Recombinant Mouse Frizzled-4

Recombinant Mouse Frizzled-4 (Fzd4) is a valuable tool for research applications focused on Wnt signaling, angiogenesis, bone biology, and vascular integrity. Its use enables precise mechanistic studies, functional assays, and therapeutic screening relevant to these biological processes.

Key scientific reasons to use Recombinant Mouse Frizzled-4:

• Wnt Signaling Studies: Fzd4 is a critical receptor in the canonical Wnt/β-catenin pathway, mediating cellular responses to Wnt ligands and Norrin. Recombinant Fzd4 allows for controlled investigation of ligand-receptor interactions, downstream signaling, and pathway modulation in vitro and in vivo.

• Angiogenesis and Vascular Biology: Fzd4 is essential for both physiological and pathological angiogenesis, particularly in the retina. It regulates endothelial cell differentiation and maintains the blood-retina barrier. Recombinant Fzd4 can be used to study these processes, screen for modulators, or develop neutralizing antibodies for functional analysis.

• Bone Formation and Osteoblast Differentiation: Fzd4 expression increases during osteoblast maturation and is required for normal bone matrix mineralization. Recombinant Fzd4 enables studies on osteoblast function, bone acquisition, and the molecular mechanisms underlying skeletal development.

• Cellular and Molecular Assays: Recombinant Fzd4 is suitable for use as an ELISA standard, in cell culture experiments, and for generating or validating antibodies. It provides a consistent, defined reagent for quantifying Fzd4 activity or presence in biological samples.

• Therapeutic Target Validation: As Fzd4 is implicated in cancer, cardiovascular, and neurovascular diseases, recombinant protein is essential for drug screening, receptor-ligand binding assays, and structure-function studies relevant to therapeutic development.

Best practices for use:

• Employ recombinant Fzd4 in binding assays to characterize ligand specificity and affinity.
• Use in cell-based functional assays to dissect downstream signaling events.
• Apply as a standard in quantitative immunoassays (e.g., ELISA) for Fzd4 detection.
• Utilize in antibody generation or validation protocols for specificity testing.

Summary:
Using recombinant Mouse Frizzled-4 enables rigorous, reproducible research into Wnt signaling, vascular and bone biology, and disease mechanisms, supporting both basic science and translational applications.

You can use recombinant Mouse Frizzled-4 protein as a standard for quantification or calibration in ELISA assays, provided the recombinant protein is well-characterized, pure, and its concentration is accurately determined. However, there are important technical considerations and limitations to ensure reliable quantification.

Key considerations:

• Standard Curve Validity: ELISA kits are typically validated using specific standards, often native or recombinant proteins that match the target antigen's structure and epitopes. If you use a recombinant Mouse Frizzled-4 protein as a standard, ensure it is structurally and immunologically similar to the endogenous protein detected by your assay. Differences in glycosylation, folding, or tags (e.g., Fc fusion) may affect antibody recognition and quantification accuracy.

• Calibration and Recovery: Recombinant proteins used as standards must be calibrated against a mass-calibrated reference standard. ELISA quantification using recombinant proteins may show discrepancies in mass values due to dilution errors, protein modifications, or differences in antibody binding. A recovery of ±25% compared to the stated amount is typical when using ELISA for protein quantification.

• Assay Validation: If your ELISA kit is designed for native Frizzled-4, confirm that the recombinant standard is recognized equivalently by the kit antibodies. Some kits specify that their standards are native proteins and may not guarantee accurate quantification with recombinant standards unless validated. Always validate the standard curve with your recombinant protein before relying on it for quantification.

• Carrier Proteins: Recombinant proteins are sometimes supplied with carrier proteins (e.g., BSA) to enhance stability. For ELISA standards, carrier-free preparations are preferred to avoid interference.

Best Practices:

• Use a well-characterized recombinant Mouse Frizzled-4 protein with a known concentration and purity.
• Validate the standard curve using the recombinant protein in your specific ELISA system.
• Compare results with a native standard if available, or perform spike-and-recovery experiments to assess accuracy.
• Use appropriate curve fitting (e.g., 4-parameter logistic, 4PL) for quantification.

