Phospho-PPP1R2 (S120/S121) Antibody

What is PPP1R2 and what are its primary functions in cellular processes?

PPP1R2 (Protein Phosphatase 1 Regulatory Subunit 2), also known as IPP-2 or Phosphatase Inhibitor 2, is a key regulatory protein that modulates the activities of Protein Phosphatase 1 (PP1) and Aurora A kinase (AURKA). PPP1R2 plays essential roles in cell cycle progression, particularly in maintaining centrosome number in cells, which is crucial for accurate chromosome distribution during mitosis. The protein is involved in both centrosome duplication during interphase and their accurate distribution to daughter cells during cytokinesis . PPP1R2 is approximately 23kD in molecular weight and contains multiple phosphorylation sites that regulate its activity and interactions with other proteins .

What is the significance of the Ser120/Ser121 phosphorylation sites on PPP1R2?

The Ser120 and Ser121 residues are critical phosphorylation sites on PPP1R2 that modulate its regulatory functions. Phosphorylation at these sites affects PPP1R2's interaction with its binding partners, particularly PP1 and AURKA. Research has shown that the phosphorylation state of PPP1R2 at these sites influences its localization to the midbody during telophase and affects its role in regulating cytokinesis . The phosphorylation status of these serine residues can determine whether PPP1R2 acts as an inhibitor or activator of PP1, thereby affecting various downstream cellular processes including central spindle structure formation and midbody assembly .

How does PPP1R2 coordinate the regulation of AURKA and PP1?

PPP1R2 serves as a coordinator between AURKA and PP1 activities through its dual binding capabilities. The C-terminus of PPP1R2 contains the binding site for AURKA, while other regions interact with PP1 . Through these interactions, PPP1R2 can modulate the phosphorylation and activity states of both AURKA and PP1 at the centrosome. Interestingly, while PPP1R2 is traditionally known as an inhibitor of PP1, research has shown that overexpression of PPP1R2 can paradoxically increase PP1 activity. This increase is thought to be an indirect result of decreased AURKA activity (an inhibitor of PP1) in PPP1R2-overexpressing cells . This complex interplay highlights PPP1R2's role as a molecular switch in the regulation of phosphorylation events during cell division.

What are the recommended applications for Phospho-PPP1R2 (S120/S121) Antibodies?

Phospho-PPP1R2 (S120/S121) Antibodies are suitable for various experimental applications including:

• Western Blot (WB): Recommended dilution ranges from 1:500 to 1:3000

• Immunohistochemistry on paraffin sections (IHC-P): Recommended dilution ranges from 1:50 to 1:100

• Enzyme-Linked Immunosorbent Assay (ELISA): Particularly effective for peptide detection

The antibody has been validated to react with human, mouse, and rat samples, making it versatile for comparative studies across these species . Optimal dilutions should be determined by each researcher based on their specific experimental conditions and sample types.

What controls should be included when using Phospho-PPP1R2 (S120/S121) Antibody in experiments?

For rigorous experimental design with Phospho-PPP1R2 (S120/S121) Antibody, researchers should include:

• Positive controls: Jurkat or JK cell lysates, which have been validated to express detectable levels of phosphorylated PPP1R2

• Negative controls:

  • Primary antibody omission control

  • Samples treated with phosphatase to remove phosphorylation

  • Non-phosphorylated peptide competition assay

• Peptide competition controls: Using both phosphorylated and non-phosphorylated peptides around the Ser120/Ser121 region to confirm specificity

• Loading controls: Appropriate housekeeping proteins when performing Western blots

These controls help ensure the specificity of the antibody for the phosphorylated form of PPP1R2 and validate experimental findings.

How can the Phospho-PPP1R2 (S120/S121) Antibody be used to study centrosome dynamics?

The Phospho-PPP1R2 (S120/S121) Antibody can be employed to investigate centrosome dynamics through several approaches:

• Immunofluorescence microscopy to track phosphorylated PPP1R2 localization at centrosomes throughout the cell cycle

• Co-localization studies with centrosomal markers (e.g., γ-tubulin) and other regulatory proteins (AURKA, PP1)

• Analyzing the effects of PPP1R2 phosphorylation state on centrosome number and function through overexpression or knockdown experiments

Research has shown that PPP1R2 plays a critical role in maintaining proper centrosome numbers, and alterations in its phosphorylation state or expression level can lead to supernumerary centrosomes . By using the phospho-specific antibody, researchers can track how the phosphorylation status of PPP1R2 at Ser120/Ser121 correlates with centrosome duplication, maturation, and separation during cell division.

