Heat and sodium arsenite act synergistically on the induction of heat shock gene expression in Xenopus laevis A6 cells

Heat shock protein (HSP) synthesis was studied in the Xenopus epithelial cell line A6 in response to heat and sodium arsenite, either singly or together. Temperatures of 33–35 °C consistently brought about the synthesis of HSPs at 87,73,70,54,31, and 30 kilodaltons (kDa), whereas sodium arsenite at 25–100 μM induced the synthesis of HSPs at 73 and 70 kDa. In cultures exposed to 10 μM sodium arsenite at 30 °C, HSP synthesis in the 68- to 73-kDa and 29- to 31-kDa regions was much greater than the HSP synthesis in response to each treatment individually. RNA dot blot analysis using homologous genomic subclones revealed that heat shock induced the accumulation of HSP 70 and 30 mRN As. The sizes of the HSP 70 and 30 mRN As determined by Northern hybridization were 2.7 and 1.5 kilobases, respectively. Sodium arsenite (10–100 μM) also induced the accumulation of both HSP 70 and 30 mRNAs. Finally, a mild heat shock (30 °C) plus a low concentration of sodium arsenite (10 μM) acted synergistically on HSP 70 and 30 mRN A accumulation in A6 cells. Thus sodium arsenite and heat act synergistically at the level of both HSP synthesis and HSP mRNA accumulation.

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Heat shock gene expression in Xenopus laevis A6 cells in response to heat shock and sodium arsenite treatments

Biochemistry and Cell Biology ◽

10.1139/o88-098 ◽

1988 ◽

Vol 66 (8) ◽

pp. 862-870 ◽

Cited By ~ 30

Author(s):

S. Darasch ◽

D. D. Mosser ◽

N. C. Bols ◽

J. J. Heikkila

Keyword(s):

Heat Shock ◽

Xenopus Laevis ◽

Sodium Arsenite ◽

Polyacrylamide Gel Electrophoresis ◽

Heat Shock Gene ◽

Epithelial Cell Line ◽

Continuous Exposure ◽

Mrna Levels ◽

Hsp 70 ◽

Mrna Accumulation

Continuous exposure of a Xenopus laevis kidney epithelial cell line, A6, to either heat shock (33 °C) or sodium arsenite (50 μM) resulted in transient but markedly different temporal patterns of heat-shock protein (HSP) synthesis and HSP 70 and 30 mRNA accumulation. Heat-shock-induced synthesis of HSPs was detectable within 1 h and reached maximum levels by 2–3 h. While sodium arsenite induced the synthesis of some HSPs within 1 h, maximal HSP synthesis did not occur until 12 h. The pattern of HSP 70 and 30 mRNA accumulation was similar to the response observed at the protein level. During recovery from heat shock, a coordinate decline in HSPs and HSP 70 and 30 mRNA was observed. During recovery from sodium arsenite, a similar phenomenon occurred during the initial stages. However, after 6 h of recovery, HSP 70 mRNA levels persisted in contrast to the declining HSP 30 mRNA levels. Two-dimensional polyacrylamide gel electrophoresis revealed the presence of 5 HSPs in the HSP 70 family, of which two were constitutive, and 16 different stress-inducible proteins in the HSP 30 family. In conclusion, heat shock and sodium arsenite induce a similar set of HSPs but maximum synthesis of the HSP is temporally separated by 12–24 h.

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Depressed expression of the inducible form of HSP 70 (HSP 72) in brain and heart after in vivo heat shock

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1995.269.3.r608 ◽

1995 ◽

Vol 269 (3) ◽

pp. R608-R613 ◽

Cited By ~ 4

Author(s):

S. C. Beck ◽

C. N. Paidas ◽

H. Tan ◽

J. Yang ◽

A. De Maio

Keyword(s):

Heat Shock ◽

Cell Types ◽

Heat Shock Gene ◽

Hsp 70 ◽

Shock Gene ◽

Heat Shock Gene Expression ◽

Total Body ◽

Different Levels ◽

Low Expression

The heat shock gene expression plays a role in the protection of cells from injury. In the present study, we have analyzed the expression of heat shock protein (HSP) 72 (the major inducible form of the HSP 70 family) in different rat organs after a total body hyperthermia. The content of HSP 72 was greatest in liver and colon. In contrast, accumulation of HSP 72 was low in heart and brain (3-5% and < 1% of the amount in liver, respectively). This low expression of HSP 72 in heart and brain could not be explained by a difference in the actual temperature within these organs. Analysis of cells in culture that resemble hepatocytes, myoblast, and neurons showed a pattern of HSP 72 expression similar to that observed in liver, heart, and brain in vivo after heat shock. These results suggest that this disparate expression of HSP 72 is due to intrinsic characteristics of the cell types rather than to physiological or environmental conditions. The differential expression of HSP 72 among different cell lines could be correlated with the different levels of protein synthesis protection.

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Heat-shock gene expression in animal embryonic systems

Canadian Journal of Genetics and Cytology ◽

10.1139/g86-153 ◽

1986 ◽

Vol 28 (6) ◽

pp. 1093-1105 ◽

Cited By ~ 56

Author(s):

John J. Heikkila ◽

L. W. Browder ◽

L. Gedamu ◽

R. W. Nickells ◽

G. A. Schultz

Keyword(s):

Heat Shock ◽

Incubation Temperature ◽

Embryo Cell ◽

In Vitro Translation ◽

Heat Shock Gene ◽

Northern Hybridization ◽

Transcriptional Level ◽

Mrna Accumulation ◽

Stress Genes

We have examined the expression of heat shock or stress genes in fish, echinoderm, amphibian, and mammalian embryonic systems. In a Chinook salmon embryo cell line, elevation of the incubation temperature or exposure to metal ions (e.g., cadmium and zinc) induced a set of heat-shock proteins HSPs. Transcriptional inhibitor, in vitro translation, and Northern hybridization studies suggest that fish HSP synthesis is regulated at the transcriptional level. The synthesis of HSPs during early development of Arbacia punctulata, Xenopus laevis, mouse, and rabbit is a stage-dependent phenomenon. In each of the developmental systems, HSP synthesis could not be induced until after cleavage stages. The ability of the embryo to undergo a heat-shock response (i.e., HSP synthesis) was correlated with the ability to detect HSP mRNA accumulation by either in vitro translation or Northern hybridization assays. Thus, the stage-dependent synthesis of HSPs appears to be controlled at the transcriptional level. Finally, in all of the organisms studied, the capacity to synthesize HSPs and accumulate HSP mRNA also coincides with acquisition of thermotolerance.Key words: heat shock, transcription, mRNA, actin, thermotolerance.

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