Introduction: The heat shock response is a highly conserved cellular defense mechanism. Stimulation of the heat shock response by a sublethal injury confers protection to cells and/or organisms later exposed to a potentially lethal stimulus. Glycosylation influences the stability and function of a variety of serum and cellular proteins and is altered during heat shock. One of the cellular processes associated with glycosylation and implicated in the heat shock response is that of intracellular trafficking. Methods: Using Hep3B cells we evaluated the development of thennotolerance in control cells and cells treated with the glycosylation inhibitors swainsonine (SW) and castanospermine (CS). Cells were preconditioned at 43oC for 1 hour allowed to recover and then exposed to 45oC for 1 hour as a lethal stimulus. Cell viability was determined 24 hours later. The effect of SW and CS on the secretion of α1-antitrypsin (A1AT) and expression of Heat Shock Protein 70(HSP 70) was also determined. HSP 70 was determined by Western analysis. A1AT was measured by evaluation of A1AT activity in cell media and is used a marker of a secreted glycoprotein to assess intracellular trafficking. Results: Preconditioned cells showed improved survival compared to cells not preconditioned when exposed to a lethal heat stress. (73% vs 58% survival) Cells exposed to SW and CS that were preconditioned and then exposed to a lethal heat stress demonstrated a survival close to non-preconditioned control cells (survival: SW 61.5% and CS 62.7%). Expression of HSP 70 was not effected by treatment with SW or CS. Heat shock decreased A1AT activity by 30%. In control cells CS, but not SW, decreased A1AT activity by 35%. A further 30% decrease in A1AT activity was observed in SW and CS treated preconditioned cells. Conclusions: Inhibiting glycosylation decreases thermotolerance without changing the expression of heat shock proteins. The decrease in A1AT activity that accompanies treatment with glycosylation inhibitors may represent interference with intracellular trafficking. We postulate glycosylation is involved in the development of thermotolerance and may function by influencing intracellular trafficking.
|Original language||English (US)|
|Journal||Critical Care Medicine|
|Issue number||12 SUPPL.|
|State||Published - 1999|
ASJC Scopus subject areas
- Critical Care and Intensive Care Medicine