Caspase-10 is recruited to and activated at the native TRAIL and CD95 death-inducing signalling complexes in a FADD-dependent manner but can not functionally substitute caspase-8

Abstract

The involvement of the death adaptor protein FADD and the apoptosis-initiating caspase-8 in CD95 and TRAIL death signalling has recently been demonstrated by the analysis of the native death-inducing signalling complex (DISC) that forms upon ligand-induced receptor cross-linking. However, the role of caspase-10, the other death-effector-domain-containing caspase besides caspase-8, in death receptor signalling has been controversial. Here we show that caspase-10 is recruited not only to the native TRAIL DISC but also to the native CD95 DISC, and that FADD is necessary for its recruitment to and activation at these two protein complexes. With respect to the function of caspase-10, we show that it is not required for apoptosis induction. In addition, caspase-10 can not substitute for caspase-8, as the defect in apoptosis induction observed in caspase-8-deficient cells could not be rescued by overexpression of caspase-10. Finally, we demonstrate that caspase-10 is cleaved during CD95-induced apoptosis of activated T cells. These results show that caspase-10 activation occurs in primary cells, but that its function differs from that of caspase-8.

Apoptosis mediated by lentiviral TRAIL transfer involves transduction-dependent and -independent effects

“…P693 cells were injected subcutaneously into nude mice to generate tumor xenografts. After 2 days, tumor nodules of approximately 50 mm 3 were detectable consisting of about 1-2 Â 10 7 cells (data not shown). Ten mice per group were injected with vehicle (PBS/BSA), LV-GFP or LV-TRAIL (1.5 Â 10 7 IU in 50 ml PBS/BSA) directly into the tumor, resulting in a MOI of approximately 1.…”

“…FLAG-TRAIL and TRAIL-R2-Fc protein have been described. 3,27 All other chemicals were from Sigma or Carl Roth (Karlsruhe, Germany).…”

“…2 Upon engagement by the ligand, the TRAIL death receptors oligomerize and form a death inducing signaling complex (DISC) by recruiting FADD, caspase-8 and -10, and FLIP. 3 At the DISC, caspase-8 is autocatalytically activated. Further caspases are either directly cleaved and activated by caspase-8 or by Bidmediated engagement of the mitochondrial apoptosis pathway.…”

Modulation of tumor necrosis factor related apoptosis-inducing ligand (TRAIL) receptors in a human osteoclast model in vitro

“…While it is known that caspase-8 and -10 are cleaved in the same manner, the importance of caspase-10 to the DISC is still the subject of controversy (Kischkel et al, 2001). One study has shown that its expression can restore apoptosis sensitivity to caspase-8-deficient cells, while another has shown the opposite (Sprick et al, 2002). It is known, though, that through the DISC, caspase-8 is autocatalytically cleaved, generating a large and a small subunit.…”

“…Of these, some have TRAIL has also been combined with proteasome inhibitors to induce apoptosis (Sprick et al, 2002). It is believed that their combinatorial effect is achieved through TRAIL expression on NK cells, though this does not completely explain the increased sensitivity (Hallett et al, 2008).…”