GO:0045092 interleukin-18 receptor complex: Components, Assembly and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0045092 (interleukin-18 receptor complex) is a plasma membrane protein complex that binds interleukin-18 (IL-18) and comprises an alpha (IL-18R1) and a beta (IL-18RAP) subunit.
• IL-18 is a pro-inflammatory cytokine that signals through this receptor complex to activate NF-kB and MAPK pathways, driving IFN-gamma production and innate immune responses.
• The receptor complex is a key therapeutic target in autoinflammatory diseases, rheumatoid arthritis, and cancer immunotherapy.
• Soluble forms of the IL-18 receptor complex serve as biomarkers in rheumatoid arthritis and other inflammatory conditions.
• IL-18BP acts as a secreted immune checkpoint that neutralizes IL-18 and limits receptor complex activation, with implications for cancer immunotherapy.
• CRISPR-based knockout, knock-in, and overexpression models enable precise dissection of IL-18 receptor complex function in health and disease.
Description
The interleukin-18 receptor complex (GO:0045092) is a heterodimeric cell surface protein complex that specifically binds the pro-inflammatory cytokine interleukin-18 (IL-18). This receptor complex is a critical component of innate and adaptive immune signaling, transducing extracellular IL-18 signals into intracellular activation of NF-kB and MAPK pathways, ultimately leading to interferon-gamma (IFN-gamma) production and inflammatory gene expression. The complex is composed of an alpha subunit (IL-18R1, also known as IL-1Rrp1) and a beta subunit (IL-18RAP, also known as AcPL), both of which belong to the interleukin-1 receptor family. Researchers study GO:0045092 because dysregulated IL-18 signaling is implicated in a wide range of human diseases, including rheumatoid arthritis, systemic lupus erythematosus, gout, and cancer. The receptor complex is also a target for therapeutic intervention, as blocking IL-18 binding or receptor activation can modulate inflammatory responses. Understanding the structure, assembly, and regulation of the interleukin-18 receptor complex is therefore essential for developing targeted therapies and diagnostic biomarkers. Recent structural studies have revealed dynamic conformational changes in IL-18 and its receptor complex during maturation and signaling, providing mechanistic insights into how the complex assembles and activates downstream pathways. These findings open new avenues for designing small molecules or biologics that modulate receptor function with high specificity.
interleukin-18 receptor complex At A Glance
| GO ID | GO:0045092 |
|---|---|
| GO term | interleukin-18 receptor complex |
| Ontology | cellular_component |
| Synonym | IL-18 receptor complex |
| Definition | A protein complex that binds interleukin-18; comprises an alpha and a beta subunit. |
| Major function | Binds IL-18 and transduces signals to activate NF-kB and MAPK pathways, leading to IFN-gamma production and inflammatory responses. |
| Subunits | Alpha subunit (IL-18R1) and beta subunit (IL-18RAP). |
| Cellular location | Plasma membrane. |
| Associated diseases | Rheumatoid arthritis, systemic lupus erythematosus, gout, cancer. |
What Is GO:0045092?
According to the Gene Ontology (QuickGO), GO:0045092 (interleukin-18 receptor complex) is defined as a protein complex that binds interleukin-18 and comprises an alpha and a beta subunit. This complex is located at the cell surface and mediates the cellular response to IL-18 by initiating intracellular signaling cascades. The alpha subunit (IL-18R1) is the primary ligand-binding subunit, while the beta subunit (IL-18RAP) is required for signal transduction and high-affinity binding.
Why Is interleukin-18 receptor complex Important in Cell Biology?
The interleukin-18 receptor complex is a central mediator of innate and adaptive immunity, and its dysregulation contributes to the pathogenesis of numerous inflammatory and autoimmune diseases. Because IL-18 signaling amplifies IFN-gamma production and cytotoxic T cell activity, the receptor complex is a high-priority target for cancer immunotherapy and for treating autoinflammatory conditions. Moreover, soluble forms of the receptor complex have emerged as promising biomarkers for disease activity in rheumatoid arthritis and other inflammatory disorders. Understanding the molecular details of receptor assembly and signaling is therefore critical for rational drug design and for interpreting genetic variants that affect receptor function.
• Mediates IL-18-induced IFN-gamma production, a key cytokine for Th1 immune responses and host defense.
• Dysregulated IL-18 signaling is linked to rheumatoid arthritis, where soluble IL-18 receptor complex levels correlate with disease activity.
• IL-18BP acts as a natural checkpoint that blocks IL-18 binding to the receptor complex, and its inhibition is being explored in cancer immunotherapy.
