that encompass mostly non-coding RNAs and pseudogenes. Silencing of ATF3 results in chromatin modifications and Pol II recruitment to many loci to which ATF3 does not bind, which are similarly affected by CSL silencing. The observed changes are of functional significance, as Bet inhibitors, which unlink activated chromatin from the basic transcription apparatus, have opposite effects of ATF3 or CSL silencing on all tested CAF effector genes. They exert a similar impact on clinically-derived CAFs both in vitro and upon topical in vivo treatment. Thus, ATF3 converges with CSL in global chromatin control of CAF activation with their loss eliciting epigenetic changes amenable to cancer and stroma-focused intervention. SOURCE: Paolo Angelino ( - SIB Swiss Institute of Bioinformatics

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