Recovery of protein synthesis after heat shock: prior heat treatment affects the ability of cells to translate mRNA.

Abstract

A mild heat shock at 350C, which induces heat shock gene expression, greatly enhances survival and the recovery of protein synthesis in Drosophila cells after a higher temperature heat shock. The 350C treatment is also effective in preventing heat-induced developmental defects in pupae. We show here that the major larval mRNAs are present in approximately normal (25C) concentrations after a 40. 1C heat shock whether or not the animals receive a pretreatment. This indicates that the pretreatment affects translation directly rather than messenger concentration. We also observe selective translation of heat shock messages and some 25WC messages during, recovery from heat shock.Pretreatment at a nonlethal temperature (30 min at 350C) dramatically improves the ability of Drosophila melanogaster larvae, pupae, adults, and cell lines to withstand a normally lethal heat shock. This type of pretreatment also prevents developmental defects (phenocopies) induced in Drosophila pupae by heat shock (1). The acquisition of resistance to heat has been described in a wide variety of plant (2, 3) and animal systems, including mammalian cell lines (4-7). Understanding the molecular basis for this phenomenon is therefore of general interest. We have shown previously that the dramatic effects on survival and phenocopy prevention are paralleled by a much more rapid recovery of protein synthesis in the animals that received the 350C pretreatment (1). We are interested in how the pretreatment improves recovery from heat shock and, in particular, in the possibility that one or more of the heat shock gene products mediates the effects on recovery through effects on regulation of RNA and protein synthesis. In this paper we show that the 350C pretreatment does not affect concentrations of the major larval messages as has been previously suggested (1,8), but rather it affects the ability of the cells to translate mRNA. MATERIALS AND METHODSFly Culture and Labeling in Vivo. Embryos. collected over a 2-hr period (9) were kept at 250C for 31/2 days. Third-instar larvae were washed and heat treated in moist vials submersed in a water bath of the temperatureindicated. Larvae recovering from heat treatment were kept in vials containing a small amount of moist yeast. Larvae were injected with [35S]methionine (3.0 kCi per larva; 1 Ci = 3.7 X 1010 becquerels) as described (10). Thirty minutes after the injection, larvae were ground in cold '10% trichloroacetic acid. Six larvae were used for each time point. The acid precipitate was washed twice with ethanol, dried, and dissolved in sample buffer. One-fifth of each sample was run on the gel.RNA Isolation and Protein Synthesis in Vitro. Larvae, wings, or salivary glands were frozen in liquid nitrogen and ground in a glass grinder in extraction buffer (0. 22 M Tris-HCl, pH 7.5/0.04 M EDTA/0.02 M NaCl/1% sodium dodecyl sulfate) plus an equal volume of phenol. One volume of chloroform was added immediately after grinding and samples were extracted (11,12). Samples were centrifuged and reextracte...

Acquisition of Thermotolerance in Soybean Seedlings

“…11D)., The localized arsenite-induced proteins are similar in size and electrophoretic properties to the HSPs found in the ribosomal fraction. (2,11,16,17,20,21,24,27,29). An earlier report by Yarwood (35) also demonstrated the development of thermal tolerance or 'adaptation' to high temperature (e.g.…”

A Class of Soybean Low Molecular Weight Heat Shock Proteins

“…Although the physiological function of HSPs has not been clearly documented, their induction is well correlated with thermotolerance in a time-and temperaturedependent manner. On the basis of this correlation, it has been hypothesized that accumulation of HSPs is an essential component for protection from heat damage (10,12,16,19). Although studies of Drosophila have provided a basis for ' This work was supported by the National Science Council of Taiwan under grant NSC79-0211-B002-02 2 Abbreviations: HSPs, heat shock proteins; HS, heat shock; LMW, low molecular weight; 2-D, 2-dimensional; HRP, horseradish peroxidase; PRS, postribosomal supematant; TBS, 20 mim Tris-HCl(pH 7.5), 0.5 M NaCl; TTBS, TBS plus 0.05% Tween 20; AU, absorbance units.…”

Formation of cytoplasmic heat shock granules in tomato cell cultures and leaves.

“…However, under certain conditions, e.g., in preinduced cultures maintained at 25°C, hsps also accumulate as soluble proteins without concomitant assembly of heat shock granules. Similar heat shock-induced cytoplasmic aggregates were also observed in other cell cultures and heat-shocked tomato leaves and corn coleoptiles.All types of eucaryotic organisms respond to supraoptimal temperatures by synthesis of heat shock proteins (hsps) (1,5,23,24), which are evidently essential for heat shock survival and recovery (2,14,16,20,23 …”