title: The human parasite Leishmania amazonensis downregulates iNOS expression via NF-κB p50/p50 homodimer: role of the PI3K/Akt pathway.
abstract: Leishmania amazonensis activates the NF-κB transcriptional repressor homodimer (p50/p50) and promotes nitric oxide synthase (iNOS) downregulation. We investigated the role of PI3K/Akt in p50/p50 NF-κB activation and the effect on iNOS expression in L. amazonensis infection. The increased occupancy of p50/p50 on the iNOS promoter of infected macrophages was observed and we demonstrated that both p50/p50 NF-κB induction and iNOS downregulation in infected macrophages depended on PI3K/Akt activation. Importantly, the intracellular growth of the parasite was also impaired during PI3K/Akt signalling inhibition and in macrophages knocked-down for Akt 1 expression. It was also observed that the increased nuclear levels of p50/p50 in L. amazonensis-infected macrophages were associated with reduced phosphorylation of 907 Ser p105, the precursor of p50. Corroborating these data, we demonstrated the increased levels of phospho-9 Ser GSK3β in infected macrophages, which is associated with GSK3β inhibition and, consequently, its inability to phosphorylate p105. Remarkably, we found that the levels of pPTEN 370 Ser, a negative regulator of PI3K, increased due to L. amazonensis infection. Our data support the notion that PI3K/Akt activity is sustained during the parasite infection, leading to NF-κB 105 phosphorylation and further processing to originate p50/p50 homodimers and the consequent downregulation of iNOS expression.
authors.affiliation: Laboratório de Parasitologia Molecular, Instituto de Biofísica Carlos Chagas Filho, CCS, UFRJ, Rio de Janeiro, Brazil.
authors.forename: Teresa C
authors.initials: TC
authors.lastname: Calegari-Silva
authors.affiliation: Laboratório de Parasitologia Molecular, Instituto de Biofísica Carlos Chagas Filho, CCS, UFRJ, Rio de Janeiro, Brazil.
authors.forename: Áislan C
authors.initials: ÁC
authors.lastname: Vivarini
authors.affiliation: Laboratório de Parasitologia Molecular, Instituto de Biofísica Carlos Chagas Filho, CCS, UFRJ, Rio de Janeiro, Brazil.
authors.forename: Marina
authors.initials: M
authors.lastname: Miqueline
authors.affiliation: Laboratório de Parasitologia Molecular, Instituto de Biofísica Carlos Chagas Filho, CCS, UFRJ, Rio de Janeiro, Brazil.
authors.forename: Guilherme R R M
authors.initials: GR
authors.lastname: Dos Santos
authors.affiliation: Laboratório de Parasitologia Molecular, Instituto de Biofísica Carlos Chagas Filho, CCS, UFRJ, Rio de Janeiro, Brazil.
authors.forename: Karina Luiza
authors.initials: KL
authors.lastname: Teixeira
authors.affiliation: Departamento de Microbiologia e Parasitologia, Da Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Alessandra Mattos
authors.initials: AM
authors.lastname: Saliba
authors.affiliation: Laboratório Cultura de Células, Departamento de Histologia e Embriologia, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Simone
authors.initials: S
authors.lastname: Nunes de Carvalho
authors.affiliation: Laboratório Cultura de Células, Departamento de Histologia e Embriologia, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Laís
authors.initials: L
authors.lastname: de Carvalho
authors.affiliation: Laboratório de Parasitologia Molecular, Instituto de Biofísica Carlos Chagas Filho, CCS, UFRJ, Rio de Janeiro, Brazil lopesu@biof.ufrj.br.
authors.forename: Ulisses G
authors.initials: UG
authors.lastname: Lopes
mesh_terms: D000818:Animals; D002460:Cell Line; D019281:Dimerization; D015536:Down-Regulation; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D007891:Leishmania / Q000235:genetics / Q000502:physiology*; D007896:Leishmaniasis / Q000378:metabolism / Q000469:parasitology / Q000473:pathology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D016328:NF-kappa B / Q000737:chemistry / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000235:genetics* / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D038362:Glycogen Synthase Kinase 3; D000071679:Glycogen Synthase Kinase 3 beta; D008070:Lipopolysaccharides; D016328:NF-kappa B; D052247:Nitric Oxide Synthase Type II; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D034741:RNA, Small Interfering; C496319:NOS2 protein, human; C000605506:GSK3B protein, human; C000605507:Gsk3b protein, mouse
keywords: Leishmania; PI3K/Akt; macrophage; nuclear factor kappa B