STAT6 (Ab-645) Antibody

What are the primary applications for STAT6 (Ab-645) Antibody?

STAT6 (Ab-645) Antibody is primarily validated for Western Blot (WB) and Immunohistochemistry (IHC) applications. The antibody specifically detects endogenous levels of total STAT6 protein in human samples, making it suitable for examining STAT6 expression patterns in various tissues and experimental conditions. When used for Western blotting, it can detect the approximately 110 kDa STAT6 protein band in cell lysates such as those from HeLa cells . For IHC applications, the recommended dilution range is typically 1:50-1:100, though optimization for specific tissues may be necessary .

How does STAT6 (Ab-645) Antibody differ from phospho-specific STAT6 antibodies?

STAT6 (Ab-645) Antibody detects total STAT6 protein regardless of its phosphorylation status, as it targets a specific peptide sequence (P-A-T-I-K) around amino acids 643-647 . In contrast, phospho-specific antibodies like anti-phospho-STAT6 (pY641) or anti-phospho-STAT6 (pThr645) selectively recognize STAT6 only when phosphorylated at these specific residues . When designing experiments to study IL-4 signaling, researchers should consider using both total and phospho-specific antibodies in parallel to simultaneously assess STAT6 expression levels and activation status. This approach provides a more comprehensive understanding of the signaling dynamics by distinguishing between changes in total protein abundance versus changes in activation state.

What secondary antibodies are compatible with STAT6 (Ab-645) Antibody?

Since STAT6 (Ab-645) Antibody is a rabbit polyclonal antibody, compatible secondary antibodies include those that specifically recognize rabbit IgG. Suitable options include:

• Goat Anti-Rabbit IgG H&L Antibody (AP)

• Goat Anti-Rabbit IgG H&L Antibody (Biotin)

• Goat Anti-Rabbit IgG H&L Antibody (FITC)

• Goat Anti-Rabbit IgG H&L Antibody (HRP)

The choice of secondary antibody depends on your detection method. For Western blots, HRP-conjugated secondaries are commonly used for chemiluminescent detection, while fluorophore-conjugated antibodies (like FITC or Alexa Fluor dyes) are preferred for immunofluorescence applications. When using secondary antibodies, ensure they do not cross-react with proteins from your experimental species to minimize background signals.

How can STAT6 (Ab-645) Antibody be utilized to study the relationship between STAT6 signaling and regulatory T cell populations?

STAT6 (Ab-645) Antibody can be instrumental in investigating the inverse relationship between STAT6 signaling and regulatory T cell (Treg) populations. Research has demonstrated that STAT6-deficient mice possess approximately twice the number of CD4+CD25HiFoxp3+ Tregs in their lungs and spleen compared to wild-type mice, both under steady-state and inflammatory conditions . To study this relationship, researchers can employ the following protocol:

• Use Western blotting with STAT6 (Ab-645) Antibody to quantify total STAT6 expression in different experimental groups (e.g., wild-type vs. STAT6-deficient, or before/after treatments that modulate STAT6).

• Perform parallel flow cytometry to enumerate Treg populations using markers like CD4, CD25, and Foxp3.

• Correlate STAT6 expression levels with Treg numbers across conditions to establish quantitative relationships.

• Complement this approach with functional assays to assess whether modulating STAT6 activity (confirmed by Western blot) affects Treg suppressive capacity or differentiation.

This multifaceted approach can provide insights into how STAT6 signaling mechanistically influences Treg homeostasis, which has implications for understanding allergic airway inflammation resistance observed in STAT6-deficient models .

What are the considerations when using STAT6 (Ab-645) Antibody alongside IL-4 stimulation experiments?

When designing experiments that involve IL-4 stimulation and STAT6 detection, several methodological considerations must be addressed:

• Stimulation Timing: STAT6 phosphorylation at Y641 occurs rapidly after IL-4 exposure, while total protein levels may not change immediately. Design a time-course experiment (e.g., 15, 30, 60 minutes, 3, 6, 24 hours) to capture both immediate phosphorylation and potential later changes in total STAT6.

• Dual Antibody Approach: Use both STAT6 (Ab-645) Antibody and phospho-STAT6 (pY641) antibodies in parallel samples to distinguish between expression and activation changes .

• Sample Preservation: For phosphorylation studies, rapid sample processing is crucial. Immediately fix cells or flash-freeze tissues to preserve phosphorylation states, as phosphatases rapidly deactivate STAT6 once stimulation ends.

