Applications : Immunohistochemistry (IHC) Analysis
Sample type: cells
Review: Immunohistochemical analysis showed that ATF1, CREB1, and CREB3 expression was significantly higher in HCC tissues than in adjacent normal tissues (*p < 0.05; **p < 0.01; ***p < 0.001).
CREB3 (also known as LZIP and Luman) belongs to the bZIP family and ATF subfamily of transcription factors. It is activated through intramembrane proteolysis (RIP) and binds to cAMP response elements (consensus sequence: 5'-GTGACGT[AG][AG]-3') found in numerous viral and cellular promoters. The protein has significant research importance due to its role in regulated cell death (RCD), ER stress response, and viral pathogenesis. Full-length CREB3 (CREB3-FL) is anchored to the nuclear inner membrane where it interacts with lamins and chromatin DNA, while its cleaved form (CREB3-CF) accumulates in the nucleus following activation . CREB3 requires host cell factor C1 (HCFC1) as a coactivator, and its activity and expression are suppressed when the HCFC1-CREB3 complex binds with CREBZF . Recent research has identified CREB3 as a key regulator of karyoptosis, a unique cell death mechanism characterized by nuclear shrinkage and membrane rupture, suggesting potential applications in cancer therapeutics .
When selecting a CREB3 antibody, consider these methodological criteria:
Target epitope location: Determine whether your research requires detection of full-length CREB3 (CREB3-FL), cleaved CREB3 (CREB3-CF), or both. Some antibodies target the N-terminal domain (aa 1-230), while others target other regions.
Application compatibility: Verify the antibody has been validated for your specific application. For example, Proteintech's 11275-1-AP has been validated for Western Blot (WB), Immunohistochemistry (IHC), Immunofluorescence (IF/ICC), Immunoprecipitation (IP), and Chromatin Immunoprecipitation (ChIP) .
Species reactivity: Confirm the antibody detects CREB3 in your experimental model. The 11275-1-AP antibody has verified reactivity with human samples and cited reactivity with mouse samples .
Validation data: Review published literature that has successfully used the antibody in applications similar to yours. Search for papers that include proper controls such as knockdown/knockout validation .
Clonality consideration: Polyclonal antibodies like 11275-1-AP offer high sensitivity but potential batch variation, while monoclonal antibodies provide consistent specificity but potentially lower sensitivity.
Always perform preliminary validation experiments with appropriate positive and negative controls before proceeding with critical experiments.
When detecting CREB3 via Western blot, expect to observe bands within the range of 40-64 kDa, although the calculated molecular weight is 44 kDa . This variation occurs due to:
Post-translational modifications: CREB3 undergoes N-glycosylation and proteolytic processing, resulting in altered migration patterns .
Isoform detection: Up to two different isoforms have been reported for CREB3, including the alternative splicing product sLZIP (CREB3-dTM) which lacks the transmembrane domain .
Tissue-specific processing: The observed molecular weight may vary depending on the cell/tissue type due to differential processing of the protein.
For optimal detection, use a gradient gel (4-20%) with a broad molecular weight marker and include positive control lysates from cells known to express CREB3, such as Jurkat or HeLa cells . When troubleshooting inconsistent molecular weights, consider using denaturing agents like urea to address potential protein aggregation, or phosphatase inhibitors to preserve phosphorylated forms.
