Phospho-VIM (S83) Antibody

What is Phospho-VIM (S83) and why is it significant in cell biology research?

Phospho-VIM (S83) refers to vimentin protein phosphorylated at serine 83. Vimentin is a type III intermediate filament protein found in various non-epithelial cells, especially mesenchymal cells, where it forms part of the cytoskeleton. Phosphorylation at S83 plays a critical regulatory role in vimentin filament disassembly, particularly during mitosis .

PLK (Polo-like kinase) phosphorylates vimentin at Ser83, which serves as a "memory phosphorylation site" for vimentin filament reorganization . This specific phosphorylation event is crucial for understanding fundamental cellular processes including:

• Cell division and mitotic progression

• Cytoskeletal dynamics and reorganization

• Cell migration and directional movement

• Cell sheet organization and polarization

Vimentin is highly expressed in fibroblasts, with some expression in T- and B-lymphocytes, and appears in many hormone-independent mammary carcinoma cell lines, making this phosphorylation site relevant to multiple tissue contexts .

What are the primary research applications for Phospho-VIM (S83) antibodies?

Phospho-VIM (S83) antibodies are utilized in several key research applications:

These applications allow researchers to:

• Monitor phosphorylation status during cell cycle progression

• Assess cytoskeletal reorganization under various stimuli

• Evaluate phosphorylation in disease models, particularly cancer

• Study regulatory mechanisms of intermediate filament dynamics

What are the optimal conditions for using Phospho-VIM (S83) antibodies in Western blotting experiments?

For optimal Western blotting with Phospho-VIM (S83) antibodies, researchers should implement the following methodological approach:

• Sample Preparation:

  • Use fresh cell lysates with phosphatase inhibitors to preserve phosphorylation status

  • Include protease inhibitors to prevent vimentin degradation

  • Maintain cold temperatures throughout processing to prevent dephosphorylation

• Antibody Selection and Dilution:

  • Most Phospho-VIM (S83) antibodies function optimally at dilutions between 1:500-1:2000

  • Rabbit-derived polyclonal or monoclonal antibodies show good specificity for this epitope

  • Expected molecular weight: 57-60 kDa (observed molecular weight may be slightly higher than calculated due to phosphorylation)

• Protocol Optimization:

  • Blocking: Use 5% BSA in TBST rather than milk to avoid interference from phosphoproteins

  • Primary antibody incubation: Overnight at 4°C yields better results than shorter incubations

  • Secondary antibody: Anti-rabbit IgG (most Phospho-VIM (S83) antibodies are rabbit-derived)

• Controls and Validation:

  • Positive control: Paclitaxel-treated cells (100nM, 20h) show enhanced phosphorylation at S83

  • Negative control: Phosphatase-treated lysates or hydroxyurea-treated cells (4mM, 20h)

  • Loading control: Total vimentin or housekeeping proteins like GAPDH

How can researchers validate the specificity of a Phospho-VIM (S83) antibody?

Validating the specificity of Phospho-VIM (S83) antibodies requires multiple complementary approaches:

• Biochemical Validation:

  • Phosphatase treatment: Signal should diminish or disappear in lambda phosphatase-treated samples

  • Peptide competition: Pre-incubate antibody with phosphorylated (QDSVD) and non-phosphorylated peptides - phospho-peptide should block signal while non-phospho-peptide should not

  • Immunogen verification: Confirm the antibody was raised against the correct phospho-epitope (typically a synthetic phosphorylated peptide around S83 of human VIM)

• Cellular Validation:

  • Stimulation experiments: Compare samples from conditions known to increase S83 phosphorylation (mitosis, paclitaxel treatment) with untreated controls

  • Genetic approaches: Test in vimentin knockdown/knockout samples, which should show no reactivity

  • Site-directed mutagenesis: S83A mutants should show no reactivity, confirming phospho-specificity

• Cross-reactivity Assessment:

  • Test against other phosphorylated proteins with similar motifs

  • Examine reactivity across species (human, mouse, rat) to confirm expected cross-reactivity

  • Evaluate potential detection of other phosphorylated sites on vimentin (especially S72 which is in proximity to S83)

What cell types and experimental conditions are ideal for studying Phospho-VIM (S83)?

For optimal study of Phospho-VIM (S83), researchers should consider:

Recommended Cell Types:

• Fibroblasts: Show naturally high vimentin expression

• HeLa cells: Commonly used in phospho-vimentin validation studies

• Mesenchymal cells: Primary vimentin-expressing cells

• Mammary carcinoma cell lines: Many hormone-independent lines express vimentin

Experimental Conditions for Enhanced S83 Phosphorylation:

Important Considerations:

• Include phosphatase inhibitors in all lysis buffers and sample preparation steps

• For cell cycle studies, synchronize cells and collect at defined timepoints

• For comparison studies, utilize Hydroxyurea-treated cells (4mM, 20h) as controls

• Consider the influence of cell density and passage number on phosphorylation status

What are common issues encountered when using Phospho-VIM (S83) antibodies and how can they be resolved?

