Tf2-3 Antibody

What is COUP-TF II/NR2F2 and what are its key biological functions?

COUP-TF II (Chicken ovalbumin upstream promoter transcription factor II), also known as ARP-1 or NR2F2, belongs to the orphan nuclear receptor family. The protein is expressed in various tissues including the tongue, follicles of vibrissae, cochlea, and in stroma of the nasal septum . COUP-TF II plays crucial roles in several developmental and physiological processes, particularly in angiogenesis, vascular remodeling, and heart development . This transcription factor interacts with multiple other nuclear receptors, functioning as part of complex regulatory networks that control gene expression.

The biological significance of COUP-TF II extends to cancer biology, where it has been implicated in metastatic progression, particularly in prostate cancer through its regulation of FOXM1 and CENPF expression . Additionally, research has shown its involvement in transcriptional regulation of retinoic acid receptor beta 2 in breast cancer cells, where it interacts with nucleolin as a coactivator . Understanding these biological functions provides the foundation for designing experiments that effectively utilize COUP-TF II antibodies.

What experimental techniques commonly employ COUP-TF II/NR2F2 antibodies?

COUP-TF II/NR2F2 antibodies are versatile tools employed across multiple experimental techniques in molecular and cellular biology research. Based on the literature, the most common applications include:

• Western Blotting: Widely used to detect and quantify COUP-TF II protein levels in cell lysates, particularly in cancer cell lines like PC3, LNCaP, and 22RV-1 . This technique allows researchers to track changes in COUP-TF II expression following experimental manipulations.

• Immunocytochemistry (ICC): Used to visualize the subcellular localization of COUP-TF II in cultured cells, including in three-dimensional models such as spheroids and cardiac assembloids .

• Immunohistochemistry (IHC): Applied to tissue sections to examine COUP-TF II expression patterns in developmental contexts and disease states, as demonstrated in mouse model studies .

• Chromatin Immunoprecipitation (ChIP): Employed to investigate COUP-TF II binding to specific genomic regions, particularly in analyzing its direct transcriptional regulation of targets like FOXM1 and CENPF .

• Gene Knockdown Validation: COUP-TF II antibodies are routinely used to confirm successful knockdown in siRNA and shRNA experiments, providing essential validation for functional studies .

Each technique requires specific optimization for the particular COUP-TF II antibody being used, including appropriate dilutions, incubation conditions, and detection methods.

How should researchers validate COUP-TF II/NR2F2 antibody specificity?

Validating antibody specificity is critical for ensuring reliable research outcomes when working with COUP-TF II/NR2F2 antibodies. Based on established practices, researchers should implement a multi-faceted validation approach:

• Knockdown/Knockout Controls: The gold standard for antibody validation involves comparing antibody signal between control samples and those with reduced target expression. The search results demonstrate this approach, showing Western blot analysis in PC3 cells transfected with siRNAs against COUP-TF II, where protein reduction confirms antibody specificity . Similar validation was performed in MCF-7 cells, where siCOUP-TFII transfection led to decreased COUP-TF II expression detectable by Western blot .

• Expression Pattern Consistency: Antibody signal should align with known expression patterns across different cell types and tissues. Compare staining patterns with published data on COUP-TF II expression in relevant model systems.

• Molecular Weight Verification: Confirm that the detected protein band appears at the expected molecular weight for COUP-TF II (~47 kDa). Multiple bands may indicate non-specific binding or post-translational modifications.

• Positive and Negative Controls: Include cell lines or tissues with known high expression (e.g., PC3 prostate cancer cells) and low/no expression of COUP-TF II to verify signal specificity.

• Reproducibility Across Techniques: Validate findings using complementary approaches (e.g., if protein reduction is seen by Western blot following knockdown, confirm with immunofluorescence).

These rigorous validation steps are essential for generating reliable and reproducible data with COUP-TF II antibodies.

What are the optimal storage and handling conditions for COUP-TF II/NR2F2 antibodies?

Proper storage and handling of COUP-TF II/NR2F2 antibodies are crucial for maintaining their specificity and activity over time. While specific manufacturer recommendations may vary, general best practices include:

• Temperature Management: Store antibody aliquots at -20°C for long-term storage to prevent protein degradation and maintain epitope recognition capacity. Avoid repeated freeze-thaw cycles by preparing appropriate working aliquots.

