CYP4V2 Antibody

What is CYP4V2 and what is its biological function?

CYP4V2 (Cytochrome P450, family 4, subfamily V, polypeptide 2) is a 525-amino acid cytochrome P450 monooxygenase primarily involved in fatty acid metabolism in ocular tissues. It catalyzes the omega-hydroxylation of polyunsaturated fatty acids (PUFAs), particularly docosahexaenoic acid (DHA) and its precursor eicosapentaenoic acid (EPA), which are essential components of retinal membranes . The enzyme plays a critical role in retinal PUFA homeostasis and contributes to lipid metabolism regulation throughout the body.

Functionally, CYP4V2 demonstrates similar catalytic rates to CYP4F2 (an established hepatic PUFA hydroxylase) when metabolizing DHA and EPA to their respective ω-hydroxylated products . Studies overexpressing functional CYP4V2 in cell models have shown that the enzyme significantly alters cellular lipid homeostasis, supporting its central role in fatty acid metabolism pathways .

What are the cellular and tissue expression patterns of CYP4V2?

CYP4V2 is expressed across diverse human tissues with particularly significant expression in ocular structures. Expression analysis of multiple cytochrome P450 genes has revealed that CYP4V2 is a major cytochrome P450 in ARPE-19 cells (a human retinal pigmented epithelium cell line) and is the only detectable CYP4 transcript in these cells . This finding emphasizes its importance in retinal epithelial function.

Immunohistochemical analyses have demonstrated that CYP4V2 protein is predominantly present in the epithelial cells of both the retina and cornea, with subcellular localization to the endoplasmic reticulum . This localization pattern aligns with the clinical manifestations of Bietti crystalline dystrophy, which primarily affects these ocular tissues.

In hepatic tissues, CYP4V2 has been implicated in metabolic pathways relevant to non-alcoholic fatty liver disease and broader metabolic syndrome . Mouse liver tissue has been confirmed as a reliable positive control for CYP4V2 expression in experimental protocols .

What types of CYP4V2 antibodies are commercially available for research applications?

Several types of CYP4V2 antibodies are available for research applications, offering different characteristics suitable for various experimental needs:

When selecting an antibody, researchers should consider:

• The experimental application (Western blot, IHC, ELISA, etc.)

• Required species reactivity

• Mono vs. polyclonal properties (affecting specificity and sensitivity)

• Conjugation needs based on detection methods

Custom antibodies have been successfully generated using purified CYP4V2 protein as the antigen, which may be necessary for specialized applications requiring high specificity .

How is CYP4V2 associated with Bietti crystalline dystrophy (BCD)?

Bietti crystalline corneoretinal dystrophy (BCD) is an autosomal recessive degenerative eye disease characterized by crystalline deposits in the retina and cornea, progressive retinal degeneration, and eventual blindness. Genetic studies have established that mutations in the CYP4V2 gene are the primary cause of this disorder .

More than 95% of BCD patients have been found to carry CYP4V2 mutations . Over 34 distinct mutations have been identified, with variations in exons 6-9 accounting for >80% of all mutations. Three founder mutations (c.802-8_810del17insGC, c.992A>C, and c.1091-2A>G) represent a significant percentage (62.7%, 7.4%, and 6.4% respectively) of mutated alleles .

The most frequent coding-region mutation, p.H331P, results in an unstable protein that is undetectable in Western blot analyses of transduced cells, suggesting that protein instability is the primary mechanism of pathogenesis . This finding indicates that BCD results from loss of functional CYP4V2, leading to disrupted lipid metabolism in ocular tissues.

Recent advances include the first-in-human clinical trial of gene therapy for BCD using an adeno-associated virus vector encoding functional CYP4V2 (rAAV2/8-hCYP4V2), offering potential treatment options for this previously untreatable condition .

How can researchers validate the specificity of CYP4V2 antibodies in experimental systems?

