NFKB1 (Ab-337) Antibody

What is the target epitope of the NFKB1 (Ab-337) Antibody?

The NFKB1 (Ab-337) Antibody specifically targets the peptide sequence around amino acids 335-339 (R-K-S-D-L) derived from Human NFkB-p105. This region is critical for recognizing both the p105 precursor and the processed p50 protein . The antibody detects endogenous levels of total NFkB-p105/p50 protein and has been validated in multiple species including human, mouse, and rat models .

How does NFKB1 function in cellular processes?

NFKB1 encodes the p105 protein which undergoes partial degradation to produce the p50 subunit. Upon stimuli, p105 is phosphorylated in its C-terminal domain containing ankyrin repeats, followed by partial degradation in an ubiquitin-proteasome dependent manner . The p50 subunit can form homodimers that typically repress gene transcription or heterodimers with other NF-κB subunits (particularly p65) that activate transcription . NFKB1 has dual functions including cytoplasmic retention of attached NF-kappa-B proteins by p105 and generation of p50 through cotranslational processing .

What is the significance of the Ser337 residue in NFKB1?

Serine 337 (Ser337) is a critical phosphorylation site in NFKB1. Research has shown that phosphorylation at this site is important for regulating NFKB1 function . Similarly, phosphorylation at Ser342 has been demonstrated to be critical for p50 homodimer assembly . These phosphorylation events represent key post-translational modifications that influence NFKB1's role in signaling pathways.

What applications is the NFKB1 (Ab-337) Antibody validated for?

The antibody has been validated for multiple applications:

Testing has confirmed specificity through blocking peptide experiments that demonstrate signal elimination when the antibody is preincubated with the peptide antigen .

How should I optimize Western blot protocols for NFKB1 (Ab-337) Antibody?

For optimal Western blot results:

• Begin with the recommended dilution range (1:500-1:1000) in 5% BSA or milk in TBST

• For detecting both p105 (~105 kDa) and p50 (~50 kDa) forms, use 8-10% polyacrylamide gels

• Include positive controls such as HT29 cell lysates, which have been validated with this antibody

• Consider running a blocking peptide control by preincubating antibody with the immunogenic peptide to confirm specificity

• Use appropriate secondaries (anti-rabbit HRP conjugates) at 1:5000-1:10000 dilutions

Western blot analysis of extracts from HT29 cells has consistently shown specific bands for both p105 and p50, with elimination of signal when the antibody is preincubated with blocking peptide .

What are the recommended protocols for studying NFKB1 phosphorylation at Ser337?

To study phosphorylation at Ser337:

• Use phospho-specific antibodies such as the NFKB1(phospho S337) antibody in conjunction with total NFKB1 antibodies

• For in situ detection of phosphorylated proteins, Proximity Ligation Assay (PLA) can be employed using dual recognition antibody pairs

• Treat cells with phosphatase inhibitors during lysate preparation to preserve phosphorylation status

• Consider using pharmacological inhibitors of kinase pathways (such as Akt inhibitors) to study the regulation of NFKB1 phosphorylation

• Validate results using phospho-mimetic or phospho-deficient mutants (S337A or S337E)

Research has demonstrated that phosphorylation events, like those at Ser337 and Ser342, are critical for NFKB1 function in regulating inflammation and cancer development .

How do I interpret changes in p105 versus p50 levels in my experiments?

Changes in the p105:p50 ratio can provide important insights:

• Increased p50 relative to p105 suggests enhanced processing, often associated with active NF-κB signaling

• Decreased p50 with stable p105 may indicate processing defects or altered stability of the p50 subunit

• Consider the balance between p50 homodimers (typically repressive) versus p50:p65 heterodimers (typically activating)

• Analyze nuclear versus cytoplasmic fractions to determine translocation patterns

• Correlate with functional readouts such as NF-κB reporter activity and target gene expression

It's important to note that in some cancer models, reduced processing of p105 to p50 correlates with increased tumor incidence, as shown in glioblastoma studies where low expression of KPC1 (a ubiquitin ligase required for p105 to p50 processing) correlated with reduced p50 levels and higher cancer incidence .

How does NFKB1 dysregulation manifest in different disease contexts?