• Working Solution Preparation: For regular use, keep small working aliquots at 4°C for up to one month. Always prepare dilutions in recommended buffers containing stabilizing proteins (typically BSA) and preservatives to prevent microbial growth.

• Centrifugation Before Use: Prior to opening, briefly centrifuge antibody vials to collect liquid at the bottom of the tube, particularly after shipping or extended storage.

• Contamination Prevention: Use sterile technique when handling antibody solutions to prevent microbial contamination. Never return unused portions to the original vial.

• Solution Composition: Many antibodies are optimally stored in buffer solutions containing sodium azide as a preservative. Note that sodium azide may inhibit peroxidase activity in some applications, requiring washing steps before use in HRP-based detection systems.

• Transportation Considerations: When transporting between laboratories, maintain cold chain conditions using dry ice or wet ice depending on distance and duration.

• Documentation: Maintain accurate records of antibody lot numbers, receipt dates, aliquoting dates, and freeze-thaw cycles to monitor antibody performance over time.

Following these guidelines will help ensure consistent experimental results and extend the useful life of valuable COUP-TF II antibodies.

How does COUP-TF II/NR2F2 contribute to cancer metastasis mechanisms?

COUP-TF II/NR2F2 plays a multifaceted role in cancer metastasis, particularly in prostate cancer, through several interconnected molecular mechanisms:

• MicroRNA Regulation Pathway: Research demonstrates that COUP-TF II is negatively regulated by miR-101 and miR-27a. Loss of these microRNAs leads to de-repression of COUP-TF II expression, subsequently promoting cancer metastasis . Experimental evidence from PC3 and LNCaP prostate cancer cell lines shows that miR-101 mimics significantly reduce invasion, while COUP-TF II knockdown similarly impairs invasive capacity .

• EMT Modulation: Western blot analysis reveals that COUP-TF II regulates epithelial-mesenchymal transition (EMT) markers. In PC3 cells, stable knockdown of COUP-TF II increased E-cadherin (epithelial marker) and decreased vimentin (mesenchymal marker) expression, indicating COUP-TF II promotes the metastatic phenotype through EMT regulation .

• Transcriptional Control of Metastasis Effectors: Gene expression profiling after COUP-TF II knockdown identified FOXM1 and CENPF as critical downstream targets. ChIP analysis confirmed COUP-TF II directly binds to the promoter regions of these genes, activating their expression . The FOXM1-CENPF axis represents a key effector pathway through which COUP-TF II drives metastatic progression.

• In Vivo Metastasis Model: Orthotopic injection of LNCaP cells with inducible COUP-TF II shRNA into NOD-SCID mice demonstrated that COUP-TF II inhibition significantly reduced metastatic potential. Immunohistochemical analysis confirmed metastatic tumor cells in lymph nodes were positive for androgen receptor, linking COUP-TF II to hormone-responsive cancer progression .

These findings collectively establish COUP-TF II as a master regulator of metastatic progression, operating through specific transcriptional networks that control cell invasion and migration capabilities.

What is the relationship between microRNAs, COUP-TF II, and cancer progression?

The interplay between microRNAs and COUP-TF II forms a critical regulatory axis in cancer progression, particularly in metastatic development. Evidence from multiple experiments reveals this complex relationship:

• miR-101 and miR-27a as COUP-TF II Repressors: Experimental data demonstrates that both miR-101 and miR-27a negatively regulate COUP-TF II expression. In prostate cancer cell lines (LNCaP and PC3), treatment with 50 nM of miR-101 and miR-27a mimics for 48 hours significantly reduced invasive capability by approximately 50% (P<0.05) . This functional impact correlates with decreased COUP-TF II expression, establishing these microRNAs as upstream regulators.

• Reciprocal Expression Pattern: Loss of miR-101 and miR-27a is frequently observed in advanced cancers, leading to de-repression of COUP-TF II. This pattern constitutes a regulatory mechanism whereby microRNA downregulation enables COUP-TF II overexpression, driving metastatic progression .

• Rescue Experiments Validating Causality: PC3 cells with inducible miR-101 expression show reduced invasiveness when miR-101 is induced with doxycycline. Critically, re-expression of COUP-TF II in these cells restores invasive capacity, demonstrating that COUP-TF II is the functional target through which miR-101 exerts its anti-metastatic effects .

