GO:1990604 IRE1-TRAF2-ASK1 complex: Components, Assembly and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:1990604 defines the IRE1-TRAF2-ASK1 complex, an endoplasmic reticulum membrane protein complex consisting of IRE1 (ERN1), TRAF2, and ASK1 (MAP3K5).
• This complex links ER stress to JNK activation and apoptosis, and is essential for ER stress-induced neuronal cell death triggered by expanded polyglutamine repeats.
• The IRE1-TRAF2-ASK1-JNK pathway can be activated by pharmacological agents such as ketamine in rat and SV-HUC-1 cells.
• Ursolic acid induces ER stress and activates ASK1-JNK signaling to trigger apoptosis in human bladder cancer T24 cells.
• The complex is a cellular component (ontology aspect: cellular_component) with the synonym ERN1-TRAF2-ASK1 complex.
• Research on this complex uses CRISPR knockout, point mutation, knock-in, overexpression, and pathway-specific inhibitors to dissect its role in disease models.
Description
The IRE1-TRAF2-ASK1 complex (GO:1990604) is a protein complex of the endoplasmic reticulum (ER) membrane that consists of IRE1 (inositol-requiring enzyme-1), TRAF2 (TNF receptor-associated factor 2), and ASK1 (apoptosis signal-regulating kinase 1, a MAP3K). This complex is a key node linking ER stress to downstream MAP kinase signaling, particularly the activation of JNK and apoptotic cell death. The assembly of this complex is triggered by ER stress and is essential for ER stress-induced neuronal cell death triggered by expanded polyglutamine repeats, as demonstrated in ASK1-deficient models. Beyond neurodegeneration, the IRE1-TRAF2-ASK1-JNK pathway is activated by ketamine in rat and SV-HUC-1 cells, where it enhances autophagy and ER stress. In human bladder cancer T24 cells, ursolic acid induces ER stress and activates ASK1-JNK signaling to induce apoptosis. These findings establish the IRE1-TRAF2-ASK1 complex as a critical signaling hub in ER stress-related pathologies, making it a target for mechanistic studies and therapeutic intervention.
IRE1-TRAF2-ASK1 complex At A Glance
| GO ID | GO:1990604 |
|---|---|
| GO term | IRE1-TRAF2-ASK1 complex |
| Ontology | cellular_component |
| Synonym | ERN1-TRAF2-ASK1 complex |
| Major function | Links ER stress to JNK activation and apoptosis via ASK1-MAP3K signaling |
| Complex components | IRE1 (ERN1), TRAF2, ASK1 (MAP3K5) |
| Subcellular location | Endoplasmic reticulum membrane |
| Pathway context | IRE1-TRAF2-ASK1-JNK pathway |
| Disease relevance | Neurodegeneration (polyglutamine diseases), cancer (bladder cancer), ER stress-related pathologies |
What Is GO:1990604?
According to the QuickGO definition, GO:1990604 (IRE1-TRAF2-ASK1 complex) is a protein complex of the endoplasmic reticulum membrane that consists of IRE1 (Inositol-requiring enzyme-1), TRAF2 (TNF receptor-associated factor 2) and ASK1 (Apoptosis signal-regulating kinase 1, a MAP3K). Its synonym is ERN1-TRAF2-ASK1 complex. In simpler terms, it is a three-protein machine on the ER membrane that transmits stress signals from the ER to the cell death machinery.
Why Is IRE1-TRAF2-ASK1 complex Important in Cell Biology?
The IRE1-TRAF2-ASK1 complex is important because it provides a direct molecular link between ER stress and the activation of ASK1-JNK signaling, a pathway that controls cell fate decisions such as apoptosis and autophagy. Its essential role in ER stress-induced neuronal cell death triggered by expanded polyglutamine repeats highlights its contribution to neurodegenerative diseases. In cancer, activation of this complex by agents such as ursolic acid leads to apoptosis in bladder cancer cells, suggesting therapeutic potential. Moreover, the complex is activated by ketamine in rat and SV-HUC-1 cells, indicating its involvement in drug-induced ER stress and autophagy. Understanding this complex is therefore critical for developing interventions in neurodegeneration, cancer, and other ER stress-related conditions.
• Links ER stress to JNK-mediated apoptosis via ASK1.
• Essential for ER stress-induced neuronal cell death in polyglutamine repeat diseases.
• Activated by ketamine, enhancing autophagy and ER stress in rat and SV-HUC-1 cells.
• Mediates ursolic acid-induced apoptosis in human bladder cancer T24 cells.
• Serves as a signaling hub for MAP3K ASK1 activation on the ER membrane.
• Potential therapeutic target in neurodegeneration and cancer.
