title: Regulation of cyclooxygenase-2 expression by heat: a novel aspect of heat shock factor 1 function in human cells.
abstract: The heat-shock response, a fundamental defense mechanism against proteotoxic stress, is regulated by a family of heat-shock transcription factors (HSF). In humans HSF1 is considered the central regulator of heat-induced transcriptional responses. The main targets for HSF1 are specific promoter elements (HSE) located upstream of heat-shock genes encoding cytoprotective heat-shock proteins (HSP) with chaperone function. In addition to its cytoprotective function, HSF1 was recently hypothesized to play a more complex role, regulating the expression of non-HSP genes; however, the non-canonical role of HSF1 is still poorly understood. Herein we report that heat-stress promotes the expression of cyclooxygenase-2 (COX-2), a key regulator of inflammation controlling prostanoid and thromboxane synthesis, resulting in the production of high levels of prostaglandin-E(2) in human cells. We show that heat-induced COX-2 expression is regulated at the transcriptional level via HSF1-mediated signaling and identify, by in-vitro reporter gene activity assay and deletion-mutant constructs analysis, the COX-2 heat-responsive promoter region and a new distal cis-acting HSE located at position -2495 from the transcription start site. As shown by ChIP analysis, HSF1 is recruited to the COX-2 promoter rapidly after heat treatment; by using shRNA-mediated HSF1 suppression and HSE-deletion from the COX-2 promoter, we demonstrate that HSF1 plays a central role in the transcriptional control of COX-2 by heat. Finally, COX-2 transcription is also induced at febrile temperatures in endothelial cells, suggesting that HSF1-dependent COX-2 expression could contribute to increasing blood prostaglandin levels during fever. The results identify COX-2 as a human non-classical heat-responsive gene, unveiling a new aspect of HSF1 function.
authors.affiliation: Institute of Translational Pharmacology, CNR, Rome, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Rossi
authors.forename: Marta
authors.initials: M
authors.lastname: Coccia
authors.forename: Edoardo
authors.initials: E
authors.lastname: Trotta
authors.forename: Mara
authors.initials: M
authors.lastname: Angelini
authors.forename: M Gabriella
authors.initials: MG
authors.lastname: Santoro
mesh_terms: D001665:Binding Sites; D051546:Cyclooxygenase 2 / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000502:physiology*; D042783:Endothelial Cells / Q000378:metabolism; D005334:Fever; D005786:Gene Expression Regulation; D000076249:Heat Shock Transcription Factors; D006358:Hot Temperature; D006801:Humans; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000502:physiology*; D014158:Transcription, Genetic
chemical_list: D004268:DNA-Binding Proteins; C000619706:HSF1 protein, human; D000076249:Heat Shock Transcription Factors; D014157:Transcription Factors; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human