ire-1 Antibody

What is IRE1 and why is it important in cellular stress research?

IRE1 (Inositol-Requiring Enzyme 1) is a transmembrane protein kinase/endoribonuclease that serves as a key sensor in the unfolded protein response (UPR). It localizes to the endoplasmic reticulum (ER) membrane and plays a critical role in ER stress signaling. Upon activation, IRE1 initiates both protective and apoptotic signaling pathways, making it crucial for understanding cellular responses to various stressors. Its importance extends to research on metabolic disorders, inflammation, and neurodegenerative diseases where ER stress is a common feature .

The most conserved ER-resident UPR regulator, IRE1, becomes activated in lipid-laden macrophages that infiltrate atherosclerotic lesions, highlighting its importance in metaflammation (metabolically induced chronic low-grade inflammation) . Understanding IRE1 function provides insights into fundamental cellular processes and potential therapeutic interventions for numerous pathological conditions.

How do I select the appropriate IRE1 antibody for my experiments?

Selection of an appropriate IRE1 antibody depends on several experimental factors:

• Target species and reactivity: Confirm the antibody's validated reactivity with your experimental model (human, mouse, rat, etc.). For example, the NB100-2324 antibody has been validated in human, mouse, and rat samples .

• Application compatibility: Choose an antibody validated for your specific application:

  • Western blot (recommended dilution 1:1000-1:2000)

  • Immunohistochemistry (recommended dilution 1:250-1:500)

  • Immunocytochemistry/Immunofluorescence (recommended dilution 1:100-1:250)

• Total vs. phospho-specific detection: Determine whether you need to detect total IRE1 or phosphorylated IRE1. For detecting phospho-IRE1 Alpha (Ser-724), specialized antibodies like NB100-2323 are recommended .

• Format requirements: Consider whether you need unconjugated antibodies or those with specific labels for your detection method.

• Validation data: Review knockout/knockdown validation data to ensure specificity and minimize non-specific binding issues .

What are the typical dilutions and protocols for IRE1 antibody use in Western blot analyses?

For optimal Western blot results with IRE1 alpha antibody:

• Sample preparation:

  • Thoroughly lyse cells in RIPA buffer with protease and phosphatase inhibitors

  • Centrifuge lysates at 14,000g for 15 minutes at 4°C

  • Collect supernatant and determine protein concentration

• Recommended dilutions:

  • Primary antibody (IRE1 alpha): 1:1000-1:2000

  • Secondary antibody: Follow manufacturer's recommendations (typically 1:5000-1:10000)

• Protocol notes:

  • Expected molecular weight: ~110 kDa (may vary due to post-translational modifications)

  • Include positive controls (cell lines known to express IRE1)

  • For phospho-specific analysis, normalize phospho-IRE1 alpha band intensity with total-IRE1 alpha

  • For studying phosphorylation states, phosphatase inhibitors are essential

• Detection considerations:

  • ECL detection works effectively for IRE1 alpha

  • Extended exposure may be necessary for low-expressing samples

Remember that observed molecular weight may differ from the theoretical 110 kDa due to post-translational modifications, cleavages, and relative charges .

How can I effectively detect IRE1 phosphorylation states, and what is their significance?

Detecting IRE1 phosphorylation requires specific methodologies and interpretive frameworks:

Detection methods:

• Phospho-specific antibodies: For IRE1 alpha phosphorylation at Ser-724, use phospho-specific antibodies like NB100-2323 . For S729 phosphorylation, specialized anti-phospho-S729 antibodies are required .

• Mobility shift assays: Phosphorylation induces a detectable molecular weight shift during SDS-PAGE analysis. This can be confirmed by treating immunoprecipitated IRE1 with λ protein phosphatase (λPPase) to reverse the shift .

• Mass spectrometry validation: LC-MS/MS analysis of immunoprecipitated IRE1 can precisely identify phosphorylated residues, as demonstrated in studies that identified S729 phosphorylation .