• In Vivo Confirmation: Studies using orthotopic injection of LNCaP cells containing inducible COUP-TF II shRNA and constructs expressing anti-miR-101 and anti-miR-27a showed that anti-miR expression promoted tumor growth and metastasis, but this effect was negated when COUP-TF II was simultaneously repressed . Quantification of luminance from IVIS imaging confirmed statistical significance (P<0.05) in these differential growth patterns.

• Therapeutic Implications: This regulatory relationship suggests potential therapeutic strategies targeting either the restoration of miR-101/miR-27a levels or direct inhibition of COUP-TF II to impede metastatic progression in prostate and potentially other cancers.

This microRNA-COUP-TF II regulatory axis represents a sophisticated molecular mechanism underlying cancer progression that can be targeted for both diagnostic and therapeutic applications.

How can COUP-TF II/NR2F2 knockdown experiments be optimized for studying downstream targets?

Optimizing COUP-TF II knockdown experiments requires careful consideration of multiple parameters to ensure robust identification and validation of downstream targets. Based on published methodologies, researchers should implement the following strategies:

• Knockdown Strategy Selection:

  • siRNA Approach: For short-term studies (48-72 hours), use multiple independent siRNAs targeting different regions of COUP-TF II mRNA. Published protocols have successfully employed two different siRNAs against COUP-TF II for 72 hours in PC3 cells, achieving efficient knockdown as verified by Western blot .

  • Stable shRNA Systems: For longer studies, inducible shRNA systems provide temporal control. PC3 cells carrying inducible COUP-TF II-Flag gene treated with doxycycline demonstrated effective knockdown suitable for downstream analysis .

• Validation of Knockdown Efficiency:

  • Protein Level: Western blot analysis using validated antibodies to confirm protein reduction, with quantification relative to loading controls (β-actin) .

  • mRNA Level: RT-qPCR to verify transcript reduction, typically showing >70% decrease in expression for effective functional studies .

• Experimental Design for Target Identification:

  • Global Approaches: Gene expression profiling following COUP-TF II knockdown. The GEO dataset GSE33182 utilized this approach, identifying genes differentially expressed (P<0.05, fold change >1.5) in COUP-TF II knockdown PC3 cells compared to control .

  • Targeted Validation: After identification of potential targets (e.g., FOXM1 and CENPF), validate expression changes using RT-qPCR and Western blot .

• Mechanistic Confirmation:

  • Promoter Analysis: Computational identification of potential COUP-TF II binding sites in promoter regions of candidate target genes .

  • ChIP Assays: Chromatin immunoprecipitation to confirm direct binding of COUP-TF II to target gene promoters, as demonstrated for FOXM1 and CENPF loci .

  • Promoter Activity Assays: Measure promoter activities in control vs. COUP-TF II knockdown conditions using luciferase reporter assays to quantify transcriptional impact .

• Functional Validation:

  • Rescue Experiments: Re-express COUP-TF II in knockdown cells to restore target gene expression and associated phenotypes .

  • Target Gene Knockdown: Perform knockdown of identified targets to determine if they recapitulate COUP-TF II knockdown phenotypes, as shown with FOXM1 and CENPF knockdown in invasion assays .

This comprehensive approach ensures reliable identification and validation of authentic COUP-TF II downstream targets while minimizing false positives due to off-target effects or secondary consequences of knockdown.

What are the experimental considerations when studying COUP-TF II interactions with FOXM1 and CENPF in cancer models?

When investigating the interactions between COUP-TF II and its downstream targets FOXM1 and CENPF in cancer models, researchers should address several critical experimental considerations:

• Model System Selection:

  • Cell Line Choice: PC3 cells have been successfully used to study this axis, showing robust COUP-TF II, FOXM1, and CENPF expression. Consider using multiple cell lines to confirm findings across different genetic backgrounds .

  • In Vivo Models: Orthotopic injection models in NOD-SCID mice provide physiologically relevant conditions for studying metastatic behavior influenced by this pathway .

• Expression Analysis Methodology:

  • Protein Detection: Western blotting has effectively detected all three proteins (COUP-TF II, FOXM1, CENPF) in single experiments, allowing correlation analysis between their expression levels .

