Disease relevance of hsp70

• This has allowed the development of an hsp70/eGFP reporter gene system in stable transgenic zebrafish that serves as a reliable yet extremely quick indicator of cell-specific toxicity in the context of the multicellular, living embryo [1].
• 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 [2].

High impact information on hsp70

• Members of the zebrafish hsp47, hsp70 and hsp90 gene families have been cloned and shown to be closely related to their counterparts in higher vertebrates [3].
• In this study, we assessed the effect of microgravity on the expression of the heat shock protein 70 (hsp70) gene in lens during development using transgenic zebrafish embryos expressing gfp under the control of hsp70 promoter/enhancer [4].
• In contrast, both the endogenous hsp70 gene and the transgene were strongly expressed throughout the embryo following heat shock at the same developmental stages [5].
• Here we report the establishment of an in vivo system that uses hsp70 gene activation as a measure of cadmium toxicity in living early larvae of transgenic zebrafish carrying a stably integrated hsp70-enhanced green fluorescent protein (eGFP) reporter gene [6].
• We demonstrate that eGFP expression in this strain of fish acts as an accurate and reproducible indicator of cell-specific induction of hsp70 gene expression [6].

Biological context of hsp70

• Weak to strong upregulation of hsp 70 levels was also registered among embryos exposed to both whole sediments and organic extracts [7].
• As endpoints, developmental parameters (mortality, abnormality, heart rate, and hatching rate) as well as stress protein responses (hsp 70 levels) in the developing embryos were recorded during a 96-h exposure [7].

Anatomical context of hsp70

• In the current study, using a zebrafish (Danio rerio) embryonic cell line (ZF4), we have compared the effects of heat shock (28-->37 degrees C) vs. cold shock (28-->20 degrees C) on the expression of ahsf1a, zhsf1b and hsp70 [8].
• Induction of hsp70 was observed upon copper exposure in liver and gonads, but not in gills [9].

Associations of hsp70 with chemical compounds

• Although cadmium is a known inducer of Hsps, it did not affect hsp70 expression significantly in the studied tissues [9].
• DMSO control embryos, on the other hand, showed a concentration-dependent increase in hsp 70 levels [10].

Other interactions of hsp70

• These results support the idea that Deltag influences hsp70 expression and differentiation in lens-specific and developmental period specific manners and that hsp family genes play a specific role in the response to Deltag [4].
• 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 [2].

Analytical, diagnostic and therapeutic context of hsp70

• Northern blot and in situ hybridization analysis indicated that the hsp70:gfp expression recapitulated endogenous hsp70 mRNA expression [4].
• These defects were strikingly similar to those observed when constitutive, lens specific Hsp70 expression was reduced through the microinjection of MO targeting hsp70 [11].
• 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 [2].

References