Effect of culture temperature on the expression of heat-shock proteins in murine ts85 cells

Abstract

The murine temperature-sensitive cell-cycle mutant, ts85, shows an abnormal induction of heat-shock proteins which is different from the wild type FM3A cells. This paper explores the effect of culture temperature on the expression of heat shock proteins in ts85 cells. When ts85 cells were maintained at 33 or 37°C, these cells synthesized heat-stock protein (hsp) 70 following continuous heating at 39°C or subsequent incubation after heating at 42°C for 15 min. In contrast, these conditions are not conducive for hsp70 synthesis by FM3A cells. Moreover, ts85 cells which were maintained at 37°C synthesized hsp70 following continuous heating at 42°C or subsequent incubation after heating at 45°C for 15 min. The syntehsis of hsp70 in these cells corresponded to an increased level of hsp70 mRNA. Furthermore, the constitutive hsp105 level of cells maintained at 33°C was only half of that of cells which were maintained at 37°C, and cells maintained at 33°C were more sensitive to subsequent heat treatment than those maintained at 37°C. These results indicate that culture temperature not only affects the induction of hsp70 mRNA, but also cellular levels of hsp105 and the resulting thermal sensitivity of ts85 cells. These findings suggest that the other phenotypic characteristic of the mutant ts85 cells is also affected by culture temperature.