Meza Lamas, Esteban; Bollain y Goytia, Juan José; Ramírez Sandoval, Roxana; Sánchez Rodríguez, Sergio; López Robles, Erendira; Avalos Díaz, Esperanza del Refugio; Herrera Esparza, Rafael
Resumen:
Fas ligand (L) is a membrane protein from the tumor necrosis factor
(TNF) family. It induces apoptosis upon contact with its Fas/CD95/APO1
receptor. Trimerization of FasL on the surface of effector cells is essential in the
binding of the Fas trimer of the target cells. The receptor then recruits an adaptor
and caspase-like proteins which lead apoptosis. This paper reports on the fate of
FasL in HEp-2 cells committed to apoptosis by induction with campthotecin.
Our main results demonstrated that in non-apoptotic cells, FasL aggregates in
the cytoplasm forming trimers of 120 kDa. Apoptosis increases the trimeric
FasL species, but also induces its dissociation into monomers of 35 kDa. In
conclusion, camptothecin appears to perturb the Fas and FasL segregation in the
cytoplasm by promoting the transit of FasL to the cell surface, thus fostering
a process of autocrine or paracrine apoptosis. FasL is trimerized prior to
Fas/FasL complex formation, and after apoptosis, FasL undergoes an intense
turnover.