title: Epidermal growth factor receptor-dependent Akt activation by oxidative stress enhances cell survival.
abstract: The serine/threonine kinase Akt (also known as protein kinase B) is activated in response to various stimuli by a mechanism involving phosphoinositide 3-kinase (PI3-K). Akt provides a survival signal that protects cells from apoptosis induced by growth factor withdrawal, but its function in other forms of stress is less clear. Here we investigated the role of PI3-K/Akt during the cellular response to oxidant injury. H(2)O(2) treatment elevated Akt activity in multiple cell types in a time- (5-30 min) and dose (400 microM-2 mm)-dependent manner. Expression of a dominant negative mutant of p85 (regulatory component of PI3-K) and treatment with inhibitors of PI3-K (wortmannin and LY294002) prevented H(2)O(2)-induced Akt activation. Akt activation by H(2)O(2) also depended on epidermal growth factor receptor (EGFR) signaling; H(2)O(2) treatment led to EGFR phosphorylation, and inhibition of EGFR activation prevented Akt activation by H(2)O(2). As H(2)O(2) causes apoptosis of HeLa cells, we investigated whether alterations of PI3-K/Akt signaling would affect this response. Wortmannin and LY294002 treatment significantly enhanced H(2)O(2)-induced apoptosis, whereas expression of exogenous myristoylated Akt (an activated form) inhibited cell death. Constitutive expression of v-Akt likewise enhanced survival of H(2)O(2)-treated NIH3T3 cells. These results suggest that H(2)O(2) activates Akt via an EGFR/PI3-K-dependent pathway and that elevated Akt activity confers protection against oxidative stress-induced apoptosis.
authors.affiliation: Cell Stress and Aging Section, Laboratory of Biological Chemistry, NIA, National Institutes of Health, Baltimore, Maryland 21224-6825, USA.
authors.forename: X
authors.initials: X
authors.lastname: Wang
authors.forename: K D
authors.initials: KD
authors.lastname: McCullough
authors.forename: T F
authors.initials: TF
authors.lastname: Franke
authors.forename: N J
authors.initials: NJ
authors.lastname: Holbrook
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002470:Cell Survival; D004789:Enzyme Activation; D066246:ErbB Receptors / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D051058:Oncogene Protein v-akt; D018384:Oxidative Stress; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D015682:Retroviridae Proteins, Oncogenic / Q000378:metabolism*
chemical_list: D015682:Retroviridae Proteins, Oncogenic; D006861:Hydrogen Peroxide; D019869:Phosphatidylinositol 3-Kinases; D066246:ErbB Receptors; D051058:Oncogene Protein v-akt