VSIG1 Antibody
Description
Introduction to VSIG1 and Its Antibody
VSIG1, or V-set and immunoglobulin domain containing 1, is a relatively newly identified member of the immunoglobulin superfamily of proteins. It was discovered to be predominantly expressed in normal stomach and testis tissues . The VSIG1 antibody serves as a vital research tool for detecting and studying this protein in various applications, including Western blot analysis and immunohistochemistry. The antibody recognizes specific epitopes of the VSIG1 protein, enabling researchers to visualize its expression patterns in different tissue samples and investigate its biological functions .
The VSIG1 gene is located on chromosome Xq22.3 and belongs to the JAM (junctional adhesion molecule) family . It functions as a cell-cell adhesion molecule, and its role in the development and progression of various cancers, particularly gastric cancer, has become an area of increasing interest in recent years . Commercial antibodies against VSIG1, such as the one referenced in the search results (14145-1-AP), have been validated for detection in human stomach and testis tissues .
Molecular Structure
VSIG1 exists in two splicing variants in humans, identified as variants 1 and 2 in the NCBI database. Variant 2, which lacks exon 3, has been shown to be the dominant form in both stomach and testis tissues, as well as in various cancer cell lines . This structural variation may have implications for the protein's function in different cellular contexts.
VSIG1 protein demonstrates a specific subcellular localization pattern. In normal gastric tissues, VSIG1 is strongly and homogeneously expressed on the membranes of gastric glandular epithelial cells in the cardia, corpus, and antrum regions, with slight cytoplasmic positivity also observed .
Expression Patterns in Normal and Cancerous Tissues
In normal tissues, VSIG1 expression is primarily restricted to the stomach and testis, making it a relatively tissue-specific marker . The expression pattern in cancerous tissues shows significant variation, with downregulation observed in many cases. For instance, 60.5% of gastric cancer specimens show loss of VSIG1 expression .
The following table summarizes VSIG1 expression patterns in various tissues where VSIG1 antibody has been used for detection:
| Tissue Type | VSIG1 Expression | Detection Method |
|---|---|---|
| Normal Stomach | Strong, homogeneous membrane expression | Immunohistochemistry (IHC) |
| Normal Testis | Positive expression | Immunohistochemistry (IHC) |
| Gastric Cancer | Downregulated in 60.5% of cases | Immunohistochemistry (IHC) |
| Lung Adenocarcinoma | Expressed in specific subtypes, particularly invasive mucinous subtype | Immunohistochemistry (IHC) |
| Pancreatic Cancer | Expressed in a subset of cases | Immunohistochemistry (IHC) |
| Ovarian Cancer | Expressed in a subset of cases | Immunohistochemistry (IHC) |
| Prostate Cancer | Expressed in a subset of cases | Immunohistochemistry (IHC) |
This tissue-specific expression pattern makes VSIG1 antibody a valuable tool for distinguishing between different tissue types and identifying specific cancer subtypes .
Immunohistochemistry Applications
VSIG1 antibody has been extensively used in immunohistochemistry to detect VSIG1 expression in various tissue samples. For optimal detection in immunohistochemistry, antigen retrieval with TE buffer pH 9.0 is recommended, although citrate buffer pH 6.0 may be used as an alternative . The antibody has been validated for positive detection in human stomach and testis tissues, aligning with the known expression pattern of VSIG1 .
Western Blot Analysis
For Western blot applications, VSIG1 antibody is typically used at dilutions ranging from 1:500 to 1:3000 . This application is particularly useful for quantifying VSIG1 protein expression levels in cell lines and tissue samples, as demonstrated in studies examining VSIG1 expression in cancer cell lines such as MKN45, which endogenously expresses VSIG1 .
Research Applications in Cancer Studies
The VSIG1 antibody has been instrumental in investigating the clinical and biological roles of VSIG1 in various cancers. For example, immunoprecipitation with anti-VSIG1 antibody followed by LC-MS/MS analysis has been used to search for VSIG1 binding partners in normal human gastric tissues . This approach has contributed to understanding the molecular interactions of VSIG1 and its potential role in cancer progression.
Prognostic Value in Gastric Cancer
The following table summarizes the relationship between VSIG1 expression and patient characteristics in gastric cancer:
| Characteristic | VSIG1 Expression | P-value |
|---|---|---|
| High (n = 143) | Low (n = 219) | |
| Sex | ||
| Male | 93 (65.0%) | 165 (75.3%) |
| Female | 50 (35.0%) | 54 (24.7%) |
| Histological grade | ||
| Moderately to well differentiated | 58 (40.6%) | 115 (52.5%) |
| Poorly differentiated and signet ring cell | 85 (59.4%) | 104 (47.5%) |
This data indicates that VSIG1 expression is significantly associated with female sex and undifferentiated histological grade in gastric cancer patients .
