NCF1 (Ab-304) Antibody

What is NCF1 and why is it important in research?

NCF1 (Neutrophil Cytosolic Factor 1), also known as p47-phox, is a critical component of the NADPH oxidase complex that plays an essential role in superoxide production. According to research findings, NCF1, along with NCF2 and a membrane-bound cytochrome b558, are required for activation of the latent NADPH oxidase which is necessary for superoxide production . The protein has multiple aliases including NOXO2, SH3PXD1A, and Nox organizer 2 .

The importance of NCF1 in research stems from its central role in:

• Oxidative burst mechanisms in immune cells

• Pathogen defense through reactive oxygen species (ROS) production

• Association with multiple autoimmune diseases and conditions like chronic granulomatous disease (CGD)

• Involvement in signaling pathways, particularly the NADPH/ROS/NF-κB axis

Recent studies have demonstrated that mutations in NCF1, particularly the p.Arg90His variant (rs201802880), are strongly associated with susceptibility to various autoimmune conditions including systemic lupus erythematosus, rheumatoid arthritis, and unexplained recurrent spontaneous abortion (URSA) .

What is the significance of phosphorylation at Ser304 in NCF1?

Phosphorylation of NCF1/p47-phox at Ser304 represents a critical regulatory event in the activation of the NADPH oxidase complex. This specific post-translational modification:

• Is essential for conformational changes that promote NCF1 interaction with other oxidase components

• Facilitates the translocation of NCF1 from the cytosol to the membrane

• Serves as a molecular switch in the activation sequence of NADPH oxidase

• Occurs in response to various stimuli including PMA, inflammatory cytokines, and UV exposure

Experimental evidence shows that this phosphorylation event can be detected in various cell types, including COS7 cells treated with UV and A549 cells . The phosphorylation status at Ser304 can be visualized through techniques such as Western blotting and 2D gel electrophoresis using phospho-specific antibodies .

How do variations in NCF1 affect ROS production and what are the implications for autoimmune disease research?

Variations in NCF1, particularly the rs201802880 (p.Arg90His) substitution, significantly impact ROS production with profound implications for autoimmune disease research:

• The p.Arg90His variant leads to reduced capacity to induce oxidative burst

• ROS levels in individuals with the wild-type GG genotype are significantly higher than those with the mutant GA genotype (p < 0.05)

• This reduced ROS production paradoxically correlates with increased autoimmune disease risk

Studies have demonstrated that "mutations in NCF1 may increase the risk of URSA via the NADPH/ROS/NF-κB signaling pathway" . The odds ratio for URSA risk with the mutant genotype was calculated at 3.257, making it one of the strongest identified genetic associations with this condition .

Experimental models further support this relationship, as "NCF1-His90 KI mice show a reduced ROS production, elevated type IFN-I scores, splenomegaly, and increased germinal center B cells and plasma cells. Moreover, NCF1-His90 KI mice but not WT littermate controls develop autoantibodies and SLE-like kidney pathology after challenge with pristane" .

How does phosphorylation at Ser304 compare with other phosphorylation sites on NCF1?

NCF1 undergoes phosphorylation at multiple serine residues during activation, with Ser304 and Ser328 being among the most well-studied sites. These distinct phosphorylation events have unique characteristics:

The temporal relationship between these phosphorylation events provides insights into the activation sequence of the NADPH oxidase complex. Research has shown that cells stimulated with PMA exhibit phosphorylation at multiple sites, which can be visualized using site-specific antibodies .

Experimentally, the phosphorylation status can be studied using 2D gel electrophoresis: "M-Mac and I-Mac were stimulated with or without PMA for 30 min, and then cell lysates were subjected to 2D gel electrophoresis. Expression of p47phox was detected by anti-p47phox and anti-phosphorylated S304 p47phox antibodies" .

What are the optimal experimental conditions for using NCF1 (Ab-304) Antibody in Western blotting?

