title: An artificial HSE promoter for efficient and selective detection of heat shock pathway activity.
abstract: Detection of cellular stress is of major importance for the survival of cells. During evolution, a network of stress pathways developed, with the heat shock (HS) response playing a major role. The key transcription factor mediating HS signalling activity in mammalian cells is the HS factor HSF1. When activated it binds to the heat shock elements (HSE) in the promoters of target genes like heat shock protein (HSP) genes. They are induced by HSF1 but in addition they integrate multiple signals from different stress pathways. Here, we developed an artificial promoter consisting only of HSEs and therefore selectively reacting to HSF-mediated pathway activation. The promoter is highly inducible but has an extreme low basal level. Direct comparison with the HSPA1A promoter activity indicates that heat-dependent expression can be fully recapitulated by isolated HSEs in human cells. Using this sensitive reporter, we measured the HS response for different temperatures and exposure times. In particular, long heat induction times of 1 or 2 h were compared with short heat durations down to 1 min, conditions typical for burn injuries. We found similar responses to both long and short heat durations but at completely different temperatures. Exposure times of 2 h result in pathway activation at 41 to 44 °C, whereas heat pulses of 1 min lead to a maximum HS response between 47 and 50 °C. The results suggest that the HS response is initiated by a combination of temperature and exposure time but not by a certain threshold temperature.
authors.affiliation: Department of Applied Life Sciences, University of Applied Sciences, FH Campus Wien, Helmut-Qualtinger-Gasse 2, A-1030, Vienna, Austria.
authors.forename: Viktoria
authors.initials: V
authors.lastname: Ortner
authors.forename: Alfred
authors.initials: A
authors.lastname: Ludwig
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Riegel
authors.forename: Sarah
authors.initials: S
authors.lastname: Dunzinger
authors.forename: Thomas
authors.initials: T
authors.lastname: Czerny
mesh_terms: D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D017930:Genes, Reporter; D057809:HEK293 Cells; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D000076249:Heat Shock Transcription Factors; D006801:Humans; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D061986:MCF-7 Cells; D051379:Mice; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D013696:Temperature; D014157:Transcription Factors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; C000619706:HSF1 protein, human; D018840:HSP70 Heat-Shock Proteins; C490786:HSPA1A protein, human; D000076249:Heat Shock Transcription Factors; D012333:RNA, Messenger; D014157:Transcription Factors; D008156:Luciferases