Dataset Information

A new C-terminal cleavage product of procaspase-8, p30, defines an alternative pathway of procaspase-8 activation.

ABSTRACT: Caspase-8 is the main initiator caspase in death receptor-induced apoptosis. Procaspase-8 is activated at the death-inducing signaling complex (DISC). Previous studies suggested a two-step model of procaspase-8 activation. The first cleavage step occurs between the protease domains p18 and p10. The second cleavage step takes place between the prodomain and the large protease subunit (p18). Subsequently, the active caspase-8 heterotetramer p18(2)-p10(2) is released into the cytosol, starting the apoptotic signaling cascade. In this report, we have further analyzed procaspase-8 processing upon death receptor stimulation directly at the DISC and in the cytosol. We have found an alternative sequence of cleavage events for procaspase-8. We have demonstrated that the first cleavage can also occur between the prodomain and the large protease subunit (p18). The resulting cleavage product, p30, contains both the large protease subunit (p18) and the small protease subunit (p10). p30 is further processed to p10 and p18 by active caspases. Furthermore, we show that p30 can sensitize cells toward death receptor-induced apoptosis. Taken together, our data suggest an alternative mechanism of procaspase-8 activation at the DISC.

SUBMITTER: Hoffmann JC

PROVIDER: S-EPMC2725745 | biostudies-literature | 2009 Aug

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

A new C-terminal cleavage product of procaspase-8, p30, defines an alternative pathway of procaspase-8 activation.

Hoffmann Julia C JC Pappa Alexander A Krammer Peter H PH Lavrik Inna N IN

Molecular and cellular biology 20090615 16

Caspase-8 is the main initiator caspase in death receptor-induced apoptosis. Procaspase-8 is activated at the death-inducing signaling complex (DISC). Previous studies suggested a two-step model of procaspase-8 activation. The first cleavage step occurs between the protease domains p18 and p10. The second cleavage step takes place between the prodomain and the large protease subunit (p18). Subsequently, the active caspase-8 heterotetramer p18(2)-p10(2) is released into the cytosol, starting the ...[more]

PMID: 19528225

Similar Datasets

Project description:Leucocyte initiation of coagulation preserves the haemostatic balance and may aberrantly contribute to vascular injury. In addition to the extrinsic activation mediated by tissue factor: factor VIIa, monocytes express an alternative procoagulant response after binding of the zymogen factor X to the integrin Mac-1 (CD11b/CD18). Here, factor X-activating activity was found in purified monocyte granules, and coincided with size-chromatographed fractions containing cathepsin G. In contrast, elastase-containing granule fractions did not activate factor X. In the presence of Ca2+ ions, purified cathepsin G, but not elastase, cleaved factor X to a approximately 54 kDa catalytically active derivative, structurally indistinguishable from the procoagulant product generated on monocytes after binding to Mac-1. Factor X activation by purified cathepsin G involved limited proteolysis of a novel Leu177-Leu178 peptide bond in the zymogen's activation peptide. Cathepsin G activation of factor X was completely inhibited by alpha 1 antichymotrypsin, or soybean trypsin inhibitor, or by a neutralizing antiserum to cathepsin G, while eglin, or an anti-elastase antibody, were ineffective. Affinity chromatography on active-site-dependent inhibitors Glu-Gly-Arg-chloromethyl ketone or benzamidine completely abolished factor Xa activity generated by cathepsin G. Cathepsin G was not constitutively detected on the monocyte surface by flow cytometry. However, inflammatory stimuli, including formyl peptide or phorbol ester, or Mac-1 engagement with its ligands fibrinogen, factor X or serum-opsonized zymosan, triggered monocyte degranulation and cathepsin G activation of factor X. These findings demonstrate that monocytes can alternatively initiate coagulation in a sequential three-step cascade, including (i) binding of factor X to Mac-1, (ii) discharge of azurophil granules, and (iii) limited proteolytic activation of membranebound factor X by cathepsin G. By rapidly forming thrombin and factor Xa in a protected membrane microenvironment, this pathway may contribute a "priming' signal for clotting, anticoagulation and vascular cell signal transduction, in vivo.

Dataset Information

A new C-terminal cleavage product of procaspase-8, p30, defines an alternative pathway of procaspase-8 activation.

Publications

A new C-terminal cleavage product of procaspase-8, p30, defines an alternative pathway of procaspase-8 activation.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets