Phospho-S1PR1 (T236) Antibody

What is Phospho-S1PR1 (T236) Antibody and what epitope does it recognize?

Phospho-S1PR1 (T236) Antibody is a rabbit polyclonal antibody specifically designed to detect endogenous levels of S1PR1 (Sphingosine 1-phosphate receptor 1) protein only when phosphorylated at threonine 236. The antibody is generated using a synthesized peptide derived from human EDG-1 (alternative name for S1PR1) around the phosphorylation site of T236. It recognizes an epitope region between amino acids 206-255 of the human S1PR1 protein. This antibody is affinity-purified from rabbit antiserum using epitope-specific immunogen to ensure high specificity for the phosphorylated form of the receptor .

What are the key technical specifications of commercially available Phospho-S1PR1 (T236) antibodies?

Commercially available Phospho-S1PR1 (T236) antibodies typically have the following specifications:

These specifications ensure optimal antibody performance in a variety of experimental contexts .

What are the optimal experimental conditions for using Phospho-S1PR1 (T236) antibody in Western Blot assays?

For optimal Western Blot results with Phospho-S1PR1 (T236) antibody:

• Sample preparation: Prepare cell or tissue lysates in a buffer containing phosphatase inhibitors to preserve phosphorylation status. TNBC cell lines show higher phospho-S1PR1 T236 levels compared to luminal breast cancer cells, making them good positive controls .

• Antibody dilution: Use the antibody at 1:500-1:2000 dilution in 5% BSA in TBST for optimal signal-to-noise ratio .

• Validation approach: Include appropriate controls:

  • Positive control: Lysates from TNBC cell lines (e.g., MIII, MIV) which exhibit elevated phospho-S1PR1 T236 levels

  • Negative control: Samples treated with phosphatase

  • Specificity control: Samples with S1PR1 T236A mutation (alanine substitution prevents phosphorylation)

• Loading control: Use ACTIN as a loading control, as demonstrated in published research .

• Detection method: Use enhanced chemiluminescence for visualization, with exposure times adjusted based on signal strength.

Western blot analysis should reveal a band corresponding to phospho-S1PR1 T236 at approximately 47 kDa, with TNBC cell lines showing significantly higher phosphorylation levels compared to non-TNBC cells, while total S1PR1 levels may remain comparable .

How can Phospho-S1PR1 (T236) antibody be effectively used in immunofluorescence experiments?

For optimal immunofluorescence results with Phospho-S1PR1 (T236) antibody:

• Cell preparation: Culture cells on coated coverslips until they reach 70-80% confluence. For cancer cell studies, TNBC cell lines like MIII or MIV cells are recommended as they display higher phospho-S1PR1 T236 levels .

• Fixation and permeabilization: Fix cells with 4% paraformaldehyde for 15 minutes at room temperature, followed by permeabilization with 0.1% Triton X-100 for 10 minutes.

• Blocking: Block with 5% normal serum (from the species of secondary antibody) for 1 hour at room temperature.

• Primary antibody incubation: Apply Phospho-S1PR1 (T236) antibody at 1:200-1:1000 dilution and incubate overnight at 4°C .

• Secondary antibody: Use appropriate fluorophore-conjugated anti-rabbit secondary antibody.

• Counterstaining: Counterstain with DAPI to visualize nuclei.

• Imaging parameters: S1PR1 is primarily a cell surface receptor, but phosphorylated forms may show internalization patterns, as demonstrated with other phosphorylation sites like Y143 . Therefore, compare membrane versus cytoplasmic localization.

• Controls: Include wild-type S1PR1 and S1PR1 T236A mutant-expressing cells to differentiate between phosphorylation-dependent localization patterns. Research has shown that phosphorylation status can significantly impact receptor localization and function .

How does phosphorylation at T236 differ from other S1PR1 phosphorylation sites, and what are the functional implications?