Role in Epithelial-Mesenchymal Transition
Recent research has identified distinct patterns of VSIG1 expression related to cancer progression. In a study of 94 gastric cancers, cases were classified based on VSIG1 expression patterns detected using VSIG1 antibody: membrane/membrane in both tumor core and invasive front; null/negative staining in both areas; and translocational patterns (membrane core/cytoplasmic buds or cytoplasmic core/null buds) .
Effects on Cell Proliferation and Migration
Functional studies utilizing VSIG1 antibody have revealed that VSIG1 overexpression significantly reduces cell proliferation rates in various cancer cell lines, including MKN1 and MKN28 gastric cancer cells and H1299 lung cancer cells . Cell cycle analysis has shown that VSIG1 overexpression leads to a significant decrease in the percentage of cells in the G2/M phase for MKN1 cells and in the S phase for MKN28 cells .
Additionally, VSIG1 overexpression significantly reduced the migration ability of MKN1, H1299, and KYSE150 (esophageal cancer) cells, as demonstrated by wound-healing scratch assays . In Transwell migration assays, VSIG1 overexpression reduced the number of migrated cells in MKN1, MKN28, H1299, and KYSE150 cells by 74%, 61%, 59%, and 64%, respectively .
Impact on Cell Invasion
The invasiveness of cancer cells was also significantly decreased by VSIG1 overexpression, as detected using VSIG1 antibody. In MKN1, MKN28, and KYSE150 cells, invasiveness was reduced by 72%, 72%, and 77%, respectively . These findings suggest that VSIG1 contributes to a less proliferative, less migratory, and less invasive cancer cell phenotype.
Relationship with Wnt/β-catenin Signaling
Recent research suggests that VSIG1 may interact with the canonical Wnt/β-catenin signaling pathway. In gastric cancer, the membrane-cytoplasmic translocation of VSIG1, as detected using VSIG1 antibody, appears to be associated with the activation of this pathway, potentially contributing to epithelial-mesenchymal transition . This finding provides insight into the molecular mechanisms underlying VSIG1's role in cancer progression.
Future Research Directions and Potential Applications
The emerging understanding of VSIG1's role in cancer biology suggests several promising avenues for future research using VSIG1 antibody. Further investigations are needed to identify molecules that interact with VSIG1 and elucidate the pathways influenced by VSIG1 . Given its tissue-specific expression pattern and association with clinical outcomes, VSIG1 may serve as a potential biomarker for certain cancer types, particularly gastric cancer .
Additionally, the discovery of organ- or lesion-specific expression patterns of VSIG1, such as its distinctive expression in sessile serrated colon adenomas/polyps compared with adenomatous polyps, could deepen our understanding of various cancers and premalignant conditions .
Product Specs
Target Background
- Studies have shown that VSIG1 is expressed specifically in both non-cancerous and cancerous tissues. VSIG1 has been found to suppress proliferation, migration, and invasion in cancer cells. PMID: 28603843
- VSIG1 expression was significantly reduced at both the mRNA and protein levels in gastric cancer tissues. The loss of VSIG1 expression was significantly correlated with poor overall survival and disease-free survival in gastric cancer patients. PMID: 22095633
- VSIG1 is expressed, at both the mRNA and protein level, in gastric, esophageal, and ovarian cancers, while expression in normal tissues was restricted to testis and stomach. PMID: 16405301
Q&A
What is VSIG1 and where is it predominantly expressed?
VSIG1 is a member of the Immunoglobulin superfamily that functions as a cell adhesion molecule. It possesses an extracellular immunoglobulin-like domain involved in intercellular adhesion and a C-terminal cytoplasmic domain bounded by a transmembrane region . In normal human tissues, VSIG1 expression was initially thought to be restricted to normal gastric mucosa and testis . Recent studies have demonstrated that other normal tissues and some epithelial tumors can also express VSIG1 . It is preferentially expressed in the stomach, testis, and certain gastric, esophageal, and ovarian cancers .
What isoforms of VSIG1 exist and how do they differ?
Three alternatively spliced isoforms of mouse Vsig1 have been identified:
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Vsig1A and Vsig1B: These isoforms differ in their 3′ untranslated regions and are expressed in the early stages of stomach development .
