Phospho-TERT (S824) Antibody

What is the Phospho-TERT (S824) Antibody and what does it detect?

The Phospho-TERT (S824) Antibody is a rabbit polyclonal antibody specifically designed to detect the telomerase reverse transcriptase (TERT) protein only when phosphorylated at serine residue 824. This antibody recognizes the phosphorylated form of TERT in the context of the surrounding amino acid sequence, typically within the 796-845 amino acid region of human TERT . The antibody is produced by immunizing rabbits with a synthetic phosphopeptide derived from human TERT containing the phosphorylated S824 site . Following production, the antibody undergoes affinity purification via sequential chromatography on phospho-peptide and non-phospho-peptide affinity columns to ensure specificity .

What is the significance of TERT phosphorylation at S824 in cellular processes?

TERT phosphorylation at S824 represents an important post-translational modification that regulates telomerase function. While the precise biological significance of S824 phosphorylation specifically requires further investigation, TERT phosphorylation at various sites plays crucial roles in determining:

• Subcellular localization: Phosphorylation events can trigger translocation between nuclear and cytoplasmic compartments

• Enzymatic activity: Affecting telomerase complex formation and catalytic function

• Protein stability: Influencing TERT degradation pathways

• Interaction capabilities: Modifying binding with telomerase RNA and associated proteins

Research has established that post-translational modifications of TERT, including phosphorylation events, can significantly impact its canonical function in telomere maintenance as well as non-canonical functions in cellular processes related to aging and apoptosis .

What are the validated applications for Phospho-TERT (S824) antibodies?

The Phospho-TERT (S824) antibody has been validated for several experimental applications, with varying levels of support across manufacturers:

Western blotting appears to be the most consistently validated application across different antibody sources, with demonstrated reactivity against human, mouse, and rat samples . For optimal results, researchers should consider pilot experiments to determine the ideal concentration for their specific experimental conditions and sample types.

How should I design experiments to study TERT phosphorylation at S824?

When designing experiments to study TERT phosphorylation at S824, consider the following methodological approach:

• Cell/tissue selection: Choose experimental models where TERT is endogenously expressed at detectable levels. Cancer cell lines often express higher levels of TERT, making them suitable models. Based on available data, validated cell lines include A549, H1792, HepG2, Panc1, and K562 .

• Stimulation conditions: Consider including experimental conditions that might modulate phosphorylation status:

  • Growth factor stimulation

  • DNA damage induction

  • Cell cycle synchronization

  • Oxidative stress induction

• Controls:

  • Positive controls: Include lysates from cell lines known to express phosphorylated TERT (e.g., K562 cells)

  • Negative controls: Consider using dephosphorylation treatments (phosphatase treatment)

  • Phosphorylation site mutants (S824A) if feasible

• Complementary techniques:

  • Pair phospho-specific antibody detection with total TERT detection

  • Consider mass spectrometry validation for unambiguous phosphorylation site identification

  • Use kinase inhibitors to modulate phosphorylation pathways

• Temporal considerations: Given that phosphorylation is a dynamic modification, consider time-course experiments to capture transient phosphorylation events.

What are the optimal storage conditions for Phospho-TERT (S824) antibodies?

To maintain antibody integrity and performance, follow these storage recommendations:

• Long-term storage: Store at -20°C for up to one year from the date of receipt

• Working storage: For frequent use and short-term storage, keep at 4°C for up to one month

• Avoid repeated freeze-thaw cycles as they can compromise antibody performance

• The antibody is typically supplied in a buffer containing PBS with 50% glycerol, 0.02% sodium azide, and sometimes 0.5% BSA

For optimal long-term preservation of antibody activity, consider aliquoting the stock solution into smaller volumes before freezing to minimize freeze-thaw cycles.

How do I properly validate a Phospho-TERT (S824) antibody for my research?

