p66shc Inhibits Pro-survival Epidermal Growth Factor Receptor/ERK Signaling during Severe Oxidative Stress in Mouse Renal Proximal Tubule Cells

• Published in: The Journal of biological chemistry Vol. 283; no. 10; pp. 6110 - 6117
• Main Authors: Arany, Istvan, Faisal, Amir, Nagamine, Yoshikuni, Safirstein, Robert L.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 07.03.2008; American Society for Biochemistry and Molecular Biology
• Subjects: Adaptor Proteins, Signal Transducing - metabolism; Animals; Cell Line, Transformed; Cell Survival; Enzyme Activation; Epithelium - metabolism; ErbB Receptors - metabolism; Extracellular Signal-Regulated MAP Kinases - metabolism; GRB2 Adaptor Protein - metabolism; Kidney Tubules, Proximal - metabolism; Kidney Tubules, Proximal - pathology; MAP Kinase Kinase Kinases - metabolism; MAP Kinase Signaling System; Mice; Oncogene Protein p21(ras) - metabolism; Oxidative Stress; Protein Binding; Protein Isoforms - metabolism; Reperfusion Injury - metabolism; Reperfusion Injury - pathology; Shc Signaling Adaptor Proteins; SOS1 Protein - metabolism; Src Homology 2 Domain-Containing, Transforming Protein 1
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M708799200

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 p66shc isoform can inhibit this p46/52shc 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 Ser36 phosphorylation of p66shc. Isoform-specific knockdown of p66shc or mutation of Ser36 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 p66shc 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, Ser36 phosphorylation of p66shc 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 Ser36 phosphorylation of p66shc or knocking down p66shc expression in vivo.