• Controls: Include both positive controls (known IL-4 responsive cells like Th2 lymphocytes) and negative controls (STAT6-deficient cells or IL-4 receptor blockers) to validate antibody specificity.

• Quantification: For Western blots, normalize phospho-STAT6 signals to total STAT6 (detected with Ab-645) to accurately assess activation independent of expression levels.

This methodical approach ensures reliable data on how IL-4 stimulation affects STAT6 in your experimental system, while controlling for potential artifacts in phosphorylation detection.

How can STAT6 (Ab-645) Antibody be employed to investigate conflicting results between in vitro and in vivo STAT6 studies?

Discrepancies between in vitro and in vivo STAT6 studies are common, particularly regarding immune cell differentiation and allergic responses. STAT6 (Ab-645) Antibody can help resolve such conflicts through comparative analyses:

• Tissue-specific STAT6 expression profiling: Using the antibody for IHC and Western blotting across different tissues and cell types in both in vitro cultures and in vivo samples to identify potential discrepancies in expression patterns.

• Microenvironment analysis: Employ the antibody in co-immunoprecipitation studies coupled with mass spectrometry to identify tissue-specific STAT6 interaction partners that may differ between in vitro and in vivo conditions.

• Post-translational modification mapping: Compare STAT6 modification patterns between in vitro and in vivo samples using the Ab-645 antibody for initial immunoprecipitation, followed by analysis with modification-specific antibodies.

• Kinetic studies: Develop time-course experiments tracking STAT6 expression and localization in both systems to identify temporal differences in regulation.

What are the optimal validation protocols for confirming STAT6 (Ab-645) Antibody specificity in new experimental systems?

To rigorously validate STAT6 (Ab-645) Antibody specificity in your experimental system, implement this comprehensive validation protocol:

• Peptide Competition Assay: Pre-incubate the antibody with excess immunizing peptide (P-A-T-I-K sequence) before application. Disappearance of the detected signal confirms specificity for the target epitope .

• Genetic Controls: Test the antibody in samples from STAT6-knockout or STAT6-knockdown models. Absence of signal in these samples confirms specificity for STAT6 protein.

• Molecular Weight Verification: In Western blots, STAT6 should appear at approximately 110 kDa. Verify this using molecular weight markers and positive control samples.

• Multiple Detection Methods: Confirm signals using alternative detection techniques (e.g., if initially using Western blot, confirm with IHC or immunofluorescence).

• Cross-species Reactivity Testing: Though primarily reactive with human STAT6, test cross-reactivity with mouse or rat samples if those species are part of your study. Different reactivity patterns across species can help confirm specificity.

• Isotype Control: Include a non-specific rabbit IgG at the same concentration to identify any non-specific binding.

Documentation of these validation steps should be included in publications to enhance reproducibility and credibility of research findings.

What are the recommended protocols for quantifying STAT6 expression in tissue samples using the Ab-645 antibody?

For quantitative analysis of STAT6 expression in tissue samples using the Ab-645 antibody, follow this standardized protocol:

For IHC Quantification:

• Sample Preparation: Fix tissues in 10% neutral buffered formalin, embed in paraffin, and section at 4-5μm thickness.

• Antigen Retrieval: Perform heat-induced epitope retrieval using citrate buffer (pH 6.0) for 20 minutes.

• Blocking and Antibody Application: Block with 5% normal goat serum, then apply STAT6 (Ab-645) Antibody at 1:50-1:100 dilution and incubate overnight at 4°C .

• Detection and Visualization: Use a standardized detection system (e.g., HRP-polymer and DAB chromogen) and counterstain with hematoxylin.

• Imaging and Analysis: Capture images at standardized magnification and exposure settings using a calibrated microscope.

• Quantification Method: Employ digital image analysis software to quantify:

  • Percentage of STAT6-positive cells

  • Staining intensity (categorized as 0, 1+, 2+, 3+)

  • H-score calculation: ∑(percentage of cells at each intensity level × intensity level)

• Controls: Include positive control tissues (human lymphoid tissues), negative controls (primary antibody omitted), and, ideally, STAT6-deficient tissues.

This standardized approach ensures reproducible and comparable quantification of STAT6 expression across different tissue samples and experimental conditions.

What troubleshooting approaches should be applied when STAT6 (Ab-645) Antibody shows inconsistent results in Western blots?