Validating antibody specificity is critical for reliable CYP4V2 research. A comprehensive validation approach should include:

• Multiple positive and negative controls:

  • Positive controls: Mouse liver tissue has been confirmed to express CYP4V2 ; ARPE-19 cells express significant levels of CYP4V2

  • Negative controls: CYP4V2-knockout cell lines or tissues

• Recombinant expression systems:

  • Overexpression of CYP4V2 in appropriate cell lines (e.g., HepG2 cells with lentiviral vectors)

  • Comparison of wild-type vs. CYP4V2-deficient backgrounds

• Protein detection specifications:

  • Expected molecular weight: Calculated 61 kDa, though observed at approximately 55 kDa in some systems

  • Examination of band patterns to identify potential isoforms or post-translational modifications

• Cross-reactivity assessment:

  • Testing against other CYP4 family members

  • Peptide competition assays using the immunizing peptide/protein

• Multiple detection techniques:

  • Correlation between Western blot, immunohistochemistry, and immunofluorescence results

  • Testing in different sample types (cell lines, primary tissues)

An exemplary validation approach was described in the literature where researchers assessed the cross-reactivity of anti-CYP4V2 antibodies against other CYP4 enzymes using both recombinant protein systems (Supersomes) and purified CYP4B1 .

What are optimal methods for studying CYP4V2 mutants associated with disease?

Studying disease-associated CYP4V2 mutants presents unique challenges, particularly due to protein instability. Research approaches should include:

• Expression system optimization:

  • Careful selection of expression vectors (viral vs. plasmid-based)

  • Codon optimization for improved expression

  • Inducible expression systems to control expression levels

• Protein stabilization strategies:

  • Culture at lower temperatures (30-32°C) to assist protein folding

  • Addition of chemical chaperones (e.g., 4-phenylbutyrate)

  • Proteasome inhibitors to prevent degradation of unstable proteins

• Detection enhancements:

  • Use of epitope tags (FLAG, His, etc.) at N- or C-terminus

  • Multiple antibodies targeting different epitopes

  • Enhanced chemiluminescence or fluorescence detection systems

• Functional characterization:

  • Enzyme activity assays using luciferin-based substrates

  • Assessment of ω-hydroxylation of PUFAs, particularly DHA and EPA

  • Lipid profiling of cells expressing mutant vs. wild-type protein

• Structural assessment:

  • Homology modeling to predict effects of mutations on protein structure

  • Analysis of mutations affecting hydrogen bonds and alpha helices in the transmembrane domain

  • Evaluation of alterations to the porphyrin ring and heme positioning

The p.H331P variant, for example, was undetectable in Western blot analyses of stably transduced HepG2 cells, indicating severe protein instability that likely explains the loss-of-function mechanism in BCD patients carrying this mutation .

How can CYP4V2 antibodies be used to investigate fatty acid metabolism pathways?

CYP4V2 antibodies are valuable tools for studying fatty acid metabolism in normal physiology and disease states:

• Co-immunoprecipitation studies:

  • Identification of protein interaction partners in fatty acid metabolism

  • Mapping of protein complexes involved in PUFA processing

  • Detection of regulatory proteins that modulate CYP4V2 activity

• Expression analysis following metabolic manipulations:

  • Quantification of CYP4V2 levels after treatment with fatty acids or inhibitors

  • Assessment of CYP4V2 regulation in response to metabolic stress

  • Correlation between CYP4V2 expression and cellular lipid profiles

• Subcellular localization studies:

  • Co-localization with lipid droplets or other lipid-rich structures

  • Tracking of CYP4V2 translocation under different metabolic conditions

  • Visualization of CYP4V2 in relation to other fatty acid metabolism enzymes

• Tissue distribution analysis:

  • Comparison of CYP4V2 expression in tissues with different metabolic profiles

  • Assessment of expression changes in metabolic disorders, particularly in retinal tissues and liver

  • Correlation with tissue-specific fatty acid compositions

• Combined antibody and activity assays:

  • Parallel quantification of protein levels and enzyme activity

  • Correlation between CYP4V2 protein levels and ω-hydroxylation of PUFAs

  • Assessment of post-translational modifications affecting enzyme activity

Research has demonstrated that overexpression of functional CYP4V2 in HepG2 cells significantly altered lipid homeostasis , providing a model system for studying the relationship between CYP4V2 expression levels and cellular lipid metabolism.

What enzyme activity assays can complement CYP4V2 antibody-based detection methods?

