title: Mild thermotolerance induced at 40 degrees C increases antioxidants and protects HeLa cells against mitochondrial apoptosis induced by hydrogen peroxide: Role of p53.
abstract: Exposure of cells to mild temperatures (40 degrees C) induces thermotolerance, which renders cells resistant to subsequent toxic insults. Thermotolerance is usually associated with accumulation of heat shock proteins. This study determines whether mild thermotolerance (40 degrees C, 3h) can induce other defense proteins (e.g. antioxidants, anti-apoptosis proteins), and protect HeLa cells against apoptosis triggered by H(2)O(2). Protein expression and enzymatic activity of MnSOD and catalase were increased in thermotolerant cells, as well as intracellular glutathione levels and gamma-glutamylcysteine synthetase expression. Furthermore, levels of reactive oxygen species (ROS) were increased in thermotolerant cells, which caused mitochondrial membrane hyperpolarisation. Mild thermotolerance inhibited activation of the mitochondrial cascade of apoptosis by H(2)O(2). This entailed inhibition of mitochondrial Bax translocation, mitochondrial membrane depolarisation, cytochrome c release, activation of caspases-9/-3 and chromatin condensation. Thermotolerance inhibited H(2)O(2)-induced caspase-independent apoptosis involving apoptosis-inducing factor, and activation of p53 and increased expression of its target protein PUMA. Thermotolerance induced at mild physiological temperatures protects cells against both caspase-dependent and caspase-independent apoptosis triggered by oxidative stress.
authors.affiliation: Département des Sciences Biologiques and TOXEN, Université du Québec à Montréal, Québec, Canada.
authors.forename: Pragathi
authors.initials: P
authors.lastname: Pallepati
authors.forename: Diana
authors.initials: D
authors.lastname: Averill-Bates
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D017209:Apoptosis; D051033:Apoptosis Inducing Factor / Q000378:metabolism; D020169:Caspases / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D006367:HeLa Cells; D006360:Heat-Shock Proteins / Q000378:metabolism; D006358:Hot Temperature; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: C494829:AIFM1 protein, human; D000975:Antioxidants; D051033:Apoptosis Inducing Factor; D006360:Heat-Shock Proteins; D017382:Reactive Oxygen Species; D016159:Tumor Suppressor Protein p53; D006861:Hydrogen Peroxide; D002374:Catalase; D013482:Superoxide Dismutase; D020169:Caspases; D005978:Glutathione