When encountering inconsistent results with STAT6 (Ab-645) Antibody in Western blotting, apply this systematic troubleshooting approach:

For optimal results with HeLa cell lysates, implementation of the following protocol has shown consistent detection:

• Load 20-30μg protein per lane

• Use 10% SDS-PAGE gel to properly resolve ~110kDa STAT6 protein

• Transfer using wet transfer (overnight at 30V, 4°C)

• Block with 5% non-fat milk in TBST for 1 hour

• Incubate with STAT6 (Ab-645) antibody (1:1000) overnight at 4°C

• Visualize with appropriate secondary antibody and ECL detection system

This approach has been validated for reliable detection of STAT6 in human cell lines and tissue samples.

How can STAT6 (Ab-645) Antibody be used to elucidate the relationship between STAT6 signaling and allergic airway inflammation?

STAT6 (Ab-645) Antibody can be instrumental in elucidating the complex relationship between STAT6 signaling and allergic airway inflammation through a multi-faceted experimental approach:

• Comparative Expression Analysis: Use the antibody to quantify STAT6 expression levels in bronchial biopsies, bronchoalveolar lavage fluid cells, or mouse lung tissues from allergic versus non-allergic subjects. This can establish correlation between STAT6 expression and disease severity.

• Cell-Specific STAT6 Profiling: Combine the antibody with cell type-specific markers in immunofluorescence or flow cytometry to determine which pulmonary cell populations express STAT6 during inflammation.

• Intervention Studies: Measure changes in STAT6 expression using this antibody following experimental interventions (e.g., corticosteroids, biologics targeting IL-4/IL-13 pathway) to identify potential mechanistic biomarkers of treatment response.

• Pathway Integration: Use co-immunoprecipitation with STAT6 (Ab-645) Antibody followed by mass spectrometry to identify novel STAT6 interaction partners in airway cells during allergic inflammation.

Research has demonstrated that STAT6-deficient mice are highly resistant to allergic airway inflammation even when provided with wild-type bone marrow or Th2 effectors, suggesting complex regulatory mechanisms . Further studies revealed that STAT6-deficient mice have increased numbers of regulatory T cells, which appears to contribute to their resistance to allergic inflammation. Depleting Tregs in STAT6-deficient mice significantly restored eosinophilic airway inflammation and allergic lung pathology . This suggests that STAT6 normally suppresses Treg populations, thereby promoting allergic inflammation.

What experimental design is recommended for investigating STAT6 phosphorylation dynamics in IL-4 versus IL-13 stimulation?

To investigate differential STAT6 phosphorylation dynamics between IL-4 and IL-13 stimulation, implement this robust experimental design using both STAT6 (Ab-645) and phospho-specific antibodies:

Experimental Protocol:

• Cell Preparation: Culture relevant cell types (e.g., bronchial epithelial cells, macrophages, B cells) in serum-free medium for 4-6 hours prior to stimulation.

• Stimulation Matrix:

  • Unstimulated control

  • IL-4 stimulation (10 ng/mL)

  • IL-13 stimulation (10 ng/mL)

  • Combined IL-4/IL-13 stimulation

• Time-Course Sampling: Collect samples at multiple timepoints (0, 5, 15, 30, 60 minutes, 3, 6, 24 hours) to capture both early and late phosphorylation events.

• Parallel Analysis:

  • Western blotting using STAT6 (Ab-645) Antibody to measure total STAT6

  • Western blotting with anti-phospho-STAT6 (pY641) to measure activated STAT6

  • Immunofluorescence to assess nuclear translocation kinetics

• Receptor Dependency: Include selective receptor blockade conditions (anti-IL-4Rα, anti-IL-13Rα1) to distinguish type I (IL-4Rα/γc) versus type II (IL-4Rα/IL-13Rα1) receptor signaling contributions.

• Downstream Validation: Monitor STAT6-dependent gene expression (e.g., CD23, CCL26) at later timepoints (6, 24, 48 hours) to correlate phosphorylation patterns with transcriptional outcomes.

• Quantification: Calculate the following parameters:

  • Time to peak phosphorylation

  • Maximum phosphorylation level (phospho-STAT6/total STAT6)

  • Duration of phosphorylation (time to 50% signal decay)

  • Area under the curve of phosphorylation over time

This comprehensive approach will reveal cytokine-specific differences in STAT6 activation kinetics, intensity, and duration, providing insights into the mechanistic basis for differential cellular responses to these related cytokines.

