Oxidative stress induces lipid-raft-mediated activation of Src homology 2 domain-containing protein-tyrosine phosphatase 2 in astrocytes

• Published in: Free radical biology & medicine 2009-06, Vol.46 (12), p.1694-1702
• Main Authors: Park, Soo Jung, Kim, Hee Young, Kim, Hyunmi, Park, Sang Myun, Joe, Eun-hye, Jou, Ilo, Choi, Youn-Hee
• Format: Article
• Language: English
• Subjects: Animals; Astrocyte; Astrocytes - metabolism; beta-Cyclodextrins - pharmacology; Cells, Cultured; Dose-Response Relationship, Drug; Enzyme Inhibitors - pharmacology; Filipin - pharmacology; Free Radical Scavengers - pharmacology; Free radicals; Hydrogen Peroxide - pharmacology; Hypoxia/reoxygenation; Membrane Microdomains - metabolism; Microglia; Oxidative stress; Oxidative Stress - physiology; Phosphorylation; Protein Tyrosine Phosphatase, Non-Receptor Type 11 - antagonists & inhibitors; Protein Tyrosine Phosphatase, Non-Receptor Type 11 - metabolism; Raft; Rats; Rats, Sprague-Dawley; Reactive oxygen species; Reactive Oxygen Species - metabolism; SHP-2; Signal Transduction - physiology; STAT-3; STAT3 Transcription Factor - metabolism; Time Factors; Translocation
• ISSN: 0891-5849; 1873-4596
• DOI: 10.1016/j.freeradbiomed.2009.03.026

Several protein phosphatases are involved in neuroprotection in response to ischemic brain injury. Here, we report that reactive oxygen species (ROS)-mediated oxidative stress promotes phosphorylation of endogenous SHP-2 through lipid rafts in rat primary astrocytes. SHP-2 was transiently phosphorylated during hypoxia/reoxygenation, an effect abrogated by a ROS scavenger and an NADPH oxidase inhibitor. Additionally, exogenous treatment with hydrogen peroxide (H 2O 2) triggered SHP-2 phosphorylation in a time- and dose-dependent manner and led to its translocation into lipid rafts. H 2O 2-mediated SHP-2 phosphorylation and translocation were inhibited by filipin III and methyl-β-cyclodextrin (MCD), lipid-raft-disrupting agents. In the presence of H 2O 2, SHP-2 formed a complex with STAT-3 and reduced the steady-state STAT-3 phosphorylation level. Interestingly, the effect of H 2O 2 on SHP-2 phosphorylation was cell-type specific. Remarkably, SHP-2 phosphorylation was induced strongly by H 2O 2 in astrocytes, but barely detectable in microglia. Our results collectively indicate that SHP-2 is activated by ROS-mediated oxidative stress in astrocytes and functions as a component of the raft-mediated signaling pathway that acts through dephosphorylation and inactivation of other phosphotyrosine proteins, such as STAT-3.