STRN3 Antibody

What is STRN3 and why is it significant in research?

STRN3 (Striatin, Calmodulin Binding Protein 3) is a regulatory protein that functions as a subunit of PP2A (Protein Phosphatase 2A) and forms part of the STRIPAK complex. Recent research has demonstrated that STRN3 is significantly upregulated in multiple tumor types, particularly hepatocellular carcinoma (HCC), where it's associated with poor prognosis . The protein plays a crucial role in promoting tumor growth by inhibiting the Hippo pathway and facilitating nuclear translocation of YAP protein, which subsequently enhances cell proliferation and migration . The significance of STRN3 in research lies in its potential as both a prognostic biomarker and therapeutic target, particularly in cancers where the Hippo-YAP signaling axis is dysregulated.

Which applications are validated for STRN3 antibodies?

STRN3 antibodies have been validated for multiple experimental applications, with varying protocols and optimization requirements:

Researchers should note that these applications have been validated in multiple tissue types, with particular success in liver cancer tissues, cell lines (including Huh7, LM3, and HeLa), and mouse stomach tissue .

How should STRN3 antibodies be stored to maintain reactivity?

For optimal storage and maintenance of STRN3 antibody reactivity:

• Store antibodies at -20°C in their original buffer conditions .

• Most commercial STRN3 antibodies are supplied in PBS with 0.02% sodium azide and 50% glycerol at pH 7.3 .

• Aliquot antibodies upon receipt to avoid repeated freeze-thaw cycles, which can significantly degrade antibody performance .

• Antibodies stored properly remain stable for 12 months from the date of receipt .

• When working with the antibody, keep it on ice during experiments and return to storage promptly.

• Some preparations (20μL sizes) may contain 0.1% BSA as a stabilizer .

Research has shown that improper storage can lead to significant variability in experimental results, particularly for applications requiring higher sensitivity like immunofluorescence.

How should researchers design validation controls when using STRN3 antibodies?

Proper validation of STRN3 antibodies requires a multi-layered control strategy:

• Positive Controls:

  • HeLa cells have been validated as positive controls for Western blot applications

  • Mouse stomach tissue serves as a reliable positive control for IHC applications

  • SH-SY5Y neuroblastoma cells have shown consistent STRN3 expression

• Negative Controls:

  • Include isotype controls (matching IgG species and concentration)

  • Consider STRN3 knockdown validation using siRNA (validated sequences: 5′-GGACUUAGUAAGAAGAAUATT-3′; 5′-GCACUUACAAUGGAGAUAATT-3′; 5′-GCAGACUUGACGGUAACAATT-3′)

• Specificity Validation:

  • Compare multiple STRN3 antibodies targeting different epitopes

  • The epitope corresponding to amino acids 200-460 of human STRN3 (NP_001077362.1) has shown high specificity

  • Validation using recombinant STRN3 protein competition assays

Cross-reactivity assessment is essential as STRN3 shares structural similarities with other Striatin family members, which can lead to false-positive results if antibodies are not properly validated.

What are the recommended protocols for detecting STRN3 in hepatocellular carcinoma samples?

Based on recent research findings on STRN3 in HCC , the following optimized protocols are recommended:

For IHC on HCC tissue:

• Perform antigen retrieval using TE buffer at pH 9.0 (alternatively citrate buffer pH 6.0)

• Block with 5% normal serum for 1 hour at room temperature

• Incubate with STRN3 antibody at 1:100-1:200 dilution overnight at 4°C

• Score STRN3 expression using both proportion (0-3) and intensity (0-3) metrics:

  • Proportion: 0 (<10% positive cells), 1 (10%-40%), 2 (40%-70%), 3 (>70%)

  • Intensity: 0 (no staining), 1 (weak), 2 (moderate), 3 (strong)

  • Define high expression as sum of scores ≥4

For Western blot detection in HCC cell lines:

• Use RIPA lysis buffer containing 1% PMSF for protein extraction

• Load 20-50μg of protein lysate per lane

• Primary antibody dilution: 1:1000-1:2000

• Incubate with HRP-conjugated secondary antibody for 2 hours at room temperature

• Expected STRN3 band size: 90-100 kDa

These protocols have been validated in studies that demonstrated significant correlation between STRN3 expression and poor prognosis in HCC patients.