Complementary enzyme activity assays provide functional data that enhances antibody-based detection methods:

• Luciferin-based assays:

  • Multiple proluciferin compounds have been tested as CYP4V2 substrates

  • Eight compounds were found to be substrates, with luciferin-BE and luciferin-3FEME being the most efficient

  • These assays provide a convenient luminescence-based readout of CYP4V2 activity

• PUFA hydroxylation assays:

  • Direct measurement of ω-hydroxylation of DHA and EPA

  • Analysis by liquid chromatography-mass spectrometry (LC-MS/MS)

  • Comparison of activity rates with other CYP4 family enzymes like CYP4F2

• Inhibitor screening systems:

  • Use of luciferin-3FEME as a probe substrate for inhibitor screening

  • HET0016 has been identified as a potent inhibitor (IC50 = 179 nM)

  • Osilodrostat has also demonstrated inhibitory effects on CYP4V2

• Recombinant expression systems:

  • Use of permeabilized cells expressing recombinant CYP4V2

  • Fission yeast strain RAJ232 coexpressing human CYP4V2 and CPR has been validated

  • Comparison of wild-type and mutant protein activities

This combination of approaches allows researchers to correlate CYP4V2 protein levels (detected by antibodies) with functional enzyme activity, providing a more complete understanding of the protein's role in health and disease.

What is the optimal protocol for Western blot analysis of CYP4V2?

The following optimized Western blot protocol is recommended for CYP4V2 detection:

Sample preparation:

• For tissues: Homogenize in RIPA buffer containing protease inhibitor cocktail

• For cells: Lyse directly in Laemmli buffer or in RIPA buffer with protease inhibitors

• Recommended protein amount: 20-40 μg per lane

SDS-PAGE and transfer:

• Use 10-12% polyacrylamide gels for optimal separation

• Transfer to PVDF membrane (preferred over nitrocellulose for this protein)

• Wet transfer at 100V for 1 hour or 30V overnight at 4°C

Antibody incubation:

• Blocking: 5% non-fat dry milk in TBST, 1 hour at room temperature

• Primary antibody:

  • For polyclonal antibody 13826-1-AP: Dilute 1:1000-1:8000 in 5% BSA in TBST

  • Incubate overnight at 4°C with gentle agitation

• Washing: 3-5 times for 5 minutes each with TBST

• Secondary antibody:

  • HRP-conjugated anti-rabbit IgG (for polyclonal) or anti-mouse IgG (for monoclonal)

  • Typically diluted 1:5000-1:10000

  • Incubate for 1 hour at room temperature

Detection:

• ECL substrate appropriate for the expected expression level

• Expected molecular weight: calculated 61 kDa, observed around 55 kDa in some systems

Controls:

• Positive control: Mouse liver tissue has been confirmed to express CYP4V2

• Loading control: Preferably an ER-resident protein like calnexin, or standard housekeeping proteins

Troubleshooting tips:

• If signal is weak, increase protein load or decrease antibody dilution

• For non-specific bands, increase blocking time or try different blocking agents

• If no signal is detected, verify sample preparation as CYP4V2 is membrane-associated and may require specialized extraction

How should CYP4V2 antibodies be used for immunohistochemistry or immunofluorescence?

This protocol is optimized for detection of CYP4V2 in tissue sections and cultured cells:

Sample preparation:

• Tissues: Fix in 4% paraformaldehyde, embed in paraffin or freeze in OCT compound

• Cells: Grow on coverslips, fix with 4% paraformaldehyde for 15 minutes

Antigen retrieval (for paraffin sections):

• Heat-induced epitope retrieval in citrate buffer (pH 6.0)

• Microwave for 20 minutes or pressure cooker for 5 minutes

Immunostaining procedure:

• Permeabilize with 0.2% Triton X-100 in PBS for 10 minutes

• Block with 10% normal serum (from secondary antibody species) with 1% BSA in PBS for 1 hour

• Incubate with primary antibody (start with 1:100-1:200 dilution) overnight at 4°C

• Wash 3 times with PBS

• Incubate with appropriate secondary antibody for 1-2 hours at room temperature

• For IHC: Develop with DAB substrate

• For IF: Mount with anti-fade medium containing DAPI

Controls and validation:

• Positive control: Retinal or corneal epithelial tissues

• Negative control: Omit primary antibody

• Co-localization studies: Co-stain with ER markers (calnexin, PDI) to confirm subcellular localization

Imaging recommendations:

• For IF: Use confocal microscopy for precise subcellular localization

• For IHC: Bright-field microscopy with appropriate color correction

• Capture multiple fields to account for expression heterogeneity

What methods are appropriate for detecting CYP4V2 protein-protein interactions?

