title: Characterization of stress sensitivity and chaperone activity of Hsp105 in mammalian cells.
abstract: Hsp105 is a major mammalian heat shock protein that belongs to the Hsp105/110 family, a diverged subgroup of the Hsp70 family. Hsp105 not only protects the thermal aggregation of proteins, but also regulates the Hsc70 chaperone system in vitro. Recently, it has been shown that Hsp105/110 family members act as nucleotide exchange factors for cytosolic Hsp70s. However, the biological functions of Hsp105/110 family proteins still remain to be clarified. Here, we examined the function of Hsp105 in mammalian cells, and showed that the sensitivity to various stresses was enhanced in the Hsp105-deficient cells compared with that in control cells. In addition, we found that deficiency of Hsp105 impaired the refolding of heat-denatured luciferase in mammalian cells. In contrast, overexpression of Hsp105α enhanced the ability to recover heat-inactivated luciferase in mammalian cells. Thus, Hsp105 may play an important role in the refolding of denatured proteins and protection against stress-induced cell death in mammalian cells.
authors.affiliation: Department of Biochemistry & Molecular Biology, Division of Biological Sciences, Kyoto Pharmaceutical University, Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Yamagishi
authors.forename: Masayasu
authors.initials: M
authors.lastname: Yokota
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Yasuda
authors.forename: Youhei
authors.initials: Y
authors.lastname: Saito
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Nagata
authors.forename: Takumi
authors.initials: T
authors.lastname: Hatayama
mesh_terms: D000818:Animals; D017209:Apoptosis; D002460:Cell Line; D005347:Fibroblasts / Q000378:metabolism / Q000502:physiology; D050957:HSP110 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D018869:Heat-Shock Response; D008156:Luciferases / Q000737:chemistry / Q000378:metabolism; D051379:Mice; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D017510:Protein Folding
chemical_list: D050957:HSP110 Heat-Shock Proteins; C490783:Hsp105 protein, mouse; D018832:Molecular Chaperones; D008156:Luciferases