title: PI3K-Akt/PKB signaling pathway in neutrophils and mononuclear cells exposed to N-nitrosodimethylamine.
abstract: Neutrophils (PMN) play diverse regulatory and effector functions in the immune system through the release of reactive nitrogen species, including nitric oxide (NO). The enzyme responsible for NO synthesis in PMN is inducible nitric oxide synthase (iNOS) that is regulated by various signaling pathways, e.g. PI3K-Akt/PKB, and transcription factors. N-Nitrosodimethylamine (NDMA), a xenobiotic widespread in the human environment, affects immune cells. The study objective here was to examine the role of the PI3K-Akt/PKB pathway in induction of NO synthesis (with involvement of iNOS) in human PMN, as well as in autologous mononuclear cells (PBMC), exposed to NDMA. Isolated cells were incubated for 2 h with a sub-lethal dose of NDMA and then the expression of several select proteins in the cell cytoplasmic and nuclear fractions were determined by Western blot analyses. The results indicated that NDMA enhanced expression of iNOS, phospho-PI3K, and phospho-IκBα in the cytoplasmic fraction of the PMN and PBMC. The nuclear fraction of these cells also had a higher NF-κB expression. Moreover, in PMN, NDMA caused an increased expression of phospho-Akt (T308), phospho-Akt (S473), and phospho-IKKαβ in the cytoplasm, and c-Jun and FosB in the nuclear fraction. Blocking of PI3K caused a decrease in expression of all these proteins in NDMA-exposed PMN. However, inhibition of PI3K led to a drop in expression of iNOS, phospho-PI3K, and phospho-IκBα in the cytoplasm, and in NF-κB in the nuclear fraction, of PBMC. The results of these studies indicated to us that NDMA activates the PI3K-Akt/PKB pathway in human PMN and that this, in turn, contributes to the activation of transcription factors NF-κB, c-Jun, and FosB involved in NO production (through modulation of iNOS expression).
authors: Department of Immunology .
authors: Wioletta
authors: W
authors: Ratajczak-Wrona
authors: Ewa
authors: E
authors: Jablonska
authors: Marzena
authors: M
authors: Garley
authors: Jakub
authors: J
authors: Jablonski
authors: Piotr
authors: P
authors: Radziwon
authors: Agnieszka
authors: A
authors: Iwaniuk
authors: Kamil
authors: K
authors: Grubczak
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D002478:Cells, Cultured; D004128:Dimethylnitrosamine / Q000494:pharmacology*; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000187:drug effects* / Q000276:immunology; D016328:NF-kappa B / Q000378:metabolism; D009504:Neutrophils / Q000187:drug effects* / Q000276:immunology; D009569:Nitric Oxide / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D051058:Oncogene Protein v-akt / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D015533:Transcriptional Activation / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects; D000077191:Wortmannin; D015262:Xenobiotics / Q000494:pharmacology*
chemical_list: D000730:Androstadienes; D004128:Dimethylnitrosamine; D016328:NF-kappa B; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; D051058:Oncogene Protein v-akt; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D000077191:Wortmannin; D015262:Xenobiotics
keywords: AP-1; NF-κB; PI3K-Akt/PKB; inducible nitric oxide synthase; mononuclear cells; neutrophils; nitric oxide