CCN1 Antibody

What is CCN1/Cyr61 and why is it significant in scientific research?

CCN1, also known as Cyr61 (cysteine-rich protein 61), is the first identified member of the CCN family comprising six secreted extracellular matrix-associated glycoproteins. Its significance in research stems from its multifunctional role in promoting cell proliferation, chemotaxis, angiogenesis, and cell adhesion . CCN1 exhibits contextual functionality in wound healing by upregulating expression of genes involved in angiogenesis, inflammation, and matrix remodeling, including VEGA-A, VEGA-C, matrix metalloproteinases (MMP1, MMP3), tissue inhibitors of metalloproteinases (TIMP1), and various integrins . Additionally, CCN1 has been implicated in multiple pathological conditions, including fibrotic disorders, rheumatoid arthritis, and cancer progression, making it a significant target for therapeutic development .

How does the structure of CCN1 relate to its functional domains?

CCN1 contains distinct structural domains that mediate specific interactions with cellular receptors and extracellular matrix components. The protein spans from Ala22 to Asp381 in humans (Accession # O00622) . Research has identified that different domains of CCN1 interact with specific binding partners. For instance, domain IV of CCN1 contains important recognition sites for certain function-blocking antibodies like YM1B . The protein's functionality is critically dependent on its disulfide linkages that maintain its native structure - a feature important when selecting antibodies for experimental purposes .

Studies have mapped specific epitope regions, such as residues 77-80, which are recognized by therapeutic monoclonal antibody 093G9, with Asn79 and Phe80 being particularly crucial for antibody binding . Understanding these structure-function relationships is essential when selecting antibodies for different experimental applications or when designing therapeutic agents targeting specific CCN1 functions.

What are the primary differences between various types of CCN1 antibodies available for research?

CCN1 antibodies vary significantly based on their species origin, clonality, epitope recognition, and functional properties:

When selecting antibodies, researchers should consider whether native conformational epitopes need to be preserved (as with YM1B, which recognizes CCN1 structure with undisturbed disulfide linkages) or if denatured epitopes are acceptable (as in some Western blot applications) . Additionally, some antibodies like YM1B demonstrate function-blocking capabilities by perturbing interactions between CCN1 and its binding partners such as vitronectin and fibronectin .

How can CCN1 antibodies be optimized for Western blot applications?

For optimal Western blot detection of CCN1, several methodological considerations are critical:

For optimal detection in Western blot:

• Load appropriate positive controls: A549 human lung carcinoma and SK-BR-3 human breast cancer cell lines have been validated as reliable positive controls for CCN1 expression .

• Use appropriate membrane and buffer systems: PVDF membranes with Immunoblot Buffer Group 2 have demonstrated success in CCN1 detection .

• Optimize antibody concentration: 1 μg/mL of anti-CCN1 antibody (such as AF6009) followed by appropriate HRP-conjugated secondary antibody typically yields specific bands .

• Consider cell-type specific post-translational modifications: The observed molecular weight may vary between cell types due to differential glycosylation patterns of CCN1.

When troubleshooting weak or non-specific signals, researchers should consider whether the antibody recognizes native CCN1 structure with intact disulfide linkages, as some antibodies like YM1B require the preservation of these structural features for optimal binding .

What are the established protocols for using CCN1 antibodies in ELISA-based quantification?

ELISA-based quantification of CCN1 requires careful protocol optimization:

A sandwich ELISA approach is commonly employed, utilizing a capture antibody (e.g., Rat Anti-Human Cyr61/CCN1 Monoclonal Antibody, MAB40551) coated on clear polystyrene microplates, followed by sample incubation and detection with a biotinylated detection antibody (e.g., Sheep Anti-Human Cyr61/CCN1 Antigen Affinity-purified Polyclonal Antibody, AF6009) .

For optimal ELISA performance:

• Generate a standard curve using serially diluted recombinant human CCN1 protein (2-fold dilutions recommended).

• Follow with streptavidin-HRP and appropriate substrate solution.

• Terminate the reaction with a stop solution and measure absorbance.

CCN1 levels can serve as biomarkers in certain conditions. For instance, in myeloma progression studies, CCN1 levels ≥401 pg/mL were associated with longer time to progression from monoclonal gammopathy of undetermined significance (MGUS) or asymptomatic multiple myeloma (AMM) to overt myeloma . For AMM specifically, CCN1 levels ≥614 pg/mL correlated with longer time to progression . Patients progressing to multiple myeloma within 3 years had significantly lower CCN1 levels than those progressing after 3 years (431 vs. 723 pg/mL) .

What are the considerations for immunohistochemical detection of CCN1 in tissue samples?