For successful Western blot detection of phosphorylated NCF1 at Ser304, researchers should consider the following optimized conditions:

• Sample preparation:

  • Prepare extracts with phosphatase inhibitors to preserve phosphorylation

  • Maintain cold conditions throughout processing

  • Use appropriate stimulation conditions (e.g., UV treatment for 15 minutes or PMA treatment)

• Loading and protein amount:

  • Optimal protein loading: approximately 30 μg per lane

  • Expected molecular weight: 44-47 kDa (predicted: 44 kDa, observed: 45 kDa)

• Antibody dilution and detection:

  • Recommended dilution: 1:500 for Western blotting

  • Secondary antibody selection based on host species (typically anti-rabbit IgG)

  • Consider enhanced chemiluminescence for optimal signal detection

• Essential controls:

  • Positive control: Extracts from stimulated cells known to induce Ser304 phosphorylation

  • Specificity control: Include immunizing peptide competition (as demonstrated in lane 3 of Western blot results)

  • Loading control: Detect housekeeping protein or total NCF1

The validation data shows successful detection in "extracts from COS7 cells treated with UV (15mins) at 30 μg" and "A549 cells extracts at 30 μg" , providing a baseline for expected results.

How can the specificity of NCF1 (Ab-304) Antibody be validated in research settings?

Rigorous validation of NCF1 (Ab-304) Antibody specificity is crucial for ensuring reliable experimental results. The following validation approaches are recommended:

• Peptide competition assay:

  • Incubate antibody with excess immunizing phosphopeptide prior to application

  • Successful competition should eliminate specific signal

  • This approach is demonstrated in the validation data, showing signal elimination in "A549 cells extracts at 30 μg with immunizing peptide"

• Phosphatase treatment control:

  • Treat duplicate samples with lambda phosphatase to remove phosphorylation

  • Compare signal between treated and untreated samples

  • Loss of signal confirms phospho-specificity

• Stimulation response:

  • Compare phospho-NCF1 levels in resting versus stimulated conditions

  • Established stimuli include PMA treatment, UV exposure, and inflammatory cytokines

  • Quantify increased signal following stimulation

• Genetic validation approaches:

  • Compare antibody reactivity in wild-type versus NCF1-knockout or knockdown models

  • Test reactivity in cells expressing phospho-site mutants (Ser304Ala)

For comprehensive validation, researchers should combine multiple approaches and document validation data systematically to establish confidence in antibody specificity for the intended application.

What considerations should be made when designing experiments to study NCF1 phosphorylation dynamics?

When designing experiments to investigate NCF1 phosphorylation dynamics, researchers should address several critical considerations:

• Temporal considerations:

  • Phosphorylation events are often transient and sequential

  • Design time-course experiments (e.g., 0, 5, 15, 30, 60 minutes post-stimulation)

  • Consider early events (seconds to minutes) for initial phosphorylation

• Stimulation protocols:

  • PMA (100 ng/ml) is commonly used to induce robust phosphorylation

  • Physiological stimuli like cytokines may produce different phosphorylation patterns

  • UV exposure (15 minutes) has been validated for inducing Ser304 phosphorylation

• Cell type considerations:

  • Expression levels vary significantly between cell types

  • Primary neutrophils express high levels but have short experimental viability

  • Established cell lines (COS7, A549) provide reproducible systems

  • Macrophage models show differential NCF1 expression based on polarization state

• Detection methodology selection:

  • Western blotting: Quantitative assessment of population-level phosphorylation

  • Immunofluorescence: Spatial information about phospho-NCF1 localization

  • Flow cytometry: Single-cell analysis of phosphorylation heterogeneity

  • 2D gel electrophoresis: Separation of differently phosphorylated isoforms

This integrated approach was successfully employed in research showing that "the expression of p47phox is increased in IL-27-induced macrophages" with corresponding changes in ROS production .

What are common sources of false positives and false negatives when using phospho-specific NCF1 antibodies?

When working with phospho-specific NCF1 antibodies, researchers should be aware of potential sources of misleading results:

Sources of false positives:

• Cross-reactivity with similar phosphorylation motifs on related proteins (particularly other NCF family members)

• Non-specific binding to highly abundant proteins

• Inadequate blocking leading to background signal

• Secondary antibody cross-reactivity with endogenous immunoglobulins

• Pseudogene products with similar epitopes

Sources of false negatives:

• Dephosphorylation during sample preparation (most common)

• Epitope masking due to protein-protein interactions

• Insufficient antigen retrieval in fixed samples

• Timing of sample collection missing transient phosphorylation window

• Insufficient sensitivity of detection method

To minimize these issues:

• Always include phosphatase inhibitors in lysis buffers

• Collect samples at multiple time points following stimulation

• Validate antibody specificity through peptide competition

• Include positive controls (e.g., extracts from UV-treated COS7 cells)

• Consider enhanced detection methods for low-abundance phosphorylation events

How should researchers interpret discrepancies between NCF1 protein detection and genetic data?

