GO:0072557 IPAF inflammasome complex: Components, Assembly and Research Methods, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0072557 (IPAF inflammasome complex) is a cellular_component defined as an inflammasome complex consisting of IPAF (NLRC4), NAIP and caspase-1 that senses bacterial flagellin from Legionella pneumophila, Salmonella typhimurium, Pseudomonas aeruginosa and Shigella flexneri.
• The IPAF inflammasome is a cytosolic innate immune platform that activates caspase-1, leading to maturation of IL-1beta and IL-18 and pyroptotic cell death.
• NAIP proteins are the direct receptors for bacterial ligands such as flagellin and type III secretion apparatus components, while IPAF/NLRC4 acts as the downstream adaptor that nucleates the complex.
• Assembly of the IPAF inflammasome can proceed independently of the adaptor ASC, although ASC can modulate its activity and cytokine release.
• Dysregulation of IPAF inflammasome signaling is implicated in infectious disease susceptibility, autoinflammatory conditions and tumor immunity.
• CRISPR-based knockout, knock-in, point-mutation and overexpression models are essential tools for dissecting IPAF inflammasome gene function and for therapeutic target validation.
Description
The IPAF inflammasome complex (GO:0072557) is a cytosolic multiprotein platform that detects bacterial flagellin and type III secretion apparatus components, thereby triggering innate immune responses. It is defined in QuickGO as an inflammasome complex that consists of three components, IPAF, NAIP and caspase-1, and includes among its functions the sensing of flagellin derived from Legionella pneumophila, Salmonella typhimurium, Pseudomonas aeruginosa and Shigella flexneri. This complex is a central node in the caspase-1 activation pathway, which processes pro-IL-1beta and pro-IL-18 into their active forms and can induce pyroptosis. Researchers study GO:0072557 because it bridges bacterial sensing to inflammatory output and because its dysregulation contributes to infectious, inflammatory and malignant diseases. The IPAF inflammasome is distinguished from other inflammasomes by its use of NAIP receptors for ligand recognition and by its capacity to signal through both ASC-dependent and ASC-independent routes. Understanding its composition, assembly and regulation is therefore essential for immunology, microbiology and drug discovery. This article integrates the QuickGO definition with verified PubMed literature to provide a research-grade overview of the IPAF inflammasome complex, including its genes, mechanisms, disease links and the CRISPR-based methods used to study it.
IPAF inflammasome complex At A Glance
| GO ID | GO:0072557 |
|---|---|
| GO term | IPAF inflammasome complex |
| Ontology | cellular_component |
| Synonym | (none) |
| Major function | Sensing of bacterial flagellin and type III secretion apparatus components, leading to caspase-1 activation and inflammatory cytokine maturation |
| Core components | IPAF (NLRC4), NAIP, caspase-1 |
| Pathogen ligands | Flagellin from Legionella pneumophila, Salmonella typhimurium, Pseudomonas aeruginosa and Shigella flexneri |
| Downstream effectors | Caspase-1, IL-1beta, IL-18, pyroptosis |
| Adaptor dependence | Can signal independently of ASC, but ASC modulates activity |
What Is GO:0072557?
In our own words, GO:0072557 describes a specific inflammasome complex built from three core components: IPAF (also known as NLRC4/CARD12/CLAN), NAIP and caspase-1. This complex functions as a cytosolic sensor of bacterial flagellin and type III secretion apparatus components from pathogens such as Legionella pneumophila, Salmonella typhimurium, Pseudomonas aeruginosa and Shigella flexneri. Upon ligand recognition, the complex assembles to activate caspase-1, which then drives maturation of pro-inflammatory cytokines and can initiate pyroptotic cell death.
Why Is IPAF inflammasome complex Important in Cell Biology?
The IPAF inflammasome complex is important because it is a primary cytosolic surveillance system for bacterial flagellin and type III secretion apparatus components, and it directly controls caspase-1-dependent inflammation and cell death. Its activity shapes host defense against major pathogens including Legionella, Salmonella, Pseudomonas and Shigella, and its dysregulation has been linked to autoinflammatory disease, impaired pathogen clearance and tumor immunity. Because it sits at the interface of infection and inflammation, GO:0072557 is a high-value target for mechanistic studies and for therapeutic strategies aimed at modulating innate immunity.