• The receptor complex is implicated in gout, where IL-18 drives neutrophil recruitment and inflammation in response to monosodium urate crystals.
• In systemic lupus erythematosus, elevated IL-18 receptor accessory protein (IL-18RAP) enhances reactive oxygen species production in neutrophils.
• IL-18 and its receptor complex are expressed in the central nervous system, where they modulate neuroinflammation and may contribute to neurodegenerative diseases.
• Structural transitions in IL-18 and its receptor complex are essential for maturation and signaling, offering targets for therapeutic intervention.
• CRISPR-based gene editing enables precise knockout or knock-in of IL18R1 and IL18RAP to study receptor function in disease models.
• The receptor complex is a potential biomarker for diagnosing and monitoring autoimmune diseases.
• Targeting the IL-18 receptor complex may enhance the efficacy of immune checkpoint inhibitors in cancer.
What Happens During interleukin-18 receptor complex?
IL-18 Binding and Receptor Assembly
In simple terms: IL-18 binds to the receptor complex on the cell surface, causing the two subunits to come together and activate the cell.
The interleukin-18 receptor complex is activated when the pro-inflammatory cytokine IL-18 binds to the alpha subunit (IL-18R1) on the plasma membrane. This initial binding recruits the beta subunit (IL-18RAP) to form a heterodimeric complex, which is required for high-affinity ligand binding and signal transduction. Structural studies have shown that IL-18 undergoes conformational transitions during maturation and receptor engagement, enabling stable complex formation. The assembly of the receptor complex is a dynamic process that ensures specificity and prevents inappropriate activation by related cytokines.
Intracellular Signaling Cascade
In simple terms: Once the receptor complex is assembled, it sends signals inside the cell that turn on genes involved in inflammation.
Upon IL-18 binding, the interleukin-18 receptor complex recruits the adaptor protein MyD88 through the Toll/IL-1 receptor (TIR) domain of the beta subunit. This recruitment initiates a signaling cascade that activates IRAK kinases, TRAF6, and downstream NF-kB and MAPK pathways. Activation of NF-kB leads to the transcription of pro-inflammatory genes, including IFNG, and enhances the production of interferon-gamma in T cells and NK cells. The signaling cascade is tightly regulated to prevent excessive inflammation, and dysregulation contributes to autoimmune and autoinflammatory diseases.
Regulation by IL-18 Binding Protein (IL-18BP)
In simple terms: A decoy protein called IL-18BP can soak up IL-18 and stop it from activating the receptor complex.
IL-18BP is a secreted protein that binds IL-18 with high affinity and prevents it from interacting with the interleukin-18 receptor complex. This acts as a natural immune checkpoint, limiting IL-18-mediated inflammation and protecting tissues from excessive immune activation. Recent studies have shown that IL-18BP is upregulated in tumors and can impede the efficacy of IL-18-based cancer immunotherapies, suggesting that blocking IL-18BP could enhance anti-tumor responses. The balance between IL-18 and IL-18BP is therefore critical for maintaining immune homeostasis.
Soluble Receptor Complex as a Biomarker
In simple terms: Parts of the receptor complex can be shed into the blood and measured to monitor diseases like rheumatoid arthritis.
Soluble forms of the interleukin-18 receptor complex, including soluble IL-18R1 and IL-18RAP, are detectable in serum and synovial fluid. In rheumatoid arthritis, elevated levels of soluble IL-18 receptor complex correlate with disease activity and joint destruction, making it a potential biomarker for diagnosis and monitoring. The shedding of these soluble receptors may modulate IL-18 signaling by acting as decoys, and their measurement can provide insights into disease pathogenesis. Further research is needed to standardize assays and validate their clinical utility.
Key Genes Involved in GO:0045092 interleukin-18 receptor complex
The following genes encode the subunits and key regulators of the interleukin-18 receptor complex and its signaling pathway.
