Membrane vesicles shed by oligodendroglioma cells induce neuronal apoptosis.
In order to investigate the mechanism by which oligodendrogliomas cause neuronal damage, media conditioned by G26/24 oligodendroglioma cells, were fractionated into shed vesicles and vesicle-free supernatants, and added to primary cultures of rat fetal cortical neurons. After one night treatment with vesicles, a reproducible, dose-dependent, inhibitory effect on neurite outgrowth was already induced and, after 48-72 h of incubation, neuronal apoptosis was evident. Vesicle-free supernatants and vesicles shed by NIH-3T3 cells had no inhibitory effects on neurons. Western blot analyses showed that treated neurons expressed a decreased amount of neurofilament (NF), growth-associated protein (GAP-43) and microtubule-associated protein (MAP-2). Moreover procaspase-3 and -8 were activated while Bcl-2 expression was reduced. Vesicles were found positive for the proapoptotic molecule, Fas-ligand (Fas-L), and for the B isoform of Nogo protein, a myelin component with inhibitory effects on neurons. Nogo B involvement in the vesicle effects was analyzed both by testing the neutralizing capability of anti-Nogo antibodies and by removing the Nogo receptor from neurons by phospholipase C digestion. These treatments did not revert the vesicle effects. To test the role of Fas-L, vesicles were treated with functional anti-Fas-L monoclonals. Vesicle inhibitory and proapoptotic effects were reduced. Vesicles shed by ovarian carcinoma cells (OvCa), which are known to vehicle biologically active Fas-L, had similar effects on neurons to those of oligodendroglioma vesicles, and their inhibitory effects were also reduced by anti Fas-L antibodies. We therefore conclude that vesicles shed by G26/24 cells induce neuronal apoptosis at least partially by a Fas-L mediated mechanism.
D'Agostino
Stefania
S
Dipartimento di Biologia Cellulare e dello Sviluppo, Università di Palermo, I-90128 Palermo, Italy.
Salamone
Monica
M
Di Liegro
Italia
I
Vittorelli
M Letizia
ML
D000818:Animals; D017209:Apoptosis; D002450:Cell Communication; D002540:Cerebral Cortex / Q000473:pathology; D022162:Cytoplasmic Vesicles / Q000737:chemistry / Q000378:metabolism*; D053222:Fas Ligand Protein / Q000032:analysis / Q000378:metabolism; D051379:Mice; D009186:Myelin Sheath / Q000378:metabolism; D041681:NIH 3T3 Cells; D009474:Neurons / Q000378:metabolism / Q000473:pathology*; D009837:Oligodendroglioma / Q000378:metabolism* / Q000648:ultrastructure; D051381:Rats; D017207:Rats, Sprague-Dawley
D053222:Fas Ligand Protein