cytochrome-c-t and Lymphoproliferative-Disorders

Polyamines are involved in the regulation of cellular growth and survival by interacting with processes like translation, transcription or ion transport. The aim of our study was to analyze whether polyamines induce apoptosis in hematopoetic cells and to investigate the molecular mechanisms involved. We found an induction of apoptosis by spermine in primary human cells and malignant tumor cell lines. Spermine-treatment resulted in an intracellular increase of reactive oxygen species. Apoptosis was mediated by a collapse of mitochondrial membrane potential, a decrease in Bcl-2 expression and a release of apoptosis mediating molecules from mitochondrial intermembrane space (cytochrome C, Smac/DIABLO). Spermine-mediated apoptosis was caspase-dependent. To test whether spermine mediates apoptosis through metabolites we analyzed the effects of several molecules that interfere with its catabolism. Aminoguanidine, an inhibitor of serum amine oxidase, aldehyde-dehydrogenase, which degrades aldehydes to less reactive molecules or N-acetyl-cysteine, a glutathion precursor, significantly inhibited spermine-mediated apoptosis. From these data we conclude that spermine-derived aldehydes and intracellular accumulation of reactive oxygen species result in mitochondria mediated apoptosis.

Topics: Acetylcysteine; Amine Oxidase (Copper-Containing); Amino Acid Chloromethyl Ketones; Apoptosis; Apoptosis Regulatory Proteins; Caspase Inhibitors; Cell Line, Tumor; Cytochromes c; Dexamethasone; fas Receptor; Humans; Hydrogen Peroxide; Intracellular Signaling Peptides and Proteins; Leukocytes, Mononuclear; Lymphoproliferative Disorders; Membrane Potentials; Mitochondria; Mitochondrial Proteins; Polyamines; Proto-Oncogene Proteins c-bcl-2; Putrescine; Reactive Oxygen Species; Spermidine; Spermine

The signaling events leading to apoptosis can be divided into two major pathways, involving either mitochondria (intrinsic) or death receptors (extrinsic). In a recent study, we have shown the involvement of the mitochondria-dependent apoptotic pathway in heat-induced male germ cell apoptosis in the rat. In additional studies, using the gld (generalized lymphoproliferation disease) and lprcg (lymphoproliferation complementing gld) mice, which harbor loss-of-function mutations in Fas L and Fas, respectively, we have shown that heat-induced germ cell apoptosis is not blocked, thus providing evidence that the Fas signaling system is not required for heat-induced germ cell apoptosis in the testis. In the present study, we have found that the initiation of apoptosis in wild-type mice was preceded by a redistribution of Bax from a cytoplasmic to paranuclear localization in heat-susceptible germ cells. The relocation of Bax is accompanied by sequestration of ultracondensed mitochondria into paranuclear areas of apoptotic germ cells, cytosolic translocation of mitochondrial cytochrome c and DIABLO, and is associated with activation of the initiator caspase 9 and the executioner caspase 3. Similar events were also noted in both gld and lprcg mice. Taken together, these results indicate that the mitochondria-dependent pathway is the key apoptotic pathway for heat-induced male germ cell death in mice.

Topics: Animals; Apoptosis; Apoptosis Regulatory Proteins; bcl-2-Associated X Protein; Biological Transport; Carrier Proteins; Caspase 3; Caspase 9; Caspases; Cell Nucleus; Cytochromes c; Cytoplasm; Cytosol; Enzyme Activation; Fas Ligand Protein; fas Receptor; Hot Temperature; Lymphoproliferative Disorders; Male; Membrane Glycoproteins; Mice; Mice, Inbred MRL lpr; Mice, Inbred Strains; Mitochondria; Mitochondrial Proteins; Mutation; Proto-Oncogene Proteins c-bcl-2; Spermatozoa; Tissue Distribution