title: Stressor-dependent regulation of the heat shock response in zebrafish, Danio rerio.
abstract: Heat shock transcription factors (HSFs) regulate expression of heat shock proteins (Hsps). We have previously shown that in zebrafish a unique isoform, zHSF1b, disappears concomitant with heat shock-induced Hsp70 expression. To characterize the role of zHSF1a and zHSF1b isoforms in the regulation of the stress response in vivo, we have carried out cadmium (10-100 microM) and copper (10-30 microM) exposures in order to specify whether the disappearance of HSF1b is specific for heat stress. After 4-h metal exposures we analyzed the expression of hsp70, zHSF1a, zHSF1b and metallothionein (MT) by reverse transcriptase polymerase chain reaction in zebrafish liver, gonads and gills. Although cadmium is a known inducer of Hsps, it did not affect hsp70 expression significantly in the studied tissues. Induction of hsp70 was observed upon copper exposure in liver and gonads, but not in gills. Neither metal affected the zHSF1a/b ratio. Both cadmium and copper exposure caused upregulation of MT, regulator of metal homeostasis and detoxification, confirming that the tissues were subjected to metal loads. Thus, hsp70 appears to be more weakly induced upon metal exposure than in response to heat shock and HSF1 isoforms may participate in stressor-specific regulation of hsp70.
authors.affiliation: Department of Biology, Laboratory of Animal Physiology, University of Turku, FIN-20014 Turku, Finland. susanna.airaksinen@rktl.fi
authors.forename: Susanna
authors.initials: S
authors.lastname: Airaksinen
authors.forename: Christina M I
authors.initials: CM
authors.lastname: Råbergh
authors.forename: Anna
authors.initials: A
authors.lastname: Lahti
authors.forename: Annukka
authors.initials: A
authors.lastname: Kaatrasalo
authors.forename: Lea
authors.initials: L
authors.lastname: Sistonen
authors.forename: Mikko
authors.initials: M
authors.lastname: Nikinmaa
mesh_terms: D000818:Animals; D004268:DNA-Binding Proteins / Q000235:genetics; D005786:Gene Expression Regulation; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics; D000076249:Heat Shock Transcription Factors; D018869:Heat-Shock Response; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors; D015027:Zebrafish / Q000502:physiology*
chemical_list: D004268:DNA-Binding Proteins; D018840:HSP70 Heat-Shock Proteins; D000076249:Heat Shock Transcription Factors; D014157:Transcription Factors