• Involved in drug-induced ER stress responses.
• Provides a model for studying ER-membrane-associated signaling complexes.
• Relevant to autophagy regulation under ER stress.
• Enables dissection of IRE1-dependent versus IRE1-independent ER stress pathways.
What Happens During IRE1-TRAF2-ASK1 complex?
ER Stress Sensing and Complex Assembly
In simple terms: When the ER gets stressed, IRE1 on the ER membrane recruits TRAF2 and ASK1 to form a signaling complex.
Under ER stress, IRE1 (ERN1) present on the endoplasmic reticulum membrane undergoes activation and serves as a scaffold for the assembly of the IRE1-TRAF2-ASK1 complex. TRAF2 and ASK1 are recruited to IRE1, forming a tripartite complex that is essential for transmitting stress signals. This assembly is a prerequisite for downstream ASK1 activation and JNK phosphorylation.
ASK1 Activation and JNK Phosphorylation
In simple terms: Once assembled, ASK1 becomes active and turns on JNK, a stress-activated kinase that can trigger cell death.
Within the IRE1-TRAF2-ASK1 complex, ASK1 (a MAP3K) is activated, leading to the phosphorylation and activation of downstream MAP kinases, particularly JNK. This IRE1-TRAF2-ASK1-JNK pathway is a key mediator of ER stress-induced apoptosis. The activation of JNK by this complex has been demonstrated in various cellular contexts, including neuronal cells challenged with expanded polyglutamine repeats.
Downstream Apoptotic Signaling
In simple terms: Activated JNK then triggers apoptosis, a form of programmed cell death.
Activation of the IRE1-TRAF2-ASK1-JNK pathway leads to apoptotic cell death in response to ER stress. This apoptotic signaling is essential for ER stress-induced neuronal cell death triggered by expanded polyglutamine repeats, as ASK1 deficiency abolishes this response. In human bladder cancer T24 cells, ursolic acid-induced ER stress activates ASK1-JNK signaling and induces apoptosis.
Autophagy Modulation
In simple terms: The same pathway can also enhance autophagy, a cellular recycling process, under certain conditions.
Ketamine has been shown to enhance autophagy and ER stress in rats and SV-HUC-1 cells via activating the IRE1-TRAF2-ASK1-JNK pathway. This indicates that the complex can modulate autophagic responses in addition to apoptotic signaling. The dual role in apoptosis and autophagy highlights the complexity of downstream outcomes.
Key Genes Involved in GO:1990604 IRE1-TRAF2-ASK1 complex
The key genes and proteins involved in the IRE1-TRAF2-ASK1 complex are listed below, with their major roles and research relevance.
| Gene | Major Role | Research Relevance |
|---|---|---|
| ERN1 (IRE1) | ER membrane sensor and scaffold for complex assembly | Central to ER stress signaling; target for knockout and knockdown studies |
| TRAF2 | Adaptor protein recruiting ASK1 to IRE1 | Mediates complex formation; studied via overexpression and mutagenesis |
| MAP3K5 (ASK1) | MAP3K that activates JNK | Essential for ER stress-induced apoptosis; knockout models available |
| MAPK8 (JNK1) | Downstream kinase phosphorylated by ASK1 | Readout of pathway activation; used in phospho-JNK assays |
| MAPK9 (JNK2) | Downstream kinase phosphorylated by ASK1 | Readout of pathway activation; used in phospho-JNK assays |
| MAPK10 (JNK3) | Neuronal JNK isoform | Implicated in neuronal apoptosis; studied in neurodegeneration models |
| ATF4 | Transcription factor in integrated stress response | Often co-analyzed with ER stress markers |
| DDIT3 (CHOP) | Pro-apoptotic transcription factor | Marker of ER stress-induced apoptosis |
| HSPA5 (BiP) | ER chaperone and stress sensor | Marker of ER stress; used in Western blots |
| XBP1 | Transcription factor downstream of IRE1 | Splicing target; distinguishes IRE1 branches |
| TNF | Cytokine that can activate TRAF2 | Context for TRAF2 signaling |
| TRAF6 | Related adaptor with similar domain | Comparative studies of TRAF family |
| MAP3K7 (TAK1) | Related MAP3K | Cross-talk with ASK1 pathways |
| CASP3 | Executioner caspase | Apoptosis readout |
| CASP9 | Initiator caspase | Apoptosis readout |
| BCL2 | Anti-apoptotic protein | Modulator of apoptosis |
| BAX | Pro-apoptotic protein | Modulator of apoptosis |
| SQSTM1 (p62) | Autophagy receptor | Autophagy readout |
How Is IRE1-TRAF2-ASK1 complex Regulated?
