Activation of the cell surface CD95 receptor triggers a cascade of signaling events, including assembly of the death-inducing signaling complex (DISC), that culminate in cellular apoptosis. In this study, we demonstrate a general requirement of receptor internalization for CD95 ligand-mediated DISC amplification, caspase activation and apoptosis in type I cells. Recruitment of DISC components t...

CD95 is a multifunctional receptor that induces cell death or proliferation depending on the signal, cell type, and cellular context. Here, we describe a thus far unknown function of CD95 as a silencer of T cell activation. Naive human T cells triggered by antigen-presenting cells expressing a membrane-bound form of CD95 ligand (CD95L) or stimulated by anti-CD3 and -CD28 antibodies in the prese...

Two distinct forms of short-term cytolysis have been described for CD8+ CTLs, the perforin/granzyme- and Fas ligand/Fas (CD95 ligand (CD95L)/CD95)-mediated pathways. However, the difference in signal transduction events leading to these cytolytic mechanisms remains unclear. We used wortmannin, an irreversible antagonist of phosphatidylinositol 3-kinase (PI3-K) activity, to investigate the role ...

Apoptosis signaling through CD95 (Fas/APO-1) involves aggregation and clustering of the receptor followed by its actin-dependent internalization. Internalization is required for efficient formation of the death-inducing signaling complex (DISC) with maximal recruitment of FADD, caspase-8/10 and c-FLIP occurring when the receptor has reached an endosomal compartment. The first detectable event d...

We have recently reported that activation of protein kinase C (PKC) plays a negative role in CD95-mediated apoptosis in human T cell lines. Here we present data indicating that although the PKC-induced mitogen-activated protein kinase pathway could be partially implicated in the abrogation of CD95-mediated apoptosis by phorbol esters in Jurkat T cells, the major inhibitory effect is exerted thr...

CD95 (Fas/APO-1)-mediated apoptosis plays an important role in immunological regulation and is related to the pathogenesis of autoimmune diseases. Immunoexpression of CD95 has been reported to frequently occur in low grade non-Hodgkin lymphomas, especially of post-germinal center histogenesis, among which those originating in mucosa-associated lymphoid tissue (MALT lymphomas). However, there is...

The mechanisms of As(2)O(3)-induced apoptosis are very complex. In the present study, we investigated the molecular mechanism of As(2)O(3) in vitro at low concentration (0.25-2.0 micro M) on three human leukemia/lymphoma cell lines: HL-60, RL and K562. As(2)O(3) inhibited the growth of these cell lines significantly. During As(2)O(3) treatment, two forms of cell death, apoptosis in HL-60 and RL...

Acid sphingomyelinase (A-SMase) plays an important role in the initiation of CD95 signaling by forming ceramide-enriched membrane domains that enable clustering and activation of the death receptors. In TNF-R1 and TRAIL-R1/R2 signaling, A-SMase also contributes to the lysosomal apoptosis pathway triggered by receptor internalization. Here, we investigated the molecular mechanism of CD95-mediate...

The elimination of activated T cells is important to maintain homeostasis and avoid immunopathology. CD95 (Fas/APO-1) has been identified as a death mediator for activated T cells in vitro but the function of CD95 in death of mature T cells in vivo is still controversial. Here we show that triggering of the costimulatory TNF receptor family member CD27 sensitized T cells for CD95-induced apopto...

CD95 (APO-1/Fas) is a death receptor used by immune cells to kill cancer cells through induction of apoptosis. However, the elimination of CD95 or its ligand, CD95L, from cancer cells results in death induced by CD95R/L elimination (DICE), a type of cell death that resembles a necrotic form of mitotic catastrophe suggesting that CD95 protects cancer cells from cell death. We now report that sti...