Phospho-TP53 (Ser392) Antibody

What is the Phospho-p53 (Ser392) Antibody and what does it detect?

Phospho-p53 (Ser392) antibody specifically recognizes p53 tumor suppressor protein when phosphorylated at the Serine 392 residue. This antibody binds to the phosphorylated epitope corresponding to amino acids 378-393 of human p53 (RHKKLMFKTEGPDS[P]D) . The antibody enables researchers to distinguish between phosphorylated and non-phosphorylated forms of p53 at this specific site, which is critical for understanding p53 activation in response to various cellular stresses . The most common applications include Western blotting and immunohistochemistry on paraffin-embedded tissues (IHC-P) .

What species reactivity does the Phospho-p53 (Ser392) Antibody demonstrate?

The available Phospho-p53 (Ser392) antibodies show reactivity with multiple species, though this varies by manufacturer and clone. Based on the information provided, commercially available antibodies typically react with human, mouse, and mink species (H, M, Mi) . This cross-species reactivity makes the antibody valuable for comparative studies across different model organisms. When selecting an antibody for your research, it's important to verify the specific species reactivity in the product documentation to ensure compatibility with your experimental system .

What are the recommended protocols for Western blotting using Phospho-p53 (Ser392) Antibody?

For Western blotting applications, the recommended dilution is typically 1:1000 . The protocol generally involves:

• Sample preparation: Treat cells with DNA-damaging agents like camptothecin (1 μM for 5 hours) to induce p53 phosphorylation

• Protein separation: Use standard SDS-PAGE methods with reducing conditions

• Transfer: Transfer proteins to PVDF membrane

• Blocking: Block with appropriate blocking buffer

• Primary antibody incubation: Apply the Phospho-p53 (Ser392) antibody at 0.1-1 μg/mL concentration

• Secondary antibody: Use HRP-conjugated anti-rabbit or anti-mouse secondary antibody depending on the host species of your primary antibody

• Detection: Visualize using chemiluminescence

The expected molecular weight for the phosphorylated p53 is approximately 53 kDa . To confirm phospho-specificity, lambda phosphatase treatment of parallel samples is recommended as a negative control .

How can I validate the specificity of Phospho-p53 (Ser392) Antibody in my experiments?

To validate the specificity of Phospho-p53 (Ser392) antibody:

• Positive control: Use cell lines known to express wild-type p53 treated with DNA-damaging agents (e.g., MCF-7 cells treated with 1 μM camptothecin for 5 hours)

• Negative control: Include untreated cells that should show minimal phosphorylation

• Phosphatase treatment: Treat parallel samples with lambda phosphatase (600 U) to remove phosphate groups, which should eliminate antibody recognition if it's truly phospho-specific

• Comparison with total p53: Reprobe membranes with a total p53 antibody to confirm that changes in phospho-signal are not simply due to changes in total protein levels

• Use cells expressing phospho-mutants: Compare cells expressing wild-type p53 with those expressing the S392A mutant, which cannot be phosphorylated at this site

How does Ser392 phosphorylation affect wild-type versus mutant p53 function?

Ser392 phosphorylation has distinct effects on wild-type p53 versus mutant p53 variants:

Wild-type p53:

• Enhances DNA binding capacity and transcriptional activation

• Increases tetramerization and stability

• Promotes growth suppressor function

• Stimulates p53 tumor suppressor activity through CK2-mediated phosphorylation

Mutant p53:

• Regulates oncogenic function of mutant p53 forms

• Non-phosphorylatable mutant variants (p53H175A392, p53W248A392) demonstrate enhanced transformation potential in cooperation with ras compared to their phosphorylatable counterparts (p53H175S392, p53W248S392)

• p53H175A392 (non-phosphorylatable) shows greater ability to confer cellular resistance to cisplatin and UV radiation compared to wild-type p53H175

• p53H175E392 (phospho-mimetic) displays reduced ability to confer resistance to DNA-damaging agents

This differential regulation suggests that Ser392 phosphorylation may serve as a regulatory mechanism that constrains the oncogenic potential of mutant p53, while enhancing the tumor suppressor functions of wild-type p53 .