The IRE1-TRAF2-ASK1 complex is regulated at multiple levels. Its assembly is triggered by ER stress, which activates IRE1 and promotes recruitment of TRAF2 and ASK1. The activity of ASK1 within the complex is controlled by phosphorylation and protein-protein interactions. Downstream, JNK activation can be modulated by phosphatases and scaffold proteins. In addition, pharmacological agents such as ketamine can enhance the pathway, leading to increased autophagy and ER stress. Ursolic acid also activates ASK1-JNK signaling in cancer cells. These regulatory inputs determine cell fate decisions between survival, autophagy, and apoptosis.
IRE1-TRAF2-ASK1 complex and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| MAP3K5 (ASK1) | Polyglutamine-induced neurodegeneration | ASK1 knockout mice and neuronal cell lines |
| ERN1 (IRE1) | ER stress-related neurodegeneration | IRE1 knockout or knockdown in neurons |
| TRAF2 | ER stress-induced apoptosis | TRAF2 knockout or overexpression cells |
| MAPK8/9/10 (JNK) | Neuronal apoptosis | JNK knockout mice and phospho-JNK assays |
| DDIT3 (CHOP) | Bladder cancer apoptosis | T24 cells treated with ursolic acid |
Neurodegenerative Diseases
The IRE1-TRAF2-ASK1 complex is essential for ER stress-induced neuronal cell death triggered by expanded polyglutamine repeats, which are characteristic of polyglutamine diseases such as Huntington's disease and spinocerebellar ataxias. ASK1 deficiency abolishes this cell death, highlighting the complex as a therapeutic target in neurodegeneration.
Cancer
In human bladder cancer T24 cells, ursolic acid induces ER stress and activates ASK1-JNK signaling, leading to apoptosis. This suggests that the IRE1-TRAF2-ASK1 complex can be exploited to induce cell death in cancer cells. Conversely, the complex may contribute to chemoresistance in some contexts, warranting further study.
Drug-Induced ER Stress and Autophagy
Ketamine enhances autophagy and ER stress in rats and SV-HUC-1 cells via activating the IRE1-TRAF2-ASK1-JNK pathway. This links the complex to drug-induced cellular stress responses and potential urological effects.
From IRE1-TRAF2-ASK1 complex-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does ASK1 mediate ER stress-induced neuronal death? | ASK1 knockout mice and primary neurons |
| Is IRE1 required for complex assembly? | IRE1 knockout cell lines |
| Does TRAF2 recruit ASK1 to IRE1? | TRAF2 knockout or point-mutant cells |
| Can the complex be activated by ketamine? | Rat models and SV-HUC-1 cells |
| Does ursolic acid induce apoptosis via ASK1-JNK? | Human bladder cancer T24 cells |
| What is the role of JNK downstream of the complex? | JNK knockout or inhibitor-treated cells |
How to Study the IRE1-TRAF2-ASK1 complex Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Co-IP | Protein-protein interactions | Detect IRE1-TRAF2-ASK1 assembly |
| Western blot | Protein levels and phosphorylation | Measure ASK1 and JNK activation |
| CRISPR knockout | Gene function loss | Test requirement of ERN1, TRAF2, MAP3K5 |
| RNAi knockdown | Gene function reduction | Transient silencing of pathway components |
| RNA-seq | Transcriptome changes | Identify ER stress and autophagy genes |
| Phospho-proteomics | Kinase substrate profiling | Map JNK substrates |
| Immunofluorescence | Subcellular localization | Visualize complex at ER membrane |
| Autophagy flux assay | Autophagic activity | Measure LC3 turnover after ketamine |
Co-Immunoprecipitation and Western Blotting
Co-immunoprecipitation (co-IP) is used to detect the physical interaction between IRE1, TRAF2, and ASK1 in the IRE1-TRAF2-ASK1 complex. Western blotting with phospho-specific antibodies measures activation of ASK1 and JNK. These methods are standard for validating complex assembly and downstream signaling.
Gene Knockout and Knockdown
Knockout or knockdown of ERN1, TRAF2, or MAP3K5 using CRISPR or RNAi is used to test the requirement of each component for ER stress-induced apoptosis. ASK1-deficient models have demonstrated the essential role of ASK1 in polyglutamine-induced neuronal death.
Pharmacological Modulation
Small molecules such as ketamine and ursolic acid are used to activate the IRE1-TRAF2-ASK1-JNK pathway in cell and animal models. These agents help dissect the pathway's role in autophagy and apoptosis.
Transcriptomic and Proteomic Profiling
RNA-seq and proteomics can identify global changes in gene expression and protein phosphorylation downstream of the complex. Such approaches reveal autophagy and apoptosis signatures.