Significance of phosphorylation states:

• S729 phosphorylation is critical for enhancing XBP1 mRNA splicing and engaging regulated IRE1-dependent decay (RIDD)

• Phosphorylation states correlate with IRE1 activation status and downstream signaling efficiency

• Different phosphorylation patterns may redirect IRE1 signaling toward specific pathways

• Monitoring phosphorylation dynamics provides insights into the temporal regulation of UPR signaling

For quantitative analysis, normalize phospho-IRE1 band intensity with total IRE1 levels to account for expression variations across samples .

What are the best approaches for studying IRE1-dependent regulation of gene expression?

To effectively study IRE1-dependent gene regulation:

Experimental approaches:

• RNA sequencing in IRE1-manipulated models:

  • Perform RNA-seq on cells/tissues with IRE1 inhibition, knockout, or hyperactivation

  • This approach has revealed IRE1's regulation of many proatherogenic genes, including cytokines and chemokines like IL-1β and CCL2

• XBP1 splicing analysis:

  • Monitor XBP1 mRNA splicing via RT-PCR with primers flanking the splice site

  • Quantify the unspliced and spliced XBP1 mRNA ratio as a direct measure of IRE1 RNase activity

• RIDD target identification:

  • Compare mRNA levels of candidate RIDD targets in IRE1-deficient versus proficient cells

  • Focus on ER-localized mRNAs that decrease during ER stress in an IRE1-dependent manner

• Reporter systems:

  • Employ UPRE-lacZ reporters to monitor IRE1 activity in various conditions

  • This approach allows high-resolution monitoring of IRE1-suppressing elements and mutations

Data interpretation considerations:

• Distinguish between XBP1-dependent and XBP1-independent effects by including XBP1-deficient controls

• Consider temporality, as early and late IRE1 responses may have different transcriptional outputs

• Account for cell-type specificity, as IRE1 function varies significantly across tissues

What experimental controls are essential when using IRE1 antibodies in immunoprecipitation studies?

Rigorous immunoprecipitation (IP) studies with IRE1 antibodies require several critical controls:

• Input controls:

  • Always include an aliquot (5-10%) of the pre-IP lysate to confirm target protein expression

  • This validates that observed differences aren't due to varying starting material

• Negative controls:

  • IgG control: Use species-matched non-specific IgG to identify non-specific binding

  • IRE1 knockdown/knockout lysates: Essential to confirm antibody specificity

  • Competing peptide: Pre-incubate antibody with the immunizing peptide to block specific binding

• Positive controls:

  • ER stress induction: Treat cells with tunicamycin or thapsigargin to increase IRE1 activation

  • Overexpression system: Include lysates from cells overexpressing tagged IRE1

• Technical validation:

  • Phosphatase treatment: When studying phosphorylation, include λPPase-treated samples to confirm phospho-specific shifts

  • Reciprocal IP: For protein-protein interactions, perform reverse IP with antibodies against the interacting partner

• Downstream verification:

  • Western blot analysis of IP fractions using different IRE1 antibodies (targeting different epitopes)

  • Mass spectrometry validation of immunoprecipitated proteins

In pulse-chase experiments coupled with IRE1 immunoprecipitation, researchers have effectively demonstrated phosphorylation-induced molecular weight shifts that were reversible by λPPase treatment .

How can I troubleshoot weak or non-specific IRE1 antibody signals in Western blot?

Common issues with IRE1 detection and their solutions:

For detecting phosphorylated IRE1, remember that observed molecular weight may be higher than the predicted 110 kDa due to phosphorylation-induced mobility shifts .

What are the considerations for using IRE1 antibodies in studying IRE1 activation in disease models?

