Acetyl-RELA (K310) Antibody

What is the biological significance of RELA K310 acetylation in NF-κB signaling?

RELA (p65) acetylation at lysine 310 represents a critical post-translational modification that regulates NF-κB transcriptional activity. Unlike other acetylation sites on RELA, K310 acetylation does not affect DNA binding or IκBα assembly, but is specifically required for the full transcriptional potential of NF-κB . Research has demonstrated that acetylation at K310 creates a docking site for the recruitment of bromodomain-containing factor Brd4, which activates CDK9 and RNA polymerase II-mediated transcription of NF-κB target genes . Functionally, K310 acetylation is important for modulating NF-κB-dependent inflammatory responses and maintaining constitutive NF-κB activity in tumors .

Experimental data demonstrates this functional importance: RelA-deficient MEFs reconstituted with wild-type RelA showed a nine-fold increase in E-selectin mRNA levels upon TNF-α stimulation, while cells expressing the K310R mutant (which cannot be acetylated at this position) showed only a three-fold increase . This confirms that K310 acetylation is essential for optimal NF-κB transcriptional activity.

How should I prepare samples to detect acetylated RELA at K310?

For optimal detection of acetylated RELA (K310), sample preparation should be tailored to the specific experimental context:

For cell culture samples:

• Stimulate cells with appropriate activators of NF-κB signaling, such as TNF-α (typically 20 ng/ml for 30-60 minutes)

• When analyzing nuclear translocation, prepare separate nuclear and cytoplasmic fractions using commercial extraction reagents (e.g., NE-PER reagents)

• For whole-cell lysates, use buffers containing deacetylase inhibitors to prevent loss of acetylation signal

• Include phosphatase inhibitors, as phosphorylation events can regulate K310 acetylation

For overexpression systems:

• Co-transfect expression vectors for RELA and p300 acetyltransferase

• For optimal acetylation, use HEK293T cells, as they provide high transfection efficiency

• Allow 36-48 hours after transfection before harvesting cells

• Consider including TNF-α stimulation (20 ng/ml for 60 minutes) to enhance acetylation

When using Acetyl-RELA (K310) antibodies, incorporating appropriate controls is essential for reliable interpretation:

Positive controls:

• HEK293T cells co-transfected with RELA and p300 expression vectors, then stimulated with TNF-α (20 ng/ml, 60 minutes)

• Cell lines with known high NF-κB activity following TNF-α stimulation

Negative controls:

• RELA K310R mutant protein or cells expressing this mutant

• Unstimulated cells (lacking NF-κB activation)

• RELA-knockout or knockdown cells

• Blocking peptide competition (using the acetylated peptide used as immunogen)

• Treatment with HDAC3 or SIRT1, which deacetylate K310

Additional validation approaches:

• Lambda phosphatase treatment to distinguish acetylation from phosphorylation signals

• Pre-absorption of antibody with acetylated peptide

• Peptide dot blot analysis comparing acetylated vs. non-acetylated synthetic peptides

Advanced Research Methodologies

RELA K310 acetylation exists within a complex network of post-translational modifications that regulate NF-κB activity:

Interplay with phosphorylation:

• Phosphorylation of RELA at serine 276 (by PKA) or serine 536 (by IKK1/IKK2) promotes assembly with p300 acetyltransferase, enhancing K310 acetylation

• Experimentally, expression of catalytically inactive mutants of PKA/MSK1 or IKK1/IKK2 significantly inhibits K310 acetylation

Interplay with methylation:

• K310 acetylation interferes with methylation of nearby lysines 314 and 315

• This protective effect prevents the subsequent ubiquitination and degradation of promoter-associated RELA

• Mechanistically, the positive charge of unmodified lysine 310 is critical for binding of the methyltransferase Set9, which contains a negatively charged "exosite" in its SET domain

• In vitro assays show that acetylated K310 peptides exhibit significantly reduced methylation by Set9 compared to unacetylated peptides

This crosstalk between modifications creates a "PTM code" that fine-tunes RELA function, with K310 acetylation playing a central role in promoting transcriptional activity while preventing methylation-dependent degradation.

What are the protocols for in vitro acetylation assays for RELA?

