Thimerosal induces apoptosis and G2/M phase arrest in human leukemia cells.
ABSTRACT Thimerosal is an organomercury compound with sulfhydryl-reactive properties. The ability of thimerosal to act as a sulfhydryl group is related to the presence of mercury. Due to its antibacterial effect, thimerosal is widely used as preservatives and has been reported to cause chemically mediated side effects. In the present study, we showed that the molecular mechanism of thimerosal induced apoptosis in U937 cells. Thimerosal was shown to be responsible for the inhibition of U937 cells growth by inducing apoptosis. Treatment with 2.5-5 microM thimerosal but not thiosalicylic acid (structural analog of thimerosal devoid of mercury) for 12 h produced apoptosis, G(2)/M phase arrest, and DNA fragmentation in a dose-dependent manner. Treatment with caspase inhibitor significantly reduced thimerosal-induced caspase 3 activation. In addition, thimerosal-induced apoptosis was attenuated by antioxidant Mn (III) meso-tetrakis (4-benzoic acid) porphyrin (Mn-TBAP). These data indicate that the cytotoxic effect of thimerosal on U937 cells is attributable to the induced apoptosis and that thimerosal-induced apoptosis is mediated by reactive oxygen species generation and caspase-3 activation.
Article: Capturing proteins that bind polyunsaturated fatty acids: demonstration using arachidonic acid and eicosanoids.[show abstract] [hide abstract]
ABSTRACT: Polyunsaturated fatty acids (PUFA) and their biological derivatives, including the eicosanoids, have numerous roles in physiology and pathology. Although some eicosanoids are known to act through receptors, the molecular actions of many PUFA remain obscure. As the three-dimensional structure of eicosanoids allows them to specifically bind and activate their receptors, we hypothesized that the same structure would allow other proteins to associate with PUFA and eicosanoids. Here, we demonstrate that biotinylation of arachidonic acid and its oxygenated derivatives 5-hydroxyeicosatetraenoic acid (5-HETE) and leukotriene (LT) B(4) can be used to pull down associated proteins. Separation of proteins by two-dimensional gel electrophoresis indicated that a large number of proteins bound each lipid and that proteins could distinguish between two enantiomers of 5-HETE. Individual proteins, identified by matrix assisted laser desorption/ionization-time of flight mass spectrometry, included proteins that are known to bind lipids, including albumin and phosphatidylethanolamine-binding protein, as well as several novel proteins. These include cytoskeletal proteins, such as actin, moesin, stathmin and coactosin-like protein, and G protein signaling proteins, such as Rho GDP dissociation inhibitor 1 and nucleoside diphosphate kinase B. This method, then, represents a relatively simple and straightforward way to screen for proteins that directly associate with, and are potentially modulated by, PUFA and their derivatives.Lipids 03/2008; 43(2):161-9. · 2.13 Impact Factor