How does the phosphorylation state of PPP1R2 at Ser120/Ser121 affect midbody formation and cytokinesis?

The phosphorylation of PPP1R2 at Ser120/Ser121 plays a crucial role in midbody formation and cytokinesis regulation. Research has demonstrated that AURKA, PP1, phospho-PPP1R2, and PPP1R2 all localize to the midbody during telophase . The phosphorylation state of PPP1R2 affects its ability to recruit PP1 to the midbody, with this recruitment requiring both terminal domains of PPP1R2 necessary for binding to AURKA and PP1 .

Experimental data indicates that overexpression of PPP1R2 and its mutants leads to:

• Increased midbody length

• Disruption of midbody architecture

• Alterations in central spindle structure

• Incomplete cytokinesis resulting in increased cellular ploidy

These effects are thought to be mediated through increased phosphatase activity at the midbody, which alters the mechanics of midbody assembly and abscission during cytokinesis . Therefore, the phosphorylation status of PPP1R2 at Ser120/Ser121 serves as a molecular switch controlling proper cell division progression.

What is the relationship between PPP1R2 phosphorylation and supernumerary centrosomes?

The relationship between PPP1R2 phosphorylation and supernumerary centrosomes involves a complex interplay of phosphorylation events and protein interactions. Studies have revealed that:

• Overexpression of PPP1R2 correlates with an increase in the frequency of supernumerary centrosomes in cells

• This centrosome amplification appears to be a consequence of errors in cell division rather than abnormal centrosome duplication

• The phosphorylation state of PPP1R2 at Ser120/Ser121 affects its ability to properly regulate AURKA and PP1 activities at the centrosome

• Aberrant cytokinesis due to PPP1R2 dysregulation leads to increased nuclear content and cellular ploidy, which can subsequently result in abnormal centrosome numbers in daughter cells

These findings suggest that maintaining proper phosphorylation levels of PPP1R2 is crucial for preventing genomic instability and centrosome amplification, both of which are hallmarks of cancer cells.

How does the dual regulation of AURKA and PP1 by PPP1R2 impact cell cycle progression?

The dual regulation of AURKA and PP1 by PPP1R2 creates a sophisticated control mechanism for cell cycle progression through several mechanisms:

• Balance of kinase and phosphatase activities: PPP1R2 modulates the opposing activities of AURKA (kinase) and PP1 (phosphatase) to ensure proper timing and execution of mitotic events

• Centrosome regulation: The PPP1R2-mediated coordination of AURKA and PP1 activities is crucial for centrosome maturation, duplication, and separation

• Cytokinesis control: Both AURKA and PP1 activities must be precisely regulated at the midbody for successful cytokinesis

• Feedback mechanisms: PPP1R2's own phosphorylation status affects its regulatory capabilities, creating feedback loops that fine-tune AURKA and PP1 activities

Research has shown that overexpression of PPP1R2 alters the activity and phosphorylation states of both AURKA and PP1 at the centrosome . This disruption leads to abnormalities in central spindle structure and cytokinesis, ultimately affecting cell cycle progression. The proper balance of these activities, coordinated by correctly phosphorylated PPP1R2, is essential for genomic stability.

What are the optimal storage and handling conditions for Phospho-PPP1R2 (S120/S121) Antibody?

For optimal performance of the Phospho-PPP1R2 (S120/S121) Antibody, the following storage and handling guidelines should be followed:

The antibody is typically supplied in phosphate buffered saline (without Mg²⁺ and Ca²⁺), pH 7.4, containing 150mM NaCl, 0.02% sodium azide, and 50% glycerol . When handling the antibody:

• Avoid repeated freeze-thaw cycles which can denature antibodies and reduce their activity

• Centrifuge the product briefly before opening the tube

• Mix gently by inversion or minimal vortexing

• Follow the manufacturer's expiration date guidelines (typically 12 months from date of receipt)

Proper storage and handling will ensure the antibody maintains its specificity and reactivity for reliable experimental results.

What are the recommended protocols for using Phospho-PPP1R2 (S120/S121) Antibody in different applications?