• Acts as a cytosolic sensor of bacterial flagellin and type III secretion apparatus components from Legionella, Salmonella, Pseudomonas and Shigella.
• Activates caspase-1, which matures IL-1beta and IL-18 and can induce pyroptosis.
• Provides a key model for understanding ASC-dependent versus ASC-independent inflammasome signaling.
• Links bacterial infection to inflammatory pathology and host defense.
• Contributes to tumor immunity and DNA damage response crosstalk through inflammasome scaffolds.
• Is implicated in autoinflammatory and infectious disease susceptibility.
• Serves as a target for CRISPR knockout and knock-in studies of innate immune genes.
• Enables structure-function dissection of NAIP-ligand and NLRC4-caspase-1 interactions.
• Provides a platform for drug discovery aimed at modulating inflammasome activity.
• Is relevant to PANoptosis and inflammatory cell death networks.
Structure and Composition of IPAF inflammasome complex
Core protein components: IPAF, NAIP and caspase-1
In simple terms: The IPAF inflammasome is built from three main proteins that work together to detect bacteria and trigger inflammation.
The IPAF inflammasome complex is defined as containing IPAF (NLRC4/CARD12/CLAN), NAIP and caspase-1. IPAF/NLRC4 functions as the central adaptor that nucleates the complex, while NAIP proteins serve as the direct receptors for bacterial ligands. Caspase-1 is the effector protease recruited to the complex, where it undergoes activation to process downstream substrates.
NAIP-mediated ligand recognition
In simple terms: NAIP proteins are the sentinels that grab onto bacterial flagellin or injection needle proteins, starting the alarm.
NAIP proteins directly bind bacterial flagellin and type III secretion apparatus components, providing ligand specificity to the IPAF inflammasome. This recognition step is essential for sensing flagellin from Legionella pneumophila, Salmonella typhimurium, Pseudomonas aeruginosa and Shigella flexneri. TLR priming can license NAIP inflammasome activation by immunoevasive ligands, indicating that upstream signals modulate ligand detection.
NLRC4/IPAF as the assembly scaffold
In simple terms: IPAF/NLRC4 acts like a molecular platform that gathers the other components together after NAIP detects bacteria.
IPAF/NLRC4 is a bona fide intracellular adaptor of the caspase-1 inflammasome and is more than a flagellin sensor, serving as a scaffold for complex assembly. Upon ligand recognition by NAIP, NLRC4 oligomerizes and recruits caspase-1, forming the active IPAF inflammasome complex. This assembly can proceed independently of ASC, although ASC can modulate the magnitude and quality of the response.
Caspase-1 recruitment and activation
In simple terms: Once the platform is built, caspase-1 is recruited and switched on to cut inflammatory proteins.
Caspase-1 is the effector component of the IPAF inflammasome complex, and its recruitment leads to autoproteolytic activation. Activated caspase-1 cleaves pro-IL-1beta and pro-IL-18 into their mature forms and can cleave gasdermin D to induce pyroptosis. Differential activation of the inflammasome by caspase-1 adaptors ASC and Ipaf highlights the distinct signaling routes controlled by this complex.
Subcellular localization and complex dynamics
In simple terms: The IPAF inflammasome forms in the cytoplasm of the cell, where it can quickly respond to invading bacteria.
The IPAF inflammasome complex is a cytosolic platform that assembles in response to bacterial ligands. Its dynamic assembly is regulated by ligand availability, NAIP receptor engagement and downstream signaling events. Inflammasome protein scaffolds can also interact with DNA damage complexes during tumor development, indicating broader cellular roles beyond infection.
Key Genes Involved in GO:0072557 IPAF inflammasome complex
The following genes and proteins are central to the IPAF inflammasome complex (GO:0072557) and are commonly studied using CRISPR-based models.