  • Transcript Quantification: RT-qPCR has demonstrated sensitivity in measuring expression changes of FOXM1 and CENPF following COUP-TF II knockdown, with statistically significant reductions (P<0.05) observed within 72 hours of knockdown .

• Transcriptional Regulation Assessment:

  • Promoter Mapping: The FOXM1 and CENPF loci contain specific COUP-TF II-binding sites that must be precisely identified for mechanistic studies .

  • ChIP Protocol Optimization: ChIP experiments require stringent controls, including IgG controls and positive control regions. Studies have successfully performed ChIP in PC3 cells treated with control and two different siRNAs against COUP-TF II for 72 hours .

  • Promoter Activity Measurement: FOXM1 and CENPF promoter activities can be measured using luciferase reporter assays in PC3 cells with inducible COUP-TF II expression, showing measurable changes with doxycycline treatment .

• Functional Relationship Analysis:

  • Sequential Knockdown Studies: To establish pathway hierarchy, perform COUP-TF II induction followed by FOXM1 and/or CENPF knockdown. Published protocols have used individual siRNA against FOXM1 and CENPF or double knockdown for 48 hours following doxycycline-induced COUP-TF II expression .

  • Phenotypic Readouts: Invasion assays provide functional confirmation of the COUP-TF II-FOXM1-CENPF axis in metastatic behavior, with statistical analysis (P<0.05, two-sided Student's t-test) confirming significance of observed changes .

• Data Interpretation Challenges:

  • Redundancy Assessment: Consider potential compensatory mechanisms between FOXM1 and CENPF by comparing individual versus double knockdown effects .

  • Temporal Dynamics: Account for time-dependent changes in expression and activity, as promoter activities may show different kinetics than protein accumulation.

By systematically addressing these experimental considerations, researchers can establish robust evidence for the functional significance of the COUP-TF II-FOXM1-CENPF axis in cancer progression.

How do epigenetic modifications affect COUP-TF II/NR2F2 expression in hormone-responsive cancers?

Epigenetic modifications play a crucial role in regulating COUP-TF II/NR2F2 expression in hormone-responsive cancers, particularly in the context of therapy resistance. The research data reveals several important mechanisms:

• DNA Methylation and Histone Acetylation Effects:

  • 5-Aza-2-deoxycytidine (DNA methyltransferase inhibitor) and trichostatin A (histone deacetylase inhibitor) treatments significantly increase COUP-TF II expression in antiestrogen-resistant breast cancer cell lines . This suggests that COUP-TF II expression is normally suppressed by DNA methylation and histone deacetylation in these cell types.

  • The combinatorial effect of these epigenetic modifiers indicates a coordinated epigenetic regulation of the COUP-TF II locus, involving both DNA methylation and histone modification mechanisms.

• Retinoic Acid Receptor Signaling Intersection:

  • COUP-TF II functions as a coregulator of retinoic acid receptor β2 (RARB2) transcription in breast cancer cells, working in conjunction with nucleolin .

  • Knockdown studies demonstrate that reduction of COUP-TF II decreases RARB2 transcription in MCF-7 cells, establishing a functional relationship between COUP-TF II and retinoic acid signaling .

  • In T47D cells treated with all-trans retinoic acid (atRA), COUP-TF II participates in the transcriptional response, suggesting epigenetic regulation of COUP-TF II impacts hormonal signaling pathways .

• Cell Line-Specific Regulatory Patterns:

  • Different breast cancer cell lines (MCF-7 and T47D) show distinct patterns of COUP-TF II regulation and function, indicating context-dependent epigenetic control mechanisms .

  • This cell-type specificity may explain differential responses to hormone therapies and the development of resistance mechanisms in certain cancer subtypes.

• Implications for Therapeutic Resistance:

  • The upregulation of COUP-TF II following treatment with epigenetic modifiers in antiestrogen-resistant cells suggests that epigenetic reprogramming during therapy may alter COUP-TF II expression .

  • This altered expression potentially contributes to resistance mechanisms by modifying downstream gene expression programs involved in cell proliferation and survival.

Understanding these epigenetic regulatory mechanisms offers potential for developing combination therapies targeting both hormone receptors and epigenetic modifiers to overcome resistance in hormone-responsive cancers.

