INDUCTION OF HEAT-SHOCK-PROTEIN-70 PROTECTS INTESTINAL EPITHELIAL IEC-18 CELLS FROM OXIDANT AND THERMAL-INJURY

The potential importance of inducible heat shock proteins (HSPs) in co nferring protection to intestinal epithelial cells was investigated us ing IEC-18 cells. To establish optimal HSP induction, [S-35]methionine and [S-35]cysteine incorporation was assessed. Two S-35-labeled prote ins of 70 and 90 kDa were preferentially synthesized. Western and Nort hern blot analyses confirmed induction of HSP70. This induction provid ed significant protection to the cells treated with the oxidant monoch loramine or lethal heat (49 degrees C). To better establish the protec tive role of HSP70, cells were stably transfected with human HSP70 und er control of the lac operator. When these cells were subjected to inj ury, they were protected by isopropylthiogalactoside-stimulated HSP70 induction under nonstress conditions. Additionally the rate of protein synthesis (assessed by [H-3]leucine incorporation) was protected. The se results demonstrate that HSPs are preferentially and rapidly induce d in IEC-18 cells and that induction of inducible HSP70 is important i n promoting protection against cellular injury.