Programmed cell clearance: s-nitrosylation of aminophospholipid translocase regulates macrophage engulfment of target cells.
Tyurina-YY; Tyurin-VA; Konduru-NV; Basova-L; Cai-P; Potapovich-AI; Bayir-H; Stoyanovsky-D; Shvedova-AA; Quinn-P; Xue-D; Fadeel-B; Kagan-VE
Sixth Human Frontier Science Program Awardees Annual Meeting, July 3-5, 2006, Paris, France. Strasbourg, Cedex, France: Human Frontier Science Program, 2006 Jul; :119
Aminophospholipid translocase (APT) is responsible for the asymmetric distribution of phosphatidylserine (PS) across the plasma membrane, thus preventing PS externalization. The enzyme can be S-nitrosylated resulting in the loss of its activity. We hypothesized that nitrosative stress - acting through APT S-nitrosylation - enhances PS externalization in cells by inhibiting APT activity. This pathway should be particularly important during inflammation whereby the 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 H-60 cells that express high APT activity. 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 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 phagocytosis towards "nitrosylated" HL-60 cells. Assessments of APT activity confirmed that S-nitrosylation is associated with an altered activity of the enzyme. We thus speculate that macrophage-induced nitrosative stress contributes to effective clearance of apoptotic cells and the regulation of inflammatory responses.
Amino-compounds; Enzymes; Cell-cultures; Cell-wall-permeability; Microscopy; Cytotoxins; Cytotoxicity; Cytotoxic-effects; Phagocytes
Abstract; Conference/Symposia Proceedings
Disease and Injury: Asthma and Chronic Obstructive Pulmonary Disease
Sixth Human Frontier Science Program Awardees Annual Meeting, July 3-5, 2006, Paris, France