title: p66shc inhibits pro-survival epidermal growth factor receptor/ERK signaling during severe oxidative stress in mouse renal proximal tubule cells.
abstract: The fully executed epidermal growth factor receptor (EGFR)/Ras/MEK/ERK pathway serves a pro-survival role in renal epithelia under moderate oxidative stress. We and others have demonstrated that during severe oxidative stress, however, the activated EGFR is disconnected from ERK activation in cultured renal proximal tubule cells and also in renal proximal tubules after ischemia/reperfusion injury, resulting in necrotic death. Studies have shown that the tyrosine-phosphorylated p46/52 isoforms of the ShcA family of adaptor proteins connect the activated EGFR to activation of Ras and ERK, whereas the p66(shc) isoform can inhibit this p46/52(shc) function. Here, we determined that severe oxidative stress (after a brief period of activation) terminates activation of the Ras/MEK/ERK pathway, which coincides with ERK/JNK-dependent Ser(36) phosphorylation of p66(shc). Isoform-specific knockdown of p66(shc) or mutation of Ser(36) to Ala, but not to Asp, attenuated severe oxidative stress-mediated ERK inhibition and cell death in vitro. Also, severe oxidative stress (unlike ligand stimulation and moderate oxidative stress, both of which support survival) increased binding of p66(shc) to the activated EGFR and Grb2. This binding dissociated the SOS1 adaptor protein from the EGFR-recruited signaling complex, leading to termination of Ras/MEK/ERK activation. Notably, Ser(36) phosphorylation of p66(shc) and its increased binding to the EGFR also occurred in the kidney after ischemia/reperfusion injury in vivo. At the same time, SOS1 binding to the EGFR declined, similar to the in vitro findings. Thus, the mechanism we propose in vitro offers a means to ameliorate oxidative stress-induced cell injury by either inhibiting Ser(36) phosphorylation of p66(shc) or knocking down p66(shc) expression in vivo.
authors.affiliation: Department of Internal Medicine, University of Arkansas for Medical Sciences and the Central Arkansas Veterans Healthcare System, Little Rock, AR 72205, USA. iarany@ped.umsmed.edu
authors.forename: Istvan
authors.initials: I
authors.lastname: Arany
authors.forename: Amir
authors.initials: A
authors.lastname: Faisal
authors.forename: Yoshikuni
authors.initials: Y
authors.lastname: Nagamine
authors.forename: Robert L
authors.initials: RL
authors.lastname: Safirstein
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000818:Animals; D002461:Cell Line, Transformed; D002470:Cell Survival; D004789:Enzyme Activation; D004848:Epithelium / Q000378:metabolism; D066246:ErbB Receptors / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D051380:GRB2 Adaptor Protein / Q000378:metabolism; D007687:Kidney Tubules, Proximal / Q000378:metabolism* / Q000473:pathology; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D020935:MAP Kinase Signaling System; D051379:Mice; D015689:Oncogene Protein p21(ras) / Q000378:metabolism; D018384:Oxidative Stress; D011485:Protein Binding; D020033:Protein Isoforms / Q000378:metabolism; D015427:Reperfusion Injury / Q000378:metabolism / Q000473:pathology; D020837:SOS1 Protein / Q000378:metabolism; D055765:Shc Signaling Adaptor Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051380:GRB2 Adaptor Protein; C495949:Grb2 protein, mouse; D020033:Protein Isoforms; D020837:SOS1 Protein; D055765:Shc Signaling Adaptor Proteins; C528034:Shc1 protein, mouse; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D066246:ErbB Receptors; D048049:Extracellular Signal-Regulated MAP Kinases; D020930:MAP Kinase Kinase Kinases; D015689:Oncogene Protein p21(ras)