title: Nitric oxide-induced cell death of cerebrocortical murine astrocytes is mediated through p53- and Bax-dependent pathways.
abstract: We have investigated the mechanism by which nitric oxide (NO) induces the death of mouse astrocytes. We show that NO (from donor diethylenetriamine-NO adduct) induces death with several features of apoptosis, including chromatin condensation, phosphatidylserine exposure on the outer leaflet of the plasma membrane, Bax translocation to the mitochondria and cytochrome c release, but no caspase activation or nuclear fragmentation is observed. Nitric oxide also elevates p53 expression, causing a concomitant increase in p53 serine 18 phosphorylation and p53 translocation from the cytoplasm to the nucleus. Activation of Bax and p53 is important for NO-induced apoptosis-like cell death because Bax- or p53-deficient astrocytes are much more resistant than wild-type cells to the same NO treatment. We further demonstrate that LY294002-sensitive kinases are responsible for controlling serine 18 phosphorylation of p53, thereby regulating the pro-apoptotic activity of p53 in astrocytes. While apoptosis is suppressed in the presence of LY294002, however, death by necrosis is increased, suggesting that LY294002-sensitive kinases additionally suppress a latent necrotic response to NO. We conclude that NO-induced death in astrocytes is mediated by p53- and Bax-dependent mechanisms, although full manifestation of apoptosis is aborted by concomitant inhibition of caspase activation. More generally, our data suggest that apoptotic mediators should be evaluated as the cause of cell death even in cases where a full apoptotic phenotype is lacking.
authors.affiliation: Department of Biochemistry, University of Cambridge, Cambridge, UK.
authors.forename: Hong Wa
authors.initials: HW
authors.lastname: Yung
authors.forename: Anna K
authors.initials: AK
authors.lastname: Bal-Price
authors.forename: Guy C
authors.initials: GC
authors.lastname: Brown
authors.forename: Aviva M
authors.initials: AM
authors.lastname: Tolkovsky
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D020169:Caspases / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051379:Mice; D018345:Mice, Knockout; D009569:Nitric Oxide / Q000494:pharmacology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D051028:bcl-2-Associated X Protein
chemical_list: C494827:Bax protein, mouse; D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein; D009569:Nitric Oxide; D020169:Caspases