| Gene | Major Role | Research Relevance |
|---|---|---|
| IL18R1 | Encodes the alpha subunit of the IL-18 receptor complex; primary ligand-binding subunit | Knockout studies reveal loss of IL-18 signaling; target for autoimmune disease research |
| IL18RAP | Encodes the beta subunit; required for signal transduction and high-affinity binding | Mutations linked to inflammatory diseases; overexpression enhances ROS production in SLE neutrophils |
| IL18 | Encodes the pro-inflammatory cytokine that binds the receptor complex | Central to IFN-gamma production; target for cancer immunotherapy and autoinflammation |
| IL18BP | Encodes a secreted decoy protein that neutralizes IL-18 | Acts as an immune checkpoint; blockade enhances IL-18 immunotherapy in cancer |
| MYD88 | Adaptor protein recruited to the receptor complex; activates NF-kB and MAPK | Essential for IL-18 signaling; knockout abolishes downstream responses |
| IRAK1 | Kinase activated by MyD88; propagates signaling from the receptor complex | Regulates inflammatory gene expression; target for anti-inflammatory drugs |
| IRAK4 | Kinase that partners with IRAK1; critical for IL-18 receptor signaling | Deficiency causes immunodeficiency; studied in autoinflammation |
| TRAF6 | E3 ubiquitin ligase that mediates NF-kB activation downstream of the receptor | Knockout impairs IL-18-induced NF-kB activation |
| NFKB1 | Transcription factor activated by IL-18 receptor signaling | Drives expression of pro-inflammatory genes including IFNG |
| MAPK1 | Kinase in the MAPK pathway activated by IL-18 receptor complex | Regulates cytokine production and cell survival |
| IFNG | Interferon-gamma; key effector cytokine induced by IL-18 signaling | Marker of Th1 responses; dysregulated in autoimmunity |
| IL12RB1 | Partners with IL-18 receptor to enhance IFN-gamma production | Co-stimulation with IL-12 boosts IL-18 responses |
| NLRP3 | Inflammasome that activates IL-18 via caspase-1 cleavage | Links innate immune sensing to IL-18 receptor activation |
| CASP1 | Caspase-1 cleaves pro-IL-18 to its mature form | Required for IL-18 secretion and receptor activation |
| GSDMD | Gasdermin D mediates IL-18 release during pyroptosis | Connects cell death to IL-18 signaling |
| IL1R1 | Related receptor that shares signaling components with IL-18 receptor | Cross-talk between IL-1 and IL-18 pathways |
| SIGIRR | Negative regulator of IL-1/IL-18 receptor signaling | Limits excessive inflammation; knockout exacerbates disease |
| TOLLIP | Regulatory protein that modulates IL-1/IL-18 receptor signaling | Influences receptor complex stability and trafficking |
How Is interleukin-18 receptor complex Regulated?
The interleukin-18 receptor complex is regulated at multiple levels. IL-18BP acts as a secreted decoy that binds IL-18 and prevents receptor activation, functioning as an immune checkpoint. Expression of the receptor subunits IL18R1 and IL18RAP is controlled by transcription factors such as NF-kB and AP-1, which are themselves activated by inflammatory stimuli. Soluble forms of the receptor complex can be shed from the cell surface and modulate signaling by sequestering IL-18. Additionally, negative regulators like SIGIRR and TOLLIP dampen receptor signaling to prevent excessive inflammation. Post-translational modifications, including phosphorylation and ubiquitination, fine-tune the signaling cascade downstream of the receptor complex.
interleukin-18 receptor complex and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| IL18R1 | Rheumatoid arthritis, autoimmunity | Knockout mice or human cell lines to assess IL-18-induced signaling |
| IL18RAP | Systemic lupus erythematosus, ROS production | Overexpression in neutrophils or CRISPR knock-in of risk variants |
| IL18 | Gout, autoinflammation | Inflammasome activation models with IL-18 knockout |
| IL18BP | Cancer immunotherapy resistance | Knockout in tumor cells to enhance IL-18 availability |
| IL18R1/IL18RAP | Neuroinflammation | Brain-specific knockout or knock-in models |
Rheumatoid Arthritis and Autoimmune Diseases
The interleukin-18 receptor complex plays a central role in rheumatoid arthritis (RA), where elevated levels of IL-18 and soluble receptor complex components are found in serum and synovial fluid. Soluble IL-18 receptor complex has been proposed as a novel biomarker for RA diagnosis and disease activity monitoring. In systemic lupus erythematosus (SLE), increased expression of IL-18RAP on neutrophils enhances reactive oxygen species production, contributing to tissue damage. These findings highlight the receptor complex as a therapeutic target in autoimmune diseases.
Gout and Autoinflammatory Disorders
Gout is an autoinflammatory disease caused by monosodium urate crystal deposition, which activates the NLRP3 inflammasome and leads to IL-18 maturation and release. IL-18 then binds to the interleukin-18 receptor complex on immune cells, amplifying neutrophil recruitment and inflammation. Genetic and epigenetic regulation of the innate immune response to gout involves components of the IL-18 signaling pathway, making the receptor complex a potential target for anti-inflammatory therapy.
