SYNTHESIS AND DEGRADATION OF HEAT-SHOCK PROTEINS DURING DEVELOPMENT AND DECAY OF THERMOTOLERANCE

Google Scholar
  • 1 January 1982
    • journal article
    • research article
    • Vol. 42  (6) , 2457-2461
Abstract
Morris [rat] hepatoma 7777 cells, heat conditioned at 43.degree. C for 0.5 h, become gradually thermoresistant during an incubation at 37.degree. C, as judged by their ability to form colonies following a 2nd heat challenge. Pulse incorporation of [35S]methionine into proteins at various times after the conditioning treatment and subsequent fractionation of the proteins by polyacrylamide gel electrophoresis indicate that the gradual putative modifications occurring at the cellular level and leading to the thermotolerance state are accompanied by an elevated synthesis above the normal level of a small set of polypeptides with apparent MW of 27,000, 65,000, 68,000, 70,000, 89,000 and 107,000. Both thermotolerance development and protein induction are completed after a 6- to 8-h period. At the end of this period, thermotolerance is at its maximum level and heat shock protein synthesis is returned to normal. This acquired thermal resistance eventually disappears between 60-80 h following conditioning treatment. In a parallel manner, the heat shock-induced proteins synthesized during the first 4 h following the conditioning treatment are maintained in the cells at a high level for several hours but become undetectable by 82 h. Heat shock proteins are apparently involved in the acquisition, maintenance and decay of thermotolerance. [Implications for multifractionated hyperthermic treatments were discussed.].