CASP8 Research Reagents

Caspase-8 is a protein in humans that is encoded by CASP8 gene. Most upstream protease of the activation cascade of caspases responsible for the TNFRSF6/FAS mediated and TNFRSF1A induced cell death. Binding to the adapter molecule FADD recruits it to either receptor. The resulting aggregate called death-inducing signaling complex (DISC) performs CASP8 proteolytic activation. The active dimeric enzyme is then liberated from the DISC and free to activate downstream apoptotic proteases. Proteolytic fragments of the N-terminal propeptide (termed CAP3, CAP5 and CAP6) are likely retained in the DISC. Cleaves and activates CASP3, CASP4, CASP6, CASP7, CASP9 and CASP10. May participate in the GZMB apoptotic pathways. Cleaves ADPRT. Hydrolyzes the small-molecule substrate, Ac-Asp-Glu-Val-Asp-|-AMC. Likely target for the cowpox virus CRMA death inhibitory protein.

The following CASP8 reagents supplied by CUSABIO are manufactured under a strict quality control system. Multiple applications have been validated and solid technical support is offered.

CASP8 Antibodies

CASP8 Antibodies for Homo sapiens (Human)

CASP8 Proteins

CASP8 Proteins for Mus musculus (Mouse)

CASP8 Proteins for Homo sapiens (Human)

CASP8 ELISA Kit

CASP8 ELISA Kit for Homo sapiens (Human)

CASP8 Background

Caspase-8, encoded by gene CASP8, is a member of the cysteine proteases that specifically cleave substrates at sites located after aspartic acid residues in target amino acid sequences [1]. Like all caspases, caspase‐8 is synthesized as an inactive monomer procaspase. Caspase-8 activation requires not only proteolytic processing but also the dimerization process [2]. Caspase-8 carries a large N-terminal prodomain with a DED (death effector domain) followed by the catalytic domain containing a large and small subunit separated by a linker region [10]. Ligation of Fas by Fas Ligand initiates recruitment of caspase-8 to the membrane-bound DISC (death-inducing signaling complex) via the adaptor protein FADD (FAS-associated death domain) through their death effector domain (DED), respectively [3]. The DISC is formed at the cytoplasmic tail of the engaged DR that also includes the adapter protein FAS-associated death domain (FADD) or TNFR-associated death domain (TRADD) [4]. Recruitment of caspase-8 monomers results in dimerization and activation. Caspase-8 activation also occurs through a feedback loop derived from the intrinsic apoptotic pathway [5]. Caspase-3 and caspase-6 can facilitate the transition of pro-caspase-8 to be an active dimer form via proteolysis [6][7]. As an initiator caspase, active caspase-8 is released to the cytosol and cleaves downstream effector caspases. In some cell types, caspase-8 cleaves the BH3-only protein Bid to promote MOMP that ultimately induces cytochrome c leakage, caspase-9 activation, and subsequent apoptosis [8]. Activated caspase‐9 further stimulates further downstream caspases, including caspase‐8. Melanie Fritsch et al. uncovered that caspase-8 represents the molecular switch that controls apoptosis, necroptosis, and pyroptosis, and prevents tissue damage during embryonic development and adulthood [9].

[1] H.R. Stennicke, G.S. et al. Properties of the caspases [J]. Biochim. Biophys. Acta, 1387 (1998), pp. 17-31.
[2] A. Oberst, C. Pop, A.G. et al. Inducible dimerization and inducible cleavage reveal a requirement for both processes in caspase-8 activation [J]. J. Biol. Chem., 285 (2010), pp. 16632-16642
[3] F.C. Kischkel, S. Hellbardt, et al. Cytotoxicity-dependent APO-1 (Fas/CD95)-associated proteins form a death-inducing signaling complex (DISC) with the receptor [J]. EMBO J., 14 (1995), pp. 5579-5588.
[4] Boldin MP, Goncharov TM, et al. Involvement of MACH, a novel MORT1/FADD-interacting protease, in Fas/APO-1- and TNF receptor-induced cell death [J]. Cell. 1996 Jun 14; 85(6):803-15.
[5] T. Kuwana, J.J. Smith, et al. Apoptosis induction by caspase-8 is amplified through the mitochondrial release of cytochrome c [J]. J. Biol. Chem., 273 (1998), pp. 16589-16594.
[6] V. Cowling, J. Downward Caspase-6 is the direct activator of caspase-8 in the cytochrome c-induced apoptosis pathway: absolute requirement for removal of caspase-6 prodomain [J]. Cell Death Differ., 9 (2002), pp. 1046-1056.
[7] D. Sohn, K. Schulze-Osthoff, et al. Caspase-8 can be activated by interchain proteolysis without receptor-triggered dimerization during drug-induced apoptosis [J]. J. Biol. Chem., 280 (2005), pp. 5267-5273.
[8] Luo X, Budihardjo I, et al. Bid, a Bcl2 interacting protein, mediates cytochrome c release from mitochondria in response to activation of cell surface death receptors [J]. Cell. 1998 Aug 21; 94(4):481-90.[9] Melanie Fritsch, Saskia D. Günther, et al. Caspase-8 is the molecular switch for apoptosis, necroptosis and pyroptosis [J]. Nature volume 575, pages683-687(2019).
[10] Fuentes-Prior P, Salvesen GS The protein structures that shape caspase activity, specificity, activation and inhibition [J]. Biochem J. 2004 Dec 1; 384(Pt 2):201-32.

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