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Vsig1C: This shorter transcript is restricted to the testis and encodes an N-terminal truncated protein. It is presumably regulated by an internal promoter located upstream of exon 1b .
In immunoblot analysis, the VSIG1 antibody recognizes a 60-kDa protein in stomach tissue and a 55-kDa protein in testis tissue . The difference in molecular weight is partly due to N-glycosylation of the protein, as enzymatic digestion with N-glycosidase F shifts the molecular mass from 60-kDa to 55-kDa .
What is the recommended protocol for immunohistochemical detection of VSIG1?
When performing immunohistochemistry for VSIG1, researchers should follow these methodological steps:
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Tissue preparation: Use formalin-fixed, paraffin-embedded tissue sections or fresh frozen sections depending on your experimental design.
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Antigen retrieval: This step is crucial for optimal staining results.
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Primary antibody incubation: Use rabbit polyclonal anti-VSIG1 antibodies at the appropriate dilution (consult specific antibody documentation) .
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Detection system: Apply an appropriate secondary antibody and visualization system.
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Controls: Include positive controls (gastric mucosa) and negative controls (omitting primary antibody) in each experiment.
For double immunostaining protocols, VSIG1 antibodies can be combined with other markers such as anti-α-catenin or anti-ZO1 to study co-localization patterns .
How does VSIG1 subcellular localization correlate with gastric cancer progression?
VSIG1 subcellular localization in gastric cancer follows distinct patterns that correlate with clinical outcomes:
What is the mechanism behind VSIG1 membrane-to-cytoplasm translocation and its significance?
The membrane-to-cytoplasm translocation of VSIG1 in gastric cancer appears to be linked to the epithelial-mesenchymal transition (EMT). Of the 20 cases showing translocational patterns, 9 demonstrated membrane-to-nuclear translocation of β-catenin and loss of E-cadherin, which are established indicators of EMT .
This hypothesis requires validation through further experimental studies, particularly those focusing on the molecular interactions between VSIG1 and components of the Wnt/β-catenin pathway.
How can I validate the specificity of my VSIG1 antibody?
To ensure the specificity of VSIG1 antibodies, researchers should implement the following validation approaches:
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Western blot analysis: Confirm that the antibody detects proteins of the expected molecular weight (approximately 60-kDa for glycosylated VSIG1 in stomach tissue and 55-kDa in testis tissue) .
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Deglycosylation experiments: Treat tissue lysates with N-glycosidase F to confirm the shift in molecular weight from 60-kDa to 55-kDa, validating that the detected protein is N-glycosylated VSIG1 .
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Tissue panel screening: Test the antibody on multiple tissues, expecting strong signals in stomach and testis with minimal background in other tissues .
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Immunofluorescence co-localization: Perform double immunostaining with established markers of cellular compartments, such as α-catenin (for adherens junctions) and ZO1 (for tight junctions), to confirm the expected subcellular localization of VSIG1 .
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Peptide competition assays: Pre-incubate the antibody with the immunizing peptide to demonstrate that this blocks specific staining.
What are the key considerations when interpreting VSIG1 immunostaining in gastric cancer samples?
When analyzing VSIG1 immunostaining in gastric cancer specimens, researchers should consider:
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Heterogeneity of expression: Evaluate both the tumor core and invasive edge separately, as VSIG1 may show different patterns in these regions .
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Subcellular localization: Carefully document whether staining is membranous, cytoplasmic, or absent, as this has prognostic implications .
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Co-expression with EMT markers: Consider co-staining for E-cadherin and β-catenin to identify potential EMT processes, particularly in cases with VSIG1 translocation patterns .
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Tumor location: Note that tumors with membrane/membrane VSIG1 pattern primarily involve the distal stomach, suggesting location-specific expression patterns .
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Histological subtype: Different histological subtypes of gastric cancer may show varying VSIG1 expression patterns .
How should I design experiments to investigate the role of VSIG1 in gastric epithelial differentiation?
Based on the crucial role of VSIG1 in gastric epithelial differentiation, researchers might consider the following experimental approaches:
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Knockout/knockdown studies: Generate VSIG1-deficient cell lines or animal models to assess the impact on gastric epithelial differentiation. The existing research shows that VSIG1-null cells differentiate into squamous epithelia inside the glandular region of chimeric stomachs, suggesting VSIG1 is required for establishing glandular versus squamous epithelia in the stomach .
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Promoter analysis: The 4.8-kb fragment located upstream of exon 1a appears sufficient to direct expression to the glandular epithelia of transgenic stomach . Researchers can use this promoter region to develop stomach-specific expression systems.
