Nitrosative stress induces phosphatidylserine externalization: signaling role in phagocytes.
Tyurina-YY; Potapovich-A; Tyurin-VA; Cai-P; Konduru-NV; Bayir-H; Fadeel-B; Stoyanovsky-D; Shvedova-AA; Kagan-VE
Toxicologist 2006 Mar; 90(1):237
Aminophospholipid translocase (APT) is responsible for asymmetric distribution of phosphatidylserine (PS) across plasma membrane. The enzyme contains catalytically competent cysteines whose oxidation/alkylation results in loss of its activity. Because protein S-nitrosylation can act as a regulatory redox-sensitive mechanism, we hypothesized that nitrosative stress enhances PS externalization in cells by inhibiting APT activity. This pathway should be particularly important during inflammation whereby oxidative/nitrosative burst generated by macrophages may cause direct nitrosylation or trans-nitrosylation of APT in target cells. To experimentally address this hypothesis we utilized HL-60 cells that express high activity of APT. S-nitroso-L-cysteine-ethyl ester (SNCEE) and S-nitroso-glutathione (GSNO) were used as prototypical cell-permeable and cell impermeable trans-nitrosylating reagents. HL-60 cells externalized PS in response to SNCEE or GSNO treatment (50-100 uM, 0.5h at 37 C) as evidenced by annexin V binding assay and fluorescence microscopy. No cytotoxic effects were induced by either of the trans-nitrosating agents. RAW 264.7 macrophages elicited enhanced phagocytizing activity towards "nitrosylated" HL-60 cells. We speculate that our proposed mechanism of macrophage induced nitrosative stress contributes to effective clearance of apoptotic cells and regulates switching of acute inflammatory response to anti-inflammatory phase as has been observed in the lung and in the brain in in vivo experiments with inhalation of single-walled carbon nanotubes and cortical trauma, respectively.
Phagocytes; Enzymes; Microscopy; Lung; In-vivo-studies; Laboratory-animals; Animals; Animal-studies; Nanotechnology
Disease and Injury: Asthma and Chronic Obstructive Pulmonary Disease
The Toxicologist. Society of Toxicology 45th Annual Meeting and ToxExpo, March 5-9, 2006, San Diego, California