Oxidative stress induces lipid-raft-mediated activation of Src homology 2 domain-containing protein-tyrosine phosphatase 2 in astrocytes.
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(2)O(2)) triggered SHP-2 phosphorylation in a time- and dose-dependent manner and led to its translocation into lipid rafts. H(2)O(2)-mediated SHP-2 phosphorylation and translocation were inhibited by filipin III and methyl-beta-cyclodextrin (MCD), lipid-raft-disrupting agents. In the presence of H(2)O(2), SHP-2 formed a complex with STAT-3 and reduced the steady-state STAT-3 phosphorylation level. Interestingly, the effect of H(2)O(2) on SHP-2 phosphorylation was cell-type specific. Remarkably, SHP-2 phosphorylation was induced strongly by H(2)O(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.
Park
Soo Jung
SJ
Department of Pharmacology, Ajou University School of Medicine, Suwon 442-721, Korea.
Kim
Hee Young
HY
Kim
Hyunmi
H
Park
Sang Myun
SM
Joe
Eun-hye
EH
Jou
Ilo
I
Choi
Youn-Hee
YH
D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005372:Filipin / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000494:pharmacology; D021962:Membrane Microdomains / Q000378:metabolism*; D018384:Oxidative Stress / Q000502:physiology*; D010766:Phosphorylation; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D013997:Time Factors; D047392:beta-Cyclodextrins / Q000494:pharmacology
D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D017382:Reactive Oxygen Species; D050796:STAT3 Transcription Factor; C494088:Stat3 protein, rat; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D005372:Filipin; D006861:Hydrogen Peroxide; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; C516727:Ptpn11 protein, rat