| Gene | Major Role | Research Relevance |
|---|---|---|
| NLRC4 (IPAF) | Central adaptor and scaffold of the IPAF inflammasome complex | Knockout and knock-in models to dissect assembly and signaling |
| NAIP | Direct receptor for bacterial flagellin and T3SS components | Ligand specificity and priming studies |
| CASP1 | Effector protease that matures IL-1beta and IL-18 | KO and point-mutation models for catalytic activity |
| ASC (PYCARD) | Adaptor that modulates inflammasome activity | ASC-dependent vs independent signaling studies |
| IL1B | Downstream cytokine processed by caspase-1 | Reporter and knockout models for inflammatory output |
| IL18 | Downstream cytokine processed by caspase-1 | Functional studies of inflammasome activation |
| GSDMD | Pore-forming protein cleaved by caspase-1 during pyroptosis | Pyroptosis assays and KO models |
| NLRC5 | Related NLR that can form PANoptosome complexes | PANoptosis and inflammation studies |
| CARD12 (CLAN) | Alternative name for IPAF/NLRC4 | Historical and functional characterization |
| CASP4/5 | Inflammatory caspases in non-canonical inflammasomes | Comparative inflammasome studies |
| TLR4 | Upstream priming receptor for inflammasome activation | Priming and licensing experiments |
| TLR2 | Upstream priming receptor for inflammasome activation | Priming and licensing experiments |
| NFKB1 | Transcription factor for inflammasome component expression | Priming and transcriptional regulation studies |
| NLRP3 | Related inflammasome sensor | Comparative inflammasome biology |
| AIM2 | Related inflammasome sensor for DNA | Comparative inflammasome biology |
| PYCARD | Alternative name for ASC | Adaptor function studies |
| NAIP2 | NAIP paralog recognizing T3SS needle proteins | Ligand specificity studies |
| NAIP5 | NAIP paralog recognizing flagellin | Flagellin sensing studies |
How Is IPAF inflammasome complex Regulated?
The IPAF inflammasome complex is regulated at multiple levels, including ligand availability, receptor engagement and upstream priming signals. TLR priming licenses NAIP inflammasome activation by immunoevasive ligands, indicating that transcriptional and post-translational priming events are required for full responsiveness. ASC can modulate the activity of the IPAF inflammasome, providing an additional layer of regulation that influences cytokine output and cell death. Inflammasome scaffolds can also interface with DNA damage response complexes during tumor development, suggesting crosstalk with broader cellular stress pathways.
IPAF inflammasome complex and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| NLRC4 (IPAF) | Bacterial infection susceptibility and autoinflammation | Knockout and knock-in mice or cell lines |
| NAIP | Impaired flagellin sensing and pathogen clearance | NAIP knockout and point-mutation models |
| CASP1 | Inflammatory cytokine dysregulation and pyroptosis | Caspase-1 knockout and catalytic-dead knock-in |
| ASC (PYCARD) | Modulation of inflammasome signaling | ASC knockout and overexpression models |
| GSDMD | Pyroptosis and inflammatory cell death | GSDMD knockout and cleavage-site mutants |
Infectious disease and bacterial sensing
The IPAF inflammasome complex is critical for detecting flagellin from Legionella pneumophila, Salmonella typhimurium, Pseudomonas aeruginosa and Shigella flexneri, and its dysfunction can impair host defense against these pathogens. NAIP-mediated ligand recognition and TLR priming are required for effective activation, linking innate immune signaling to infection outcomes.
Autoinflammatory and inflammatory disease
Dysregulated inflammasome activity, including that of the IPAF inflammasome, can drive excessive IL-1beta and IL-18 maturation and pyroptosis, contributing to inflammatory pathology. The balance between ASC-dependent and ASC-independent signaling influences the severity and character of inflammatory responses.
Cancer and tumor immunity
Inflammasome protein scaffolds can interact with DNA damage complexes during tumor development, indicating roles in tumor suppression and immune surveillance. PANoptosis, a form of inflammatory cell death driven by complexes such as the PANoptosome, is also linked to cancer and inflammation.
PANoptosis and cell death networks
The IPAF inflammasome is part of a broader network of inflammatory cell death pathways, including PANoptosis, which integrates pyroptosis, apoptosis and necroptosis. Understanding these interactions is important for therapeutic targeting of inflammatory diseases and cancer.
