Related Experiment Video

Updated: Aug 30, 2026

In Vitro Cleavage Assays using Purified Recombinant Drosophila Caspases for Substrate Screening
08:16

In Vitro Cleavage Assays using Purified Recombinant Drosophila Caspases for Substrate Screening

Published on: October 6, 2022

Substrate cleavage by caspases generates protein fragments with Smac/Diablo-like activities

K Hell1, M Saleh, G D Crescenzo

  • 1Merck Research Laboratories, Merck Frosst Centre for Therapeutic Research, PO Box 1005, Pointe Claire-Dorval, Quebec, Canada H9R 4P8.

Cell Death and Differentiation
|October 25, 2003
PubMed

Insights

New findings reveal that cleaved cell death substrates can mimic Smac/Diablo (SMAC/DIABLO) to inhibit IAP proteins like XIAP, enhancing apoptosis. This mechanism may be relevant in Alzheimer's disease.

Area of Science:

  • Cellular Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Inhibitor of Apoptosis Proteins (IAPs) regulate programmed cell death.
  • Smac/Diablo (SMAC/DIABLO) and HtrA2/Omi antagonize IAPs, promoting apoptosis.
  • X-linked inhibitor of apoptosis (XIAP) is a key IAP target.

Purpose of the Study:

  • To investigate novel mechanisms of IAP antagonism.
  • To explore the role of caspase-mediated cleavage in apoptosis regulation.
  • To examine the relevance of these findings in Alzheimer's disease.

Main Methods:

  • Analysis of caspase-mediated proteolysis of cell death substrates.
  • Biochemical assays to assess binding of cleaved substrates to XIAP.
  • Investigation of the functional consequences of substrate cleavage on apoptosis.

Main Results:

  • Caspase cleavage of specific substrates exposes N-termini with Smac/Diablo-like activity.
  • These cleaved substrates effectively bind and antagonize XIAP.
  • The caspase-generated C31 peptide from Alzheimer's disease exhibits Smac/Diablo-like properties post-cleavage.

Conclusions:

  • A novel feedforward mechanism sensitizes the apoptotic pathway.
  • This process contributes to the functional redundancy of IAP antagonism.
  • The findings suggest a potential role in Alzheimer's disease pathogenesis.

More Related Videos

Measuring Caspase Activity Using a Fluorometric Assay or Flow Cytometry05:29

Measuring Caspase Activity Using a Fluorometric Assay or Flow Cytometry

Published on: March 24, 2023

Identifying Caspases and their Motifs that Cleave Proteins During Influenza A Virus Infection08:16

Identifying Caspases and their Motifs that Cleave Proteins During Influenza A Virus Infection

Published on: July 21, 2022

Related Concept Videos

Caspases01:24

Caspases

Caspase, a family of cysteine proteases, serve as effectors in apoptosis. The ced3 gene in C.elegans was first identified to be involved in apoptosis. This gene encodes the ced-3 caspase that is similar to the interleukin-1-beta converting enzyme or ICE in mammals. In addition to apoptosis, caspases also function in the inflammatory response. Inflammatory caspases are essential in activating pro-inflammatory cytokines that recruit immune cells and block the replication of pathogens inside cells.
The Intrinsic Apoptotic Pathway01:31

The Intrinsic Apoptotic Pathway

Internal cellular stress, such as cellular injury or hypoxia, triggers intrinsic apoptosis. The B-cell lymphoma 2 (Bcl-2) family of proteins are the primary regulators of the intrinsic apoptotic pathway. For example, during DNA damage, checkpoint proteins, such as Ataxia Telangiectasia Mutated (ATM protein) and Checkpoints Factor-2 (Chk2) proteins, are activated. These proteins phosphorylate p53 which further activates pro-apoptotic proteins, such as Bax, Bak, PUMA, and Noxa, and inhibits...
The Extrinsic Apoptotic Pathway01:17

The Extrinsic Apoptotic Pathway

The extrinsic apoptotic pathway is initiated when extracellular death-inducing signals, such as specific cytokines, activate the death receptors expressed on the cell surface. The immune cells involved in this pathway are natural killer cells (NK cells) and cytotoxic T-lymphocytes. NK cells are critical in innate immune response, while cytotoxic T-lymphocytes are associated with adaptive immune response. These cells recognize specific receptors expressed on the altered cells and activate...
The Proteasome02:18

The Proteasome

Eukaryotic cells can degrade proteins through several pathways. One of the most important amongst these is the ubiquitin-proteasome pathway. It helps the cell eliminate the misfolded, damaged, or unwarranted cytoplasmic proteins in a highly specific manner.
In this pathway, the target proteins are first tagged with small proteins called ubiquitin. A series of enzymes carry out the ubiquitination of the target proteins - E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3...
The Proteasome01:13

The Proteasome

Eukaryotic cells can degrade proteins through several pathways. One of the most important among these is the ubiquitin-proteasome pathway. It helps the cell eliminate the misfolded, damaged, or unwarranted cytoplasmic proteins in a highly specific manner.
In this pathway, the target proteins are first tagged with small proteins called ubiquitin. This involves participation of a series of enzymes including— E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3 (ubiquitin...
Membrane Asymmetry Regulating Transporters01:19

Membrane Asymmetry Regulating Transporters

Enzymes like flippase, floppase, and scramblase transfer phospholipids from one layer to another in the membrane, thereby affecting membrane asymmetry.
Flippase
Eukaryotic flippases are type-IV P-type ATPases or P4-ATPases belonging to P-type ATPase family proteins that are membrane-bound pumps involved in the ATP-mediated transport of ions and molecules across the membrane. Flippases flip specific phospholipids from the outer to the inner leaflet of a membrane. All P4-ATPases have one...