When using IRE1 antibodies to study disease models:

• Model-specific validation:

  • Validate antibody specificity in your specific disease model

  • For atherosclerosis studies, confirm reactivity in lipid-laden macrophages

  • In B cell studies, verify detection in both resting and activated states

• Activation state assessment:

  • Use both total and phospho-specific antibodies to distinguish between expression and activation

  • Consider additional activation markers like XBP1 splicing

  • For comprehensive analysis, combine antibody-based detection with functional assays

• Tissue/cell-specific considerations:

  • Optimize extraction protocols for different tissues (brain vs. liver vs. immune cells)

  • Account for tissue-specific IRE1 expression levels

  • Consider cell-type heterogeneity within tissues

• Temporal dynamics:

  • Design time-course experiments to capture transient activation events

  • Account for adaptation and feedback mechanisms in chronic disease models

• Comparative analyses:

  • Include both affected and non-affected tissues/regions

  • Compare disease models with different severities

  • Include age-matched controls for age-related diseases

In atherosclerosis research, IRE1 antibody staining has revealed increased IRE1 protein levels in neointima in situ, while phospho-specific antibodies have helped track IRE1 activation status in inflammatory contexts .

How can IRE1 antibodies be optimized for immunofluorescence and immunohistochemistry applications?

Optimizing IRE1 antibodies for microscopy-based applications requires attention to several parameters:

• Fixation optimization:

  • For paraffin sections: Test both heat-mediated and enzymatic antigen retrieval methods

  • For frozen sections and cultured cells: Compare 4% paraformaldehyde, methanol, and acetone fixation

  • Fixation time can significantly impact epitope accessibility

• Dilution optimization:

  • For immunocytochemistry/immunofluorescence: Start with 1:100-1:250 dilution

  • For immunohistochemistry (paraffin): Begin with 1:250-1:500 dilution

  • Always perform a dilution series to determine optimal signal-to-noise ratio

• Signal enhancement strategies:

  • Consider tyramide signal amplification for low-abundance detection

  • For co-localization studies, use high-quality confocal microscopy

  • Z-stack imaging helps confirm true co-localization versus overlapping signals

• Controls for microscopy:

  • IRE1 knockout/knockdown samples are essential negative controls

  • Include ER stress-induced samples as positive controls

  • Use co-staining with ER markers (calnexin, PDI) to confirm expected localization

• Interpretation guidelines:

  • IRE1 predominantly localizes to the endoplasmic reticulum

  • Upon activation, IRE1 forms clusters visible as punctate structures

  • Quantify signal intensity, distribution patterns, and co-localization with other markers

For studying IRE1 in tissue sections, researchers have successfully used IHC to analyze IRE1 protein levels in carotid artery sections, demonstrating increased IRE1α protein levels in neointima in situ .

How can I effectively study IRE1 activation in relation to inflammasome function using antibody-based approaches?

IRE1's role in inflammasome activation can be effectively studied using coordinated antibody-based approaches:

• Sequential detection strategy:

  • First, assess IRE1 activation status using phospho-specific antibodies

  • Then examine inflammasome components (NLRP3, ASC, pro-caspase-1)

  • Finally, detect mature inflammatory cytokines (IL-1β, IL-18)

• Co-immunoprecipitation approaches:

  • Use IRE1 antibodies to immunoprecipitate protein complexes

  • Probe for inflammasome components in the precipitates

  • Investigate adaptor proteins that might link IRE1 signaling to inflammasome activation

• Proximity ligation assays (PLA):

  • Apply PLA to detect close associations between IRE1 and inflammasome components

  • This technique can reveal transient or weak interactions that traditional co-IP might miss

• Intervention studies:

  • Combine antibody detection with IRE1 inhibitors like STF-083010

  • Monitor both IRE1 phosphorylation status and inflammasome activation markers

  • Correlate IRE1 inhibition with reductions in IL-1β and IL-18 production

Research has shown that IRE1 inhibition blocks NLRP3 inflammasome activation, cleavage of caspase-1, and secretion of IL-1β induced by various stimuli including ATP, Alum, and cholesterol crystals . Importantly, IRE1 inhibition specifically affects the NLRP3 inflammasome without altering other inflammasome complexes such as NLRC4 or AIM2 .

What are the considerations for studying the IRE1-RIDD pathway using antibody-based detection methods?