From IPAF inflammasome complex-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does NLRC4/IPAF mediate flagellin sensing? | NLRC4 knockout cell lines and mice |
| Which NAIP paralog recognizes a specific ligand? | NAIP point-mutation and knockout models |
| Is caspase-1 catalytic activity required for cytokine maturation? | CASP1 catalytic-dead knock-in |
| How does ASC modulate IPAF inflammasome output? | ASC knockout and tagged knock-in |
| Can overexpression drive ligand-independent activation? | NLRC4 or NAIP overexpression cell lines |
| What is the role of IPAF inflammasome in tumors? | Conditional knockout and syngeneic tumor models |
How to Study the IPAF inflammasome complex Process
| Method | What It Measures | Typical Application |
|---|---|---|
| CRISPR knockout | Loss of gene function | Testing requirement for NLRC4, NAIP or CASP1 |
| CRISPR knock-in | Tagged or mutant protein expression | Localization and interaction studies |
| Co-immunoprecipitation | Protein-protein interactions | Identifying inflammasome components |
| Mass spectrometry | Proteome and interactome | Mapping caspase-1 substrates |
| Live-cell imaging | Complex assembly and cell death | Visualizing pyroptosis |
| RNA-seq | Transcriptional changes | Inflammatory gene expression profiling |
| Cytokine ELISA | IL-1beta and IL-18 levels | Quantifying inflammasome output |
| LDH release assay | Membrane integrity | Measuring pyroptosis |
Genetic perturbation with CRISPR
CRISPR knockout, knock-in and point-mutation models are used to dissect the roles of NLRC4, NAIP, CASP1 and downstream effectors in IPAF inflammasome signaling. These models allow causal testing of gene function in infection and inflammation.
Biochemical and proteomic analysis
Co-immunoprecipitation, affinity purification and mass spectrometry can identify components and interactors of the IPAF inflammasome complex. Proteomics can quantify caspase-1 substrates and cytokine processing.
Imaging and cell death assays
Fluorescence microscopy and live-cell imaging can visualize inflammasome assembly and pyroptosis, while LDH release and caspase-1 activity assays quantify cell death.
Transcriptomic and cytokine profiling
RNA-seq and cytokine arrays measure inflammatory gene expression and IL-1beta/IL-18 output following IPAF inflammasome activation.
How CRISPR Can Be Used to Study GO:0072557 IPAF inflammasome complex
Knockout
CRISPR knockout of NLRC4, NAIP or CASP1 is used to test the requirement for these genes in IPAF inflammasome activation and downstream cytokine maturation. Knockout models help distinguish essential versus redundant components.
Point Mutation
Point mutations can be introduced into NLRC4, NAIP or CASP1 to dissect catalytic activity, ligand binding and assembly interfaces. These models are valuable for structure-function studies.
Knock-in
Knock-in of tagged or reporter alleles allows visualization and purification of IPAF inflammasome components in native contexts. This approach supports interaction and localization studies.
Overexpression
Overexpression of NLRC4, NAIP or caspase-1 can drive ligand-independent activation and is useful for gain-of-function studies. Overexpression models complement loss-of-function approaches.
How EDITGENE Supports IPAF inflammasome complex Research
Researchers studying IPAF inflammasome complex-related genes often need to determine whether a candidate gene is causally involved in bacterial sensing, caspase-1 activation or inflammatory disease. EDITGENE provides CRISPR-based cell models and screening services to accelerate this discovery process.
Contact EDITGENE today to design your custom CRISPR model for IPAF inflammasome complex research.
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| NLRC4 Knockout HEK293 Cell Line | EDJ-KQ505 | Human | 58484 | Details Get a Quote |
| CASP1 Knockout HEK293 Cell Line | EDJ-KQ1456 | Human | 834 | Details Get a Quote |
| NAIP Knockout HEK293 Cell Line | EDJ-KQ5299 | Human | 4671 | Details Get a Quote |
| CASP1 Knockout HeLa Cell Line | EDJ-KQ22323 | Human | 834 | Details Get a Quote |
| NAIP Knockout A-549 Cell Line | EDJ-KQ28355 | Human | 4671 | Details Get a Quote |
| NAIP Knockout HCT 116 Cell Line | EDJ-KQ28356 | Human | 4671 | Details Get a Quote |
| NAIP Knockout HeLa Cell Line | EDJ-KQ28357 | Human | 4671 | Details Get a Quote |
| NLRC4 Knockout HeLa Cell Line | EDJ-KQ56937 | Human | 58484 | Details Get a Quote |
| CASP1 Knockout A-549 Cell Line | EDJ-KQ61258 | Human | 834 | Details Get a Quote |
| NLRC4 Knockout A-549 Cell Line | EDJ-KQ65443 | Human | 58484 | Details Get a Quote |
| CASP1 Knockout HCT 116 Cell Line | EDJ-KQ69754 | Human | 834 | Details Get a Quote |
| NLRC4 Knockout HCT 116 Cell Line | EDJ-KQ73880 | Human | 58484 | Details Get a Quote |
| Nlrc4 Knockout IBMDM Cell Line | EDC07958 | Mouse | 268973 | Details Get a Quote |
Displaying Records 1 To 13 Of 13 Records
Frequently Asked Questions About IPAF inflammasome complex
What is the IPAF inflammasome complex?
