INDUCTION OF THE DNA-BINDING AND TRANSCRIPTIONAL ACTIVITIES OF HEAT-SHOCK FACTOR-1 IS UNCOUPLED IN XENOPUS OOCYTES

The DNA-binding and transcriptional activities of the beat shock trans cription factor 1 (HSF1) are repressed under normal conditions and rap idly upregulated by heat stress. Here, we tested for the ability of va rious stress agents to activate HSF1 in the Xenopus oocyte model syste m, The HSE-binding activity of HSF1 was induced by a number of chemica l stresses including cadmium, aluminum, iron, mercury, arsenite, ethan ol, methanol, and salicylate. HSE-binding was not induced by several s tresses known to induce the synthesis of hsps in other cell types in d ifferent organisms including zinc, copper, cobalt, manganese, recovery from anoxia, UV-irradiation, and increased pH. The inability of sever al known inducers of the stress response to activate the HSE-bifiding ability of HSF1 suggests that certain stress activation pathways may b e absent or inactive in oocytes. The transcriptional activity of oocyt e HSF1 was induced by heat, cadmium, and arsenite, but many of the age nts that induced HSE-binding failed to stimulate HSF1-mediated transcr iption. The apparent uncoupling of inducible HSE-binding and transcrip tional activities of HSF1 under a variety of stress regimes indicates that these events are regulated by independent mechanisms in the oocyt e. (C) 1998 Elsevier Science B.V.