Studying Regulated IRE1-Dependent Decay (RIDD) using antibody-based approaches requires specific methodological considerations:

• Experimental design framework:

  • Compare IRE1-deficient versus XBP1-deficient systems to isolate RIDD effects

  • Use S729 phosphorylation as a marker for RIDD activation

  • Combine antibody detection with mRNA stability measurements

• Key detection targets:

  • IRE1 phosphorylation status (especially S729)

  • Total IRE1 protein levels and oligomerization state

  • RIDD target proteins (to confirm mRNA degradation leads to protein reduction)

  • XBP1s levels (to distinguish XBP1 splicing from RIDD activity)

• Technical approach optimization:

  • Use pulse-chase experiments with IRE1 immunoprecipitation to track phosphorylation dynamics

  • Combine with phosphatase treatments to confirm post-translational modifications

  • Implement subcellular fractionation to enrich for ER-associated IRE1

• Validation strategies:

  • Confirm antibody specificity using B cell-specific XBP1 knockout models

  • Verify RIDD activity using targeted RT-qPCR of known RIDD substrates

  • Use mass spectrometry to identify phosphorylation sites with precision

Research has demonstrated that S729 phosphorylation of IRE1 is critical for enhancing XBP1 mRNA splicing and engaging RIDD in cultured B cells and plasma cells in immunized mice . Custom phospho-specific antibodies against S729 have been valuable tools for monitoring this regulatory mechanism .

How can I integrate IRE1 antibody-based detection with functional assays to comprehensively assess UPR activation?

An integrated approach to UPR assessment combines antibody detection with functional readouts:

• Multi-parameter assessment framework:

  Parameter	Antibody Detection	Functional Assay
  IRE1 activation	Anti-phospho-IRE1	XBP1 splicing RT-PCR
  RIDD activity	IRE1 S729 phosphorylation	mRNA decay of RIDD targets
  UPR output	XBP1s protein detection	UPRE-lacZ reporter assay
  ER stress severity	BiP/GRP78 upregulation	ATF6 cleavage analysis
  Inflammatory response	IL-1β protein levels	Inflammasome assembly assay

• Sequential analytical approach:

  • Begin with non-invasive reporter systems (UPRE-lacZ)

  • Follow with protein-level detection via Western blot

  • Confirm with mRNA-level analysis of UPR targets

  • Validate with functional outcomes specific to your research context

• Advanced integration strategies:

  • Time-course analysis capturing both early and late UPR events

  • Dose-response studies with ER stressors to establish activation thresholds

  • Genetic manipulation (IRE1 mutants) combined with antibody detection

  • Pharmacological intervention with IRE1 inhibitors coupled with readouts

• Contextual interpretation:

  • Consider cell-type specific UPR signatures

  • Account for cross-talk between UPR branches

  • Correlate molecular markers with functional/phenotypic outcomes

Research has shown that mutations in IRE1's regulatory domains (like Subregion I of the NUCR) can significantly alter its activity, which can be detected through both antibody-based methods and functional UPRE-lacZ reporter assays . This integrated approach provides robust validation of IRE1 activity states.

How can I use IRE1 antibodies to investigate the role of IRE1 in tissue-specific disease pathology?

To effectively investigate tissue-specific IRE1 functions in disease:

• Tissue optimization strategy:

  • Adapt extraction protocols for tissue-specific components

  • Optimize antibody concentrations for different tissues (brain tissue may require higher concentrations)

  • For atherosclerosis research, focus on aortic root lesions and macrophage-rich regions

• Comparative tissue analysis:

  • Compare IRE1 activation across multiple tissues in the same disease model

  • For atherosclerosis, examine both plaque regions and healthy vessel areas

  • In metabolic disorders, compare liver, adipose tissue, and pancreatic islets

• Cell-type resolution approaches:

  • Combine IRE1 antibody staining with cell-type markers

  • For atherosclerotic lesions, co-stain with macrophage markers (CD68)

  • Use laser capture microdissection to isolate specific cell populations for analysis

• Intervention assessment:

  • Track changes in IRE1 phosphorylation following therapeutic interventions

  • In atherosclerosis models, monitor effects of IRE1 inhibitors on plaque IRE1 activity

  • Correlate IRE1 activity changes with disease progression markers

Research has demonstrated that IRE1 inhibitor treatment reduced IL-1β expression in aortic root lesions of atherosclerotic mice, establishing a link between IRE1 activity and disease progression . Additionally, researchers have used IRE1 antibodies to detect increased IRE1 protein levels in neointima in carotid artery sections , showing the utility of these approaches in tissue-specific contexts.