How can researchers investigate STRN3's role in the Hippo signaling pathway?

To investigate STRN3's role in Hippo signaling, researchers should employ a multi-faceted approach:

• Co-immunoprecipitation (Co-IP) assay:

  • Use STRN3 antibody for immunoprecipitation followed by western blotting for Hippo pathway components (MST1/2, LATS1/2, YAP)

  • Alternatively, immunoprecipitate YAP and probe for STRN3 interaction

• Phosphorylation analysis:

  • Monitor YAP phosphorylation status (Ser127) after STRN3 knockdown or overexpression

  • Western blotting with phospho-specific antibodies to assess MST1/2 phosphorylation (Thr183/Thr180)

• Nuclear/cytoplasmic fractionation:

  • Analyze YAP nuclear translocation in response to STRN3 modulation

  • Combine with immunofluorescence to visualize YAP localization

• Functional assays:

  • CCK8 and colony formation assays to assess cell proliferation

  • Transwell and wound healing assays to evaluate migration capability

  • Flow cytometry for apoptosis analysis after STRN3 knockdown

• Gene Set Variation Analysis (GSVA):

  • Analyze enrichment scores of Hippo pathway genes in relation to STRN3 expression levels

  • Pearson correlation analysis between STRN3 and Hippo pathway components

Recent research has shown that STRN3 knockdown significantly inhibits cell proliferation and migration while promoting apoptosis, indicating its role as a negative regulator of the Hippo pathway.

What methodologies are most effective for studying STRN3 subcellular localization?

For accurate determination of STRN3 subcellular localization:

• Multiple immunofluorescence (mIF):

  • Combine STRN3 antibody (1:50-1:100 dilution) with markers for subcellular compartments

  • Co-stain with YAP antibody to assess co-localization

  • Use 3D HISTECH Panoramic Scanner for imaging

  • Analysis by experienced researchers for quantification of positively stained cells

• Subcellular fractionation:

  • Separate nuclear and cytoplasmic fractions before western blotting

  • Include appropriate markers for fraction purity (e.g., Lamin B for nuclear fraction)

  • Quantify relative STRN3 distribution between compartments

• Confocal microscopy with z-stack imaging:

  • Use high-resolution confocal microscopy to precisely locate STRN3

  • Analysis of co-localization coefficients with compartment markers

• Live-cell imaging:

  • For dynamic studies, consider generating GFP-tagged STRN3 constructs

  • Monitor protein trafficking in response to stimuli

Human Protein Atlas database analysis has shown that STRN3 primarily localizes to the cell cytosol and nucleoplasm, which aligns with its proposed role in regulating YAP nuclear translocation . Gene Ontology (GO) cellular component analysis confirms this distribution pattern, indicating STRN3's presence in both compartments .

How can single-cell analysis be optimized for STRN3 detection?

Single-cell analysis of STRN3 requires careful optimization:

• Single-cell RNA sequencing (scRNA-seq):

  • Use Seurat (version 4.3.0 or later), dplyr (1.1.0+), and patchwork (1.1.2+) packages for data analysis

  • Follow normalization, dimensionality reduction, PCA analysis, and Umap/Tsne clustering protocols

  • STRN3 has been successfully analyzed in epithelial/tumor cell clusters, with expression patterns similar to YAP

  • Include cell type-specific markers for proper clustering:

    • EPCAM, ALDH1A1, ALB for epithelial and tumor cells

    • CD79A, MS4A1 for B cells

    • CD3D, CD3E for T cells

    • FGFBP2 for NK cells

    • ITGAM, CD33, CD68, CD14, CD163 for monocytes/macrophages

    • ACTA2, COL1A2 for fibroblasts

• Mass cytometry (CyTOF):

  • Metal-conjugated STRN3 antibodies for single-cell protein analysis

  • Multi-parameter analysis with Hippo pathway components

• Multi-color flow cytometry:

  • Intracellular staining protocols with STRN3 antibody (post-fixation/permeabilization)

  • Co-staining with cell-type specific markers

Research has demonstrated significant overlap between STRN3 and AFP distribution in HCC cells, suggesting cell type-specific expression patterns that can be leveraged for targeted therapeutic approaches .

