TMPRSS4 Antibody

What is TMPRSS4 and what are its primary biological functions?

TMPRSS4 (Transmembrane protease serine 4) is a plasma membrane-anchored serine protease that belongs to the peptidase S1 family. It serves multiple biological functions:

• In viral infection: Facilitates SARS-CoV-2 infection in gut epithelial cells through cleavage of coronavirus spike glycoproteins, activating them for host cell entry

• In cancer progression: Directly induces processing of pro-uPA/PLAU into active form through proteolytic activity

• In cellular transformation: Promotes epithelial-mesenchymal transition (EMT) by activating the Raf/MEK/ERK1/2 signaling pathway

• In angiogenesis: Suppresses RECK expression, an inhibitor of angiogenesis, thereby promoting tumor-induced angiogenesis

TMPRSS4 is significantly overexpressed in multiple cancer types including pancreatic, thyroid, colorectal, hepatocellular, and gastric cancers, where it promotes invasion, migration, and metastasis .

What types of TMPRSS4 antibodies are available for research applications?

Research-grade TMPRSS4 antibodies come in several formats with varying applications:

Selection should be based on specific experimental requirements, targeting epitopes, and validated applications as documented in peer-reviewed publications.

How should researchers optimize TMPRSS4 antibody-based immunohistochemistry protocols?

Optimization of IHC protocols for TMPRSS4 requires careful consideration of several parameters:

Antigen Retrieval Methods:

• For formalin-fixed paraffin-embedded tissues, heat-induced epitope retrieval with TE buffer pH 9.0 is recommended

• Alternative approach: citrate buffer pH 6.0 has also proven effective

Antibody Dilution Ranges:
For optimal staining with minimal background:

• IHC applications: 1:100-1:400 dilution

• Western blot applications: 1:500-1:2000 dilution

Tissue-Specific Considerations:
Positive TMPRSS4 staining has been validated in:

• Pancreatic cancer tissue

• Colon tissue and colon cancer tissue

• Stomach cancer tissue

• Hepatocellular carcinoma

Controls and Validation:

• Include both positive controls (SW 1990 cells, BxPC-3 cells, mouse stomach tissue)

• Implement negative controls using isotype-matched antibodies

• Consider siRNA/knockdown validation to confirm specificity

The resulting staining pattern should show cytoplasmic and/or membrane localization depending on the tissue type examined.

What are the technical challenges when using TMPRSS4 antibodies for protein detection in Western blotting?

Researchers face several challenges when detecting TMPRSS4 by Western blotting:

Molecular Weight Discrepancy:

• Calculated molecular weight: 48 kDa

• Observed molecular weight: 55 kDa

• This discrepancy likely results from post-translational modifications

Sample Preparation Considerations:

• Membrane protein extraction requires careful optimization

• Use appropriate detergents (RIPA buffer with protease inhibitors)

• Avoid excessive heating which may cause aggregation of membrane proteins

Optimization Strategies:

• Test multiple antibodies targeting different epitopes

• Use positive control lysates (SW 1990 cells, BxPC-3 cells)

• Optimize transfer conditions for high molecular weight membrane proteins

• Consider gradient gels for better resolution

Validation Approaches:

• Compare TMPRSS4-overexpressing cells with control cells

• Include TMPRSS4 knockdown samples as specificity controls

• Verify band identity using mass spectrometry if questions persist

How can TMPRSS4 antibodies be utilized to investigate EMT mechanisms in cancer progression?

TMPRSS4 antibodies serve as valuable tools for investigating EMT mechanisms in cancer:

Experimental Design Approach:

• Compare morphological changes induced by TMPRSS4 overexpression

• Perform immunofluorescence to visualize:

  • Enhanced vimentin expression

  • Reduced E-cadherin expression

  • Changes in cell shape from epithelial cobblestone to elongated/irregular morphology

Molecular Pathway Analysis:
TMPRSS4 overexpression triggers a cascade of events:

• Activates C-Raf/MEK/ERK1/2 signaling pathway

• Upregulates EMT transcription factors (snail and slug)

• Enhances fibronectin and vimentin expression

• Suppresses E-cadherin expression

Functional Validation:

• Inhibit ERK1/2 with U0126 to demonstrate pathway dependency

• Conduct rescue experiments with TMPRSS4 siRNA

• Perform migration and invasion assays to correlate TMPRSS4 expression with functional outcomes

Research findings demonstrate that TMPRSS4-induced EMT can be reversed by ERK1/2 inhibition, suggesting a potential therapeutic approach for TMPRSS4-expressing tumors.

What is the prognostic significance of TMPRSS4 expression in gastric cancer and how should researchers quantify this expression?

TMPRSS4 expression serves as a significant prognostic biomarker in gastric cancer:

Expression Pattern and Quantification:

• TMPRSS4 upregulation observed in 44.9% of gastric cancer patients following surgical resection

• Immunohistochemical analysis remains the gold standard for evaluation

• Standardized scoring systems should be employed for consistency

Prognostic Correlations:

Treatment Response Prediction:
For patients receiving TS-1 cancer drug formulation:

• With dosage ≥45%: TMPRSS4-positive patients showed 65.2% 5-year OS vs. 79.2% for TMPRSS4-negative patients (p=0.0284)

• This suggests TMPRSS4 status may predict chemotherapy response

Implementation Recommendations:

• Use standardized IHC protocols with appropriate controls

• Implement digital image analysis for objective quantification

• Correlate TMPRSS4 expression with multiple clinicopathological parameters

• Consider combining with other biomarkers for enhanced prognostic power

How does TMPRSS4 expression in different tissues correlate with SARS-CoV-2 tropism and COVID-19 manifestations?