Immunohistochemical (IHC) detection of CCN1 requires careful attention to fixation, antigen retrieval, and antibody validation:

• Tissue preparation: Formalin-fixed, paraffin-embedded (FFPE) tissues are commonly used, but the fixation time should be optimized as overfixation may mask CCN1 epitopes.

• Antigen retrieval: Heat-induced epitope retrieval methods are generally recommended for CCN1 detection, with citrate buffer (pH 6.0) being commonly employed.

• Antibody selection: Validated antibodies for IHC-P (paraffin sections) should be selected. The rabbit polyclonal CCN1/CYR61 antibody (ab228592) has been validated for IHC-P applications in human and rat samples .

• Controls: Proper positive and negative controls are crucial. For positive controls, tissues known to express CCN1 (such as wound healing tissues or certain cancer types) should be included.

• Signal interpretation: CCN1 expression patterns can be complex, showing both stromal and epithelial localization depending on the pathological context. In fibrotic tissues, for example, CCN1 expression by fibroblasts contributes to collagen fiber organization .

When analyzing CCN1 expression in pathological samples, consider that expression levels may vary depending on disease stage and cellular context. For instance, in fibrotic conditions, CCN1 appears to have context-dependent effects, sometimes promoting and other times inhibiting fibrosis .

How do CCN1 antibodies help elucidate integrin-dependent signaling pathways?

CCN1 engages multiple integrin receptors to activate distinct signaling pathways, and function-blocking antibodies have been instrumental in dissecting these mechanisms:

Function-blocking antibodies like YM1B have demonstrated that CCN1 induces actin reorganization, lamellipodia formation, and cell migration/invasion through the αV integrins/Rac1/ERK signaling axis in breast cancer cells . By blocking specific CCN1-integrin interactions, these antibodies help identify which integrins are involved in particular cellular processes.

The engagement of different integrins by CCN1 leads to distinct and sometimes opposing outcomes:

• Integrin αvβ3 interaction promotes cell proliferation, survival, and angiogenesis

• Integrin α6β1 and heparan sulfate proteoglycans interaction promotes apoptosis and senescence through sustained reactive oxygen species (ROS) production

• Integrin αMβ2 interaction induces a proinflammatory M1-like genetic program in macrophages

Mutation studies complement antibody approaches, showing that disruption of a single integrin α6β1 binding domain in CCN1 produces a senescence-defective CCN1 protein and enhances fibrotic responses to wounding . Function-blocking antibodies can mimic these effects by specifically targeting CCN1-integrin binding interfaces.

What are the contradictory findings regarding CCN1's role in tissue repair and fibrosis, and how might researchers address these contradictions?

Research on CCN1's role in tissue repair and fibrosis has yielded seemingly contradictory results that require careful experimental design to reconcile:

Contradictory findings include:

• Pro-fibrotic evidence: CCN1 expression by fibroblasts contributes to bleomycin-induced skin fibrosis, with loss of CCN1 resulting in disorganized collagen fiber networks, suggesting CCN1 acts as a molecular chaperone for collagen organization .

• Pro-fibrotic evidence in lung: CCN1 is overexpressed in acute lung injury, and adenoviral-mediated overexpression of CCN1 in mouse lung promotes inflammation and fibrosis .

• Anti-fibrotic evidence in liver: Adenoviral-based overexpression of CCN1 in portal myofibroblasts suppresses fibrogenesis by causing cellular senescence through an unfolded protein stress response .

To address these contradictions, researchers should consider:

• Dose-dependent effects: CCN1 generates reactive oxygen species (ROS), which at low levels promote signaling while high levels induce stress responses. Low CCN1 levels may promote fibrotic signaling, while higher amounts may cause myofibroblast death, limiting collagen deposition .

• Context-dependent integrin engagement: Different cell types express different integrin receptors, and CCN1's effects depend on which integrin is engaged. Experimental design should account for the integrin expression profile of the target cells .

• Tissue-specific factors: The liver, skin, and lung microenvironments differ substantially, potentially explaining different outcomes of CCN1 activity.

Researchers investigating CCN1 in fibrosis should employ tissue-specific models, carefully control CCN1 expression levels, and characterize the integrin expression profile of target cells.

What methodological approaches can resolve the molecular mechanisms of CCN1 antibody therapeutic effects?

Understanding the therapeutic effects of CCN1-targeting antibodies requires multi-faceted methodological approaches:

• Epitope mapping: Detailed structural studies, such as X-ray crystallography of antibody-CCN1 complexes, can reveal critical binding interfaces. For example, the crystal structure of the 093G9 Fab in complex with a cyclic peptide of CCN1 (residues 75-81) at 2.7 Å resolution revealed that residues Asn79 and Phe80 are critical for antibody recognition .

