Differential regulation of spontaneous and heat‐induced HSP 70 expression in developing zebrafish (Danio rerio)

Abstract

A spontaneous high expression of heat shock protein 70 (HSP 70) was found to arise in zebrafish (Danio rerio) at the larval stage (84 hr after fertilization). The level of HSP 70 in 84-hr-old larvae was estimated to be six- to eightfold that of 12-hr-old embryos. As heat-induced HSP 70 synthesis in many eukaryotic organisms is known to be mediated by a transcriptional-dependent pathway activated by heat shock factor 1 (HSF-1), we then examined if the spontaneous and heat-induced HSP 70 synthesis in zebrafish were controlled by the same mechanism. Although the transient increase of a 62-kDa HSF-1-like polypeptide in 72- to 96-hr-old larvae seemed to correlate with the onset of the spontaneous HSP 70 production, an anti-HSF-1 antibody cocktail supershifted the heat shock element (HSE) binding complex induced by stressed but not by unstressed zebrafish extracts. Northern blot and quantitative RT-PCR analysis demonstrated the predominant presence of the cognate form of hsp 70 mRNA (hsc 70 mRNA) in developing zebrafish. The extent of heat-induced HSP 70 production in 84-hr-old larvae matched well with a dramatic increase in hsp 70 mRNA accumulation, while no apparent increase in total hsp 70 mRNA could be detected in 72- to 84-hr-old unstressed larvae by northern blot analysis. The stable expression of hsc 70 mRNA specific to beta-actin mRNA in normal zebrafish was confirmed by RT-PCR analysis. Hence, the spontaneous high expression of HSP 70 in zebrafish is believed to be controlled by a mechanism different from the HSF-1-dependent transcriptional activation of hsp 70 under heat stress. J. Exp. Zool. 293:349-359, 2002.

Advances and perspectives on the regulation and expression of piscine heat shock proteins

“…Temporal hsp70 gene expression was demonstrated for zebrafish embryos, as highest amounts of hsp70 transcript were detected at 84 h post fertilization in comparison to transcript amounts measured at 12-60 h and at 108 h post fertilization (Yeh and Hsu 2000). Later studies suggested that the spontaneous high expression of hsp70 in zebrafish embryos may be regulated via a mechanism that was different from the widely accepted HSF1/hsp70 gene transcription pathway (Yeh and Hsu 2002). Evidence towards the role and importance of different HSP70 forms is also starting to emerge as it was found that inducible hsp70 gene expression is strongly and specifically expressed within the first 38 h post fertilization only whereas the hsc70 form was sporadically detected in different zebrafish embryonic tissues (Blechinger et al 2002).…”

Heat shock-inducible Cre/Lox approaches to induce diverse types of tumors and hyperplasia in transgenic zebrafish

“…By contrast, untreated hsp70-Cre embryos expressed 2.9 Ϯ 2.0% of the Cre transcript levels compared with siblings heat shocked for 1 h (n ϭ 4; heat shock from 24-25 hpf at 37°C and assessed for Cre expression at 28 hpf). Thus, the hsp70 promoter can be induced by heat shock treatment; however, the promoter is active at low levels during development even in the absence of heat shock (18,19).…”

Differences in heat shock protein 70 expression during larval and early spat development in the Eastern oyster, Crassostrea virginica (Gmelin, 1791)

“…Interestingly, in a wide range of organisms, the expression of HSP 70 has also been shown to vary during development (Dix 1997;Feder and Hofmann 1999;Giudice et al 1999;Wood et al 1999;Yeh and Hsu 2002;Karouna-Renier et al 2003;Chang 2005;Mahroof et al 2005). The differential expression has been studied during events that involve morphological changes in organisms such as gametogenesis, embryogenesis, and metamorphosis (Feder and Hofmann 1999).…”