What is the relationship between Ser392 phosphorylation and p53 mRNA localization?

Recent research has revealed an intriguing relationship between p53 Ser392 phosphorylation and mRNA localization:

• The 3'UTR of TP53 mRNA influences the phosphorylation status of Ser392

• p53 expressed without its 3'UTR (p53CR) shows higher levels of Ser392 phosphorylation compared to p53 expressed with its native 3'UTR (p53UTR)

• DNA damage induces changes in TP53 mRNA localization which correlates with increased phosphorylation on Ser392

• CK2, which phosphorylates p53 on Ser392, is relocalized to the perinuclear cytoplasm in transformed cells, suggesting a spatial regulation mechanism

This data indicates a complex regulatory circuit where mRNA localization influences protein modification, which in turn affects p53 activity. The subcellular localization of TP53 mRNA appears to influence accessibility to kinases like CK2, thereby regulating Ser392 phosphorylation levels and subsequent p53 function .

What cellular stresses and signaling pathways regulate p53 Ser392 phosphorylation?

p53 Ser392 phosphorylation is regulated by multiple stresses and signaling pathways:

The casein kinase 2 (CK2) is a primary kinase responsible for Ser392 phosphorylation in vivo . The cyclin-dependent kinase-activating kinase (CAK) can also phosphorylate this site in vitro . The RAS pathway influences CK2 localization to the perinuclear region, affecting its ability to phosphorylate p53 .

How can I design experiments to study the functional consequences of p53 Ser392 phosphorylation?

To investigate functional consequences of p53 Ser392 phosphorylation, consider these experimental approaches:

• Phosphorylation site mutants:

  • Generate S392A (non-phosphorylatable) and S392E/D (phospho-mimetic) p53 mutants

  • Express these in p53-null cells to study phosphorylation-specific functions

  • Compare with wild-type p53 in functional assays

• Kinase manipulation:

  • Inhibit CK2 using specific inhibitors or siRNA knockdown

  • Overexpress CK2 to enhance phosphorylation

  • Analyze effects on p53 stability, localization, and function

• 3'UTR regulation studies:

  • Compare p53 constructs with and without the 3'UTR

  • Analyze differences in phosphorylation patterns and functional outcomes

  • Study mRNA localization using RNA FISH concurrently with phospho-p53 immunostaining

• Functional readouts:

  • Measure DNA binding capacity using chromatin immunoprecipitation (ChIP)

  • Assess transcriptional activity using reporter assays

  • Analyze target gene expression profiles by RNA-seq

  • Evaluate cell cycle arrest and apoptosis induction

• In vivo models:

  • Generate knock-in mice with S392A or S392E mutations

  • Study tumor development in carcinogen-induced or genetic cancer models

  • Analyze tissue-specific differences in phosphorylation patterns

What is the clinical significance of p53 Ser392 phosphorylation in cancer?

p53 Ser392 phosphorylation has significant clinical implications in cancer:

• Increased phosphorylation at Ser392 has been observed in human tumors

• In breast cancer tissues expressing mutant p53 (including p53H175), non-phosphorylated p53 at Ser392 has been detected, suggesting altered phosphorylation patterns in cancer cells

• The phosphorylation status at Ser392 regulates the oncogenic function of mutant p53, where non-phosphorylatable mutants show enhanced transformation potential

• Phosphorylation at this site affects cellular responses to chemotherapeutic agents like cisplatin, with non-phosphorylatable p53H175A392 conferring greater resistance to DNA-damaging treatments

These findings suggest that Ser392 phosphorylation status could potentially serve as a biomarker for p53 functionality in tumors and as a predictor of response to certain therapies. The complex relationship between phosphorylation and mutant p53 function indicates that targeting this modification or its regulatory pathways might offer therapeutic opportunities .

What controls should I include when using Phospho-p53 (Ser392) Antibody in my experiments?