Thorough antibody validation is essential for generating reliable data. Consider these validation approaches:

• Specificity testing:

  • Compare signals with and without phosphatase treatment

  • Peptide competition assay using phosphorylated and non-phosphorylated peptides

  • TERT knockout/knockdown controls

  • Phospho-site mutant (S824A) expression

• Cross-reactivity assessment:

  • Test across relevant species based on sequence conservation

  • Check for non-specific bands in Western blot

• Functional validation:

  • Correlation with known stimuli that induce TERT phosphorylation

  • Correlation with biological outcomes associated with TERT phosphorylation

• Technical validation:

  • Titration experiments to determine optimal antibody concentration

  • Comparison with alternative antibodies (if available)

  • Reproducibility assessment across multiple experiments

How does phosphorylation at S824 interact with other post-translational modifications of TERT?

TERT undergoes multiple post-translational modifications that work in concert to regulate its function. While the specific interplay between S824 phosphorylation and other modifications requires further research, available data suggests several important interactions:

• Phosphorylation network:

  • Phosphorylation at Tyr-707 under oxidative stress leads to cytoplasmic translocation of TERT and reduces its antiapoptotic activity

  • Phosphorylation at Ser-227 by the AKT pathway promotes nuclear localization

  • Phosphorylation at Ser-457 by DYRK2 during G2/M phase promotes ubiquitination and degradation

• Ubiquitination connection:

  • The E3 ligase complex EDVP targets TERT following phosphorylation at Ser-457, leading to proteasomal degradation

  • During HIV-1 infection, this degradation pathway can be hijacked through interaction between HIV-1 Vpr and DCAF1/VPRBP

• Potential crosstalk:
  Understanding the hierarchy and potential crosstalk between S824 phosphorylation and these other modifications may provide insights into the complex regulation of TERT function, subcellular localization, and stability.

What is the relationship between TERT phosphorylation at S824 and the DNA damage response?

The relationship between TERT phosphorylation at S824 and the DNA damage response presents an intriguing research area. While direct evidence linking S824 phosphorylation to DNA damage response is still emerging, several connections can be drawn:

Understanding this relationship could provide insights into how telomere maintenance is coordinated with genome stability mechanisms, particularly in cancer cells where TERT is highly active.

How can I use Phospho-TERT (S824) antibodies in cancer research?

Phospho-TERT (S824) antibodies offer valuable tools for cancer research, given the critical role of telomerase in cancer cell immortalization. Consider these research applications:

• Diagnostic and prognostic biomarker development:

  • Evaluate whether S824 phosphorylation status correlates with cancer progression or treatment response

  • Compare phosphorylation levels across tumor grades and stages

• Therapeutic target assessment:

  • Monitor changes in S824 phosphorylation in response to telomerase inhibitors or other anticancer agents

  • Determine if specific kinase inhibitors affect TERT phosphorylation and subsequent telomerase activity

• Mechanistic investigations:

  • Examine how oncogenic signaling pathways modulate S824 phosphorylation

  • Assess whether S824 phosphorylation affects TERT's non-canonical functions in cancer cells

• Combination studies:

  • Pair phospho-TERT detection with cell cycle markers (e.g., PCNA) to analyze cell cycle-dependent regulation

  • Combine with DNA damage markers (e.g., 53BP1, γH2AX) to explore connections between telomerase activity and genomic stability

• Translational research:

  • Analyze patient-derived xenografts or clinical samples for phospho-TERT status

  • Correlate findings with response to therapies targeting telomerase or related pathways

How do I troubleshoot non-specific binding when using Phospho-TERT (S824) antibodies?

Non-specific binding is a common challenge when working with phospho-specific antibodies. Consider these troubleshooting strategies:

• Optimize blocking conditions:

  • Test different blocking agents (BSA, non-fat milk, commercial blockers)

  • Note that for phospho-epitopes, milk should generally be avoided as it contains phosphatases

• Adjust antibody dilution:

  • Perform titration experiments using a range of dilutions (starting with manufacturer recommendations of 1:500-1:2000 for WB)

  • Higher dilutions may reduce background while maintaining specific signal

• Modify washing steps:

  • Increase number and duration of washes

  • Add low concentrations of detergent (0.05-0.1% Tween-20) to washing buffer

• Sample preparation:

  • Include phosphatase inhibitors in lysis buffers

  • Optimize protein loading to avoid overloading, which can increase background

• Consider peptide competition:

  • Pre-incubate antibody with phosphorylated peptide to confirm specificity

  • Parallel blots with and without peptide competition can identify non-specific bands

• Signal enhancement methods:

  • For low abundance targets, consider using enhanced chemiluminescence or fluorescent secondary antibodies

  • Optimize exposure times to balance signal and background

What controls should I include when using Phospho-TERT (S824) antibodies?

