Document Detail


Obligatory role of heat shock protein 90 in iNOS induction.
MedLine Citation:
PMID:  21430289     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Inducible nitric oxide (NO) synthase (iNOS) plays an important role in cell injury and host defense. While undetectable in normal tissues, iNOS expression is induced by endotoxins and inflammatory cytokines primarily via the IκB kinase/nuclear factor-κB (IKK-NF-κB) and Janus kinase (JAK)-signal transducers and activators of transcription 1 (STAT1) pathways. Our previous studies found that heat shock protein 90 (Hsp90) associates with iNOS, and this association enhances iNOS activity. Here we show that Hsp90 is also essential for iNOS induction. With mouse macrophages, Hsp90 inhibition by geldanamycin or knockdown with small interfering RNA (siRNA) prevented lipopolysaccharide (LPS) or interferon-γ (IFN-γ)-stimulated iNOS protein expression. RT-PCR experiments showed that iNOS mRNA transcription was blocked by Hsp90 inhibition. Radicicol, another Hsp90 inhibitor whose structure is different from that of geldanamycin, also blocked iNOS mRNA transcription. These cell biology findings were confirmed in infarcted myocardium where iNOS expression was markedly attenuated by Hsp90 inhibition in vivo. Intriguingly, further analyses showed that inhibiting Hsp90 had no significant effect on the activation of either IKK-NF-κB or JAK-STAT1 in LPS/IFN-γ-stimulated cells. Neither was the nuclear transport of active NF-κB or STAT1 affected by Hsp90 inhibition. But Hsp90 inhibition markedly reduced the binding of active NF-κB and STAT1 to their DNA elements. Chromatin immunoprecipitation assays confirmed that Hsp90 was essential for NF-κB and STAT1 bindings to iNOS promoters inside cells. These studies reveal that besides acting as an allosteric enhancer, Hsp90 is also required for transcriptional factor binding amid iNOS mRNA transcription. In view of the essential role of Hsp90 in iNOS gene transactivation, targeting Hsp90 may represent a new approach to intervene iNOS expression in diseases.
Authors:
Suxin Luo; Tingting Wang; Honghua Qin; Han Lei; Yong Xia
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2011-03-23
Journal Detail:
Title:  American journal of physiology. Cell physiology     Volume:  301     ISSN:  1522-1563     ISO Abbreviation:  Am. J. Physiol., Cell Physiol.     Publication Date:  2011 Jul 
Date Detail:
Created Date:  2011-06-28     Completed Date:  2011-09-06     Revised Date:  2012-09-20    
Medline Journal Info:
Nlm Unique ID:  100901225     Medline TA:  Am J Physiol Cell Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  C227-33     Citation Subset:  IM    
Affiliation:
Davis Heart and Lung Research Institute, Division of Cardiovascular Medicine, Department of Molecular and Cellular Biochemistry, The Ohio State University College of Medicine, Columbus, Ohio 43210, USA.
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MeSH Terms
Descriptor/Qualifier:
Animals
Benzoquinones / pharmacology
Cells, Cultured
Chromatin Immunoprecipitation
DNA-Binding Proteins / antagonists & inhibitors
Enzyme Induction
Enzyme Inhibitors / pharmacology
HSP90 Heat-Shock Proteins / genetics,  metabolism*
I-kappa B Kinase / metabolism
Interferon-gamma / metabolism
Janus Kinases / metabolism
Lactams, Macrocyclic / pharmacology
Lipopolysaccharides / metabolism
Macrolides / pharmacology
Macrophages / drug effects,  metabolism*
Mice
Mice, Inbred C57BL
Myocardial Infarction / metabolism
NF-kappa B / metabolism
Nitric Oxide Synthase Type II / biosynthesis*,  genetics*
Polymerase Chain Reaction
Promoter Regions, Genetic
RNA Interference
RNA, Small Interfering
STAT1 Transcription Factor / metabolism
Transcriptional Activation
Grant Support
ID/Acronym/Agency:
HL-77575/HL/NHLBI NIH HHS; HL-86965/HL/NHLBI NIH HHS
Chemical
Reg. No./Substance:
0/Benzoquinones; 0/DNA-Binding Proteins; 0/Enzyme Inhibitors; 0/HSP90 Heat-Shock Proteins; 0/Lactams, Macrocyclic; 0/Lipopolysaccharides; 0/Macrolides; 0/NF-kappa B; 0/RNA, Small Interfering; 0/STAT1 Transcription Factor; 12772-57-5/monorden; 30562-34-6/geldanamycin; 82115-62-6/Interferon-gamma; EC 1.14.13.39/Nitric Oxide Synthase Type II; EC 2.7.10.2/Janus Kinases; EC 2.7.11.10/I-kappa B Kinase
Comments/Corrections

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