Researchers frequently encounter these challenges when working with Phospho-VIM (S83) antibodies:

• Weak or No Signal in Western Blots:

  • Possible causes: Insufficient phosphorylation, epitope masking, dephosphorylation during preparation

  • Methodological solutions:

    • Increase antibody concentration within recommended range (1:500-1:2000)

    • Ensure fresh samples with comprehensive phosphatase inhibitor cocktails

    • Validate mitotic enrichment with a mitotic marker (phospho-histone H3)

    • Consider enhanced chemiluminescence detection systems

• High Background:

  • Possible causes: Insufficient blocking, excessive antibody concentration, inadequate washing

  • Methodological solutions:

    • Use 5% BSA (not milk) for blocking and antibody dilution

    • Optimize antibody dilution through titration experiments

    • Extend washing steps with 0.1% Tween-20 in PBS

    • Consider longer primary antibody incubation at lower concentration

• Multiple Bands or Unexpected Molecular Weight:

  • Possible causes: Vimentin degradation, detection of multiple phosphorylation states, cross-reactivity

  • Methodological solutions:

    • Validate with phosphatase treatment to confirm phospho-specificity of all bands

    • Use fresh samples with comprehensive protease inhibitors

    • Run non-phosphorylated vimentin controls to identify mobility shifts

    • Perform immunoprecipitation followed by Western blotting to confirm specificity

• Inconsistent Results Between Experiments:

  • Possible causes: Variable phosphorylation levels, inconsistent sample preparation, antibody lot variation

  • Methodological solutions:

    • Standardize cell harvesting protocols (e.g., mitotic shake-off vs. scraping)

    • Maintain consistent antibody lots when possible

    • Include consistent positive and negative controls in each experiment

    • Quantify and normalize phospho-signal to total vimentin

How should researchers interpret changes in Phospho-VIM (S83) levels during cell cycle progression?

Interpreting Phospho-VIM (S83) patterns during cell cycle progression requires careful analysis:

• Expected Phosphorylation Pattern:

  • Low phosphorylation in G1/G0 phases

  • Increasing phosphorylation as cells enter mitosis

  • Peak phosphorylation during metaphase through anaphase

  • Gradual dephosphorylation during telophase and cytokinesis

• Mechanistic Interpretation Framework:

  • S83 phosphorylation follows a sequential pattern: CDK1 first phosphorylates vimentin at S56, creating a binding site for PLK1

  • PLK1 then phosphorylates vimentin at S83, contributing to filament disassembly needed during mitosis

  • This modification serves as a "memory phosphorylation site" that regulates filament reorganization

• Quantitative Analysis Approach:

  • Normalize phospho-vimentin to total vimentin to account for expression differences

  • Use flow cytometry with cell cycle markers (DNA content) to correlate with cell cycle phases

  • Perform time-course experiments with synchronized cells for temporal resolution

  • Implement immunofluorescence to visualize spatial distribution of phosphorylated protein

• Interpreting Abnormal Patterns:

  • Sustained phosphorylation outside mitosis may indicate dysregulation (relevant in cancer contexts)

  • Reduced phosphorylation during mitosis might suggest defects in kinase pathways

  • Changes in phosphorylation kinetics may correlate with abnormal mitotic progression or cytoskeletal defects

How can Phospho-VIM (S83) analysis be integrated into cancer research frameworks?

Phospho-VIM (S83) analysis offers several sophisticated applications in cancer research:

• Epithelial-Mesenchymal Transition (EMT) Studies:

  • Methodological approach: Track changes in Phospho-VIM (S83) during EMT induction in epithelial cancer cells

  • Analysis framework: Correlate phosphorylation patterns with invasive properties and other EMT markers

  • Significance: Vimentin expression increases during EMT, but phosphorylation status may provide additional mechanistic insights into metastatic potential

• Therapeutic Response Monitoring:

  • Methodological approach: Assess Phospho-VIM (S83) levels before and after treatment with cytoskeleton-targeting drugs

  • Analysis framework: Determine whether changes in phosphorylation correlate with treatment efficacy

  • Application: Could help identify responsive patient subgroups in personalized medicine approaches

• Cancer Immunotherapy Applications:

  • Methodological approach: Based on research findings, phosphorylated vimentin peptides can elicit helper T lymphocyte (HTL) responses