Summary Table: Recombinant Protein as ELISA Standard

In conclusion, recombinant Mouse Frizzled-4 can be used as an ELISA standard if properly validated and calibrated, but you must ensure compatibility with your assay and account for potential quantification discrepancies.

Recombinant Mouse Frizzled-4 has been validated for several key applications in published research, primarily in studies of Wnt signaling, angiogenesis, bone biology, and cell differentiation.

Validated Applications:

• ELISA (Enzyme-Linked Immunosorbent Assay):Used for quantitative detection of Frizzled-4 protein in biological samples, including direct ELISAs for specificity and cross-reactivity studies.

• Western Blotting:Applied to detect Frizzled-4 expression in tissue and cell lysates, confirming protein presence and size.

• Immunohistochemistry (IHC):Utilized to localize Frizzled-4 in tissue sections, such as mouse embryoid bodies and bone tissue, enabling visualization of spatial expression patterns.

• Flow Cytometry:Used to quantify Frizzled-4 expression on the surface of cells, particularly in differentiated embryoid bodies derived from mouse embryonic stem cells.

• Functional Assays:Recombinant Frizzled-4 has been used in binding studies (e.g., surface plasmon resonance) to characterize interactions with ligands such as Norrin, and to validate disease-associated mutations affecting ligand-receptor binding.

• In Vivo and In Vitro Models:Recombinant Frizzled-4 and its antibodies have been used to study physiological and pathological angiogenesis in the retina, maintenance of the blood-retina barrier, and bone acquisition/mineralization in genetically modified mice.

Research Areas and Experimental Contexts:

• Retinal Angiogenesis and Blood-Retina Barrier:Recombinant Frizzled-4 and neutralizing antibodies have been used to dissect its role in retinal vascular development, pathological neovascularization, and endothelial cell differentiation.

• Bone Biology:Studies have validated Frizzled-4 in osteoblast differentiation and bone mineralization, using immunofluorescence and gene knockout models to assess its function in bone acquisition.

• Wnt/β-Catenin Signaling:Recombinant Frizzled-4 is central to studies of canonical Wnt signaling, including ligand-receptor binding assays and pathway activation analyses.

• Cancer and Stem Cell Research:Frizzled-4 is investigated as a drug target and signaling mediator in cancer, cardiovascular, and stem cell biology, with recombinant protein used for mechanistic and therapeutic studies.

Summary Table of Validated Applications

These applications are supported by peer-reviewed studies and technical validation in the context of mouse models, cell culture, and biochemical assays.

Reconstitution Protocol

Initial Preparation

Begin by briefly centrifuging the vial prior to opening to bring the lyophilized protein contents to the bottom of the tube. Allow the vial and any reconstitution buffer to equilibrate to room temperature before proceeding.

Reconstitution Solution

Reconstitute the protein in deionized sterile water to achieve a final concentration of 0.1–1.0 mg/mL. For example, if you have 100 µg of protein, add between 100 µL and 1 mL of water to reach the desired concentration range. Add the water gradually and allow 15–30 minutes for reconstitution with gentle agitation. If flakes remain visible, continue mixing for approximately 2 hours at room temperature.

Carrier Protein and Cryoprotectant Addition

To enhance protein stability, add glycerol to a final concentration of 5–50% by volume. This cryoprotectant is particularly important for long-term storage and helps prevent protein denaturation during freeze-thaw cycles.

Storage Recommendations

Long-Term Storage

Aliquot the reconstituted protein solution into working portions and store at –20°C or –80°C for extended storage. Store for up to 12 months under these conditions.

Short-Term Storage

If needed, short-term storage at 2–8°C is permissible for up to 1 month. Storage at room temperature is acceptable for up to 30 days.

Critical Storage Considerations

Avoid repeated freeze-thaw cycles, as these significantly affect protein stability and can cause pH changes and protein denaturation. Use a manual defrost freezer and prepare working aliquots containing at least 10 µL of protein solution to minimize handling. Always consult the product-specific documentation for any protein-dependent storage modifications.