title: Mammalian 105 kDa heat shock family proteins suppress hydrogen peroxide-induced apoptosis through a p38 MAPK-dependent mitochondrial pathway in HeLa cells.
abstract: Hsp105alpha and Hsp105beta are major heat shock proteins in mammalian cells that belong to a subgroup of the HSP70 family, HSP105/110. Previously, we have shown that Hsp105alpha has opposite effects on stress-induced apoptosis depending on the cell type. However, it is not fully understood how Hsp105 regulates stress-induced apoptosis. In this study, we examined how Hsp105alpha and Hsp105beta regulate H2O2-induced apoptosis by using HeLa cells in which expression of Hsp105alpha or Hsp105beta was regulated using doxycycline. Overexpression of Hsp105alpha and Hsp105beta suppressed the activation of caspase-3 and caspase-9 by preventing the release of cytochrome c from mitochondria in H2O2-treated cells. Furthermore, both c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (p38 MAPK) were activated by treatment with H2O2, and the activation of both kinases was suppressed by overexpression of Hsp105alpha and Hsp105beta. However, H2O2-induced apoptosis was suppressed by treatment with a potent inhibitor of p38 MAPK, SB202190, but not a JNK inhibitor, SP600125. These findings suggest that Hsp105alpha and Hsp105beta suppress H2O2-induced apoptosis by suppression of p38 MAPK signaling, one of the essential pathways for apoptosis.
authors.affiliation: Department of Biochemistry, Division of Biological Sciences, Kyoto Pharmaceutical University, Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Yamagishi
authors.forename: Youhei
authors.initials: Y
authors.lastname: Saito
authors.forename: Takumi
authors.initials: T
authors.lastname: Hatayama
mesh_terms: D000818:Animals; D017209:Apoptosis; D045304:Cytochromes c / Q000378:metabolism; D050957:HSP110 Heat-Shock Proteins / Q000378:metabolism*; D006367:HeLa Cells; D018869:Heat-Shock Response; D006801:Humans; D006861:Hydrogen Peroxide / Q000037:antagonists & inhibitors*; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D020935:MAP Kinase Signaling System; D051379:Mice; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D050957:HSP110 Heat-Shock Proteins; C490783:Hsp105 protein, mouse; D045304:Cytochromes c; D006861:Hydrogen Peroxide; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases