Induction of heat shock proteins as a measure of chemical cytotoxicity.
Exposure of human keratinocytes to non-lethal heat shock treatment (43 degrees C for 90 min) followed by a recovery period of 2 hr at 37 degrees C resulted in the rapid accumulation of two proteins with polypeptide molecular weights of 72 and 90 kDa. Exposure of human keratinocytes to sodium arsenite (10-200 mug/ml) for 90 min at 37 degrees C resulted in the synthesis of proteins with polypeptide molecular weights of 110, 90, 72, 46 and 28 kDa. The 72 kDa heat- or sodium arsenite-induced protein was identified by immunoprecipitation as the 72 kDa heat shock protein. In contrast, the human epithelial tumour cell line (A431) synthesized only the 72 and 28 kDa heat shock proteins in response to arsenite treatment with all other stress proteins being expressed constitutively. General protein synthesis was inhibited in cells exposed to elevated temperature or sodium arsenite. Using immunofluorescence a rapid and reversible accumulation of the 72 kDa heat shock protein was demonstrated within the nucleolus of heat stressed human fibroblasts and keratinocytes.
Edwards
M J
MJ
Department of Medicine, Section of Dermatology, University of Wales College of Medicine, Heath Park, Cardiff CF4 4XN, UK.
Dykes
P J
PJ
Donovan
M R
MR
Merrett
V R
VR
Morgan
H E
HE
Marks
R
R