Effects of hyperthermic temperatures and the synthesis of heat-shock proteins on the lateral diffusion of H-2K^k

Abstract

The effect of hyperthermia, fractionated heat and the synthesis of heat shock proteins on the lateral diffusion of H-2K^k was examined in RDM-4, Ch-1 and mouse L cells. Cells in suspension were examined immediately after heating, adaptation to growth at 40°C for 72 h or 6 h after exposure to sodium arsenite (5 μM), iodoacetamide (10 μM) or a 20 min heat shock at 45°C. No heat shock protein synthesis could be measured in CH-1 cells in response to either heat or chemical stress. Synthesis of these proteins was observed in both RDM-4 and mouse L cells in response to heat or chemical treatments, and the kinetics of synthesis were similar to those reported in the literature for other eukaryotic cell lines. The diffusion of fluorescein isothiocyanate-labelled monoclonal anti-H-2K^k bound to heat (or chemically) treated cells was measured by the technique of fluorescence recovery after pattern photobleaching. After a 30 min exposure to temperatures between 41°C and 45°C, a temperature-dependent decrease in recovery was observed. At 45°C, 75–100% of the surface antigen was found to be immobile. The diffusion coefficients of the mobile fractions were not significantly changed at all the temperatures examined. Heat effects on the recovery patterns of all the three cell lines were qualitatively similar and unaffected by the presence or absence of heat or chemically induced heat shock proteins. After 48–60 h following a heat shock, the recovery patterns were similar to those of unheated control cells.

Key Words:

• Lateral diffusion
• heat shock proteins
• hyperthermia