Recombinant Mouse Fractalkine

Using Recombinant Mouse Fractalkine (CX3CL1) in research applications is essential for studying the CX3CL1–CX3CR1 signaling axis, which plays a critical role in neurobiology, immunology, and inflammation. Recombinant protein provides a controlled, consistent, and species-specific tool for dissecting the molecular and cellular mechanisms of fractalkine signaling in vitro and in vivo.

Key reasons to use recombinant mouse fractalkine include:

• Functional Studies of Chemotaxis and Cell Signaling: Recombinant fractalkine is bioactive and can be used to stimulate or inhibit CX3CR1-expressing cells, enabling precise analysis of chemotactic responses, receptor binding, and downstream signaling pathways in mouse models or cell lines.
• Neuroinflammation and Neuroprotection Research: CX3CL1–CX3CR1 signaling modulates microglial activation, neuroinflammation, and neuroprotection. Recombinant fractalkine has been shown to enhance oligodendrocyte regeneration, promote remyelination, and attenuate neuroinflammatory responses in mouse models of demyelination and brain injury.
• Immunological Applications: The fractalkine axis is involved in leukocyte recruitment, macrophage polarization, and immune cell trafficking. Recombinant protein allows for controlled experiments on immune cell migration, polarization (e.g., M1/M2 macrophage phenotypes), and cytokine secretion.
• Disease Modeling: Recombinant mouse fractalkine is used to model and manipulate disease processes such as multiple sclerosis, stroke, neurodegeneration, and transplant rejection, where the CX3CL1–CX3CR1 axis is implicated.
• Assay Development: It serves as a standard or stimulant in ELISA, Western blot, cell-based assays, and binding studies, ensuring reproducibility and specificity in quantifying fractalkine or assessing receptor-ligand interactions.

Advantages of using recombinant protein:

• Species specificity: Mouse protein ensures physiological relevance in murine systems, avoiding cross-species artifacts.
• Batch-to-batch consistency: Recombinant production yields highly pure, defined protein, minimizing variability.
• Defined structure: Full-length or domain-specific constructs allow targeted studies of fractalkine’s adhesive and chemotactic functions.

In summary, recombinant mouse fractalkine is a versatile and essential reagent for dissecting the biological roles of the CX3CL1–CX3CR1 axis in mouse models, enabling mechanistic studies, therapeutic exploration, and assay development with high specificity and reproducibility.

Yes, recombinant mouse Fractalkine (CX3CL1) can be used as a standard for quantification and calibration in ELISA assays. The recombinant protein produced in insect cell expression systems is specifically designed and validated for this purpose.

Production and Purity Standards

Recombinant mouse Fractalkine used as ELISA standards is typically produced in Sf21 insect cell expression systems and is highly purified to ensure quality and reliability. The protein material contains no infectious agents, making it suitable for research applications. The recombinant protein generally spans the full-length sequence (Gln25-Arg337) with a C-terminal 6-His tag for identification and purification purposes.

Formulation Considerations

When selecting recombinant Fractalkine for use as an ELISA standard, you should consider the formulation carefully. Recombinant proteins formulated with carrier proteins such as BSA are specifically recommended for use in cell or tissue culture applications and as ELISA standards. This formulation helps maintain protein stability and prevents non-specific binding during the assay.

Standard Curve Performance

The recombinant protein performs reliably across typical ELISA assay ranges. Standard curves generally span from approximately 0.274 to 200 ng/mL, with sensitivity levels around 300 pg/mL or better depending on the specific assay configuration. The protein demonstrates excellent inter-assay and intra-assay precision, with coefficients of variation typically less than 12% and 10%, respectively.

Important Limitation

It is critical to note that while recombinant Fractalkine serves excellently as an ELISA standard for quantification purposes, ELISA standard recombinant proteins are not recommended for bioassay applications where you need to assess biological activity, as they are not tested for such functional applications. If you require the protein for functional studies involving cell chemotaxis or receptor binding assays, you should verify that the specific product has been validated for bioassay use.

Recombinant Mouse Fractalkine (CX3CL1) has been validated for multiple applications in published research, primarily in bioassays, binding assays, and in vivo functional studies.