In vitro acetylation assays provide a controlled system to study RELA acetylation. The following protocol has been validated for studying K310 acetylation:

Preparation of p300 for in vitro acetylation:

• Seed HEK293T cells (2×10^5/ml) in 100 mm dishes

• When cells reach 60-80% confluency, transfect with 15 μg of HA-tagged p300 plasmid using the calcium phosphate method

• 36 hours post-transfection, lyse cells in IP buffer at 4°C for 10-15 minutes

• Immunoprecipitate p300 using anti-HA antibody and protein A/G beads

• Store immunoprecipitated p300 at -80°C in aliquots

In vitro acetylation reaction:

• Combine:

  • 4 μl of 5× HAT assay buffer

  • 1 μg of recombinant RELA protein

  • 2 μl of [14C]-acetyl-CoA or non-radioactive acetyl-CoA

  • p300 immunoprecipitated beads

  • Distilled water to 20 μl total volume

• Incubate at 30°C for 1 hour with occasional shaking

• Collect supernatant by centrifugation

• Stop reaction by adding SDS loading buffer and boiling for 5 minutes

• Analyze by SDS-PAGE followed by:

  • For radioactive assays: gel fixing, fluorography, and autoradiography

  • For non-radioactive assays: transfer to nitrocellulose and immunoblotting with anti-acetylated lysine 310 antibody

Commercial recombinant GST-p300 HAT domain fusion proteins may have limited activity toward RELA compared to full-length p300 immunoprecipitated from cells .

How can I utilize Acetyl-RELA (K310) antibodies in ChIP assays to study transcriptional regulation?

Chromatin immunoprecipitation (ChIP) with Acetyl-RELA (K310) antibodies allows researchers to investigate the recruitment of acetylated RELA to specific gene promoters:

ChIP Protocol Optimization for Acetyl-RELA (K310):

• Stimulate cells with appropriate NF-κB activators (e.g., TNF-α 20 ng/ml for 30-60 minutes)

• Cross-link proteins to DNA using 1% formaldehyde (10 minutes at room temperature)

• Quench with 0.125 M glycine

• Lyse cells and sonicate chromatin to yield fragments of 200-500 bp

• Pre-clear chromatin with protein A/G beads and control IgG

• Immunoprecipitate with anti-acetyl-RELA (K310) antibody (use ChIP-grade antibody )

• Wash extensively to remove non-specific binding

• Reverse cross-linking and purify DNA

• Analyze by qPCR with primers specific for NF-κB target gene promoters

Technical considerations:

• Always include a ChIP with total RELA antibody for comparison

• Use IgG as a negative control

• Include input DNA controls for normalization

• Compare acetylated RELA recruitment kinetics at different time points after stimulation

• Consider sequential ChIP (re-ChIP) to study co-occupancy with other factors

Research has demonstrated that acetylated RELA at K310 can be detected at the promoters of NF-κB target genes such as E-selectin following TNF-α stimulation, with real-time PCR quantitation showing increased promoter-bound acetylated RELA at 60 minutes compared to 30 minutes after stimulation .

How does TNF-α stimulation affect the dynamics of RELA K310 acetylation?

TNF-α stimulation induces a time-dependent increase in RELA K310 acetylation that follows a specific temporal pattern related to NF-κB activation:

Temporal dynamics following TNF-α stimulation:

• Initial detection of acetylated RELA occurs at approximately 10 minutes post-stimulation

• Acetylation levels increase progressively from 10-60 minutes

• This timeline correlates with IκBα degradation (observed at 10 minutes) and subsequent resynthesis (detectable by 20 minutes)

Kinetics at the chromatin level:

• ChIP assays with acetyl-RELA (K310) antibodies show increased promoter binding over time

• Quantitative PCR analysis reveals higher levels of promoter-bound acetylated RELA at 60 minutes compared to 30 minutes post-stimulation

Experimental approach for studying acetylation dynamics:

• Treat cells with TNF-α (20 ng/ml) for various time points (0, 10, 20, 30, 45, 60 minutes)

• Prepare whole-cell lysates or nuclear extracts

• Analyze by Western blot with anti-acetyl-RELA (K310) antibodies

• In parallel, perform ChIP assays at selected time points

• Compare acetylation patterns with other NF-κB activation markers (IκBα degradation, nuclear translocation)

This dynamic pattern of acetylation provides insight into how post-translational modifications regulate the temporal aspects of NF-κB signaling.

How can I troubleshoot weak or absent signals when detecting acetylated RELA (K310)?

When researchers encounter difficulties detecting acetylated RELA at K310, several methodological adjustments may improve results:

For Western blotting applications:

• Ensure proper NF-κB activation: Verify activation using total RELA translocation to nuclear fractions

• Preserve acetylation status:

  • Add deacetylase inhibitors (e.g., TSA 400 nM, nicotinamide 5 mM) to all buffers

  • Process samples rapidly and keep cold throughout preparation

• Optimize protein loading: Load 30-50 μg of total protein for whole cell lysates, or 10-20 μg for nuclear extracts

• Enhance transfer efficiency: Use PVDF membranes for enhanced protein binding

• Optimize blocking: Use 5% BSA rather than milk (which contains deacetylases)

• Increase antibody incubation time: Consider overnight incubation at 4°C

• Use enhanced chemiluminescence detection systems with increased sensitivity

For immunoprecipitation:

• Increase starting material: Begin with more cells/tissue

• Use appropriate lysis conditions: Ensure complete extraction of nuclear RELA

• Consider crosslinking: Brief formaldehyde crosslinking may preserve interactions

• Validate antibody performance: Test with positive control samples (TNF-α stimulated cells co-expressing RELA and p300)

How do I distinguish between specific and non-specific bands when using acetyl-RELA (K310) antibodies?