NFKB1 dysregulation shows tissue-specific effects:

Research has shown that NFKB1 knockout mice display increased inflammation and susceptibility to certain forms of DNA damage, leading to cancer and a rapid aging phenotype .

What are common causes of weak or no signal when using NFKB1 (Ab-337) Antibody in Western blots?

When troubleshooting weak or absent signals:

• Protein degradation: Ensure complete protease inhibitor cocktails are used during sample preparation

• Insufficient protein loading: Consider increasing loading amount to 30-50 μg of total protein

• Inefficient transfer: Check transfer efficiency using Ponceau S staining of membranes

• Antibody concentration: Try a more concentrated antibody dilution (1:250-1:500)

• Exposure time: Increase exposure time or use more sensitive detection methods

• Blocking conditions: Test different blocking agents (BSA vs. milk) as milk proteins may interfere with phospho-specific detection

Additionally, verify sample preparation conditions, as NFKB1 processing can be affected by cell lysis methods .

How can I verify the specificity of the NFKB1 (Ab-337) Antibody in my experimental system?

To confirm antibody specificity:

• Perform blocking peptide experiments by preincubating the antibody with the immunogenic peptide

• Include positive controls (HT29 cells) and negative controls (tissues or cells with NFKB1 knockdown)

• Validate with multiple techniques (WB, IHC, IF) to ensure consistent target recognition

• Use NFKB1 knockout or knockdown systems as definitive negative controls

• For phospho-specific studies, treat samples with phosphatases to eliminate signal

Published validation results show that preincubation with the blocking peptide eliminates signal in both Western blot and immunohistochemistry applications, confirming specificity .

How can I investigate the role of NFKB1 phosphorylation in tumor development models?

To study NFKB1 phosphorylation in tumor models:

• Generate phospho-deficient (S337A) or phospho-mimetic (S337E) mutants for functional studies

• Use the NFKB1 (Ab-337) Antibody alongside phospho-specific antibodies to track changes in phosphorylation status during tumor progression

• Employ proximity ligation assays to detect specific phosphorylation events in situ

• Correlate phosphorylation status with tumor characteristics and patient outcomes in clinical samples

• Consider the interplay between different phosphorylation sites (S337, S342, S927) in regulating NFKB1 function

Research has demonstrated that phosphorylation at Ser342 is critical for p50 homodimer assembly, and mice with S342A mutation display increased neutrophil numbers, neutrophil chemokine expression, and increased tumor burden in hepatocellular carcinoma models .

What are the current approaches to study NFKB1's dual role as both tumor promoter and suppressor?

To investigate NFKB1's context-dependent roles:

• Implement tissue-specific and inducible knockout models to study organ-specific effects

• Use cell type-specific promoters to drive NFKB1 expression in different compartments (epithelial vs. immune)

• Analyze the balance between p50 homodimers (typically repressive) and p50:p65 heterodimers (typically activating)

• Examine p50 interaction partners (such as Bcl-3) that can convert p50 homodimers from repressors to activators

• Perform ChIP-seq to identify genome-wide binding patterns of different NFKB1-containing complexes

Research has shown that Nfkb1−/− mice develop spontaneous chronic liver disease and liver cancer characterized by dysplastic nodules and features of steatohepatitis and fibrosis, demonstrating its tumor-suppressive role in this context . Conversely, other studies demonstrate that NFKB1 and p65 are found at higher levels in gastric cancer cell lines and primary human gastric tumors compared to normal gastric epithelial cells, correlating with poor survival in patients .

How does NFKB1 interact with the PI3K/Akt pathway in oncogenic transformation?

The relationship between NFKB1 and PI3K/Akt pathway can be studied by:

• Examining NF-κB activity using reporter assays in cells with constitutively active PI3K or Akt

• Using PI3K/Akt inhibitors to assess effects on NFKB1 phosphorylation and processing

• Co-expressing super-repressor IκB (IκBSR) with oncogenic PI3K or Akt to determine functional dependence

• Analyzing phosphorylation patterns of NFKB1 at multiple sites following PI3K/Akt activation

• Performing co-immunoprecipitation studies to identify direct or indirect interactions