When working with Phospho-p53 (Ser392) antibody, include these essential controls:

• Positive controls:

  • MCF-7 human breast cancer cells treated with 1 μM camptothecin for 5 hours

  • UV-irradiated cells expressing wild-type p53

  • Cells overexpressing wild-type p53 treated with CK2 activators

• Negative controls:

  • Untreated cells showing basal phosphorylation

  • p53-null cells (e.g., H1299, PC-3) to confirm antibody specificity

  • Lambda phosphatase-treated samples to verify phospho-specificity

• Specificity controls:

  • Total p53 antibody detection on the same samples

  • Samples expressing S392A mutant p53 (should show no signal)

  • Peptide competition assay using the phosphopeptide immunogen

• Technical controls:

  • Secondary antibody only (no primary) to detect non-specific binding

  • Loading controls (β-actin, GAPDH) to normalize protein amounts

  • Molecular weight markers to confirm correct band identification

These controls ensure reliable interpretation of results and help troubleshoot potential issues with antibody specificity or experimental conditions .

How can I optimize immunohistochemistry protocols using Phospho-p53 (Ser392) Antibody?

For optimal IHC-P results with Phospho-p53 (Ser392) antibody:

• Antigen retrieval:

  • Use high-temperature antigen retrieval with either:

    • 10 mM citrate buffer (pH 6.0) or

    • 1 mM EDTA-NaOH buffer (pH 8.0)

  • Methods include microwave heating or pressure cooker treatment

• Antibody dilution and incubation:

  • Recommended dilution: 10 μg/ml

  • Incubation options: 1 hour at room temperature or overnight at 4°C

• Detection system:

  • Standard ABC (Avidin-Biotin Complex) technique with DAB+ as chromogen

  • Consider amplification systems for low abundance targets

• Positive control tissues:

  • Breast carcinoma samples with high levels of wild-type p53

  • UV-irradiated skin samples

• Counterstaining and analysis:

  • Use hematoxylin for nuclear counterstaining

  • Evaluate both nuclear and cytoplasmic staining patterns

  • Quantify percentage of positive cells and staining intensity

• Troubleshooting:

  • For high background: Increase blocking time or reduce antibody concentration

  • For weak signal: Extend primary antibody incubation or optimize antigen retrieval

  • For non-specific staining: Include additional blocking steps or use more stringent washing

What are the current knowledge gaps regarding p53 Ser392 phosphorylation?

Despite extensive research, several knowledge gaps remain regarding p53 Ser392 phosphorylation:

• The precise temporal dynamics of Ser392 phosphorylation in response to different stressors remains incompletely characterized

• The interplay between Ser392 phosphorylation and other post-translational modifications of p53 needs further elucidation

• Tissue-specific differences in phosphorylation patterns and their functional significance are not well understood

• The mechanistic basis for how the TP53 3'UTR influences Ser392 phosphorylation requires additional investigation

• The potential for targeting Ser392 phosphorylation therapeutically in cancers with mutant p53 remains unexplored

Future research addressing these gaps will enhance our understanding of p53 regulation and potentially identify new therapeutic strategies for cancer treatment .

How might emerging technologies advance research on p53 Ser392 phosphorylation?

Emerging technologies offer promising avenues for advancing p53 Ser392 phosphorylation research:

• CRISPR-based approaches:

  • Generation of phospho-site mutants in endogenous p53 loci

  • Creation of reporter systems to monitor phosphorylation dynamics

  • Manipulation of kinases and phosphatases in physiologically relevant contexts

• Advanced imaging techniques:

  • Live-cell imaging of phosphorylation using phospho-specific fluorescent probes

  • Super-resolution microscopy to study subcellular localization

  • Multiplexed imaging to simultaneously track multiple phosphorylation sites

• Single-cell technologies:

  • Single-cell proteomics to analyze phosphorylation heterogeneity

  • Correlation of transcriptional responses with phosphorylation status

  • Analysis of rare cell populations with distinct phosphorylation patterns

• Structural biology approaches:

  • Cryo-EM studies of phosphorylated versus non-phosphorylated p53 tetramers

  • Molecular dynamics simulations to understand conformational changes

  • Structure-based design of molecules that mimic or interfere with phosphorylation effects