S1PR1 undergoes phosphorylation at multiple sites with distinct functional outcomes:

• T236 phosphorylation (mediated by AKT):

  • Primarily associated with TNBC invasiveness and migration

  • Levels significantly elevated in TNBC cells compared to luminal breast cancer cells

  • Phosphorylation at this site does not affect total S1PR1 expression levels

  • Plays a crucial role in promoting cancer cell invasion and migration

  • Serves as a potential biomarker for TNBC progression

• Y143 phosphorylation:

  • Critical for S1PR1 internalization in endothelial cells

  • Phosphorylation occurs within 5 minutes of S1P exposure and remains elevated for up to 15 minutes

  • Maximal S1PR1 internalization occurs at 20 minutes post-stimulation

  • Y143 dephosphorylation correlates with receptor recycling back to the cell surface within 60 minutes

  • Regulates endothelial barrier function through modulating cell surface receptor availability

• C-terminus serine phosphorylation (S351, S353, S355, S358, S359):

  • Induced by FTY720P (not discussed in detail in the search results)

  • Promotes interaction with ubiquitin ligase WWP2

  • Leads to receptor polyubiquitylation and degradation

  • Results in reduced receptor responsiveness to S1P

These distinct phosphorylation events illustrate the complex regulation of S1PR1 signaling, with T236 phosphorylation specifically linked to pathological processes in cancer progression, while Y143 phosphorylation appears more involved in physiological regulation of endothelial barrier function .

What is the relationship between AKT activation and S1PR1 T236 phosphorylation in triple-negative breast cancer?

The relationship between AKT activation and S1PR1 T236 phosphorylation in TNBC is characterized by a positive feedback mechanism that promotes cancer progression:

• AKT as upstream kinase:

  • AKT directly phosphorylates S1PR1 at T236 in TNBC cells

  • Inhibition of AKT with MK2206 (a pan-AKT inhibitor) reduces phospho-S1PR1 T236 levels

  • Western blot analysis shows correlation between phospho-AKT S473 levels and phospho-S1PR1 T236 levels in TNBC cell lines

• Functional consequences:

  • AKT-mediated phosphorylation of S1PR1 T236 promotes TNBC cell migration in vitro

  • Mutation of T236 to alanine (T236A) prevents phosphorylation and reduces migration

  • Treatment with AKT inhibitor MK2206 (0.3 μM) significantly reduces phospho-S1PR1 T236 levels and inhibits migration

  • MK2206's ability to inhibit TNBC cell migration depends on AKT-mediated phosphorylation of S1PR1 T236

• In vivo relevance:

  • Zebrafish xenograft models show that MK2206 treatment reduces invasion of TNBC cells expressing wild-type S1PR1

  • Quantification of fluorescence intensity demonstrates significantly reduced invasion of tumor cells outside the injection area following MK2206 treatment

  • This inhibitory effect on invasion is dependent on the phosphorylation status of S1PR1 T236

These findings collectively establish a critical role for AKT-mediated phosphorylation of S1PR1 T236 in promoting TNBC invasiveness, suggesting potential therapeutic strategies targeting this specific phosphorylation event .

How can researchers effectively design experiments to study the role of S1PR1 T236 phosphorylation in cancer cell invasion?

To effectively study S1PR1 T236 phosphorylation in cancer cell invasion, researchers should implement the following comprehensive experimental design:

• Cell model selection:

  • Use TNBC cell lines (e.g., MIII, MIV) which exhibit high levels of phospho-S1PR1 T236

  • Include non-TNBC cells (e.g., luminal breast cancer cells) as comparative controls

  • Consider using isogenic cell progression models to study relationship with cancer progression

• Genetic manipulation approaches:

  • Generate cells expressing wild-type S1PR1, phosphorylation-defective S1PR1 T236A, and phosphomimetic mutants

  • Use luciferase-expressing control cells for comparison

  • Confirm expression levels by Western blot analysis using both phospho-specific and total S1PR1 antibodies

• In vitro invasion assays:

  • Wound-scratch assay to measure cell migration over time (e.g., 0 and 19 hours post-scratching)

  • Transwell invasion assays with Matrigel to assess invasive capacity

  • Live-cell imaging to track cell movement and morphological changes

• In vivo models:

  • Zebrafish xenograft models: Inject RFP+ cancer cells and quantify fluorescence intensity of invasive tumor cells outside the injection area at 3 days post-transplantation

  • Consider mouse models for longer-term studies of metastatic potential

• Pharmacological interventions:

  • AKT inhibitor (MK2206) at 0.3 μM to study the role of AKT in S1PR1 T236 phosphorylation

  • FTY720 treatment (2 μM) to assess effects on cell viability and invasion

  • Dose-response experiments to determine optimal drug concentrations

• Analytical methods:

  • Western blot analysis to quantify phospho-S1PR1 T236, total S1PR1, phospho-AKT S473, total AKT, and apoptosis markers like active CASPASE 3

  • Fluorescence microscopy to visualize cancer cell invasion in vivo

  • Quantitative analysis of cell migration rates, invasion distances, and cell viability

This comprehensive experimental approach enables researchers to establish both the mechanisms and functional significance of S1PR1 T236 phosphorylation in cancer progression .

