Related Experiment Video
Updated: May 22, 2026
09:04
Activation and Measurement of NLRP3 Inflammasome Activity Using IL-1β in Human Monocyte-derived Dendritic Cells
Published on: May 22, 2014
Proteolytic processing of Nlrp1b is required for inflammasome activity
Bradley C Frew1, Vineet R Joag, Jeremy Mogridge
1Department of Laboratory Medicine and Pathobiology, University of Toronto. Toronto, Ontario, Canada.
Plos Pathogens
|April 27, 2012
Summary
Proteolytic processing of Nlrp1b within its FIIND domain is essential for inflammasome activation. This post-translational modification enables the NOD-like receptor to detect anthrax lethal toxin and recruit pro-caspase-1.
Area of Science:
- Immunology
- Molecular Biology
- Biochemistry
Background:
- Nlrp1b is a NOD-like receptor crucial for detecting anthrax lethal toxin.
- It forms an inflammasome platform for pro-caspase-1 activation.
- Nlrp1b possesses NACHT and Function to Find (FIIND) domains involved in oligomerization.
Purpose of the Study:
- To investigate the role of proteolytic processing within the FIIND domain of Nlrp1b.
- To determine the functional significance of Nlrp1b cleavage in inflammasome activation.
Main Methods:
- Analyzing Nlrp1b cleavage products using biochemical assays.
- Employing site-directed mutagenesis to block or induce Nlrp1b processing.
- Utilizing a heterologous TEV protease site insertion to study cleavage-induced activity.
- Assessing pro-caspase-1 recruitment to inflammasomes with wild-type and mutant Nlrp1b.
Main Results:
- Proteolytic cleavage within the FIIND domain generates stable N-terminal and C-terminal Nlrp1b fragments.
- Mutations preventing FIIND cleavage abolish Nlrp1b's ability to activate pro-caspase-1.
- TEV protease-mediated cleavage of an engineered site in FIIND induced inflammasome activity.
- FIIND cleavage is required for functional inflammasome assembly and pro-caspase-1 recruitment.
Conclusions:
- Post-translational proteolytic processing of Nlrp1b is a critical step for its function.
- Cleavage within the FIIND domain enables Nlrp1b to assemble a functional inflammasome.
- This modification is essential for sensing anthrax lethal toxin and initiating immune responses.
Related Concept Videos
01:31The 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...
01:31Regulation of the Unfolded Protein Response
Inositol-requiring kinase one or IRE1 is the most conserved eukaryotic unfolded protein response (UPR) receptor. It is a type I transmembrane protein kinase receptor with a distinctive site-specific RNase activity. As the binding mechanics of the misfolded proteins with the N-terminal domain of IRE-1 are unclear, three binding models — direct, indirect, and allosteric -- are proposed for receptor activation. Nevertheless, it is known that once a misfolded protein associates with IRE1, it...
01:24Caspases
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.
02:26NF-κB-dependent Signaling Pathway
The transcription factor NF-κB was discovered in 1986 in the lab of Nobel laureate Professor David Baltimore, for its interaction with the immunoglobulin light chain enhancer in B-cells. After more than three decades of study, it is now evident that NF-κB regulates the expression of over 100 genes. Most of these genes play an essential role in the innate and adaptive immune responses as well as the inflammatory responses of animals.
NF-κB-dependent Signaling Mechanism
The heterodimer of NF-κB...
NF-κB-dependent Signaling Mechanism
The heterodimer of NF-κB...
01:17The 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...
01:37The Unfolded Protein Response
The ER is the hub of protein synthesis in a cell. It has robust systems to quality control protein folding and also for degradation of terminally misfolded proteins. Under normal conditions, a small proportion of misfolded proteins that cannot be salvaged need to be transported to the cytoplasm by the ER-associated degradation or ERAD pathways. However, if the ERAD cannot handle the misfolded proteins, the cell activates the unfolded protein response or UPR to adjust the protein folding...