Subsets of NFkappaB-dependent genes are differentially regulated after combined treatment with hyperthermia and cytokine

Heat shock transcription factor 1 (HSF1) is responsible for triggering stress-induced activation of the HSP genes. HSF1 is also involved in the regulation of many other genes associated with multiple cellular processes including cell signaling, development, fertility, cell death and metabolism, e.g. NFkappaB transcription factor. Here we aimed to establish a global picture for the association between hyperthermia-modulated expression of NFkappaB-dependent genes and HSF1 binding in regulatory regions of target genes. The global pattern of HSF1 binding was analyzed after 10 and 20 minutes of hyperthermia using the ChIP-Seq approach. The analysis revealed about 25,000 HSF1 binding sites in chromatin of control untreated U-2 OS cells, which nearly doubled in cells subjected to hyperthermia. The presence of hyperthermia-induced HSF1 binding was established in regulatory regions of hyperthermia-affected genes and in TNF-affected genes. In most cases hyperthermia pre-conditioning inhibited cytokine-mediated activation of NF-κB-dependent genes. However, our results also revealed novel gene subsets that included TNFalpha-regulated and hyperthermia-unaffected genes, as well as genes (co)repressed, (co)stimulated, or antagonized by both types of stimuli.