Re-induction of hsp70 synthesis: An assay for thermotolerance

Abstract

Of the many heat shock proteins (HSPs), hsp70 appears to correlate best with heat resistance, either permanent or transient. We have investigated various approaches to quantify the concentration of hsp 70, and examined the relationship between hsp70 and cells' thermal sensitivity during the development and decay of thermotolerance in model systems. Here, experiments were performed to determine the possibility of using the rate of synthesis of hsp70 after a second test heat shock to predict the kinetics of thermotolerance. Specifically, we studied the relationship between the retained thermotolerance in a murine tumor cell line SQ-1 and a human tumor cell line, HCT-8, after fractionated heat doses and the cells' ability to re-initiate synthesis of hsp70 in response to an additional test heat dose in vitro. Monolayers of cells were exposed to a first heat treatment (e.g., 41 degrees C, 4 h) and then incubated at 37 degrees C for 0-72 h. At various times after the first heat treatment, cells were either challenged with a 45 degrees C, 45 min heat shock to assess the residual thermotolerance by colony formation, or labelled with [35S]methionine before or after an additional test heat dose (e.g. 43.5 degrees C, 15 min). We found that the cells' ability to re-initiate hsp70 synthesis in response to the test heat shock inversely correlated with retained thermotolerance. Our data suggest the level of hsp70 in thermotolerant cells regulates the rate of synthesis of additional hsp70 in response to the subsequent heat challenge. Furthermore, the results showed that the rate of re-induction of hsp70 synthesis after a test shock can be used as a rapid measure of retained thermotolerance. This study suggests an approach for quantifying the level of retained thermotolerance during a course of fractionated hyperthermia.

Thermo-tolerance and heat shock protein of Escherichia coli ATCC 25922 under thermal stress using test cell method

“…However, the increased level of HSP 70 protein after heat shock was similar to results obtained by Auffray et al, (1995) and Juneja et al, (1998). This is because the loss of normal cellular functions due to sudden temperature increase is recovered by the synthesis of stress proteins such as Hsps (Juneja et al, 1998;Li and Mak, 1989;Urban-Chmiel et al, 2013).…”

Acquisition of thermotolerance induced by heat and arsenite in HeLa S3 cells: Multiple pathways to induce tolerance?

“…Role of protein (HSP) synthesis in thermotolerance Levels of HSP70 (Laszlo and Li, 1985;Li, 1985;Laszlo, 1988a;Li and Mak, 1989), and more recently also HSP27 (Chretien and Landry, 1988;Landry et al, 19891, were shown to correlate fairly well with the development and decay of thermotolerance as well as with the heat sensitivity of various (resistant) cell lines. Also, a role for HSP90 in thermotolerance has been suggested (see Lindquist and Craig, 1988 for review).…”

“…Particularly good correlations were reported for heat tolerance and cellular HSP70 levels (Laszlo and Li, 1985;Laszlo, 1988b;Li and Mak, 1989;Li et al, 1991) and, more recently, HSP27 levels (Chretien and Landry, 1988;Landry et al, 1989). However, inhibition of protein (and HSP) synthesis during TT development by cycloheximide (CHX), did not always (totally) inhibit the expression of thermotolerance at the survival level.…”

“…In some cases, it was reported that the CHX effect on TT expression depended on the test temperature used Dewey, 1987a, 1988). Furthermore, some heat-resistant variants showed elevated HSP levels (Laszlo and Li, 1985;Chretien and Landry, 1988;Landry et al, 1989;Li and Mak, 1989) while others did not (Anderson et al, 1986). Finally, slow rates of heating can cause substantial thermotolerance, with greatly reduced or no detectable HSP synthesis (Tomasovic et al, 1983;Anderson et al, 1988).…”

“…It has been repeatedly suggested (Hahn and Li, 1982;Laszlo and Li, 1985;Li, 1985;Chretien and Landry, 1988;Laszlo, 1988a,b;Landry et al, 1989;Li and Mak, 1989) that heat shock proteins (HSP), synthesized a t enhanced rate duringlafter hyperthermia, are related to the acquisition of thermotolerance. Particularly good correlations were reported for heat tolerance and cellular HSP70 levels (Laszlo and Li, 1985;Laszlo, 1988b;Li and Mak, 1989;Li et al, 1991) and, more recently, HSP27 levels (Chretien and Landry, 1988;Landry et al, 1989).…”