Inhibition of heat shock (stress) protein induction by deuterium oxide and glycerol: Additional support for the abnormal protein hypothesis of induction

Abstract

The patterns of radioactively labeled proteins from cultured chicken embryo cells stressed in the presence of either D2O or glycerol were analyzed by using one-dimensional polyacrylamide gel electrophoresis. These hyperthermic protectors blocked the induction of stress proteins during a 1-hour heat shock at 44 degrees C. The inhibitory effect of glycerol but not D2O on the induction of heat shock proteins could be overcome by increased temperature. By using transcriptional run-on assays of isolated nuclei and cDNA probes to detect hsp70- and hsp88-specific RNA transcripts, it was shown that the D2O and glycerol blocks occurred at or before transcriptional activation of the hsp70 and hsp88 genes. After heat-stressed cells were returned to 37 degrees C and the protectors were removed, heat shock proteins were inducible by a second heating. This result and the fact that the chemical stressor sodium arsenite induced stress proteins in glycerol medium indicated that the treatments did not irreversibly inhibit the induction pathways and that the stress response could be triggered even in the presence of glycerol by a stressor other than heat. In principle then, cells incurring thermal damage during a 1-hour heat shock at 44 degrees C in D2O or glycerol medium should be competent to respond by inducing heat shock proteins during a subsequent recovery period at 37 degrees C in normal medium. We found that heat shock proteins were not induced in recovering cells, suggesting that glycerol and D2O protected heat-sensitive targets from thermal damage. Evidence that the heat-sensitive target(s) is likely to be a protein(s) is summarized. During heat shocks of up to 3 hours duration, neither D2O nor glycerol significantly altered hsp23 gene activity, a constitutively expressed chicken heat shock gene whose RNA transcripts and protein products are induced by stabilization (increased half-life). During a 2-hour heat shock, glycerol treatment blocked the heat-induced stabilization of hsp23 RNA and proteins; however, D2O treatment only blocked RNA transcript stabilization, effectively uncoupling the hsp23 protein stabilization pathway from hsp23 RNA stabilization and transcriptional activation of hsp70 and hsp88 genes.

Expression of heat shock protein 70 in a permanent cell line (EPC) exposed to sediment extracts from the North Sea and the Baltic Sea

“…Another kind of effect, an inhibition of hsp70 synthesis, may be responsible for this result. An inhibition of the hsp70 synthesis by substances like glycerol, copper and some flavonoids was described by several research groups (Edington et al, 1989;Hosokawa et al, 1990;Sanders & Martin, 1994). Werner et al (1998) in the course of a bioassay-directed fractionation (data not shown).…”

Activation of heat-shock transcription factor 1 by hypertonic shock in 3T3 cells

“…Interestingly, neuronal volume has been found to be altered more by exposure to hyperosmolar conditions resulting from impermeable or poorly permeable osmolytes than to those resulting from glycerol [32]. However, it should be borne in mind that glycerol, in common with other polyols, may well protect proteins from denaturation [33].…”

Heat shock response: hsp70 in environmental monitoring

“…de Pomerai [35] argues that screening for one particular class of stress proteins only, may not provide a sufficiently sensitive bioindicator for a wide range of pollutants because different agents induce different families of stress proteins and with widely differing efficiencies. A few xenobiotic compounds such as fluorathene [92] and glycerol [93] have been reported that inhibit the expression of stress proteins. This may pose further complication in interpreting data from field studies, where generally mixtures of xenobiotic compounds are present.…”