Document Detail


Astrocytes, but Not Microglia, Rapidly Sense H2O2 via STAT6 Phosphorylation, Resulting in Cyclooxygenase-2 Expression and Prostaglandin Release.
MedLine Citation:
PMID:  22504638     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Emerging evidence has established that astrocytes, once considered passive supporting cells that maintained extracellular ion levels and served as a component of the blood-brain barrier, play active regulatory roles during neurogenesis and in brain pathology. In the current study, we demonstrated that astrocytes sense H(2)O(2) by rapidly phosphorylating the transcription factor STAT6, a response not observed in microglia. STAT6 phosphorylation was induced by generators of other reactive oxygen species (ROS) and reactive nitrogen species, as well as in the reoxygenation phase of hypoxia/reoxygenation, during which ROS are generated. Src-JAK pathways mediated STAT6 phosphorylation upstream. Experiments using lipid raft disruptors and analyses of detergent-fractionated cells demonstrated that H(2)O(2)-induced STAT6 phosphorylation occurred in lipid rafts. Under experimental conditions in which H(2)O(2) did not affect astrocyte viability, H(2)O(2)-induced STAT6 phosphorylation resulted in STAT6-dependent cyclooxygenase-2 expression and subsequent release of PGE(2) and prostacyclin, an effect also observed in hypoxia/reoxygenation. Finally, PGs released from H(2)O(2)-stimulated astrocytes inhibited microglial TNF-α expression. Accordingly, our results indicate that ROS-induced STAT6 phosphorylation in astrocytes can modulate the functions of neighboring cells, including microglia, through cyclooxygenase-2 induction and subsequent release of PGs. Differences in the sensitivity of STAT6 in astrocytes (highly sensitive) and microglia (insensitive) to phosphorylation following brief exposure to H(2)O(2) suggest that astrocytes can act as sentinels for certain stimuli, including H(2)O(2) and ROS, refining the canonical notion that microglia are the first line of defense against external stimuli.
Authors:
Soo Jung Park; Jee Hoon Lee; Hee Young Kim; Youn Hee Choi; Jung Sup Park; Young Ho Suh; Sang Myun Park; Eun-Hye Joe; Ilo Jou
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-4-13
Journal Detail:
Title:  Journal of immunology (Baltimore, Md. : 1950)     Volume:  -     ISSN:  1550-6606     ISO Abbreviation:  -     Publication Date:  2012 Apr 
Date Detail:
Created Date:  2012-4-16     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  2985117R     Medline TA:  J Immunol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Department of Pharmacology, Ajou University School of Medicine, Suwon 442-721, Korea;
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