Robust experimental design requires appropriate controls to validate findings and ensure reliable interpretation:

Inclusion of these controls strengthens data interpretation and facilitates troubleshooting if unexpected results are obtained.

What is the cross-reactivity of Phospho-TERT (S824) antibodies across different species?

Understanding species cross-reactivity is crucial for experimental design, particularly in comparative studies or when working with model organisms:

For experimental validation across species:

• Verify sequence conservation around the S824 phosphorylation site

• Conduct preliminary tests with appropriate positive controls from each species

• Consider species-specific optimization of experimental conditions

• Be aware that phosphorylation sites may be regulated differently across species despite sequence conservation

Cross-reactivity information helps researchers select the most appropriate model systems for their studies and interpret comparative data accurately.

How does TERT phosphorylation status change throughout the cell cycle?

Understanding the dynamics of TERT phosphorylation throughout the cell cycle offers insights into telomerase regulation. Current research suggests:

• Cell cycle-dependent regulation:

  • TERT undergoes phosphorylation at Ser-457 specifically during the G2/M phase by DYRK2, promoting its ubiquitination and degradation

  • This indicates that different phosphorylation events on TERT may be coordinated with specific cell cycle phases

• Experimental approaches to study S824 phosphorylation across the cell cycle:

  • Synchronize cells at different cell cycle stages using established methods (double thymidine block, nocodazole, serum starvation)

  • Perform time-course analysis following synchronization release

  • Combine with cell cycle markers such as PCNA to identify cells in S-phase

  • Use flow cytometry to separate cells by cell cycle stage followed by Western blot analysis

• Technical considerations:

  • Include controls for synchronization efficiency (e.g., flow cytometry validation)

  • Consider the impact of synchronization methods on cellular stress responses

  • Account for potential heterogeneity in phosphorylation status within populations

Examining S824 phosphorylation across the cell cycle may reveal important regulatory mechanisms controlling telomerase activity during DNA replication and cell division processes.

What techniques can be combined with Phospho-TERT (S824) antibody detection for comprehensive studies?

Integrating multiple techniques with phospho-specific antibody detection enhances the depth and reliability of research findings:

• Complementary protein analysis techniques:

  • Immunoprecipitation: Isolate phosphorylated TERT to identify interacting partners

  • Mass spectrometry: Confirm phosphorylation site occupancy and identify co-occurring modifications

  • Proximity ligation assay: Visualize interactions between phosphorylated TERT and potential binding partners in situ

• Functional assays:

  • Telomerase activity assays (TRAP): Correlate S824 phosphorylation with enzymatic activity

  • DNA fiber analysis: Examine telomere replication dynamics in relation to TERT phosphorylation

  • Telomere length measurements: Assess long-term consequences of altered phosphorylation

• Genomic and transcriptomic approaches:

  • ChIP-seq with phospho-TERT antibodies: Map genomic binding sites

  • RNA-seq following modulation of S824 phosphorylation: Identify downstream transcriptional changes

  • CRISPR-based approaches: Create S824 phospho-mimetic or phospho-dead mutations

• Advanced imaging:

  • Super-resolution microscopy: Visualize subcellular localization with nanometer precision

  • Live-cell imaging with phospho-sensors: Monitor dynamic changes in phosphorylation

  • Co-localization studies with DNA damage markers or telomere-associated proteins

Combining these approaches provides a multi-dimensional understanding of how S824 phosphorylation affects TERT function in different cellular contexts.