Several complementary methods can be used to investigate CYP4V2 protein interactions:

Co-immunoprecipitation (Co-IP):

• Lyse cells in a non-denaturing buffer (e.g., 50 mM Tris-HCl pH 7.4, 150 mM NaCl, 1% NP-40)

• Pre-clear lysate with protein A/G beads

• Incubate with CYP4V2 antibody (e.g., M29-P3B10 ) overnight at 4°C

• Add protein A/G beads and incubate for 2-4 hours

• Wash extensively with non-denaturing buffer

• Elute and analyze by Western blot for potential interaction partners

Proximity Ligation Assay (PLA):

• Fix and permeabilize cells as for immunofluorescence

• Incubate with primary antibodies against CYP4V2 and potential interaction partner

• Follow manufacturer's protocol for secondary antibody-linked oligonucleotides

• Perform ligation and rolling circle amplification

• Visualize interaction signals (typically appearing as fluorescent dots)

Bimolecular Fluorescence Complementation (BiFC):

• Create fusion constructs of CYP4V2 and potential partners with split fluorescent protein fragments

• Co-transfect into appropriate cells

• Allow 24-48 hours for protein expression and potential interaction

• Analyze by fluorescence microscopy

Considerations for CYP4V2-specific studies:

• The membrane-associated nature of CYP4V2 requires careful buffer optimization

• Detergent selection is critical; mild non-ionic detergents (0.5-1% NP-40 or Triton X-100) are recommended

• Cross-linking prior to lysis may help capture transient interactions

• Control experiments should include antibody-only controls and irrelevant protein controls

What strategies are recommended for quantifying CYP4V2 expression levels?

Several methods can be used to quantify CYP4V2 expression levels, each with specific advantages:

Western Blot Densitometry:

• Perform Western blot as described in section 3.1

• Capture images in the linear range of detection

• Analyze band intensity using ImageJ or similar software

• Normalize to appropriate loading controls

• Include calibration standards if absolute quantification is needed

qRT-PCR for mRNA quantification:

• Extract total RNA using standard methods

• Perform reverse transcription

• Use validated CYP4V2-specific primers

• Normalize to appropriate reference genes (GAPDH, ACTB, etc.)

• Calculate relative expression using the ΔΔCt method

ELISA:

• Several antibodies are validated for ELISA applications

• Commercial ELISA kits may be available

• Develop sandwich ELISA using capture and detection antibodies if needed

Immunofluorescence quantification:

• Perform immunofluorescence as described in section 3.2

• Capture images with identical acquisition parameters

• Measure mean fluorescence intensity using ImageJ or similar software

• Normalize to appropriate cellular markers

Mass Spectrometry:

• For absolute quantification, targeted proteomics approaches can be used

• Multiple reaction monitoring (MRM) with stable isotope-labeled peptide standards

• Data-independent acquisition (DIA) for broader proteomic profiling

Considerations for CYP4V2 quantification:

• Expression can vary significantly between tissues and cell types

• Consider both protein and mRNA quantification as post-transcriptional regulation may occur

• For studies of BCD-associated mutations, protein stability may significantly impact observed levels

How can researchers identify and characterize potential CYP4V2 inhibitors?

A systematic approach to identifying and characterizing CYP4V2 inhibitors includes:

Initial screening methods:

• Luciferin-based assays:

  • Luciferin-3FEME has been validated as an efficient probe substrate

  • Provides convenient luminescence-based detection

  • Suitable for high-throughput screening formats

• PUFA hydroxylation assays:

  • Direct measurement of ω-hydroxylation of physiological substrates (DHA, EPA)

  • More physiologically relevant but lower throughput

  • Typically analyzed by LC-MS/MS

Established inhibitors for positive controls:

• HET0016 has been identified as a potent inhibitor with an IC50 of 179 nM

• Osilodrostat has demonstrated significant inhibitory effects

Secondary characterization:

• IC50 determination:

  • Use serial dilutions of potential inhibitors

  • Plot concentration-response curves

  • Calculate IC50 values for comparison with other inhibitors

• Selectivity profiling:

  • Test against related CYP4 family members

  • Use homology modeling and docking experiments to understand selectivity

• Mechanism of inhibition:

  • Determine competitive, non-competitive, or mixed inhibition patterns

  • Evaluate time-dependent inhibition characteristics

Cellular validation:

• Test effects on CYP4V2-dependent lipid metabolism in cellular systems

• Assess impacts on cellular lipid profiles

• Evaluate potential off-target effects

What is the significance of CYP4V2 inhibition in pharmacological research?

CYP4V2 inhibition has important implications in pharmaceutical research and drug development:

Potential therapeutic applications:

• Modulation of fatty acid metabolism in metabolic disorders

• Potential applications in non-alcoholic fatty liver disease research

• Understanding lipid metabolism regulation in various tissues

Off-target concerns:

• Inhibition of CYP4V2 by pharmaceutical compounds may potentially cause visual disability as an adverse effect

• Marketed drugs like osilodrostat have demonstrated CYP4V2 inhibitory properties

• Such off-target effects require careful monitoring, especially for long-term treatments

Drug-drug interaction considerations:

• Co-administration of CYP4V2 inhibitors may affect the metabolism of endogenous substrates

• Potential impacts on retinal PUFA homeostasis

• Cumulative effects of multiple weak inhibitors require investigation

Research tools:

• Selective CYP4V2 inhibitors can serve as valuable research tools

• Chemical biology approaches to understand CYP4V2 function

• Development of probe compounds for mechanism elucidation

How are CYP4V2 antibodies being used in gene therapy research for Bietti crystalline dystrophy?

CYP4V2 antibodies play a critical role in the development and validation of gene therapy approaches for BCD:

Preclinical development:

• Verification of transgene expression following viral vector delivery

• Quantification of CYP4V2 protein in target tissues

• Confirmation of proper subcellular localization of expressed protein

Clinical trial applications:

• The first-in-human clinical trial of gene therapy for BCD (NCT04722107) utilized a recombinant adeno-associated-virus-serotype-2/8 vector encoding human CYP4V2 (rAAV2/8-hCYP4V2)

• Antibodies can be used to monitor CYP4V2 expression in accessible tissues

• Assessment of immune responses to the therapeutic protein

Immune monitoring:

• Detection of anti-CYP4V2 antibodies in patient samples

• All participants in the clinical trial showed negative humoral responses to CYP4V2 protein

• T-cell immune responses to CYP4V2 were monitored before and after treatment, with responses tending to elevate at 1-3 months post-treatment and then declining

Future directions:

• Optimizing gene therapy vectors for enhanced CYP4V2 expression

• Development of minimally invasive methods to monitor treatment efficacy

• Combination approaches targeting multiple aspects of BCD pathophysiology

What role does CYP4V2 play in emerging research on metabolic disorders?

Recent research has expanded our understanding of CYP4V2's involvement in metabolic conditions beyond ocular disease:

Non-alcoholic fatty liver disease (NAFLD):

• CYP4V2 has been implicated in the progression of NAFLD

• Antibodies can be used to assess CYP4V2 expression changes in liver tissues

• Correlation of CYP4V2 levels with disease severity and lipid profiles

Metabolic syndrome components:

• Emerging evidence suggests roles in broader metabolic regulation

• Potential implications for insulin resistance and dyslipidemia

• Mechanistic studies using CYP4V2 antibodies can help elucidate these connections

Lipid metabolism regulation:

• CYP4V2 mutant cells show elevated triglycerides and free cholesterol

• Lack of specific fatty acid-binding proteins (FABPs) in CYP4V2-deficient states

• Decreased metabolism of pro-inflammatory PUFAs with potential immunomodulatory effects

Inflammatory pathways:

• CYP4V2's presence in immune cells suggests regulatory roles in inflammatory responses

• Potential connections to chronic inflammatory conditions

• Antibody-based detection in immune cell subsets can map expression patterns

This expanding understanding of CYP4V2's roles beyond the eye opens new research avenues where CYP4V2 antibodies will be essential tools for tissue-specific and condition-specific expression analysis.