For optimal Western blot detection of CREB3, follow this methodological approach:
Sample preparation:
Lyse cells in RIPA buffer supplemented with protease inhibitors and phosphatase inhibitors
Include detergents suitable for membrane proteins since CREB3 localizes to the ER and nuclear membrane
Sonicate briefly to shear DNA and reduce sample viscosity
SDS-PAGE and transfer:
Load 20-40 μg of protein per lane
Use 10-12% polyacrylamide gels to resolve proteins in the 40-64 kDa range
Transfer to PVDF membrane at 100V for 60-90 minutes in cold transfer buffer with 10-20% methanol
Antibody incubation:
Block membrane with 5% non-fat milk in TBST for 1 hour at room temperature
Incubate with primary CREB3 antibody (e.g., Proteintech 11275-1-AP) at dilution 1:500-1:1000 overnight at 4°C
Wash 3× with TBST, 5 minutes each
Incubate with HRP-conjugated secondary antibody at 1:5000 for 1 hour at room temperature
Wash 3× with TBST, 5 minutes each
Detection:
Apply chemiluminescent substrate (e.g., SuperSignal West Pico)
Image using a digital imager system like ImageQuant LAS 4000
Troubleshooting tips:
If detecting multiple bands, confirm specificity with CREB3 knockdown controls
For weak signals, extend primary antibody incubation time or increase concentration
To distinguish between CREB3-FL and CREB3-CF, compare samples with and without ER stress induction
For high-quality CREB3 immunofluorescence that accurately reveals subcellular localization:
Cell preparation:
Culture cells on glass coverslips or chamber slides
Consider using cell lines with confirmed CREB3 expression (e.g., U2OS, HeLa, Jurkat)
Include experimental conditions that modify CREB3 localization (e.g., ER stress inducers like thapsigargin or tunicamycin)
Fixation and permeabilization:
Fix cells with 4% paraformaldehyde for 15 minutes at room temperature
Block with PBS containing 0.02% Tween-20 and 1% BSA for 1 hour at 37°C
Antibody incubation:
Dilute primary CREB3 antibody (e.g., 11275-1-AP) 1:200-1:800 in blocking buffer
Incubate overnight at 4°C in a humidified chamber
Wash 3× with PBS-T
Incubate with fluorophore-conjugated secondary antibody for 1 hour at room temperature
Wash 3× with PBS-T
Counterstain nuclei with DAPI
Co-localization studies:
For ER/Golgi localization: Co-stain with organelle markers (e.g., calnexin for ER, GM130 for Golgi)
For nuclear membrane studies: Co-stain with nuclear lamin proteins (mCherry-Lamin A or mCherry-Lamin B1)
Use confocal microscopy for accurate subcellular localization
Advanced analysis:
Perform time-lapse imaging to track CREB3 translocation under stress conditions
Consider using super-resolution microscopy for detailed localization at the nuclear membrane
Quantify nuclear/cytoplasmic ratios to measure CREB3 activation
To investigate CREB3's role in regulated cell death, particularly karyoptosis:
Experimental design strategies:
Overexpression systems:
Knockdown/knockout approaches:
Implement siRNA or CRISPR-Cas9 to deplete CREB3
Validate knockdown efficiency by Western blot
Assess impact on cell viability under normal and stress conditions
Stress induction methods:
Cell death analysis techniques:
Morphological assessment:
Molecular markers:
Assess DNA fragmentation via TUNEL assay
Measure caspase activation to differentiate from apoptosis
Evaluate nuclear membrane integrity using lamin staining
Mechanistic investigation:
Analyze CREB3 cleavage patterns under different death-inducing conditions
Identify protein interactions using co-immunoprecipitation with CREB3 antibodies
Perform chromatin immunoprecipitation (ChIP) to determine transcriptional targets during cell death
CREB3 functions as a sensor and mediator of ER stress responses. Here's a methodological framework for using CREB3 antibodies in ER stress research:
Experimental system setup:
Stress induction protocols:
Chemical inducers: thapsigargin (1 μM, 0.5-24h), tunicamycin (1-5 μg/ml, 0.5-24h), DTT (1-2 mM, 0.5-4h)
Physiological stressors: glucose deprivation, hypoxia, viral infection
Include time course experiments to capture transient responses
Cell systems:
Analytical approaches:
Protease-dependent activation:
Subcellular trafficking:
Perform subcellular fractionation followed by Western blot
Use immunofluorescence to track CREB3 movement from ER to nucleus
Employ live-cell imaging with fluorescently tagged CREB3
Transcriptional activity:
Validation approaches:
Use CREB3 knockdown/knockout cells as negative controls
Include HCFC1 and CREBZF analysis to assess cofactor relationships
Compare results with other UPR branches (PERK, IRE1α, ATF6) to determine pathway specificity
To investigate CREB3 interactions with nuclear membrane components:
Co-immunoprecipitation approaches:
Standard co-IP:
Crosslinking IP:
Treat cells with membrane-permeable crosslinkers (DSP, formaldehyde)
Perform IP with CREB3 antibody
Reverse crosslinks and analyze by mass spectrometry to identify novel interactions
Proximity labeling:
Express CREB3 fused to BioID or APEX2
Allow biotinylation of proximal proteins
Purify biotinylated proteins and identify by mass spectrometry