Key validated applications include:

• Bioassays:
  Recombinant Mouse Fractalkine is widely used to measure its ability to chemoattract cells expressing CX3CR1, such as human peripheral blood lymphocytes and BaF3 mouse pro‑B cells transfected with mouse CX3CR1. It is also used to study microglial polarization, monocyte recruitment, and macrophage phenotype switching in various inflammation and neurodegeneration models.

• Binding Assays:
  The protein is used in quantitative receptor-ligand binding assays to analyze interactions between CX3CL1 and CX3CR1, including cell-substrate contact zone studies.

• In Vivo Functional Studies:
  Recombinant fractalkine has been administered in animal models to investigate its effects on neurological outcomes, inflammation, hematoma resolution, and immune cell recruitment. For example, it has been shown to improve neurobehavioral outcomes and promote hematoma resolution in neonatal brain injury models by modulating microglial polarization. It is also used to study the role of the fractalkine-CX3CR1 axis in acute organ rejection, cardiovascular inflammation, and autoimmune CNS inflammation.

• Cell Culture and ELISA Standard:
  Recombinant fractalkine is recommended as a standard for ELISA and for use in cell or tissue culture experiments to study chemokine signaling and immune cell migration.

• Western Blot:
  It is used as a positive control or antigen in Western blot assays to detect fractalkine or its receptor.

• 3D Cell Culture and Cell/Gene Therapy Research:
  The protein is applied in advanced cell culture systems and gene therapy studies to investigate chemokine-mediated cell migration and signaling.

Representative published research applications:

• Microglial repopulation and neuroprotection:
  Studies have used recombinant fractalkine to examine microglial dynamics and neuroprotective signaling in retinal and CNS injury models.

• Inflammation and immune cell trafficking:
  It is validated for investigating monocyte and T lymphocyte recruitment in models of emphysema, arthritis, and cardiovascular disease.

• Transplantation and rejection:
  The fractalkine-CX3CR1 axis is studied in acute heart transplant rejection models, with recombinant protein used to probe immune mechanisms and therapeutic interventions.

Summary Table of Validated Applications

In summary, recombinant mouse fractalkine is a versatile tool validated for bioassays, binding assays, in vivo functional studies, ELISA, Western blot, and cell culture applications in published research, especially in the fields of immunology, neuroscience, and inflammation biology.

Reconstitution Protocol

Recombinant Mouse Fractalkine (CX3CL1) is typically supplied in lyophilized form and requires proper reconstitution before use in cell culture experiments. Begin by briefly centrifuging the vial to concentrate the lyophilized powder at the bottom of the tube.

For reconstitution, add sterile PBS containing at least 0.1% human serum albumin or bovine serum albumin to the vial. Alternatively, some formulations can be reconstituted with sterile, distilled water. The recommended reconstitution concentration ranges from 0.1 to 1.0 mg/mL. For example, if you have 100 µg of protein, you would add between 100 µL and 1 mL of diluent to achieve the desired concentration.

Some preparations may be formulated in acetonitrile and TFA, in which case reconstitution at 100 µg/mL in sterile PBS is recommended. Always consult the product-specific data sheet or Certificate of Analysis for your particular preparation, as reconstitution requirements can vary depending on the formulation and expression system used.

Storage Recommendations

Lyophilized protein: Store at -20°C upon arrival. Short-term storage at 4°C (up to 6 months) or room temperature (up to 30 days) is permissible.

Reconstituted protein solutions: Store working aliquots at -20°C to -80°C for extended storage. For shorter-term use, reconstituted protein can be stored at 4°C for 2-7 days. When preparing stock solutions, concentrations of 50-100 µg/mL in appropriate sterile buffer are suitable for storage at -20°C or colder.

Critical consideration: Avoid multiple freeze-thaw cycles, as repeated freezing and thawing will significantly affect protein stability, alter pH, and potentially cause protein denaturation. Aliquot your reconstituted protein into smaller portions to minimize freeze-thaw exposure during your experiments.

Expression System Considerations

Recombinant Mouse Fractalkine may be produced in different expression systems (E. coli, insect cells, or mammalian cells), which affects post-translational modifications like glycosylation. For in vitro cell culture studies, the expression system typically does not significantly impact biological activity. However, for in vivo applications, mammalian or insect cell-derived preparations generally exhibit longer half-lives due to glycosylation-mediated protection from protease degradation.