Thermotolerance and cell death are distinct cellular responses to stress: dependence on heat shock proteins

A Samali, C I Holmberg, L Sistonen, S Orrenius

Research output: Contribution to journalArticleScientificpeer-review


We tested the hypothesis that heat shock protein (Hsp) induction and cell death are mutually exclusive responses to stress. Despite activation of heat shock transcription factor 1 at temperatures ranging from 40 to 46 degrees C, Hsp72 and Hsp27 were not induced above 42 degrees C. Moreover, cells underwent apoptosis at 44 degrees C and necrosis at 46 degrees C, with mitochondrial cytochrome c release at both temperatures. However, only apoptosis was associated with caspase activation. Treatment of cells with z-VAD-fmk prior to heat shock at 44 degrees C failed to restore Hsp induction despite inhibition of heat-induced apoptosis. Furthermore, accumulation of Hsps after incubation at 42 degrees C rendered the cells resistant to apoptosis. These results suggest that lack of Hsp induction is the cause rather than the consequence of cell death.

Original languageEnglish
Pages (from-to)306-10
Number of pages5
JournalFEBS Letters
Issue number3
Publication statusPublished - 19 Nov 1999
MoE publication typeA1 Journal article-refereed


  • Apoptosis/genetics
  • Caspases/physiology
  • Gene Expression Profiling
  • Gene Expression Regulation
  • Heat-Shock Proteins/physiology
  • Hot Temperature
  • Humans
  • Jurkat Cells
  • Kinetics
  • Mitochondria/physiology
  • Stress, Physiological/genetics


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