Cancer Immunotherapy
IL-18 signaling through its receptor complex promotes anti-tumor immunity by inducing IFN-gamma production and enhancing cytotoxic T cell and NK cell activity. However, tumors often upregulate IL-18BP, which neutralizes IL-18 and limits receptor activation. Blocking IL-18BP or engineering IL-18 variants that resist IL-18BP binding has emerged as a promising strategy to enhance cancer immunotherapy. The interleukin-18 receptor complex is therefore a key node in the design of next-generation immunotherapies.
Neuroinflammation and CNS Disorders
IL-18 and its receptor complex are expressed in the central nervous system, where they modulate neuroinflammation and synaptic function. Elevated IL-18 levels have been associated with neurodegenerative diseases such as Alzheimer's disease and multiple sclerosis, although the precise mechanisms remain under investigation. Targeting the interleukin-18 receptor complex in the CNS may offer therapeutic opportunities for neuroinflammatory conditions.
From interleukin-18 receptor complex-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of IL18R1 abolish IL-18-induced IFN-gamma production? | IL18R1 knockout cell line (e.g., THP-1 or primary T cells) |
| How do disease-associated variants in IL18RAP affect receptor signaling? | Point mutation knock-in using CRISPR in human cell lines |
| Can a tagged IL-18 receptor complex be used to track receptor trafficking? | Knock-in of fluorescent or epitope tags at endogenous loci |
| Does overexpression of IL-18RAP enhance ROS production in SLE neutrophils? | CRISPR activation or lentiviral overexpression in neutrophil-like cells |
| What is the role of IL-18BP in tumor immune evasion? | IL18BP knockout in mouse tumor models or human cancer cell lines |
| Can soluble IL-18 receptor complex be used as a biomarker? | ELISA-based detection in patient serum samples |
How to Study the interleukin-18 receptor complex Process
| Method | What It Measures | Typical Application |
|---|---|---|
| CRISPR knockout | Loss of IL18R1 or IL18RAP function | Determine requirement for IL-18 signaling in immune cells |
| CRISPR knock-in | Introduction of point mutations or tags | Study disease variants or track receptor localization |
| RNA-seq | Transcriptional changes upon IL-18 stimulation | Identify downstream target genes and pathways |
| Immunoprecipitation-mass spectrometry | Protein-protein interactions of the receptor complex | Discover novel signaling components |
| Flow cytometry | Surface expression of IL-18R1 and IL-18RAP | Profile receptor levels on immune cell subsets |
| ELISA | Soluble IL-18 receptor complex concentration | Biomarker detection in rheumatoid arthritis |
| Live-cell imaging | Receptor internalization and trafficking | Visualize dynamic receptor complex behavior |
| Multiplex cytokine profiling | IL-18, IL-18BP, and related cytokines | Assess pathway activity in patient samples |
CRISPR Knockout and Knock-in Models
CRISPR-Cas9 genome editing enables the generation of IL18R1 or IL18RAP knockout cell lines and animal models to study loss-of-function phenotypes. Knock-in of disease-associated point mutations or epitope tags allows precise interrogation of receptor function and trafficking. These models are essential for validating the causal role of the interleukin-18 receptor complex in inflammatory diseases.
Transcriptomics and Proteomics
RNA sequencing (RNA-seq) can quantify expression of IL18R1, IL18RAP, and downstream target genes such as IFNG in response to IL-18 stimulation. Proteomic approaches, including immunoprecipitation coupled to mass spectrometry, can identify novel interacting partners of the receptor complex. These methods provide a systems-level view of IL-18 signaling networks.
Flow Cytometry and Imaging
Flow cytometry is used to measure surface expression of IL-18R1 and IL-18RAP on immune cell subsets. Fluorescence microscopy and live-cell imaging can track receptor complex assembly, internalization, and trafficking in real time. These techniques are valuable for studying receptor dynamics in primary cells and cell lines.
Biomarker Detection in Clinical Samples
Enzyme-linked immunosorbent assays (ELISAs) can quantify soluble IL-18 receptor complex in serum and synovial fluid from patients with rheumatoid arthritis and other inflammatory diseases. Multiplex cytokine profiling allows simultaneous measurement of IL-18, IL-18BP, and receptor subunits to assess pathway activity. These methods support clinical research and biomarker validation.
