Tumour Necrosis Factor-Related Apoptosis-Inducing Ligand (TRAIL), a proapoptotic/proinflammatory cytokine of the TNF superfamily abundantly expressed by injuried neurons, has been proven to be a potent mediator of neurotoxicity related to various noxious stimuli, eventually setting into motion the apoptotic machinery in neuronal cells. Evidence shows that neutralization of the TRAIL death pathway in human neuronal cells is eventually associated with partial abrogation amyloid beta-related neurotoxicity. Similarly to TRAIL, the cytokine Glucocorticoid-induced TNF receptor ligand (GITRL) is able to transduce apoptotic signals. In spite of an array of reports suggesting redundant, additive effects between TRAIL and an array of cytokines, scanty data are, so far, available about a TRAIL/GITRL crosstalk. Here, we investigated possible interactions between TRAIL and the GITRL system in an in vitro model of neurodegeneration, using the human cortical neuronal cell line HCN-2. To accomplish this task, HCN-2 cells were treated with TRAIL in different experimental conditions. Real-time PCR analysis of cell lysates showed that HCN-2 cells did not express GITRL mRNA constitutively, whereas the latter was potently induced by treatment of cultured cells with TRAIL. In addition, HCN-2 cells did not express the GITRL receptor GITR mRNA, neither in control cultures, nor after treatment with TRAIL. Real-time PCR data were corroborated by western blot analysis, showing similar pattern of the correspondent proteins at the level of protein expression. The MTT cell viability assay showed that TRAIL, when combined with GITRL, was able to exert additive toxic, lethal effects on HCN-2 cells. A counterproof to the latter data was provided in experiments performed using a GITRL neutralizing antibody, resulting in significantly attenuated TRAIL-mediated neurotoxicity in HCN-2 cells. Results suggest that TRAIL/GITRL redundancy during neurodegenerative processes implies reciprocal potentiation of detrimental effects of both cytokines on neurons, eventually leading to larger cell damage and death. Finally, characterization of novel molecular targets within the TRAIL/GITRL interplay may represent a platform for innovative treatment of neurodegenerative diseases.
Tumor necrosis factor-related apoptosis inducing ligand/glucocorticoid-induced TNF receptor ligand redundancy in neurodegenerative processes
P GUARNERI;
2014
Abstract
Tumour Necrosis Factor-Related Apoptosis-Inducing Ligand (TRAIL), a proapoptotic/proinflammatory cytokine of the TNF superfamily abundantly expressed by injuried neurons, has been proven to be a potent mediator of neurotoxicity related to various noxious stimuli, eventually setting into motion the apoptotic machinery in neuronal cells. Evidence shows that neutralization of the TRAIL death pathway in human neuronal cells is eventually associated with partial abrogation amyloid beta-related neurotoxicity. Similarly to TRAIL, the cytokine Glucocorticoid-induced TNF receptor ligand (GITRL) is able to transduce apoptotic signals. In spite of an array of reports suggesting redundant, additive effects between TRAIL and an array of cytokines, scanty data are, so far, available about a TRAIL/GITRL crosstalk. Here, we investigated possible interactions between TRAIL and the GITRL system in an in vitro model of neurodegeneration, using the human cortical neuronal cell line HCN-2. To accomplish this task, HCN-2 cells were treated with TRAIL in different experimental conditions. Real-time PCR analysis of cell lysates showed that HCN-2 cells did not express GITRL mRNA constitutively, whereas the latter was potently induced by treatment of cultured cells with TRAIL. In addition, HCN-2 cells did not express the GITRL receptor GITR mRNA, neither in control cultures, nor after treatment with TRAIL. Real-time PCR data were corroborated by western blot analysis, showing similar pattern of the correspondent proteins at the level of protein expression. The MTT cell viability assay showed that TRAIL, when combined with GITRL, was able to exert additive toxic, lethal effects on HCN-2 cells. A counterproof to the latter data was provided in experiments performed using a GITRL neutralizing antibody, resulting in significantly attenuated TRAIL-mediated neurotoxicity in HCN-2 cells. Results suggest that TRAIL/GITRL redundancy during neurodegenerative processes implies reciprocal potentiation of detrimental effects of both cytokines on neurons, eventually leading to larger cell damage and death. Finally, characterization of novel molecular targets within the TRAIL/GITRL interplay may represent a platform for innovative treatment of neurodegenerative diseases.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