Distinguishing specific acetyl-RELA (K310) signals from non-specific background is crucial for accurate data interpretation:

Verification strategies:

• Molecular weight confirmation: Acetylated RELA typically appears at 65-75 kDa

• Stimulation-dependent changes: Signal should increase following TNF-α treatment

• Comparison with mutants: K310R RELA mutant should show minimal or no signal

• Acetylation inhibitors: Treatment with histone acetyltransferase inhibitors should reduce signal

• Deacetylase overexpression: HDAC3 or SIRT1 overexpression should decrease signal

• Peptide competition: Pre-incubation of antibody with acetylated K310 peptide should abolish specific signals

• siRNA validation: RELA knockdown should eliminate the specific band

Example validation data:
In controlled experiments, the following pattern should be observed:

• Lane 1: HEK-293 cells transfected with wild-type RELA (minimal signal)

• Lane 2: HEK-293 cells transfected with RELA and p300, treated with TNF-α (strong signal at 65-75 kDa)

• Lane 3: Same as lane 2 but with K310R RELA mutant (minimal to no signal)

How can I use Acetyl-RELA (K310) antibodies to investigate the relationship between RELA acetylation and methylation?

Investigating the interplay between RELA acetylation and methylation requires specific experimental approaches:

Sequential modification analysis:

• Perform in vitro acetylation of RELA with p300 followed by in vitro methylation with Set9

• Compare with the reverse order (methylation followed by acetylation)

• Analyze modifications using acetyl-RELA (K310) and methyl-RELA antibodies

Peptide-based assays:

• Synthesize peptides representing RELA around K310-K315 in different modification states:

  • Unmodified

  • K310-acetylated

  • K314/315-methylated

  • Combinations of modifications

• Use these peptides for:

  • In vitro enzymatic assays with acetyltransferases and methyltransferases

  • Binding studies with purified domains (e.g., SET domain of Set9)

  • Competition assays with antibodies

Research has demonstrated that while methylated peptides can be acetylated by p300 to the same extent as unmethylated peptides, acetylated K310 peptides show substantially reduced methylation by Set9 compared to unacetylated peptides . This suggests a unidirectional relationship where acetylation blocks methylation but not vice versa.

What are the considerations for optimizing acetylation conditions in cellulose-based experimental systems?

While not directly related to RELA, the principles of acetylation optimization from cellulose research can be applied to protein acetylation studies:

Key parameters affecting acetylation efficiency:

• Temperature: Affects reaction kinetics, with higher temperatures generally increasing reaction rates

• Molar ratios: The ratio of substrate to acetylating agent significantly impacts yield

• Reaction time: Must be optimized to achieve desired modification levels

• Catalyst concentration: Affects reaction efficiency

Example optimization data from cellulose acetylation:

These principles can be adapted when designing in vitro acetylation systems for RELA, taking into account the need for physiologically relevant conditions for protein-based systems .

How can I develop quantitative assays for measuring RELA K310 acetylation levels?

For researchers interested in precisely quantifying RELA K310 acetylation, several approaches can be employed:

ELISA-based quantification:

• Develop a sandwich ELISA with:

  • Capture antibody: anti-RELA

  • Detection antibody: anti-acetyl-RELA (K310)

• Create standard curves using recombinant acetylated RELA protein

• Normalize to total RELA levels

Mass spectrometry approaches:

• Immunoprecipitate RELA from cells under different conditions

• Perform tryptic digestion and analyze peptides by LC-MS/MS

• Quantify the ratio of acetylated to non-acetylated K310-containing peptides

• Use heavy isotope-labeled synthetic peptides as internal standards for absolute quantification

Western blot quantification:

• Run samples alongside a standard curve of recombinant acetylated RELA

• Use fluorescent secondary antibodies for extended linear range

• Quantify signal using appropriate imaging software

• Always normalize to total RELA levels from the same samples

These quantitative approaches enable researchers to precisely measure changes in K310 acetylation under different experimental conditions, facilitating more rigorous analysis of this post-translational modification in various biological contexts.