What considerations are important when using IRE1 antibodies in challenging experimental systems like primary cells or patient samples?

Working with primary cells and patient samples introduces several challenges for IRE1 antibody applications:

• Sample preservation and handling:

  • For patient biopsies, optimize preservation methods to maintain epitopes

  • Process tissues rapidly to prevent artifactual UPR activation

  • For primary B cells and macrophages, minimize activation during isolation

• Limited material strategies:

  • Implement protein concentration methods for small samples

  • Consider signal amplification techniques for IHC/IF in limited biopsies

  • Adapt protocols for micro-scale Western blotting

• Heterogeneity management:

  • Account for patient-to-patient variability in baseline IRE1 expression

  • Include larger sample sizes to overcome intrinsic variability

  • Consider single-cell approaches when feasible

• Validation requirements:

  • Always include appropriate positive controls (stress-induced cell lines)

  • When possible, validate findings in matched cell lines or animal models

  • For patient samples, compare with healthy donor-matched tissues/cells

• Interpretation framework:

  • Correlate IRE1 activation with clinical parameters and outcomes

  • Consider confounding factors (medications, comorbidities)

  • Distinguish chronic from acute ER stress signatures

Research with B cell-specific XBP1 knockout mice has shown that careful extraction and immunoprecipitation protocols can successfully detect IRE1 phosphorylation states even in primary B cell populations . These approaches can be adapted for patient-derived samples with appropriate modifications.

How can advanced microscopy techniques enhance IRE1 antibody-based detection in complex cellular contexts?

Advanced microscopy significantly enhances IRE1 antibody applications in complex systems:

• Super-resolution microscopy applications:

  • Structured Illumination Microscopy (SIM) can resolve IRE1 clustering during activation

  • Stochastic Optical Reconstruction Microscopy (STORM) enables visualization of individual IRE1 molecules

  • These techniques can distinguish between diffuse and clustered IRE1 states indicating activation

• Live-cell imaging strategies:

  • Combine antibody fragments with cell-permeable delivery systems

  • Use proximity-based reporters combined with fixed-cell antibody validation

  • Track IRE1 dynamics and correlate with subsequent antibody-based detection

• Multiplex imaging approaches:

  • Implement spectral unmixing for simultaneous detection of multiple UPR components

  • Cyclic immunofluorescence for sequential staining of >10 targets on the same sample

  • Mass cytometry imaging (IMC) for highly multiplexed protein detection in tissues

• Correlative microscopy methods:

  • Combine light microscopy with electron microscopy to correlate IRE1 localization with ER ultrastructure

  • Use cryoEM techniques to visualize IRE1 clustering at molecular resolution

  • Validate with immunogold labeling using IRE1 antibodies

• Quantitative image analysis:

  • Implement machine learning algorithms to quantify IRE1 activation patterns

  • Analyze IRE1 cluster size, intensity, and distribution

  • Correlate spatial organization with functional outcomes

Researchers have used immunohistochemistry with IRE1 antibodies to analyze IRE1α protein levels in arterial sections, revealing differences between wild-type and experimental conditions . These approaches can be enhanced with advanced microscopy methods to provide deeper insights into IRE1 biology in complex tissues.

What emerging applications of IRE1 antibodies should researchers be aware of?

Several emerging applications of IRE1 antibodies show promise for advancing our understanding of cellular stress responses:

• Single-cell protein analysis:

  • Application of IRE1 antibodies in mass cytometry (CyTOF) for single-cell resolution of UPR states

  • Integration with single-cell transcriptomics to correlate protein and mRNA states

  • Exploration of heterogeneous UPR activation within seemingly uniform cell populations

• Extracellular vesicle (EV) analysis:

  • Detection of IRE1 and its targets in EVs as potential biomarkers

  • Investigation of stress-induced communication via EVs in disease contexts

  • Correlation of EV-associated IRE1 with disease progression and therapeutic response

• Proximity labeling approaches:

  • Combination of BioID or APEX2 with IRE1 antibodies to map the dynamic IRE1 interactome

  • Identification of novel regulatory partners and substrates

  • Temporal tracking of interaction networks during stress induction and resolution

• Structural biology integration:

  • Validation of structural models with phospho-specific antibodies

  • Correlation of structural states with functional activation

  • Investigation of conformational changes associated with different phosphorylation patterns

• Therapeutic monitoring applications:

  • Development of IRE1-targeted therapeutics for inflammatory and metabolic diseases

  • Use of IRE1 phosphorylation as a pharmacodynamic marker

  • Correlation of IRE1 inhibition with reductions in downstream inflammatory mediators like IL-1β

The advancement of IRE1 inhibitors as potential therapeutics for atherosclerosis and other inflammatory conditions highlights the importance of reliable antibody-based methods for monitoring IRE1 activity in both research and potential clinical applications .

How should researchers approach the validation and benchmarking of new IRE1 antibodies?

A systematic approach to validating new IRE1 antibodies includes:

• Essential validation experiments:

  Validation Approach	Implementation Method	Expected Outcome
  Genetic validation	IRE1 knockout/knockdown controls	No signal in knockout samples
  Peptide competition	Pre-incubation with immunizing peptide	Signal elimination/reduction
  Stimulus response	Treatment with known ER stressors (tunicamycin)	Enhanced signal/phosphorylation
  Phosphatase treatment	λPPase treatment of samples	Elimination of phospho-specific signals
  Cross-reactivity testing	Testing across species and closely related proteins	Confirmation of species specificity

• Application-specific validation:

  • For Western blot: Confirm expected molecular weight (~110 kDa) and stimulus-responsive bands

  • For IP: Verify enrichment and co-immunoprecipitation of known interactors

  • For IHC/IF: Validate subcellular localization (endoplasmic reticulum)

  • For phospho-antibodies: Confirm specificity for phosphorylated versus non-phosphorylated forms

• Benchmark comparison:

  • Compare new antibodies with established, well-characterized reagents

  • Test across multiple experimental conditions and cell types

  • Evaluate sensitivity, specificity, and signal-to-noise ratio

• Reproducibility assessment:

  • Test antibody performance across different lots

  • Validate in multiple laboratory settings

  • Document detailed protocols for consistent application

• Advanced validation approaches:

  • Mass spectrometry confirmation of immunoprecipitated targets

  • Structural validation of epitope accessibility

  • Functional correlation with IRE1 activity assays (XBP1 splicing, RIDD)

Researchers have successfully validated IRE1 antibodies using knockout models and demonstrated their specificity through mass spectrometry analysis of immunoprecipitated proteins , establishing a gold standard for antibody validation.

What are the most promising directions for integrating IRE1 antibody-based detection with other molecular and cellular techniques?

The integration of IRE1 antibody detection with complementary techniques offers powerful new research avenues:

• Multi-omics integration strategies:

  • Correlate antibody-detected IRE1 phosphorylation with phosphoproteomics datasets

  • Integrate protein-level data with transcriptomics to connect IRE1 activation to downstream effects

  • Combine with metabolomics to link ER stress to metabolic adaptations

• Spatial biology approaches:

  • Implement spatial transcriptomics alongside IRE1 antibody staining

  • Map IRE1 activation patterns within complex tissues and tumor microenvironments

  • Correlate IRE1 activity with cellular neighborhoods and microenvironmental factors

• Functional genomics combinations:

  • Pair CRISPR screens with IRE1 antibody-based readouts

  • Identify novel regulators of IRE1 activation and signaling

  • Map genetic dependencies in IRE1-mediated stress responses

• Systems biology frameworks:

  • Position IRE1 antibody data within computational models of UPR networks

  • Develop predictive models of stress response trajectories

  • Simulate therapeutic interventions targeting the IRE1 pathway

• Translational research applications:

  • Develop standardized IRE1 activation assays for patient stratification

  • Correlate IRE1 activity with disease progression and therapeutic response

  • Establish IRE1 phosphorylation as a biomarker for stress-related pathologies