Microscopy-based methods:
Co-localization analysis:
FRET/FLIM analysis:
Express CREB3 and interacting partners with appropriate fluorophore pairs
Measure FRET efficiency to quantify direct interactions
Use acceptor photobleaching to confirm specific interactions
Super-resolution microscopy:
Apply STORM or PALM techniques for nanoscale resolution of interactions
Perform quantitative analysis of clustering at the nuclear membrane
Functional validation approaches:
Generate truncated CREB3 constructs to map interaction domains
Create site-directed mutants to disrupt specific interactions
Assess functional consequences of disrupted interactions on nuclear membrane integrity and karyoptosis
Distinguishing CREB3-mediated karyoptosis from other cell death mechanisms requires a multi-parameter approach:
Morphological characterization:
Nuclear morphology assessment:
Live-cell imaging with nuclear dyes (Hoechst, DRAQ5)
Quantify nuclear shrinkage, deformation, and loss of nuclear components
Track nuclear membrane integrity using fluorescent nuclear membrane markers
Differential markers:
Molecular signature analysis:
Pathway-specific markers:
Cell Death Type | Key Markers | CREB3-Karyoptosis Differences |
---|---|---|
Apoptosis | Caspase-3/7 activation, PARP cleavage | Caspase-independent, distinct nuclear morphology |
Necroptosis | RIPK1/RIPK3/MLKL phosphorylation | No MLKL involvement, nuclear-focused |
Autophagy | LC3-II conversion, p62 degradation | No characteristic autophagosome formation |
Pyroptosis | Gasdermin D cleavage, IL-1β release | No inflammatory component |
Karyoptosis | CREB3-CF accumulation, nuclear membrane rupture | Distinct nuclear morphology with preserved cytoplasm |
Inhibitor profiling:
Test caspase inhibitors (z-VAD-fmk), necroptosis inhibitors (Necrostatin-1), and autophagy inhibitors (3-MA)
Determine if CREB3-mediated death persists despite these inhibitors
Use protease inhibitors to block CREB3 cleavage and assess effects on cell death
Genetic manipulation approaches:
Compare outcomes in cells with:
CREB3 overexpression (FL vs. CF vs. dTM variants)
CREB3 knockdown/knockout
Mutations in key death pathway components (caspases, RIPK1/3, etc.)
Evaluate transcriptional responses:
When facing inconsistent CREB3 detection in Western blots, implement this systematic troubleshooting approach:
Sample preparation issues:
Protein degradation:
Include fresh protease inhibitors in lysis buffer
Maintain samples at 4°C during processing
Add phosphatase inhibitors to preserve post-translational modifications
Extraction efficiency:
For membrane-bound CREB3-FL, use stronger detergents (1% SDS, 1% Triton X-100)
Sonicate samples briefly to enhance solubilization
For nuclear CREB3-CF, include nuclear extraction steps
Detection challenges:
Variable band patterns:
Weak signal:
High background:
Increase blocking time (2 hours at room temperature)
Add 0.1% Tween-20 to antibody dilution buffers
Try alternative blocking agents (5% BSA instead of milk)
Validation approaches:
Control experiments:
Alternative antibody validation:
Test a different CREB3 antibody recognizing a distinct epitope
Consider using epitope-tagged CREB3 constructs with tag-specific antibodies
Verify CREB3 expression at the mRNA level by RT-PCR
For successful Chromatin Immunoprecipitation (ChIP) with CREB3 antibodies:
Chromatin preparation optimization:
Crosslinking parameters:
Use 1% formaldehyde for 10 minutes at room temperature
For transient interactions, try dual crosslinking with DSG followed by formaldehyde
Quench with 125 mM glycine for 5 minutes
Sonication conditions:
Optimize sonication to achieve 200-500 bp fragments
Verify fragment size by agarose gel electrophoresis
Include spike-in controls to normalize for sonication efficiency
Immunoprecipitation optimization:
Antibody selection:
IP protocol parameters:
Pre-clear chromatin with protein A/G beads
Use 3-5 μg antibody per ChIP reaction
Incubate overnight at 4°C with rotation
Include negative control IgG and positive control antibody (e.g., anti-Histone H3)
Washing stringency:
Test different wash buffer compositions (varying salt and detergent concentrations)
Perform at least 4-5 washes to reduce background
Include a final wash in TE buffer
PCR and analysis optimization:
Primer design for CREB3 targets:
Data analysis approaches:
Use percent input or fold enrichment over IgG for quantification
Compare CREB3 binding under normal vs. stress conditions
Validate findings with reporter assays for functional significance
Advanced ChIP applications:
ChIP-seq considerations:
Increase starting material (10-20 million cells)
Include input controls and spike-in for normalization
Use bioinformatics to identify enriched motifs matching CRE consensus sequences
Sequential ChIP (Re-ChIP):
A comprehensive assessment of CREB3's role in disease requires integrating antibody-based detection with functional assays:
Experimental design framework:
Expression profiling:
Quantify CREB3 levels in disease vs. normal tissues/cells by immunoblotting
Determine CREB3 cleavage status and subcellular localization by IF/IHC