What are common pitfalls in STRN3 antibody-based experiments and how can they be addressed?

Common challenges in STRN3 antibody experiments include:

Additionally, when working with tissue samples:

• Fresh samples consistently yield better results than archival material

• Optimization of antigen retrieval is critical for consistent IHC results

• For multi-labeling experiments, carefully test antibody combinations to avoid cross-reactivity

How should researchers address contradictory results between different STRN3 detection methods?

When faced with contradictory results across different detection methods:

• Systematic validation approach:

  • Compare results from at least three detection methods (e.g., WB, IHC, and IF)

  • Use multiple antibodies targeting different epitopes of STRN3

  • Include genetic validation (siRNA knockdown) to confirm specificity

• Technical considerations:

  • Different methods may detect different protein states (denatured vs. native)

  • Post-translational modifications may affect epitope recognition

  • Some antibodies work better in certain applications (check validation data)

• Reconciliation strategies:

  • Functional assays can help resolve contradictions (e.g., proliferation/migration effects)

  • Consider protein-protein interaction studies to verify biological activity

  • Genetic approaches (CRISPR/Cas9) provide definitive validation

• Reporting guidelines:

  • Transparently report contradictory results

  • Document all experimental conditions that may influence outcomes

  • Include appropriate controls for each detection method

Research on STRN3 in HCC has shown that complementary approaches yield more reliable results, with protein-level (Western blot, IHC) and mRNA-level (qRT-PCR) analyses providing consistent findings regarding STRN3 upregulation in tumor tissues .

How can STRN3 antibodies be utilized in studying the STRIPAK complex in cancer progression?

STRN3 functions as a regulatory subunit of PP2A within the STRIPAK complex, presenting unique research opportunities:

• STRIPAK complex composition analysis:

  • Use STRN3 antibodies for co-immunoprecipitation followed by mass spectrometry

  • Identify novel interaction partners in cancer vs. normal cells

  • Apply proximity ligation assays to visualize protein-protein interactions in situ

• Phosphoproteomic approaches:

  • Combine STRN3 knockdown with phosphoproteomic analysis

  • Identify substrates affected by STRN3-containing STRIPAK complexes

  • Focus on dephosphorylation events in the Hippo pathway

• Dynamic regulation studies:

  • Monitor STRIPAK complex assembly/disassembly in response to cellular stress

  • Investigate STRN3 post-translational modifications affecting complex formation

  • Develop FRET-based sensors for real-time monitoring

• Therapeutic targeting strategies:

  • Screen for compounds disrupting STRN3 interaction with other STRIPAK components

  • Evaluate effects on downstream signaling (especially YAP activation)

  • Test combination approaches targeting both STRN3 and YAP pathways

Recent findings indicate that STRN3 forms the PP2A holoenzyme by binding to two additional subunits (PP2Aa and PP2Ac) through its coiled-coil domain . This complex plays a significant role in dephosphorylating MST1/2 and YAP, thereby inhibiting the Hippo pathway and promoting cancer progression.

What methodological approaches are recommended for studying STRN3 in patient-derived samples?

For translational research using patient-derived samples:

• Tissue microarray (TMA) analysis:

  • Optimize STRN3 IHC protocol for TMA applications

  • Use scoring system combining intensity (0-3) and proportion (0-3)

  • Define high expression as sum of scores ≥4

  • Correlate with clinical parameters and survival data

• Patient-derived organoids (PDOs):

  • Establish PDOs from tumor and adjacent normal tissues

  • Apply IF to assess STRN3 expression patterns

  • Test response to targeted therapies in relation to STRN3 expression

• Single-cell analysis of patient samples:

  • Apply scRNA-seq to characterize STRN3 expression across cell types

  • Focus on tumor heterogeneity and microenvironment interactions

  • Integrate with proteomics data when possible

• Circulating tumor cells (CTCs):

  • Develop protocols for STRN3 detection in CTCs

  • Evaluate potential as liquid biopsy biomarker

Research with a cohort of 24 HCC patients demonstrated that STRN3 mRNA expression was significantly higher in tumor tissues compared to adjacent non-cancerous tissues, with patients showing high STRN3 expression experiencing higher recurrence rates after surgery . This highlights the prognostic value of STRN3 assessment in patient samples.