When faced with discrepancies between NCF1 protein detection using antibodies and genetic analysis results, researchers should consider several potential explanations:

• Pseudogene interference in genetic analysis:

  • NCF1 has two pseudogenes (NCF1B and NCF1C) sharing 98% sequence similarity

  • Standard genetic approaches may not differentiate between functional gene and pseudogenes

  • Specialized approaches like nested PCR and TaqMan assays are needed for accurate genotyping

• Post-translational modifications affecting antibody recognition:

  • Phosphorylation state may affect epitope accessibility

  • Other modifications (ubiquitination, acetylation) may alter protein detection

  • Different antibodies may detect different forms of the protein

• Alternative splicing and protein isoforms:

  • NCF1 can exist in multiple isoforms with different functional properties

  • Some mutations may affect splicing rather than protein sequence

Research has shown that proper verification of apparent NCF1 variants is essential, as "The 22 samples were validated, and only 15 samples were found to have mutations in NCF1" , highlighting the importance of confirmation steps when working with this challenging gene.

How can NCF1 (Ab-304) Antibody be used to study the NADPH/ROS/NF-κB signaling pathway?

The NCF1 (Ab-304) Antibody provides a valuable tool for investigating the NADPH/ROS/NF-κB signaling pathway, which has significant implications in immune regulation and disease pathogenesis:

• Integrated pathway analysis approach:

  • Monitor NCF1 phosphorylation at Ser304 as an indicator of NADPH oxidase activation

  • Correlate phosphorylation with ROS production using detection methods like H2O2 assays

  • Assess downstream NF-κB activation through RELA nuclear translocation or expression

  • Measure target gene expression to complete the signaling cascade analysis

• Research findings supporting this approach:

  • Studies have shown that "mutations in NCF1 may lead to URSA through the NADPH/ROS/NF-κB signaling pathway"

  • Research demonstrated that "ROS levels in the URSA group with the GG genotype were significantly higher than those in the group with the GA genotype (p < 0.05)"

  • "RELA expression in URSA patients with the GA genotype was considerably higher than that in control individuals with the GG genotype"

This integrated approach enables researchers to establish mechanistic links between NCF1 activation, ROS production, and downstream NF-κB signaling in various physiological and pathological contexts.

What is the relevance of studying NCF1 in the context of autoimmune and inflammatory conditions?

Studies of NCF1 have revealed its critical importance in multiple autoimmune and inflammatory conditions:

• Strong genetic associations:

  • The NCF1-339 variant (rs201802880, p.Arg90His) is "one of the strongest SNPs outside the human leukocyte antigen region that is associated with autoimmune diseases"

  • Meta-analysis shows "the GTF2I-NCF1 intergenic locus is associated with multiple autoimmune diseases"

  • Specific conditions linked to NCF1 variants include:

    • Systemic lupus erythematosus (SLE)

    • Rheumatoid arthritis

    • Chronic granulomatous disease (CGD)

    • Unexplained recurrent spontaneous abortion (URSA)

• Paradoxical role of reduced ROS in autoimmunity:

  • Counterintuitively, reduced ROS production (associated with the p.Arg90His variant) increases autoimmune disease risk

  • This highlights the complex immunoregulatory role of ROS beyond pathogen killing

  • The NCF1-His90 variant "leads to a lower capacity to induce oxidative burst" and is "strongly associated with URSA"

• Research applications:

  • Biomarker development for disease susceptibility

  • Mechanistic studies of oxidative regulation in immune tolerance

  • Therapeutic targeting of the NADPH/ROS/NF-κB pathway

  • Personalized medicine approaches based on NCF1 genotype

• Experimental models support clinical findings:

  • "Compared to wild type (WT) littermate controls, NCF1-His90 KI mice show a reduced ROS production, elevated type IFN-I scores, splenomegaly, and increased germinal center B cells and plasma cells"

  • Animal models with NCF1 deficiency develop "SLE-like kidney pathology after challenge with pristane"

These findings collectively demonstrate the significance of NCF1 in immune regulation and highlight its potential as both a biomarker and therapeutic target in autoimmune and inflammatory conditions.