Western Blot Protocol:

• Prepare protein samples with appropriate lysis buffer containing phosphatase inhibitors

• Separate proteins using SDS-PAGE (10-12% gel recommended)

• Transfer proteins to PVDF or nitrocellulose membrane

• Block with 5% BSA in TBST for 1 hour at room temperature

• Incubate with Phospho-PPP1R2 (S120/S121) Antibody at 1:500-1:3000 dilution in blocking buffer overnight at 4°C

• Wash membrane with TBST (3 × 10 minutes)

• Incubate with HRP-conjugated secondary antibody (anti-rabbit IgG) for 1 hour at room temperature

• Wash membrane with TBST (3 × 10 minutes)

• Develop using chemiluminescence detection

Immunohistochemistry Protocol:

• Deparaffinize and rehydrate sections

• Perform antigen retrieval (citrate buffer pH 6.0 recommended)

• Block endogenous peroxidase with 3% H₂O₂

• Block non-specific binding with 5% normal serum

• Incubate with Phospho-PPP1R2 (S120/S121) Antibody at 1:50-1:100 dilution overnight at 4°C

• Wash sections with PBS (3 × 5 minutes)

• Apply appropriate detection system following manufacturer's protocol

• Counterstain, dehydrate, and mount

These protocols should be optimized for specific experimental conditions and sample types .

How can researchers validate the specificity of Phospho-PPP1R2 (S120/S121) Antibody in their experimental system?

To validate the specificity of Phospho-PPP1R2 (S120/S121) Antibody, researchers should employ multiple complementary approaches:

• Peptide competition assay:

  • Pre-incubate the antibody with excess phosphorylated and non-phosphorylated peptides

  • A specific antibody will show signal reduction only with the phosphorylated peptide

• Phosphatase treatment:

  • Treat duplicate samples with lambda phosphatase

  • Signal should be reduced or eliminated in phosphatase-treated samples

• Genetic validation:

  • Use PPP1R2 knockdown/knockout cells

  • Compare with cells expressing phospho-site mutants (S120A/S121A)

• Correlation with known biological stimuli:

  • Treat cells with reagents known to affect PPP1R2 phosphorylation

  • Verify expected changes in phosphorylation signal

• Multiple detection methods:

  • Compare results across different applications (WB, IHC, IF)

  • Use alternative antibodies targeting the same phospho-sites

• Mass spectrometry validation:

  • Confirm phosphorylation at Ser120/Ser121 in immunoprecipitated samples

These validation steps ensure that experimental observations accurately reflect the phosphorylation state of PPP1R2 at Ser120/Ser121.

What are common issues encountered when using Phospho-PPP1R2 (S120/S121) Antibody and how can they be resolved?

When troubleshooting, it's important to remember that phosphorylation is a dynamic process that can be affected by numerous variables including cell cycle stage, growth conditions, and sample handling procedures.

How should researchers interpret different patterns of PPP1R2 phosphorylation in relation to cell cycle and disease states?

Interpretation of PPP1R2 phosphorylation patterns requires careful consideration of cellular context:

Cell Cycle-Related Patterns:

• Increased Ser120/Ser121 phosphorylation during mitosis may indicate proper regulation of PP1 activity

• Aberrant phosphorylation patterns correlate with disrupted cytokinesis and supernumerary centrosomes

• Changes in subcellular localization of phosphorylated PPP1R2 throughout the cell cycle (particularly at the midbody during telophase) reflect its dynamic regulatory functions

Disease-Related Interpretations:

• Elevated phosphorylation may contribute to genomic instability in cancer cells through disruption of cytokinesis

• Analysis of phosphorylation patterns should consider the complex network of kinases and phosphatases that may be dysregulated in disease states

• Correlation with other markers (e.g., centrosome number, ploidy, AURKA activity) provides context for interpretation

When interpreting phosphorylation data, researchers should:

• Use multiple detection methods for confirmation

• Correlate phosphorylation with functional outcomes

• Consider temporal dynamics of phosphorylation/dephosphorylation cycles

• Analyze multiple phosphorylation sites on PPP1R2 simultaneously when possible

How can researchers differentiate between the effects of PPP1R2 overexpression and phosphorylation state changes on cellular phenotypes?