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Lineage tracing: Monitor the fate of VSIG1-expressing cells during stomach development using lineage tracing techniques.
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Rescue experiments: In VSIG1-deficient models, reintroduce different VSIG1 isoforms to determine which are essential for proper differentiation.
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Cell adhesion assays: Examine how VSIG1 expression affects cell-cell adhesion properties in gastric epithelial cells.
What methods can be used to study VSIG1 interactions with the Wnt/β-catenin signaling pathway?
To investigate the relationship between VSIG1 and the Wnt/β-catenin pathway, researchers could employ:
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Co-immunoprecipitation: Identify potential physical interactions between VSIG1 and components of the Wnt/β-catenin pathway.
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TOP/FOP luciferase assays: Measure β-catenin transcriptional activity in cells with different levels of VSIG1 expression.
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Subcellular fractionation: Assess how VSIG1 expression or translocation affects the nuclear localization of β-catenin.
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Immunofluorescence co-localization: Determine whether VSIG1 translocation coincides with β-catenin redistribution in cell culture models or tissue samples.
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Phosphorylation studies: Examine how VSIG1 expression affects the phosphorylation status of key Wnt signaling components.
What are common pitfalls when working with VSIG1 antibodies?
Researchers often encounter these challenges when working with VSIG1 antibodies:
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Cross-reactivity: Some VSIG1 antibodies may cross-react with other immunoglobulin superfamily members. Validate specificity using appropriate controls and knockout/knockdown models.
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Glycosylation interference: The N-glycosylation of VSIG1 can affect antibody binding, particularly in certain fixation conditions. Consider testing both native and deglycosylated samples .
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Isoform specificity: Current antibodies may not distinguish between all VSIG1 isoforms. When studying specific isoforms, combine antibody-based detection with PCR-based approaches to confirm isoform expression .
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Background staining: Optimize blocking conditions and antibody dilutions to minimize non-specific staining, particularly in tissues with high endogenous peroxidase activity.
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Fixation artifacts: Different fixation methods may affect VSIG1 epitope accessibility. Test multiple fixation protocols if staining results are inconsistent.
How can I optimize immunohistochemical detection of VSIG1 in formalin-fixed, paraffin-embedded tissues?
To enhance VSIG1 detection in FFPE samples:
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Antigen retrieval optimization: Test both heat-induced epitope retrieval methods (citrate buffer, EDTA, Tris-EDTA at varying pH) and enzymatic retrieval to determine optimal conditions.
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Antibody selection: Use antibodies raised against different epitopes of VSIG1 (N-terminal, C-terminal, or specific internal domains) to identify those least affected by formalin fixation .
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Signal amplification: Consider using polymer-based detection systems or tyramide signal amplification for weak signals.
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Counterstaining adjustment: Optimize counterstaining intensity to ensure it doesn't mask VSIG1 signals while still providing adequate tissue context.
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Automated versus manual staining: Compare results from automated immunostainers versus manual protocols to identify the most consistent approach.
What are promising areas for future research on VSIG1 in cancer biology?
Based on current knowledge, these research directions appear particularly promising:
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VSIG1 as a prognostic biomarker: Further investigate the correlation between VSIG1 subcellular localization patterns and patient outcomes across larger cohorts and different cancer types .
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Therapeutic targeting: Explore whether targeting VSIG1 or its downstream pathways could inhibit gastric cancer progression, particularly in cases showing translocational patterns.
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Regulation mechanisms: Investigate the molecular mechanisms controlling VSIG1 expression and subcellular localization during normal development and cancer progression.
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Relationship with immune response: As a member of the immunoglobulin superfamily, explore potential roles of VSIG1 in tumor-immune interactions.
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Diagnostic applications: Develop standardized VSIG1 immunohistochemistry protocols for potential inclusion in gastric cancer diagnostic panels.
How might VSIG1 function in the context of the tumor microenvironment?
While current research focuses primarily on VSIG1's role in epithelial cells, future studies should investigate:
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Stromal-epithelial interactions: Does VSIG1 mediate adhesion between epithelial cells and stromal components?
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Immune cell recognition: Could VSIG1 serve as a ligand for receptors on immune cells, potentially influencing immune surveillance?
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Extracellular matrix interactions: Does VSIG1 play a role in cell-matrix adhesion in addition to cell-cell adhesion?
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Microenvironment pH influence: How does the acidic microenvironment of the stomach affect VSIG1 function in normal versus malignant conditions?
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Exosomal VSIG1: Is VSIG1 secreted in exosomes, potentially influencing distant cells within the tumor microenvironment?
