Heat transient related changes in stress-protein synthesis

A slow temperature transient from 37 to 42°C over 3 hr instead of the usual rapid 4- to 7-min transient increases thermal resistance twofold in MTC tumor cells and yet reduces the rates of synthesis of the 70- and 22-kDa heat-stress proteins (hsp) immediately prior to and during expression of thermal resistance-2 to 8 hr after reaching 42°C [S. P. Tomasovic, P. A. Steck, and D. Heitzman, Radiat. Res. 95, 399-413 (1983)]. However, examination of hsp synthesis at earlier times reaching 42°C (0.5 to 2 hr) has revealed differential expression of the individual hsp that is dependent on the rate of heating. Within 30 min of reaching 42°C, cells exposed to slow transients had higher rates of synthesis of the 112- and 90- but not the 70-kDa hsp. However, cells exposed to rapid transients had a higher rate of synthesis of the 70-kDa hsp by 1 hr after reaching 42°C. The rate of synthesis of the 22-kDa hsp was similar in cells heated by either method. Rates of synthesis of the 112-, 90-, and 22-kDa hsp in cells expo...