How CRISPR Can Be Used to Study GO:0045092 interleukin-18 receptor complex
Knockout
CRISPR-Cas9 knockout of IL18R1 or IL18RAP completely abolishes interleukin-18 receptor complex function, providing a clean genetic model to test the contribution of IL-18 signaling to inflammatory responses. Knockout cell lines and mice are widely used to validate drug targets and to dissect signaling pathways.
Point Mutation
CRISPR-mediated point mutation knock-in allows the introduction of specific disease-associated variants into the endogenous IL18R1 or IL18RAP loci. This approach is ideal for studying how single nucleotide polymorphisms affect receptor assembly, ligand binding, and downstream signaling.
Knock-in
Knock-in of fluorescent proteins, epitope tags, or reporter genes at the IL18R1 or IL18RAP locus enables real-time tracking of receptor expression and localization in live cells. Tagged knock-in models are valuable for imaging receptor trafficking and for proteomic analysis of the receptor complex.
Overexpression
CRISPR activation (CRISPRa) or lentiviral overexpression can drive high-level expression of IL18RAP or IL18R1 to study gain-of-function phenotypes, such as enhanced ROS production in SLE neutrophils. Overexpression models complement knockout studies by revealing the consequences of receptor hyperactivation.
How EDITGENE Supports interleukin-18 receptor complex Research
Researchers studying interleukin-18 receptor complex-related genes often need to determine whether a candidate gene is causally involved in inflammatory signaling or disease pathogenesis. EDITGENE provides end-to-end CRISPR solutions to generate precisely engineered cell models, enabling rigorous functional validation of IL18R1, IL18RAP, and related pathway components.
Contact EDITGENE today to design your custom CRISPR model for interleukin-18 receptor complex research.
Frequently Asked Questions About interleukin-18 receptor complex
What is the interleukin-18 receptor complex?
The interleukin-18 receptor complex (GO:0045092) is a cell surface protein complex that binds interleukin-18 and consists of an alpha subunit (IL-18R1) and a beta subunit (IL-18RAP). It mediates inflammatory signaling.
What genes are involved in the interleukin-18 receptor complex?
The core genes are IL18R1 (alpha subunit) and IL18RAP (beta subunit). Other pathway genes include IL18, IL18BP, MYD88, IRAK1, IRAK4, TRAF6, and NFKB1.
What diseases are associated with the interleukin-18 receptor complex?
It is implicated in rheumatoid arthritis, systemic lupus erythematosus, gout, cancer, and neuroinflammatory conditions.
How is the interleukin-18 receptor complex regulated?
It is regulated by IL-18BP, which acts as a decoy, and by negative regulators like SIGIRR and TOLLIP. Soluble receptor forms can also modulate signaling.
What is the role of IL-18BP in IL-18 signaling?
IL-18BP is a secreted protein that binds IL-18 and prevents it from activating the interleukin-18 receptor complex, acting as an immune checkpoint.
Can the interleukin-18 receptor complex be used as a biomarker?
Yes, soluble IL-18 receptor complex levels are elevated in rheumatoid arthritis and correlate with disease activity, suggesting biomarker potential.
How can CRISPR be used to study the interleukin-18 receptor complex?
CRISPR knockout of IL18R1 or IL18RAP abolishes receptor function, while knock-in of point mutations or tags allows precise functional studies.
What cell models are available for IL-18 receptor research?
Common models include THP-1, primary T cells, NK cells, and neutrophil-like cell lines, which can be engineered using CRISPR.
What is the structure of the interleukin-18 receptor complex?
It is a heterodimer composed of IL-18R1 and IL-18RAP, both belonging to the IL-1 receptor family. Structural transitions in IL-18 enable receptor assembly and signaling.
Why is the interleukin-18 receptor complex important in cancer?
IL-18 signaling through the receptor complex promotes anti-tumor immunity, but tumors can evade it by upregulating IL-18BP. Blocking IL-18BP enhances immunotherapy.
Conclusion
The interleukin-18 receptor complex (GO:0045092) is a critical mediator of IL-18 signaling, with essential roles in innate and adaptive immunity, inflammation, and disease. Its heterodimeric structure, comprising IL-18R1 and IL-18RAP, enables specific ligand binding and activation of NF-kB and MAPK pathways. Dysregulation of this complex is linked to rheumatoid arthritis, lupus, gout, and cancer, making it a prime target for therapeutic intervention. Advances in CRISPR genome editing and structural biology are accelerating our understanding of the receptor complex and its role in health and disease. EDITGENE's comprehensive CRISPR services, including knockout, knock-in, point mutation, and overexpression models, empower researchers to dissect IL-18 receptor biology and develop novel therapeutics.
References
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