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Respiratory syncytial virus decreases p53 protein to prolong survival of airway epithelial cells
Journal article   Peer reviewed

Respiratory syncytial virus decreases p53 protein to prolong survival of airway epithelial cells

Dayna J Groskreutz, Martha M Monick, Timur O Yarovinsky, Linda S Powers, Dawn E Quelle, Steven M Varga, Dwight C Look and Gary W Hunninghake
The Journal of immunology (1950), Vol.179(5), pp.2741-2747
09/01/2007
DOI: 10.4049/jimmunol.179.5.2741
PMID: 17709487

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Abstract

Respiratory syncytial virus (RSV) is a clinically important pathogen. It preferentially infects airway epithelial cells causing bronchiolitis in infants, exacerbations in patients with obstructive lung disease, and life-threatening pneumonia in the immunosuppressed. The p53 protein is a tumor suppressor protein that promotes apoptosis and is tightly regulated for optimal cell growth and survival. A critical negative regulator of p53 is murine double minute 2 (Mdm2), an E3 ubiquitin ligase that targets p53 for proteasome degradation. Mdm2 is activated by phospho-Akt, and we previously showed that RSV activates Akt and delays apoptosis in primary human airway epithelial cells. In this study, we explore further the mechanism by which RSV regulates p53 to delay apoptosis but paradoxically enhance inflammation. We found that RSV activates Mdm2 1-6 h after infection resulting in a decrease in p53 6-24 h after infection. The p53 down-regulation correlates with increased airway epithelial cell longevity. Importantly, inhibition of the PI3K/Akt pathway blocks the activation of Mdm2 by RSV and preserves the p53 response. The effects of RSV infection are antagonized by Nutlin-3, a specific chemical inhibitor that prevents the Mdm2/p53 association. Nutlin-3 treatment increases endogenous p53 expression in RSV infected cells, causing earlier cell death. This same increase in p53 enhances viral replication and limits the inflammatory response as measured by IL-6 protein. These findings reveal that RSV decreases p53 by enhancing Akt/Mdm2-mediated p53 degradation, thereby delaying apoptosis and prolonging survival of airway epithelial cells.
Epithelial Cells - metabolism Interleukin-6 - antagonists & inhibitors Respiratory Syncytial Viruses - physiology Tumor Suppressor Protein p53 - antagonists & inhibitors Cell Survival Humans Tumor Suppressor Protein p53 - metabolism Piperazines - metabolism Phosphatidylinositol 3-Kinases - metabolism Respiratory System - cytology Respiratory System - virology Virus Replication Respiratory System - metabolism Epithelial Cells - virology Proteasome Inhibitors Proto-Oncogene Proteins c-akt - metabolism Proto-Oncogene Proteins c-mdm2 - metabolism Apoptosis Imidazoles - metabolism

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