To differentiate between effects caused by PPP1R2 overexpression versus its phosphorylation state, researchers should implement the following experimental strategies:

• Phospho-mimetic and phospho-null mutants:

  • Compare wild-type PPP1R2 overexpression with S120D/S121D (phospho-mimetic) and S120A/S121A (phospho-null) mutants

  • This approach separates abundance effects from phosphorylation effects

• Inducible expression systems:

  • Use tetracycline-inducible or similar systems to control expression levels

  • Monitor cellular phenotypes at different expression levels while assessing phosphorylation status

• Rescue experiments:

  • Deplete endogenous PPP1R2 and rescue with either wild-type or mutant forms

  • This approach controls for total protein levels while varying phosphorylation state

• Temporal analysis:

  • Monitor changes in phenotype and phosphorylation over time after induction

  • Early changes may reflect direct phosphorylation effects before secondary consequences of overexpression

• Pharmacological approach:

  • Use kinase inhibitors to alter phosphorylation without changing expression

  • Compare with overexpression phenotypes

What is the potential role of Phospho-PPP1R2 (S120/S121) as a biomarker in cancer research?

The potential of Phospho-PPP1R2 (S120/S121) as a cancer biomarker stems from its role in regulating cell division and maintaining genomic stability. Researchers investigating this biomarker potential should consider:

• PPP1R2 overexpression correlates with supernumerary centrosomes, a hallmark of many cancer types

• Aberrant phosphorylation of PPP1R2 disrupts midbody structure and cytokinesis, potentially contributing to chromosomal instability

• The PPP1R2-regulated balance between AURKA and PP1 activities is frequently dysregulated in cancer

Methodologically, researchers can assess:

• Tissue microarrays of various cancer types to evaluate phospho-PPP1R2 expression patterns

• Correlation between phospho-PPP1R2 levels and clinical outcomes

• Multivariate analysis including other cell cycle regulators to develop comprehensive biomarker panels

The phosphorylation status of PPP1R2 at Ser120/Ser121 may provide insights into cancer progression mechanisms and potentially serve as a predictive biomarker for therapeutic response, particularly for drugs targeting mitotic processes.

How can the Phospho-PPP1R2 (S120/S121) Antibody be used in high-throughput screening for modulators of cell division?

The Phospho-PPP1R2 (S120/S121) Antibody can be employed in high-throughput screening (HTS) approaches through several methodologies:

• Automated immunofluorescence-based screening:

  • Cells grown in multi-well plates and treated with compound libraries

  • Automated staining for phospho-PPP1R2, DNA, and centrosome markers

  • High-content imaging to quantify:

    • Phospho-PPP1R2 levels and localization

    • Centrosome number and positioning

    • Nuclear morphology and ploidy

• ELISA-based screening:

  • Develop a sandwich ELISA using capture antibodies against total PPP1R2 and detection with phospho-specific antibody

  • Quantify phosphorylation changes in response to compounds

• Bead-based multiplex assays:

  • Simultaneous detection of multiple phosphorylation sites on PPP1R2 and related proteins

  • Assess pathway-wide effects of potential modulators

• Cell-based reporter systems:

  • Create fluorescent or luminescent reporters linked to PPP1R2 phosphorylation state

  • Monitor real-time changes in living cells

Data analysis should include:

• Dose-response relationships

• Temporal dynamics of phosphorylation changes

• Correlation with cellular phenotypes (cytokinesis defects, multinucleation)

• Secondary assays to confirm mechanism of action

This approach could identify novel compounds that modulate cell division through effects on the PPP1R2-PP1-AURKA regulatory network.

What are the emerging research areas involving PPP1R2 phosphorylation beyond cell cycle regulation?

While PPP1R2's role in cell cycle regulation is well-established, several emerging research areas are exploring its broader functions:

• Neuronal function and neurodegeneration:

  • PPP1R2 is highly expressed in the brain

  • Phosphorylation state may regulate PP1 activity in neurons

  • Potential implications for synaptic plasticity and neurodegenerative disorders

• Metabolic regulation:

  • PPP1R2 has been implicated in glycogen metabolism through PP1 regulation

  • Phosphorylation at different sites may create a regulatory network integrating cell cycle with metabolic status

• Stress response pathways:

  • Emerging evidence suggests PPP1R2 phosphorylation changes under various cellular stresses

  • May represent a mechanism to coordinate stress response with cell cycle arrest

• Development and differentiation:

  • PPP1R2 expression and phosphorylation patterns change during development

  • May play roles in balancing proliferation and differentiation decisions

• Interaction with non-canonical partners:

  • Beyond PP1 and AURKA, phosphorylated PPP1R2 may interact with additional proteins

  • Phospho-proteomics approaches can identify novel interaction networks