How can STAT6 (Ab-645) Antibody be used to investigate the crosstalk between STAT6 and other signaling pathways?

STAT6 (Ab-645) Antibody can be leveraged to investigate signaling crosstalk through these methodological approaches:

• Co-Immunoprecipitation Studies: Use STAT6 (Ab-645) Antibody to immunoprecipitate STAT6 complexes from cells stimulated with various cytokines (IL-4, IL-13, IFN-γ, TNF-α), then probe for co-precipitating signaling molecules (e.g., STAT1, STAT3, NF-κB components, MAPK pathway members) to identify physical interactions.

• Sequential Chromatin Immunoprecipitation (Re-ChIP): First immunoprecipitate with STAT6 (Ab-645) Antibody, then perform a second immunoprecipitation with antibodies against other transcription factors to identify genomic regions co-occupied by multiple factors, revealing potential synergistic or antagonistic transcriptional regulation.

• Phosphorylation Analysis in Pathway Inhibition Experiments: Treat cells with inhibitors of other pathways (e.g., JAK1/2 inhibitors, p38 MAPK inhibitors, PI3K inhibitors) before IL-4 stimulation, then use Western blotting with STAT6 (Ab-645) Antibody and phospho-specific antibodies to assess how other pathways influence STAT6 expression and activation.

• Proximity Ligation Assay: Combine STAT6 (Ab-645) Antibody with antibodies against components of other signaling pathways to visualize and quantify protein-protein interactions within intact cells at single-molecule resolution.

• Multi-parameter Flow Cytometry: Simultaneously detect total STAT6 (using conjugated Ab-645 antibody) and activated forms of other signaling molecules to identify cell populations with coordinated pathway activation at single-cell resolution.

This multi-faceted approach can uncover important regulatory interactions between STAT6 and other signaling components, particularly in contexts like T helper cell differentiation, where STAT6 (IL-4 driven) pathways interact with STAT1 (IFN-γ driven), STAT3 (IL-6 driven), and STAT5 (IL-2 driven) pathways to determine cell fate and function.

What is the optimal protocol for using STAT6 (Ab-645) Antibody in chromatin immunoprecipitation (ChIP) assays?

While STAT6 (Ab-645) Antibody is primarily validated for Western blot and IHC applications , it can be adapted for ChIP assays with the following optimized protocol:

ChIP Protocol for STAT6 (Ab-645) Antibody:

• Cell Preparation and Crosslinking:

  • Stimulate cells with IL-4 (10ng/ml) for 1 hour to induce STAT6 nuclear translocation

  • Crosslink protein-DNA complexes with 1% formaldehyde for 10 minutes at room temperature

  • Quench with 0.125M glycine for 5 minutes

• Chromatin Preparation:

  • Lyse cells in SDS lysis buffer supplemented with protease and phosphatase inhibitors

  • Sonicate chromatin to generate fragments of 200-500bp (optimize sonication conditions for your specific cell type)

  • Verify fragmentation by agarose gel electrophoresis

• Immunoprecipitation:

  • Pre-clear chromatin with protein A/G beads and non-immune rabbit IgG

  • Incubate pre-cleared chromatin with 5-10μg STAT6 (Ab-645) Antibody overnight at 4°C

  • Include parallel samples with non-immune rabbit IgG as negative control

  • Add protein A/G beads and incubate for 2-3 hours at 4°C

• Washing and Elution:

  • Wash immunoprecipitated complexes sequentially with low salt, high salt, LiCl, and TE buffers

  • Elute protein-DNA complexes in SDS/NaHCO₃ buffer

  • Reverse crosslinks by heating at 65°C overnight

• DNA Purification and Analysis:

  • Treat samples with RNase A and Proteinase K

  • Purify DNA using phenol-chloroform extraction or commercial kits

  • Analyze enrichment by qPCR targeting known STAT6-binding regions (e.g., promoters of CCL11, CCL26, FCER2)

• Validation Controls:

  • Input chromatin (non-immunoprecipitated, typically 1-5%)

  • IgG negative control

  • Positive control loci (established STAT6 binding sites)

  • Negative control loci (regions without STAT6 binding)

This protocol has been optimized to account for the specific characteristics of STAT6 as a transcription factor that requires activation for nuclear translocation and DNA binding. The phosphate-buffered formulation of the antibody is compatible with standard ChIP buffers, though additional optimization may be needed for specific cell types or experimental conditions.