TMPRSS4 exhibits distinct expression patterns that may explain SARS-CoV-2 tropism:

Gastrointestinal Expression Pattern:
TMPRSS4 is abundantly expressed throughout the GI tract:

• Oesophagus: Epithelial cells, submucosal glands, lower muscularis mucosae

• Small intestine: Weak cytoplasmic staining in goblet cells and enterocytes

• Jejunum and ileum: More pronounced cytoplasmic expression compared to large intestine

• Colon: Cytoplasmic and weak nuclear membrane staining in goblet cells and enterocytes

• Stomach: Surface epithelial cells and mucinous parietal cells

• Liver: Hepatocytes, bile ducts and ductules

• Pancreas: Pronounced cytoplasmic staining of acinar cells

Pulmonary Expression Profile:

• Extensive expression in lung adenocarcinoma and lung squamous cell carcinoma

• High expression in tumor-adjacent morphologically normal lung tissue

• Particularly prominent in bronchial and alveolar epithelial cells

• Elevated expression in COPD patients

Research Implications:

• TMPRSS4 may contribute to both respiratory and gastrointestinal manifestations of COVID-19

• Expression patterns correlate with clinical observations of SARS-CoV-2 tropism

• Patients with TMPRSS4-overexpressing conditions (cancer, COPD) may have increased susceptibility

• Pharmacological inhibition of TMPRSS4 represents a potential therapeutic strategy

What methodological approaches can researchers use to investigate TMPRSS4-mediated SARS-CoV-2 entry in experimental systems?

Investigating TMPRSS4's role in SARS-CoV-2 entry requires specialized experimental approaches:

Cell-Based Assays:

• Overexpression studies:

  • Transfect TMPRSS4 in susceptible cell lines

  • Measure viral entry efficiency using pseudotyped virus systems

  • Quantify spike protein cleavage by Western blotting

• Knockdown/inhibition studies:

  • Use siRNA or CRISPR to deplete TMPRSS4

  • Apply serine protease inhibitors (camostat, nafamostat)

  • Assess impact on viral entry and replication kinetics

Tissue-Specific Analysis:

• Organoid models:

  • Develop gut, lung, or multi-organ organoids

  • Characterize TMPRSS4 expression by immunofluorescence

  • Evaluate organoid susceptibility to SARS-CoV-2 infection

• Ex vivo tissue models:

  • Process fresh human tissue samples

  • Map TMPRSS4 expression using immunohistochemistry

  • Correlate with ACE2 expression and tissue susceptibility

Mechanistic Investigations:

• Biochemical assays:

  • Purify recombinant TMPRSS4

  • Perform in vitro cleavage assays with spike protein

  • Determine enzyme kinetics and inhibitor profiles

• Structural studies:

  • Analyze TMPRSS4-spike protein interactions

  • Identify critical residues for proteolytic activity

  • Design targeted inhibitors based on structural information

How should researchers resolve contradictory findings between TMPRSS4 antibodies from different sources?

When facing contradictory results between different TMPRSS4 antibodies:

Systematic Validation Approach:

• Antibody characterization:

  • Compare epitope mapping information

  • Review validation data from manufacturers

  • Check antibody performance in published literature

• Controlled comparison studies:

  • Test multiple antibodies simultaneously on the same samples

  • Include positive and negative control tissues/cells

  • Compare staining patterns and intensities

• Specificity verification:

  • Perform peptide blocking experiments

  • Use TMPRSS4 knockout/knockdown samples

  • Test cross-reactivity with related proteases

Resolution Strategies:

• For research applications: Use multiple antibodies targeting different epitopes

• For diagnostic applications: Select antibodies with extensive clinical validation

• For contradictory findings: Consider differences in:

  • Sample preparation methods

  • Detection systems

  • Scoring/quantification approaches

Standardization Recommendations:

• Document detailed methodological protocols

• Include appropriate technical and biological controls

• Use consistent quantification methods

• Consider interlaboratory validation for critical findings

What factors affect TMPRSS4 protein expression detection in clinical samples and how can these be controlled?

Several factors influence TMPRSS4 detection in clinical samples:

Pre-analytical Variables:

• Tissue procurement and fixation:

  • Time to fixation affects protein preservation

  • Fixative type and duration impact epitope availability

  • Standardize protocols across sample collections

• Storage conditions:

  • FFPE block age can affect antigenicity

  • Tissue microarray construction techniques influence representativeness

  • Control for storage time and conditions

Analytical Considerations:

• Antibody selection:

  • Different clones have varying sensitivities

  • Polyclonal vs. monoclonal antibodies show different staining patterns

  • Batch-to-batch variability within the same product

• Protocol optimization:

  • Antigen retrieval methods significantly impact detection

  • Blocking reagents affect background levels

  • Detection systems vary in sensitivity

Biological Confounders:

• Tumor heterogeneity:

  • TMPRSS4 expression varies within tumors

  • Sampling strategy influences detected expression levels

  • Multiple cores or whole sections may be needed for accurate assessment

• Contextual expression patterns:

  • TMPRSS4 expression is influenced by tumor microenvironment

  • Inflammatory conditions may alter expression

  • Treatment effects can modify expression patterns

Standardization Approach:

• Implement detailed standard operating procedures

• Include universal control samples in each run

• Use digital pathology and computer-assisted quantification

• Participate in proficiency testing programs

By addressing these variables, researchers can improve reproducibility and reliability of TMPRSS4 expression assessment in clinical samples.