| We show here that Saccharomyces cerevisiae Hsp104 mediates the refolding of previously aggregated firefly luciferase in conjunction with human Hsp70 together with either Hdj2 or Hdj1. Hsp104 produced from a transgene in mammalian cells is biochemically active in refolding model substrate in cell-free extracts of the transgenic cell lines and in both the cytoplasm and nucleoplasm of intact cells. Indirect immunofluorescence confirmed that Hsp104 was distributed to both the cytoplasm and nucleoplasm of mammalian cells. We did not, however, observe a robust contribution by Hsp104 to thermoresistance in the mammalian cells tested. Preliminary studies suggest that the soluble protein extract of liver derived from rats exposed to whole body hyperthermia may possess not only the ability, like Hsp104, to refold previously aggregated luciferase in cooperation with human Hsp70 and Hdj2, but also the ability to reactivate significant amounts of aggregates on its own. |