How CRISPR Can Be Used to Study GO:1990604 IRE1-TRAF2-ASK1 complex
Knockout
CRISPR knockout of ERN1, TRAF2, or MAP3K5 can abolish IRE1-TRAF2-ASK1 complex formation and downstream JNK activation. Such models are essential to establish causality in ER stress-induced apoptosis.
Point Mutation
Point mutations can be introduced into key domains of IRE1, TRAF2, or ASK1 to disrupt specific interactions or catalytic activity. For example, mutation of ASK1 kinase domain can prevent JNK activation while preserving complex assembly.
Knock-in
Knock-in of tagged versions (e.g., FLAG, HA) of IRE1, TRAF2, or ASK1 allows endogenous complex purification and imaging. This approach preserves physiological expression levels.
Overexpression
Overexpression of wild-type or mutant components can amplify pathway activation and facilitate biochemical studies. However, overexpression may cause artifacts, so results should be validated with endogenous models.
How EDITGENE Supports IRE1-TRAF2-ASK1 complex Research
Researchers studying IRE1-TRAF2-ASK1 complex-related genes often need to determine whether a candidate gene is causally involved in ER stress signaling, apoptosis, or autophagy. EDITGENE provides a comprehensive suite of CRISPR services to enable such functional studies with precision and reproducibility.
Contact EDITGENE today to design your custom CRISPR model for IRE1-TRAF2-ASK1 complex research.
Frequently Asked Questions About IRE1-TRAF2-ASK1 complex
What is the IRE1-TRAF2-ASK1 complex?
It is a protein complex on the endoplasmic reticulum membrane consisting of IRE1, TRAF2, and ASK1, which links ER stress to JNK activation and apoptosis.
What genes are involved in the IRE1-TRAF2-ASK1 complex?
The core genes are ERN1 (IRE1), TRAF2, and MAP3K5 (ASK1), with downstream MAPK8/9/10 (JNK).
What is the function of GO:1990604?
GO:1990604 defines the IRE1-TRAF2-ASK1 complex, a cellular component that mediates ER stress-induced ASK1-JNK signaling.
How is the IRE1-TRAF2-ASK1 complex activated?
It is activated by ER stress, which triggers IRE1 to recruit TRAF2 and ASK1, leading to ASK1 activation and JNK phosphorylation.
What diseases are associated with the IRE1-TRAF2-ASK1 complex?
It is implicated in neurodegenerative diseases such as polyglutamine disorders and in cancers like bladder cancer.
Can ketamine affect the IRE1-TRAF2-ASK1 complex?
Yes, ketamine enhances autophagy and ER stress via activating the IRE1-TRAF2-ASK1-JNK pathway in rats and SV-HUC-1 cells.
Does ursolic acid target the IRE1-TRAF2-ASK1 complex?
Ursolic acid induces ER stress and activates ASK1-JNK signaling, leading to apoptosis in human bladder cancer T24 cells.
What experimental models are used to study this complex?
Common models include ASK1 knockout mice, IRE1 or TRAF2 knockout cells, and cancer cell lines treated with pharmacological agents.
How can CRISPR help study the IRE1-TRAF2-ASK1 complex?
CRISPR knockout, point mutation, knock-in, and overexpression enable precise dissection of each component's role in the complex.
What methods detect IRE1-TRAF2-ASK1 complex activity?
Co-IP, Western blot for phospho-JNK, RNA-seq, and autophagy flux assays are commonly used.
Conclusion
The IRE1-TRAF2-ASK1 complex (GO:1990604) is a critical ER membrane signaling hub that connects ER stress to JNK-mediated apoptosis and autophagy. Its essential role in polyglutamine-induced neurodegeneration and its activation in cancer cells make it a compelling target for therapeutic intervention. Continued research using advanced CRISPR models and multi-omics approaches will further elucidate its mechanisms and disease relevance.
References
- 1. Yu Y et al.. 2021. Ketamine enhances autophagy and endoplasmic reticulum stress in rats and SV-HUC-1 cells via activating IRE1-TRAF2-ASK1-JNK pathway.. Cell Cycle 20(18):1907-1922 PMID: 34427546
- 2. Nishitoh H et al.. 2002. ASK1 is essential for endoplasmic reticulum stress-induced neuronal cell death triggered by expanded polyglutamine repeats.. Genes Dev 16(11):1345-55 PMID: 12050113
- 3. Zheng QY et al.. 2013. Ursolic acid induces ER stress response to activate ASK1-JNK signaling and induce apoptosis in human bladder cancer T24 cells.. Cell Signal 25(1):206-13 PMID: 23000344