Correlate expression with disease parameters and patient outcomes
Functional manipulation:
Generate stable cell lines with CREB3 overexpression, knockdown, or knockout
Create disease-relevant mutations based on literature findings
Compare wild-type vs. mutant CREB3 for functional differences
Integrated analytical approaches:
For viral infection studies:
For cancer research applications:
For ER stress pathway analysis:
Multi-omics integration:
Data integration strategies:
Approach | Methodology | Integration with Antibody Data |
---|---|---|
Transcriptomics | RNA-seq of CREB3-modulated cells | Correlate with ChIP-seq using CREB3 antibodies |
Proteomics | Mass spectrometry of CREB3 interactome | Validate interactions by co-IP with CREB3 antibodies |
Phenotypic assays | Cell viability, migration, invasion | Correlate phenotypes with CREB3 expression/cleavage patterns |
Validation in disease models:
Translate in vitro findings to animal models using tissue IHC with CREB3 antibodies
Analyze patient samples for CREB3 expression/cleavage patterns
Correlate antibody-based measurements with disease outcomes and treatment responses
CREB3 plays a significant role in viral infection processes, and antibodies can be instrumental in elucidating these mechanisms:
Experimental approaches for virus-host interactions:
Infection time course analysis:
Subcellular trafficking studies:
Use immunofluorescence to track CREB3 location during infection
Co-stain for viral proteins to identify co-localization
Perform live-cell imaging with fluorescently tagged CREB3
Functional investigation methods:
Viral egress analysis:
Mechanistic pathway analysis:
Advanced applications:
Host-range determinant studies:
Compare CREB3 processing across cell types with different viral susceptibility
Use species-specific CREB3 antibodies to evaluate virus compatibility with host factors
Investigate viral proteins that modulate CREB3 activation
Therapeutic targeting assessment:
Test compounds that inhibit CREB3 processing
Evaluate effects on viral replication and release
Use CREB3 antibodies to monitor target engagement
CREB3's role in karyoptosis presents opportunities for cancer therapeutic development, which can be explored using antibody-based methods:
Target validation strategies:
Expression analysis in cancer tissues:
Compare CREB3 expression and processing between tumor and normal tissues
Perform immunohistochemistry with CREB3 antibodies on tissue microarrays
Correlate CREB3 status with patient outcomes and treatment responses
Functional characterization in cancer models:
Therapeutic development approaches:
Drug screening platforms:
Develop cell-based assays monitoring CREB3 cleavage
Screen compound libraries for modulators of CREB3 processing
Use Western blotting with CREB3 antibodies to validate hits
Combination therapy assessment:
Test CREB3 pathway modulators with conventional chemotherapeutics
Evaluate synergy with ER stress inducers
Monitor CREB3 processing and nuclear accumulation as pharmacodynamic markers
Mechanistic investigation methods:
DNA damage response connection:
Cellular senescence induction:
Analyze senescence markers in CREB3-CF expressing cells
Investigate the relationship between karyoptosis and senescence
Use antibodies to detect senescence-associated secretory phenotype (SASP) factors
Integrating CREB3 antibody applications with multi-omics approaches enables comprehensive pathway analysis:
Integrated analytical framework:
ChIP-seq and transcriptomics integration:
Perform ChIP-seq with CREB3 antibodies to identify genome-wide binding sites
Conduct RNA-seq under normal and stress conditions
Integrate datasets to identify direct CREB3 transcriptional targets
Validate key targets with ChIP-qPCR and RT-qPCR
Proteomics and interactomics:
Immunoprecipitate CREB3 using validated antibodies
Identify interacting partners by mass spectrometry
Compare interactome under normal vs. stress conditions
Validate key interactions with co-IP and Western blotting
Pathway analysis approaches:
Signaling network reconstruction:
Omics Layer | CREB3 Antibody Application | Integration Method |
---|---|---|
Transcriptomics | ChIP-seq for binding sites | Correlate binding with expression changes |
Proteomics | IP-MS for interactome | Map protein-protein interaction networks |
Phosphoproteomics | Phospho-specific antibodies | Connect kinase pathways to CREB3 activation |
Epigenomics | ChIP-seq for histone marks | Correlate chromatin state with CREB3 binding |
Cellular response mapping:
Analyze temporal dynamics of CREB3 processing during stress responses
Correlate with global changes in transcriptome and proteome
Identify feedback mechanisms and regulatory circuits
Advanced computational approaches:
Network modeling:
Use antibody-derived data as anchor points for network construction
Model CREB3 pathway activation dynamics
Predict potential therapeutic intervention points
Multi-scale integration:
Connect molecular findings to cellular phenotypes
Map pathway alterations to disease progression
Integrate patient-derived data with experimental models