CD95 (APO-1/Fas) linkage to the actin cytoskeleton through ezrin in human T lymphocytes: a novel regulatory mechanism of the CD95 apoptotic pathway.
CD95 (APO-1/Fas) is a member of the tumor necrosis factor receptor family, which can trigger apoptosis in a variety of cell types. However, little is known of the mechanisms underlying cell susceptibility to CD95-mediated apoptosis. Here we show that human T cells that are susceptible to CD95-mediated apoptosis, exhibit a constitutive polarized morphology, and that CD95 colocalizes with ezrin at the site of cellular polarization. In fact, CD95 co-immunoprecipitates with ezrin exclusively in lymphoblastoid CD4(+) T cells and primary long-term activated T lymphocytes, which are prone to CD95-mediated apoptosis, but not in short-term activated T lymphocytes, which are refractory to the same stimuli, even expressing equal levels of CD95 on the cell membrane. Pre-treatment with ezrin antisense oligonucleotides specifically protected from the CD95-mediated apoptosis. Moreover, we show that the actin cytoskeleton integrity is essential for this function. These findings strongly suggest that the CD95 cell membrane polarization, through an ezrin-mediated association with the actin cytoskeleton, is a key intracellular mechanism in rendering human T lymphocytes susceptible to the CD95-mediated apoptosis.
Parlato
S
S
Laboratories of Virology, Istituto Superiore di Sanità Viale Regina Elena 299, 00161 Rome, Italy.
Giammarioli
A M
AM
Logozzi
M
M
Lozupone
F
F
Matarrese
P
P
Luciani
F
F
Falchi
M
M
Malorni
W
W
Fais
S
S
D008841:Actin Cytoskeleton / Q000378:metabolism*; D017209:Apoptosis / Q000502:physiology*; D001798:Blood Proteins / Q000378:metabolism; D015153:Blotting, Western; D016764:Cell Polarity; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000378:metabolism; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006801:Humans; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000378:metabolism; D008840:Microfilament Proteins / Q000378:metabolism; D008855:Microscopy, Electron, Scanning; D018715:Microscopy, Video; D016376:Oligonucleotides, Antisense; D010750:Phosphoproteins / Q000378:metabolism*; D011485:Protein Binding; D013601:T-Lymphocytes / Q000166:cytology* / Q000378:metabolism; D019014:fas Receptor / Q000378:metabolism* / Q000502:physiology; D000099149:Ezrin
D001798:Blood Proteins; D003598:Cytoskeletal Proteins; D008565:Membrane Proteins; D008840:Microfilament Proteins; D016376:Oligonucleotides, Antisense; D010750:Phosphoproteins; D019014:fas Receptor; D000099149:Ezrin; C071058:moesin; C071776:radixin