Insight into the cellular effects of nitrated phospholipids: Evidence for pleiotropic mechanisms of action

Nitrated phospholipids have been recently identified in biological systems and showed to display anti-oxidant and anti-inflammatory potential in models of inflammation in vitro. Here, we have explored the effects of nitrated 1-palmitoyl-2-oleyl-phosphatidyl choline (NO₂-POPC) in cellular models. We have observed that NO₂-POPC, but not POPC, induces cellular changes consisting in cytoskeletal rearrangement and cell shrinking, and ultimately, loss of cell adhesion or impaired cell attachment. NO₂-POPC releases NO in vitro and induces accumulation of NO in cells. Nevertheless, the effects of NO₂-POPC are not superimposable with those of NO donors, which points to distinctive mechanisms of action. Notably, they show a stronger parallelism, although not complete overlap, with the effects of nitrated fatty acids. Interestingly, redistribution of vimentin by NO₂-POPC is attenuated in a C328S mutant, thus indicating that this residue may be a target for direct or indirect modification in NO₂-POPC-treated cells. Additionally, NO₂-POPC interacts with several typical lipoxidation targets in vitro, including vimentin and PPARγ constructs, likely through cysteine residues. Therefore, nitrated phospholipids emerge as potential novel electrophilic lipid mediators with selective actions.