BMC Pharmacology

, 7:P3 | Cite as

LPS-induced down-regulation of NO-sensitive guanylyl cyclase in astrocytes occurs by proteasomal degradation in nuclear bodies

  • María Antonia Baltrons
  • Paula Pifarré
  • María Teresa Berciano
  • Miguel Lafarga
  • Agustina García
Open Access
Poster presentation
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Keywords

Guanylyl Cyclase Nuclear Body Calpain Inhibitor Soluble Guanylyl Cyclase Proteasome Inhibitor MG132 

Background

We have previously shown that inflammatory agents (LPS, IL-1β, β-amyloid peptides) that induce reactivity and NOS-2 expression in glial cells down-regulate astroglial soluble guanylyl cyclase (sGC) in vitro and in vivo [1, 2].

Results

Here we show that the decrease in sGC activity and β1 subunit protein induced by LPS (10 ng/ml, 24 h) in cultured rat cerebellar astrocytes is prevented by inhibitors of proteasome activity (MG132 5 μM; lactacystin 10 μM) whereas other protease inhibitors (calpain inhibitor 25 μM; ICE inhibitor II 100 μM and leupeptin 5 μM) were not effective. Furthermore, immunocytochemistry and confocal laser microscopy revealed that in LPS-treated cells a strong sGC β1 immunorreactivity is evident in aggregates in the cell nuclei where it co-localizes with 20S proteasomes and ubiquitin in clastosomes, nucleoplasmic substructures involved in ubiquitin-proteasome-dependent nuclear proteolysis, but do not colocalize with others proteasome-enriched structures include promyelocytic leukaemia bodies and splicing speckles. In contrast, in untreated astrocytes clastosomes are scarce and sGC β1 immunorectivity shows a diffuse cytoplasmic pattern, while in the nucleus it is very weak. A similar distribution is observed when cells are treated with LPS and the proteasome inhibitor MG132 or the protein synthesis inhibitor cycloheximide.

Conclusion

LPS orchestrates the recruitment of sGC-β1 protein and components of the ubiquitin-proteasome system to specialized nuclear bodies, clastosomes, suggesting a mechanism for inflammation-induced down-regulation of sGC in astrocytes.

Notes

Acknowledgements

This work was supported by a SAF2004-01717 grant (Spain).

References

  1. 1.
    Baltrons MA, Pedraza CE, Heneka MT, García A: β-Amyloid peptides decrease soluble guanylyl cyclase expression in astroglial cells. Neurobiol Dis. 2002, 10: 39-149. 10.1006/nbdi.2002.0492.CrossRefGoogle Scholar
  2. 2.
    Pedraza CE, Baltrons MA, Heneka MT, García A: Interleukin-1β and lipopolysaccharide decrease soluble guanylyl cyclase in cells of the CNS: NO-independent destabilization of protein and NO-dependent decrease of mRNA. J Neuroimmunol. 2003, 144: 80-90. 10.1016/j.jneuroim.2003.08.034.CrossRefPubMedGoogle Scholar

Copyright information

© Baltrons et al; licensee BioMed Central Ltd. 2007

This article is published under license to BioMed Central Ltd.

Authors and Affiliations

  • María Antonia Baltrons
    • 1
  • Paula Pifarré
    • 1
  • María Teresa Berciano
    • 2
  • Miguel Lafarga
    • 2
  • Agustina García
    • 1
  1. 1.Institute of Biotechnology and Biomedicine and Department of Biochemistry and Molecular BiologyAutonomous University of BarcelonaSpain
  2. 2.Department of Anatomy and Cell Biology and Biomedicine UnitCSIC, University of CantabriaSpain

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