• Molecular interaction studies: Investigating how antibodies perturb CCN1's interactions with binding partners such as vitronectin and fibronectin can explain function-blocking mechanisms. The YM1B antibody exerts its CCN1-blocking effect by disrupting these interactions, which are essential for integrin activation .

• Downstream signaling analysis: Comprehensive analysis of signaling pathways affected by CCN1-blocking antibodies helps elucidate mechanism of action. For instance, YM1B suppresses CCN1-induced Rac1 activation and ERK phosphorylation in breast cancer cells .

• Disease-specific models: Testing antibodies in relevant disease models provides context-specific insights. The 093G9 antibody effectively antagonizes the effects of CCN1 in rheumatoid arthritis models , while YM1B shows potential for suppressing breast cancer progression .

• Combined approaches: Integrating structural biology, cell signaling, and in vivo studies provides comprehensive understanding. For example, correlating the structural basis of antibody-CCN1 interaction with functional outcomes in disease models connects molecular mechanisms to therapeutic effects.

How do CCN1 antibodies contribute to understanding cancer progression and potential therapeutic interventions?

CCN1 antibodies have provided crucial insights into cancer biology and therapeutic targeting:

In breast cancer research, CCN1 function-blocking antibodies like YM1B have demonstrated that CCN1 induces actin reorganization, lamellipodia formation, and cell migration/invasion through the αV integrins/Rac1/ERK signaling axis . By blocking these processes, YM1B effectively suppresses CCN1-dependent cancer cell activities, suggesting therapeutic potential.

Western blot applications using anti-CCN1 antibodies have confirmed CCN1 expression in multiple cancer cell lines, including A549 human lung carcinoma and SK-BR-3 human breast cancer cells , providing important tools for expression studies.

In myeloma research, CCN1 has emerged as a microenvironmental biomarker. Quantitative analysis using CCN1-specific antibodies in ELISA has demonstrated that CCN1 levels ≥401 pg/mL are associated with longer time to progression in MGUS/AMM patients . Patients who progress to multiple myeloma within less than 3 years after MGUS/AMM diagnosis have significantly lower CCN1 levels than those progressing after 3 years (431 vs. 723 pg/mL) .

Regarding melanoma, CCN1 affects vascular interactions during metastasis. Deletion of Ccn1 in endothelial cells inhibits the binding of melanoma cancer cells to blood vessels, a critical step in metastatic progression .

These findings collectively support the development of CCN1-targeting antibodies as potential cancer therapeutics, particularly for cases where CCN1 promotes cancer progression.

What is the evidence for CCN1's role in rheumatoid arthritis, and how have antibodies helped characterize this relationship?

CCN1 plays a significant role in rheumatoid arthritis pathogenesis, with antibodies providing critical insights:

CCN1 has been demonstrated to participate in the pathogenesis of rheumatoid arthritis through various pathways, though the specific mechanisms were not fully detailed in the provided search results . The monoclonal antibody 093G9 has proven effective in antagonizing the effects of CCN1 and shows potential therapeutic benefits against rheumatoid arthritis .

Structural studies using crystallography have revealed that 093G9 recognizes a specific epitope mapped to residues 77-80 of CCN1, with a cyclic peptide encompassing residues 75-81 displaying high binding affinity for the antibody . The crystal structure of the 093G9 Fab-peptide complex (2.7 Å resolution) showed that residues Asn79 and Phe80 of CCN1 are critical for antibody recognition as they insert into cavities formed by complementarity-determining regions of the antibody .

This structural information has provided insights into how 093G9 blocks CCN1 function in rheumatoid arthritis, enabling the development of more effective therapeutic antibodies or peptide mimetics that could potentially treat rheumatoid arthritis by specifically targeting CCN1 function.

How can CCN1 antibodies be utilized to investigate the contradictory roles of CCN1 in fibrotic disorders?

CCN1 antibodies serve as valuable tools for dissecting the complex and seemingly contradictory roles of CCN1 in fibrotic disorders:

• Tissue-specific function assessment: By using domain-specific CCN1 antibodies in different tissue contexts, researchers can determine if the pro- or anti-fibrotic effects of CCN1 are tissue-dependent. For example, CCN1 appears to promote fibrosis in skin and lung but may inhibit it in liver .

• Integrin-binding domain analysis: Specific antibodies that block CCN1 interaction with particular integrins can help determine which integrin-mediated pathways contribute to fibrosis. CCN1 promotes cell proliferation and survival via integrin αvβ3, but it promotes apoptosis and senescence through integrin α6β1 and heparan sulfate proteoglycans .