What are the optimal protocols for using COUP-TF II/NR2F2 antibodies in Western blotting?

Optimizing Western blotting protocols for COUP-TF II/NR2F2 detection requires attention to several critical parameters based on published methodologies:

• Sample Preparation:

  • Cell Lysis: Use RIPA buffer supplemented with protease inhibitors for efficient protein extraction from nuclear factors like COUP-TF II .

  • Protein Quantification: Bradford or BCA assay to ensure equal loading (typically 20-50 μg total protein per lane).

  • Denaturation: Heat samples at 95°C for 5 minutes in Laemmli buffer containing reducing agent.

• Gel Electrophoresis Parameters:

  • Gel Percentage: 10% SDS-PAGE gels provide optimal resolution for COUP-TF II (~47 kDa).

  • Running Conditions: 100-120V constant voltage for approximately 1.5 hours in standard Tris-Glycine running buffer.

• Transfer Optimization:

  • Membrane Selection: PVDF membranes (0.45 μm pore size) show superior performance for COUP-TF II detection.

  • Transfer Conditions: Wet transfer at 100V for 1 hour or 30V overnight at 4°C in Tris-Glycine buffer with 20% methanol.

• Antibody Incubation:

  • Blocking: 5% non-fat dry milk in TBST for 1 hour at room temperature to minimize background.

  • Primary Antibody: Multiple studies have successfully used anti-COUP-TF II antibodies at 1:1000 dilution in 5% BSA-TBST, incubated overnight at 4°C .

  • Washing: At least 3×10 minutes with TBST to remove unbound antibody.

  • Secondary Antibody: HRP-conjugated anti-species antibody at 1:5000-1:10000 dilution in blocking buffer for 1 hour at room temperature.

• Detection Strategy:

  • Enhanced Chemiluminescence (ECL) detection has been widely used in published COUP-TF II Western blots .

  • Exposure times typically range from 30 seconds to 5 minutes depending on expression levels.

• Controls and Validation:

  • Loading Control: β-actin has been effectively used as a loading control in multiple studies .

  • Positive Control: Include lysate from cells known to express COUP-TF II (e.g., PC3 cells).

  • Negative Control: Use lysate from cells with COUP-TF II knockdown to confirm specificity .

• Quantification Approach:

  • Densitometric analysis of COUP-TF II bands normalized to loading control (β-actin) using ImageJ or similar software.

  • Present data as relative expression compared to control samples.

Following these optimized protocols will help ensure consistent and reliable detection of COUP-TF II protein in Western blotting applications.

How can researchers effectively design COUP-TF II/NR2F2 ChIP experiments?

Designing effective Chromatin Immunoprecipitation (ChIP) experiments for COUP-TF II/NR2F2 requires careful consideration of multiple technical factors to ensure reliable identification of genuine binding sites:

• Experimental Design Considerations:

  • Cell Type Selection: Choose cell lines with documented COUP-TF II expression (e.g., PC3 cells for prostate cancer studies) .

  • Treatment Conditions: Consider including treatments that modulate COUP-TF II activity, such as siRNA knockdown for specificity validation .

  • Biological Replicates: Include at least three independent biological replicates for statistical robustness, as demonstrated in published COUP-TF II ChIP studies .

• Chromatin Preparation Protocol:

  • Crosslinking: Formaldehyde (1% final concentration) for 10 minutes at room temperature has been effective for COUP-TF II ChIP.

  • Quenching: Glycine (125 mM final concentration) for 5 minutes to stop crosslinking.

  • Sonication Optimization: Titrate sonication conditions to achieve chromatin fragments of 200-500 bp, verified by agarose gel electrophoresis.

• Immunoprecipitation Strategy:

  • Antibody Selection: Use ChIP-validated COUP-TF II antibodies with demonstrated specificity in immunoprecipitation applications.

  • Pre-clearing: Incubate chromatin with protein A/G beads before adding antibody to reduce non-specific binding.

  • Immunoprecipitation Conditions: Overnight incubation at 4°C with 2-5 μg antibody per ChIP reaction.

  • Control Reactions: Include IgG control immunoprecipitation to establish background enrichment levels.

• Target Site Identification:

  • Bioinformatic Prediction: Use motif analysis to identify potential COUP-TF II binding sites, such as those found in the FOXM1 and CENPF loci .