  • Key finding: Phospho-vimentin peptides, including those containing S83, have shown immunogenicity in colorectal cancer patients

  • Therapeutic potential: Combination of phospho-vimentin peptide vaccines with chemotherapy represents a novel approach for cancer treatment

• Multi-omics Integration:

  • Methodological approach: Combine Phospho-VIM (S83) protein analysis with phosphoproteomics and transcriptomics

  • Analysis framework: Use network analysis to identify signaling pathways connected to vimentin phosphorylation

  • Implementation: Correlate phosphorylation patterns with clinical outcomes to identify prognostic signatures

What molecular mechanisms regulate vimentin S83 phosphorylation and how can they be experimentally manipulated?

The regulation of vimentin S83 phosphorylation involves specific molecular mechanisms that can be experimentally manipulated:

• Key Regulatory Kinases:

  • PLK1 (Polo-like kinase 1): Primary kinase responsible for S83 phosphorylation

  • CDK1: Phosphorylates vimentin at S56, creating a docking site for PLK1

  • Experimental manipulation: Use specific inhibitors like BI2536 (PLK1) or RO-3306 (CDK1) to block phosphorylation

• Phosphatases and Dephosphorylation:

  • PP1/PP2A: Likely involved in dephosphorylating vimentin after mitosis

  • Experimental manipulation: Use okadaic acid or calyculin A to inhibit phosphatases and prolong phosphorylation

  • Analysis approach: Time-course studies following release from mitotic arrest can reveal dephosphorylation kinetics

• Cross-talk with Other Post-translational Modifications:

  • O-glycosylation: Occurs at sites identical or close to phosphorylation sites and may interfere with phosphorylation status

  • S-nitrosylation: Induced by interferon-gamma and oxidatively-modified LDL

  • Experimental approach: Use site-specific mutations to eliminate competing modifications and isolate phosphorylation effects

• Methodological Approaches for Manipulation:

  • Genetic tools: Express phosphomimetic (S83D/E) or non-phosphorylatable (S83A) mutants

  • Pharmacological tools: Combination of kinase activators/inhibitors with phosphatase inhibitors

  • Physical manipulation: Mechanical stress application to trigger cytoskeletal reorganization

  • Quantification methods: Phospho-specific antibodies in combination with total vimentin antibodies to determine stoichiometry of modification

How does phosphorylation at S83 functionally differ from other vimentin phosphorylation sites?

Vimentin contains multiple phosphorylation sites with distinct functional roles:

Methodological Approaches for Comparative Analysis:

• Site-specific Antibody Analysis:

  • Use antibodies targeting different phosphorylation sites in parallel experiments

  • Compare temporal patterns during cell cycle progression

  • Analyze spatial distribution through immunofluorescence

• Mutational Analysis:

  • Generate non-phosphorylatable (S→A) and phosphomimetic (S→D/E) mutants for each site

  • Express in vimentin-null backgrounds to avoid interference from endogenous protein

  • Compare effects on filament assembly, cellular localization, and interaction networks

• Functional Differentiation:

  • S83 phosphorylation appears particularly important for mitotic progression

  • S39 phosphorylation shows promise as an immunotherapeutic target

  • Combined mutations reveal hierarchical relationships between modifications

What recent technological advances have improved detection and quantification of Phospho-VIM (S83)?

Recent technological developments have enhanced the study of Phospho-VIM (S83):

• Improved Antibody Development:

  • Higher specificity phospho-specific antibodies with validated cross-reactivity profiles

  • Multiple commercial options with defined applications (WB, ELISA, IHC)

  • Detailed validation data for research applications

• Mass Spectrometry Approaches:

  • Phosphoproteomic workflows with improved sensitivity for detecting vimentin modifications

  • Parallel reaction monitoring (PRM) for targeted quantification of specific phospho-sites

  • Top-down proteomics to analyze intact vimentin with its full complement of modifications

• Single-Cell Analysis Technologies:

  • Flow cytometry with phospho-specific antibodies for cell-by-cell quantification

  • Mass cytometry (CyTOF) for simultaneous detection of multiple phosphorylation sites

  • Single-cell sequencing to correlate transcriptomic profiles with protein phosphorylation

• Advanced Imaging Methods:

  • Super-resolution microscopy for visualizing phosphorylated vimentin at nanoscale resolution

  • FRET-based biosensors to monitor phosphorylation events in real-time

  • Proximity ligation assays to detect S83 phosphorylation and protein interactions simultaneously

These technological advances provide researchers with unprecedented tools to study vimentin phosphorylation in various biological contexts, from basic cytoskeletal dynamics to complex disease processes such as cancer progression and metastasis .