Toxoplasma gondii infection of activated J774-A1 macrophages causes inducible nitric oxide synthase degradation by the proteasome pathway.

Abstract

Classically activated macrophages produce nitric oxide (NO), which is a potent microbicidal agent. NO production is catalyzed by inducible nitric oxide synthase (iNOS), which uses arginine as substrate producing NO and citruline. However, it has been demonstrated that NO production is inhibited after macrophage infection of Toxoplasma gondii, the agent of toxoplasmosis, due to iNOS degradation. Three possible iNOS degradation pathways have been described in activated macrophages: proteasome, calpain and lysosomal. To identify the iNOS degradation pathway after T. gondii infection, J774-A1 macrophage cell line was activated with lipopolysaccharide and interferon-gamma for 24 h, treated with the following inhibitors, lactacystin (proteasome), calpeptin (calpain), or concanamycin A (lysosomal), and infected with the parasite. NO production and iNOS expression were evaluated after 2 and 6 h of infection. iNOS was degraded in J774-A1 macrophages infected with T. gondii. However, treatment with lactacystin maintained iNOS expression in J774-A1 macrophages infected for 2 h by T. gondii, and after 6 h iNOS was localized in aggresomes. iNOS was degraded after parasite infection of J774-A1 macrophages treated with calpeptin or concanamycin A. NO production confirmed iNOS expression profiles. These results indicate that T. gondii infection of J774-A1 macrophages caused iNOS degradation by the proteasome pathway.

• Authors: Juliana da Cruz Padrão, Gabriel Rabello de Abreu Cabral, Maria de Fátima Sarro da Silva, Sergio Henrique Seabra, Renato Augusto DaMatta
• Journal: Parasitology international (Parasitol Int) Vol. 63 Issue 5 Pg. 659-63 (Oct 2014) ISSN: 1873-0329 [Electronic] Netherlands
• PMID: 24845536 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Chemical References

• Dipeptides
• Macrolides
• calpeptin
• Nitric Oxide
• concanamycin A
• Nitric Oxide Synthase Type II
• Proteasome Endopeptidase Complex

Topics

• Animals
• Cell Line
• Cell Survival
• Dipeptides (pharmacology)
• Gene Expression Regulation, Enzymologic (physiology)
• Macrolides (pharmacology)
• Macrophages (parasitology)
• Mice
• Nitric Oxide (metabolism)
• Nitric Oxide Synthase Type II (genetics, metabolism)
• Proteasome Endopeptidase Complex (genetics, metabolism)
• Toxoplasma (physiology)