  • Primer Design: Design qPCR primers spanning predicted binding sites and control regions (typically 80-150 bp amplicons).

  • Published examples include successful ChIP for COUP-TF II binding sites in PC3 cells treated with control and two different siRNAs against COUP-TF II .

• Data Analysis Approach:

  • Enrichment Calculation: Percent input method or fold enrichment over IgG control, with statistical significance established by Student's t-test (P<0.05) .

  • Validation Strategy: Confirm binding site functionality through promoter activity assays using luciferase reporters, as demonstrated for FOXM1 and CENPF promoters .

• Troubleshooting Considerations:

  • Low Signal: Increase cell number, optimize antibody concentration, or modify sonication conditions.

  • High Background: Increase washing stringency or pre-clear chromatin more extensively.

  • Poor Reproducibility: Standardize cell culture conditions and harvesting protocols across replicates.

By implementing these detailed ChIP protocol specifications, researchers can effectively identify and characterize authentic COUP-TF II binding sites in target gene promoters.

What are the best approaches for combining COUP-TF II/NR2F2 studies with microRNA research?

Integrating COUP-TF II/NR2F2 studies with microRNA research requires specialized approaches that bridge transcription factor biology with non-coding RNA regulation. Based on successful research strategies, the following methodological framework is recommended:

• Computational Prediction and Validation:

  • Target Prediction: Utilize algorithms (e.g., TargetScan, miRanda) to identify potential miRNA binding sites in COUP-TF II 3'UTR. Focus on highly conserved sites and those predicted by multiple algorithms.

  • Expression Correlation Analysis: Analyze public datasets to identify inverse correlations between miRNA expression and COUP-TF II levels across tissue samples or cancer progression stages.

  • Published work has established miR-101 and miR-27a as significant COUP-TF II regulators using this approach .

• Direct Interaction Assessment:

  • Luciferase Reporter Assays: Clone the COUP-TF II 3'UTR downstream of a luciferase reporter to evaluate direct targeting by candidate miRNAs.

  • Site-Directed Mutagenesis: Introduce mutations in predicted miRNA binding sites to confirm specificity of interaction.

  • RNA Immunoprecipitation: Perform Ago2-RIP followed by qRT-PCR to confirm COUP-TF II mRNA and candidate miRNA co-localization in RISC complexes.

• Functional Impact Evaluation:

  • miRNA Mimic/Inhibitor Studies: Transfect cells with miRNA mimics (50 nM concentration has been effective for miR-101) or inhibitors and assess changes in COUP-TF II expression by Western blot and qRT-PCR .

  • Rescue Experiments: After miRNA-mediated suppression, re-express COUP-TF II using constructs lacking the 3'UTR to determine if phenotypic effects are specifically due to COUP-TF II regulation.

  • PC3 cells carrying inducible miR-101 have been successfully used for such experiments, with invasion assays as functional readouts .

• Combined Knockdown Approaches:

  • Sequential Manipulation: Inhibit miRNAs (e.g., miR-101) using antisense RNA in conjunction with COUP-TF II knockdown to establish pathway hierarchy.

  • 22RV-1 cells treated with miR-101 inhibitor combined with COUP-TF II knockdown demonstrated the functional relationship in invasion assays .

• In Vivo Validation Models:

  • Engineered Model Systems: Develop cell lines containing both inducible COUP-TF II shRNA and constructs expressing anti-miRNAs (anti-miR-101 and anti-miR-27a).

  • Orthotopic Injection: Implant these cells into appropriate animal models (e.g., NOD-SCID mice for prostate cancer) and monitor tumor growth and metastasis using luciferase reporters.

  • Published protocols have established the efficacy of doxycycline induction (1 mg/ml in drinking water) for controlling COUP-TF II expression in vivo .

• Downstream Target Profiling:

  • Integrated Analysis: Compare gene expression profiles after miRNA manipulation versus COUP-TF II knockdown to identify common downstream pathways.

  • ChIP-seq following miRNA modulation to determine how miRNA-mediated changes in COUP-TF II levels affect genome-wide binding patterns.

This comprehensive methodological framework enables researchers to robustly investigate the complex regulatory relationships between miRNAs and COUP-TF II in various biological contexts.