Creating conditions similar to those that occur during exposure of cells to microgravity induces apoptosis in human lymphocytes by 5-lipoxygenase-mediated mitochondrial uncoupling and cytochrome c release.
Creating conditions similar to those that occur during exposure of cells to microgravity induced a sixfold increase of apoptotic bodies and DNA fragments in human lymphocytes, paralleled by an early (within 2 h) fourfold increase in 5-lipoxygenase (5-LOX) activity and a fivefold decrease in mitochondrial membrane potential and increase in cytochrome c release (within 4 and 8 h, respectively). Similar membrane potential and cytochrome c release were observed in isolated mitochondria treated with physiological amounts of 5-LOX and were enhanced by creating conditions similar to those that occur during exposure of cells to microgravity. 5-LOX inhibitors, 5,8,11,14-eicosatetraynoic acid and caffeic acid, completely prevented apoptosis, whereas the phospholipase A(2) inhibitor methyl-arachidonoyl fluorophosphonate and the 5-LOX activating protein inhibitor MK886 reduced it to 65-70%. The intracellular calcium chelator EGTA-acetoxymethylester reduced 5-LOX activity and apoptosis to 30-40% of controls, whereas the p38 mitogen-activated protein kinase inhibitor SB203580 was ineffective. The caspase-3 and caspase-9 inhibitors Z-Asp(OCH(3))-Glu(OCH(3))-Val-Asp(OCH(3))-fluoromethylketone (FMK) and Z-Leu-Glu(OCH(3))-His-Asp(OCH(3))-FMK reduced apoptotic bodies to 25-30% of the control cells. Finally, creating conditions similar to those that occur during exposure of cells to microgravity did not induce apoptosis in human lymphoma U937 cells, which did not express an active 5-LOX.
Maccarrone
Mauro
M
Department of Biomedical Sciences, University of Teramo, Italy. Maccarrone@vet.unite.it
Battista
Natalia
N
Meloni
Mariantonia
M
Bari
Monica
M
Galleri
Grazia
G
Pippia
Proto
P
Cogoli
Augusto
A
Finazzi-Agrò
Alessandro
A
D000328:Adult; D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism*; D016718:Arachidonic Acid / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D053148:Caspase 3; D053453:Caspase 9; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003574:Cytochrome c Group / Q000378:metabolism*; D004533:Egtazic Acid / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D016859:Lipoxygenase Inhibitors; D008214:Lymphocytes / Q000473:pathology*; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D010741:Phospholipases A / Q000037:antagonists & inhibitors; D020298:U937 Cells / Q000187:drug effects / Q000378:metabolism; D018474:Weightlessness Simulation; D048051:p38 Mitogen-Activated Protein Kinases
D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D003574:Cytochrome c Group; D004791:Enzyme Inhibitors; D016859:Lipoxygenase Inhibitors; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D016718:Arachidonic Acid; D004533:Egtazic Acid; D001094:Arachidonate 5-Lipoxygenase; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D010741:Phospholipases A; C505407:CASP3 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053453:Caspase 9; D002118:Calcium