The IPAF inflammasome complex (GO:0072557) is a cytosolic inflammasome consisting of IPAF (NLRC4), NAIP and caspase-1 that senses bacterial flagellin and type III secretion apparatus components.
What genes are involved in the IPAF inflammasome complex?
The core genes are NLRC4 (IPAF), NAIP and CASP1, with modulators such as ASC (PYCARD) and downstream effectors IL1B, IL18 and GSDMD.
Which bacteria are sensed by the IPAF inflammasome?
It senses flagellin from Legionella pneumophila, Salmonella typhimurium, Pseudomonas aeruginosa and Shigella flexneri.
How does the IPAF inflammasome activate caspase-1?
NAIP receptors bind bacterial ligands, NLRC4 oligomerizes and recruits caspase-1, leading to its autoproteolytic activation.
Does the IPAF inflammasome require ASC?
It can assemble and signal independently of ASC, but ASC can modulate its activity and cytokine output.
What diseases are linked to the IPAF inflammasome?
It is linked to bacterial infection susceptibility, autoinflammatory conditions, tumor immunity and PANoptosis.
How can I study the IPAF inflammasome with CRISPR?
CRISPR knockout, knock-in, point-mutation and overexpression models can be used to dissect gene function in IPAF inflammasome signaling.
What is the role of NAIP in the IPAF inflammasome?
NAIP proteins are the direct receptors for bacterial flagellin and type III secretion apparatus components.
What cytokines are produced by IPAF inflammasome activation?
Activated caspase-1 matures IL-1beta and IL-18, which drive inflammation.
What is the difference between IPAF and NLRC4?
IPAF is an alternative name for NLRC4, the central adaptor of the IPAF inflammasome complex.
Conclusion
The IPAF inflammasome complex (GO:0072557) is a cytosolic innate immune platform composed of IPAF/NLRC4, NAIP and caspase-1 that detects bacterial flagellin and type III secretion apparatus components from major pathogens. Its activation drives caspase-1-dependent cytokine maturation and pyroptosis, linking infection to inflammation and cell death. Dysregulation of this complex is implicated in infectious disease, autoinflammation, tumor immunity and PANoptosis. CRISPR-based knockout, knock-in, point-mutation and overexpression models are indispensable for dissecting the molecular details of IPAF inflammasome assembly and function. EDITGENE provides comprehensive cell model and screening services to support this research and accelerate therapeutic target validation.
References
- 1. Sundaram B et al.. 2024. NLRC5 senses NAD(+) depletion, forming a PANoptosome and driving PANoptosis and inflammation.. Cell 187(15):4061-4077.e17 PMID: 38878777
- 2. Shen C et al.. 2024. Inflammasome protein scaffolds the DNA damage complex during tumor development.. Nat Immunol 25(11):2085-2096 PMID: 39402152
- 3. Abdelaziz DH et al.. 2010. Nlrc4/Ipaf/CLAN/CARD12: more than a flagellin sensor.. Int J Biochem Cell Biol 42(6):789-91 PMID: 20067841
- 4. Mariathasan S. 2007. ASC, Ipaf and Cryopyrin/Nalp3: bona fide intracellular adapters of the caspase-1 inflammasome.. Microbes Infect 9(5):664-71 PMID: 17382568
- 5. Grayczyk JP et al.. 2024. TLR priming licenses NAIP inflammasome activation by immunoevasive ligands.. Proc Natl Acad Sci U S A 121(48):e2412700121 PMID: 39556752
- 6. Mariathasan S et al.. 2004. Differential activation of the inflammasome by caspase-1 adaptors ASC and Ipaf.. Nature 430(6996):213-8 PMID: 15190255
- 7. Zhao Y et al.. 2011. The NLRC4 inflammasome receptors for bacterial flagellin and type III secretion apparatus.. Nature 477(7366):596-600 PMID: 21918512
- 8. Pétrilli V et al.. 2007. The inflammasome: a danger sensing complex triggering innate immunity.. Curr Opin Immunol 19(6):615-22 PMID: 17977705
