Activation of Initiator Caspases through a Stable Dimeric Intermediate

Chen, Min; Orozco, Aaron; Spencer, David M.; Wang, Jin

doi:10.1074/jbc.m210356200

Cited by 61 publications

(49 citation statements)

References 39 publications

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“…These procaspase-8/procaspase-10 heterodimers have been reported to be catalytically inactive. 32 Consequently, procaspase-10 would be largely processed by neighboring procaspase-8 homodimers, but not by autoprocessing. This difference in the processing mechanisms of procaspase-8 and procaspase-10 in the chain, for example, processing in homodimer versus heterodimer, respectively, might result in the different rates of generation of the intermediate cleavage products and prodomains.…”

Section: Resultsmentioning

confidence: 99%

Molecular architecture of the DED chains at the DISC: regulation of procaspase-8 activation by short DED proteins c-FLIP and procaspase-8 prodomain

et al. 2015

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The CD95/Fas/APO-1 death-inducing signaling complex (DISC), comprising CD95, FADD, procaspase-8, procaspase-10, and c-FLIP, has a key role in apoptosis induction. Recently, it was demonstrated that procaspase-8 activation is driven by death effector domain (DED) chains at the DISC. Here, we analyzed the molecular architecture of the chains and the role of the short DED proteins in regulating procaspase-8 activation in the chain model. We demonstrate that the DED chains are largely composed of procaspase-8 cleavage products and, in particular, of its prodomain. The DED chain also comprises c-FLIP and procaspase-10 that are present in 10 times lower amounts compared with procaspase-8. We show that short c-FLIP isoforms can inhibit CD95-induced cell death upon overexpression, likely by forming inactive heterodimers with procaspase-8. Furthermore, we have addressed mechanisms of the termination of chain elongation using experimental and mathematical modeling approaches. We show that neither c-FLIP nor procaspase-8 prodomain terminates the DED chain, but rather the dissociation/association rates of procaspase-8 define the stability of the chain and thereby its length. In addition, we provide evidence that procaspase-8 prodomain generated at the DISC constitutes a negative feedback loop in procaspase-8 activation. Overall, these findings provide new insights into caspase-8 activation in DED chains and apoptosis initiation.

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Section: Resultsmentioning

confidence: 99%

Molecular architecture of the DED chains at the DISC: regulation of procaspase-8 activation by short DED proteins c-FLIP and procaspase-8 prodomain

et al. 2015

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“…It should be noted that, in the absence of death ligand, exogenous expression of caspase-8 induces its dimerization through a process termed 'induced-proximity'. 7,10,13 Importantly, caspase-8 was not highly overexpressed, and most transfected cells displayed a B2-fold increase in the total amount of caspase-8 (Supplementary Figure S2a). It is likely that dimerization occurred between exogenously expressed inactive caspase-8 mutants (DM1-GFP and C360S-GFP) and endogenous caspase-8.…”

Section: Resultsmentioning

confidence: 99%

“…7,8 The dimerization of two caspase-8 monomers (p55/p55) results in the conformational change, which exposes the active site of the caspase through the so-called mechanism of 'induced proximity'. 7,[9][10][11] Dimerization has been demonstrated to be sufficient for activation of caspase-8, but it has been proposed that full activity requires selfcleavage. [11][12][13][14] Caspase-8 initially cleaves itself between the p18 and p10 domains forming a heterodimer within a heterotetrameric complex (p43-p10/p43-p10) (See Figure 1a).…”