• ROS-signaling investigations: Antibodies can help determine how CCN1 levels correlate with ROS production in different contexts. Low levels of CCN1-induced ROS may promote profibrotic signaling, while higher levels may cause myofibroblast death and limit collagen deposition .

• Temporal expression studies: Using CCN1 antibodies for immunohistochemistry at different stages of fibrosis development can reveal temporal aspects of CCN1 function. This approach might reconcile contradictory findings by demonstrating that CCN1 plays different roles during initiation versus progression of fibrosis.

• Targeting specific CCN1 domains: Function-blocking antibodies against different CCN1 domains can determine which structural features are responsible for pro- versus anti-fibrotic activities.

What are the common technical challenges in using CCN1 antibodies, and how can researchers address them?

Researchers frequently encounter several technical challenges when working with CCN1 antibodies:

• Epitope accessibility issues: Since CCN1's functionality depends on its native conformation with intact disulfide linkages, some antibodies like YM1B specifically recognize the native CCN1 structure . For applications requiring such antibodies, researchers should:

  • Avoid excessive reducing conditions

  • Consider non-denaturing sample preparation methods

  • Use native protein detection techniques when appropriate

• Variable molecular weight detection: CCN1 is detected at approximately 40 kDa in Western blots under reducing conditions but at approximately 52 kDa in Simple Western analysis . This variability could be due to:

  • Post-translational modifications

  • Different sample preparation methods

  • Cell-type specific factors
    Researchers should include appropriate positive controls (such as A549 or SK-BR-3 cell lines) to establish expected band patterns .

• Cross-reactivity concerns: When using polyclonal antibodies, cross-reactivity with other CCN family members is possible due to structural similarities. Researchers should:

  • Validate antibody specificity using recombinant proteins

  • Include appropriate negative controls

  • Consider using monoclonal antibodies for higher specificity applications

• Quantitative analysis variability: For ELISA applications, researchers should establish standardized protocols, including consistent standard curve preparation and calculation methods, to ensure reproducible CCN1 quantification across experiments.

How should researchers select the most appropriate CCN1 antibody for their specific experimental applications?

Selecting the appropriate CCN1 antibody requires consideration of multiple factors:

• Application compatibility: Different antibodies perform optimally in specific applications. For instance, antibody AF6009 functions well as an ELISA detection antibody when paired with MAB40551 , while antibody ab228592 is suitable for Western blot, IHC-P, and ICC/IF applications .

• Epitope considerations:

  • For structural studies: Antibodies recognizing linear epitopes may work better in denatured conditions

  • For functional studies: Antibodies binding conformational epitopes (like YM1B) that recognize the native CCN1 structure with undisturbed disulfide linkages are preferable

  • For domain-specific analysis: Consider antibodies targeting specific CCN1 domains relevant to your research question

• Species reactivity: Verify the antibody's reactivity with your species of interest. For example, ab228592 reacts with human and rat samples .

• Clonality selection:

  • Monoclonal antibodies offer higher specificity and reproducibility

  • Polyclonal antibodies provide broader epitope recognition

  • For therapeutic studies, function-blocking monoclonal antibodies like YM1B or 093G9 may be required

• Validation evidence: Review published literature and manufacturer data demonstrating the antibody's validation in your specific application and cell/tissue type.

What methodological approaches can enhance the reproducibility of CCN1 antibody-based experiments?

Ensuring reproducibility in CCN1 antibody-based experiments requires rigorous methodological approaches:

• Antibody validation protocols:

  • Confirm antibody specificity using knockout/knockdown controls

  • Verify lot-to-lot consistency through standardized quality control measures

  • Document detailed antibody information including catalog number, lot number, and dilution factors

• Standardized experimental conditions:

  • For Western blot: Standardize protein extraction methods, sample loading amounts, and develop consensus protocols for reducing conditions as CCN1 detection varies under different conditions (40 kDa under reducing Western blot vs. 52 kDa in Simple Western)

  • For ELISA: Establish consistent standard curve preparations using recombinant human CCN1 protein with serially diluted 2-fold concentrations

  • For IHC: Standardize fixation protocols, antigen retrieval methods, and blocking procedures

• Comprehensive reporting:

  • Document all experimental conditions, including buffer compositions and incubation times

  • Report both positive and negative results

  • Include appropriate controls in all experiments and report their outcomes

• Cross-validation strategies:

  • Use multiple antibodies targeting different CCN1 epitopes

  • Employ orthogonal detection methods to confirm findings

  • Validate key findings across different cell lines or tissue types

These methodological considerations will help ensure that CCN1 antibody-based experiments yield reproducible and reliable results across different laboratories and experimental setups.