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FasL (CD95L/APO-1L) resistance of neurons mediated by phosphatidylinositol 3-kinase-Akt/protein kinase B-dependent expression of lifeguard/neuronal membrane protein 35.

ABSTRACT: The contribution of Fas (CD95/APO-1) to cell death mechanisms of differentiated neurons is controversially discussed. Rat cerebellar granule neurons (CGNs) express high levels of Fas in vitro but are resistant to FasL (CD95L/APO-1L/CD178)-induced apoptosis. We here show that this resistance was mediated by a phosphatidylinositol 3-kinase (PI 3-kinase)-Akt/protein kinase B (PKB)-dependent expression of lifeguard (LFG)/neuronal membrane protein 35. Reduction of endogenous LFG expression by antisense oligonucleotides or small interfering RNA lead to increased sensitivity of CGNs to FasL-induced cell death and caspase-8 cleavage. The inhibition of PI 3-kinase activity sensitized CGNs to FasL-induced caspase-8 and caspase-3 processing and caspase-dependent fodrin cleavage. Pharmacological inhibition of PI 3-kinase, overexpression of the inhibitory protein IkappaB, or cotransfection of an LFG reporter plasmid with dominant-negative Akt/PKB inhibited LFG reporter activity, whereas overexpression of constitutively active Akt/PKB increased LFG reporter activity. Overexpression of LFG in CGNs interfered with the sensitization to FasL by PI 3-kinase inhibitors. In contrast to CGNs, 12 glioma cell lines, which are sensitive to FasL, did not express LFG. Gene transfer of LFG into these FasL-susceptible glioma cells protected against FasL-induced apoptosis. These results demonstrate that LFG mediated the FasL resistance of CGNs and that, under certain circumstances, e.g., inhibition of the PI 3-kinase-Akt/PKB pathway, CGNs were sensitized to FasL.

SUBMITTER: Beier CP

PROVIDER: S-EPMC6725360 | biostudies-literature | 2005 Jul

REPOSITORIES: biostudies-literature

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FasL (CD95L/APO-1L) resistance of neurons mediated by phosphatidylinositol 3-kinase-Akt/protein kinase B-dependent expression of lifeguard/neuronal membrane protein 35.

Beier Christoph P CP Wischhusen Jörg J Gleichmann Marc M Gerhardt Ellen E Pekanovic Ana A Krueger Andreas A Taylor Verdon V Suter Ueli U Krammer Peter H PH Endres Matthias M Weller Michael M Schulz Jörg B JB

The Journal of neuroscience : the official journal of the Society for Neuroscience 20050701 29

The contribution of Fas (CD95/APO-1) to cell death mechanisms of differentiated neurons is controversially discussed. Rat cerebellar granule neurons (CGNs) express high levels of Fas in vitro but are resistant to FasL (CD95L/APO-1L/CD178)-induced apoptosis. We here show that this resistance was mediated by a phosphatidylinositol 3-kinase (PI 3-kinase)-Akt/protein kinase B (PKB)-dependent expression of lifeguard (LFG)/neuronal membrane protein 35. Reduction of endogenous LFG expression by antisen ...[more]

PMID: 16033886

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Project description:Preeclampsia is a hypertensive syndrome that manifests after 20 wk of gestation. Contemporary understanding of the maternal-fetal interface in preeclampsia suggests a major role for placental oxidative stress resulting from ischemia-reperfusion injury. We hypothesized that the pregnancy hormone relaxin would reduce cytotrophoblast apoptosis and necrosis (aponecrosis) and, hence, the export of placental debris into the maternal circulation. If so, then relaxin might be employed as a therapeutic intervention to diminish the activation of the maternal systemic inflammatory response central to the development of clinical disease. HTR-8/SVneo cells, a model for first trimester extravillous trophoblast, were subjected to serum deprivation and hypoxia or hypoxia-reoxygenation. The cells were treated with recombinant human relaxin or vehicle and apoptosis and/or necrosis evaluated by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL), CellEvent Caspase-3/7 and SYTOX AADvanced kit, and propidium iodide staining as determined by fluorescence microscopy or flow cytometry. To interrogate mechanisms of relaxin cytoprotection, HTR-8/SVneo cells were pretreated with pharmacological inhibitors of PI3-kinase LY294004, Akt/PKB MK-2206, or DMSO vehicle. HTR-8/SVneo cell identity was first confirmed by RT-PCR. The cells expressed placental alkaline phosphatase, aromatase, and human leukocyte antigen G. In addition, the cells expressed the relaxin receptor RXFP1 as well as H1 and H2 relaxins. Serum deprivation and hypoxia increased apoptotic cell death in HTR-8/SVneo cells, which was significantly ameliorated by concurrent treatment with relaxin. Serum deprivation and hypoxia-reoxygenation increased necrotic cell death in HTR-8/SVneo cells, which was also significantly rescued by concurrent treatment with relaxin. Pretreatment with LY294002 or MK-2206, to inhibit the phosphatidylinositol 3-kinase-Akt/protein kinase B cell survival pathway, significantly blunted the cytoprotective effect of relaxin. We demonstrated trophoblast cytoprotection by intervention with supraphysiological concentrations of relaxin, a process in part mediated through the PI3-kinase-Akt/PKB cell survival pathway. These results provide further rationale for clinical investigation of relaxin as a potential therapeutic in preeclampsia.

Dataset Information

FasL (CD95L/APO-1L) resistance of neurons mediated by phosphatidylinositol 3-kinase-Akt/protein kinase B-dependent expression of lifeguard/neuronal membrane protein 35.

Publications

FasL (CD95L/APO-1L) resistance of neurons mediated by phosphatidylinositol 3-kinase-Akt/protein kinase B-dependent expression of lifeguard/neuronal membrane protein 35.

Similar Datasets

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