How can quantitative immunoblotting with STAT6 (Ab-645) Antibody be implemented to accurately measure STAT6 expression levels?

To achieve precise quantification of STAT6 expression levels using STAT6 (Ab-645) Antibody in immunoblotting, implement this quantitative protocol:

Quantitative Immunoblotting Protocol:

• Standard Curve Preparation:

  • Generate a standard curve using recombinant STAT6 protein at known concentrations (0, 0.1, 0.25, 0.5, 1, 2.5, 5, 10 ng)

  • Load standards alongside experimental samples

• Sample Preparation:

  • Extract proteins using a standardized lysis buffer (RIPA buffer with protease inhibitors)

  • Quantify total protein using BCA or Bradford assay

  • Load equal amounts of total protein (20-30μg) per lane

• Electrophoresis and Transfer Optimization:

  • Use 7.5% or gradient gels to optimize resolution of the ~110kDa STAT6 protein

  • Implement wet transfer at constant 30V overnight at 4°C for efficient transfer of high molecular weight proteins

• Blocking and Antibody Incubation:

  • Block with 5% BSA in TBST for 1 hour at room temperature

  • Incubate with STAT6 (Ab-645) Antibody at 1:1000 dilution overnight at 4°C

  • Use fluorescently-labeled secondary antibodies for linear detection range

• Imaging and Quantification:

  • Capture images using a digital fluorescence imaging system

  • Ensure all signals fall within the linear range of detection

  • Use imaging software to quantify band intensities

• Normalization Strategy:

  • Normalize STAT6 signals to:
    a) Housekeeping proteins (β-actin, GAPDH) for relative quantification
    b) Total protein staining (Ponceau S, SYPRO Ruby) for more accurate normalization
    c) Recombinant protein standard curve for absolute quantification

• Validation and Quality Control:

  • Include positive control samples (HeLa cell lysate)

  • Test antibody specificity using peptide competition

  • Ensure coefficient of variation across technical replicates is <10%

This rigorous approach enables reliable comparison of STAT6 protein levels across experimental conditions, cell types, or clinical samples with high reproducibility and quantitative accuracy.

What approaches can be used to evaluate STAT6 (Ab-645) Antibody cross-reactivity with other STAT family proteins?

To rigorously assess potential cross-reactivity of STAT6 (Ab-645) Antibody with other STAT family members, implement this comprehensive evaluation protocol:

Cross-Reactivity Assessment Protocol:

• Recombinant Protein Analysis:

  • Perform Western blotting using purified recombinant proteins for all STAT family members (STAT1, STAT2, STAT3, STAT4, STAT5a, STAT5b, STAT6)

  • Load equivalent molar amounts of each protein

  • Probe with STAT6 (Ab-645) Antibody at recommended concentration

  • Quantify signal intensity for each STAT protein relative to STAT6

• Epitope Sequence Comparison:

  • Analyze sequence homology between the immunizing peptide (P-A-T-I-K around aa.643-647 of STAT6) and corresponding regions in other STAT proteins

  • Predict potential cross-reactivity based on sequence similarity

• Overexpression System Testing:

  • Transfect cells with expression vectors for individual STAT family members

  • Perform Western blotting with STAT6 (Ab-645) Antibody

  • Include untransfected controls and STAT6-transfected positive controls

• Knockdown/Knockout Validation:

  • Use siRNA or CRISPR/Cas9 to generate STAT6-depleted cells

  • Perform Western blotting and immunostaining with STAT6 (Ab-645) Antibody

  • Absence of signal confirms specificity for STAT6

• Immunodepletion Studies:

  • Pre-adsorb the antibody with recombinant STAT6 protein

  • Test residual antibody reactivity against lysates containing other STAT proteins

  • Persistent signal would indicate cross-reactivity

• Two-Dimensional Western Blotting:

  • Separate proteins by isoelectric point in the first dimension and molecular weight in the second

  • This technique provides enhanced resolution of STAT family members

  • Probe with STAT6 (Ab-645) Antibody and compare spot positions with known STAT protein coordinates

• Parallel Antibody Comparison:

  • Test samples with alternative STAT6-specific antibodies targeting different epitopes

  • Compare detection patterns to identify potential cross-reactivity artifacts

This systematic approach provides comprehensive evidence regarding the specificity of STAT6 (Ab-645) Antibody and helps researchers confidently interpret their experimental results, particularly in systems where multiple STAT proteins are expressed or activated simultaneously.