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confidence: 99%

BID is cleaved by caspase-8 within a native complex on the mitochondrial membrane

et al. 2010

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Caspase-8 stably inserts into the mitochondrial outer membrane during extrinsic apoptosis. Inhibition of caspase-8 enrichment on the mitochondria impairs caspase-8 activation and prevents apoptosis. However, the function of active caspase-8 on the mitochondrial membrane remains unknown. In this study, we have identified a native complex containing caspase-8 and BID on the mitochondrial membrane, and showed that death receptor activation by Fas or tumor necrosis factor-related apoptosisinducing ligand (TRAIL) induced the cleavage of BID (tBID formation) within this complex. tBID then shifted to separate mitochondria-associated complexes that contained other BCL-2 family members, such as BAK and BCL-X L . We report that cells stabilize active caspase-8 on the mitochondria in order to specifically target mitochondria-associated BID, and that BID cleavage on the mitochondria is essential for caspase-8-induced cytochrome c release. Our findings indicate that during extrinsic apoptosis, caspase-8 can specifically target BID where it is mostly needed, on the surface of mitochondria.

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“…In this context, apoptosis is thought to be the outcome of caspase-8 dimerization through catalytic domain interaction, as single point mutants in the dimer interface, which are unable to undergo dimerization, exhibit greatly reduced apoptosis induction [52]. To determine whether HSV-2 R1 could prevent apoptosis induced by caspase-8 over-expression, we transfected into HeLa cells a GFPtagged version of caspase-8 (casp-8 GFP depicted in Fig.…”

Section: Hsv-2 R1 Impairs Apoptosis Induced By Caspase-8 Over-expressionmentioning

confidence: 99%

The ribonucleotide reductase R1 subunits of herpes simplex virus types 1 and 2 protect cells against TNFα- and FasL-induced apoptosis by interacting with caspase-8

et al. 2010

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We previously reported that HSV-2 R1, the R1 subunit (ICP10; UL39) of herpes simplex virus type-2 ribonucleotide reductase, protects cells against apoptosis induced by the death receptor (DR) ligands tumor necrosis factor-alpha-(TNFa) and Fas ligand (FasL) by interrupting DR-mediated signaling at, or upstream of, caspase-8 activation. Further investigation of the molecular mechanism underlying HSV-2 R1 protection showed that extracellularregulated kinase 1/2 (ERK1/2), phosphatidylinositol 3-kinase (PI3-K)/Akt, NF-jB and JNK survival pathways do not play a major role in this antiapoptotic function. Interaction studies revealed that HSV-2 R1 interacted constitutively with caspase-8. The HSV-2 R1 deletion mutant R1(1-834)-GFP and Epstein-Barr virus (EBV) R1, which did not protect against apoptosis induced by DR ligands, did not interact with caspase-8, indicating that interaction is required for protection. HSV-2 R1 impaired caspase-8 activation induced by caspase-8 over-expression, suggesting that interaction between the two proteins prevents caspase-8 dimerization/activation. HSV-2 R1 bound to caspase-8 directly through its prodomain but did not interact with either its caspase domain or Fas-associated death domain protein (FADD). Interaction between HSV-2 R1 and caspase-8 disrupted FADD-caspase-8 binding. We further demonstrated that individually expressed HSV-1 R1 (ICP6) shares, with HSV-2 R1, the ability to bind caspase-8 and to protect cells against DR-induced apoptosis. Finally, as the long-lived Fas protein remained stable during the early period of infection, experiments with the HSV-1 UL39 deletion mutant ICP6D showed that HSV-1 R1 could be essential for the protection of HSV-1-infected cells against FasL.Keywords FasL Á ICP6 Á ICP10 Á Viral inhibitor of apoptosis Á Caspase-8Electronic supplementary material The online version of this article

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Activation of Initiator Caspases through a Stable Dimeric Intermediate

Cited by 61 publications

References 39 publications

Molecular architecture of the DED chains at the DISC: regulation of procaspase-8 activation by short DED proteins c-FLIP and procaspase-8 prodomain

Molecular architecture of the DED chains at the DISC: regulation of procaspase-8 activation by short DED proteins c-FLIP and procaspase-8 prodomain

BID is cleaved by caspase-8 within a native complex on the mitochondrial membrane

The ribonucleotide reductase R1 subunits of herpes simplex virus types 1 and 2 protect cells against TNFα- and FasL-induced apoptosis by interacting with caspase-8

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