What are the critical controls needed when studying S1PR1 T236 phosphorylation in experimental systems?

• Phosphorylation-specific controls:

  • Positive phosphorylation control: TNBC cell lines (MIII, MIV) known to have elevated phospho-S1PR1 T236 levels

  • Negative phosphorylation control: Samples treated with phosphatase to remove phosphorylation

  • Phosphorylation-defective mutant: Cells expressing S1PR1 T236A (alanine substitution) that cannot be phosphorylated at the T236 position

  • Phosphomimetic mutant: Consider creating T236D (aspartate substitution) to mimic constitutive phosphorylation for comparison

• Expression controls:

  • Vector-only control: Cells transfected with empty vector or irrelevant protein (e.g., luciferase)

  • Wild-type S1PR1 control: Cells expressing non-mutated S1PR1 for comparison with phosphorylation-site mutants

  • Expression level control: Western blot for total S1PR1 to ensure comparable expression levels between wild-type and mutant constructs

• Specificity controls:

  • Antibody specificity: Compare detection in wild-type vs. T236A mutant-expressing cells

  • Peptide competition: Pre-incubate antibody with phospho-peptide immunogen to block specific binding

  • Alternative phosphorylation sites: Monitor other phosphorylation sites (e.g., Y143) to assess site specificity

• Treatment controls:

  • Vehicle control: DMSO or other solvent used for inhibitor/drug delivery

  • Time course controls: Appropriate time points to capture phosphorylation dynamics

  • Dose-response controls: Multiple concentrations of inhibitors like MK2206 (AKT inhibitor) or FTY720

• Technical controls:

  • Loading control: ACTIN or other housekeeping proteins for Western blot normalization

  • Membrane fraction control: Na+/K+ ATPase or other membrane markers when studying receptor localization

  • Cell viability control: Assess whether treatments affect cell survival, which could confound migration/invasion results

Implementing these controls allows researchers to confidently attribute observed phenotypes to S1PR1 T236 phosphorylation specifically, rather than to confounding factors .

How does S1PR1 T236 phosphorylation correlate with triple-negative breast cancer progression and what are the therapeutic implications?

S1PR1 T236 phosphorylation shows a strong positive correlation with TNBC progression and offers several promising therapeutic implications:

• Correlation with TNBC progression:

  • Phospho-S1PR1 T236 levels are significantly elevated in TNBC cells compared to luminal breast cancer cells, while total S1PR1 levels remain relatively constant

  • Analysis of human TNBC samples (n=41) versus non-TNBC samples (n=385) reveals distinct expression patterns

  • Western blot analysis across multiple human TNBC cell lines (n=6) and luminal cell lines (n=10) consistently shows elevated phospho-S1PR1 T236 to S1PR1 ratio in TNBC cells

  • In isogenic cancer progression models (MI, NeoT, MIII, and MIV cells), phospho-S1PR1 T236 levels increase with advancing stages of malignancy

• Functional role in TNBC invasiveness:

  • Phosphorylation at T236 is essential for TNBC cell migration and invasion

  • Expression of phosphorylation-defective S1PR1 T236A mutant decreases TNBC cell migration in vitro and disease invasion in zebrafish xenografts

  • AKT-mediated phosphorylation of S1PR1 T236 is critical for driving invasive behavior

• Therapeutic targeting approaches:

  • AKT inhibition: Pan-AKT inhibitor MK2206 suppresses S1PR1 T236 phosphorylation and reduces TNBC cell migration in vitro and tumor invasion in vivo

  • FTY720 (Fingolimod): This FDA-approved drug for multiple sclerosis acts as an S1P1 functional antagonist and suppresses TNBC cell migration in vitro and tumor invasion in vivo

  • TNBC cells with AKT activation and elevated phospho-S1PR1 T236 show particular sensitivity to FTY720-induced cytotoxic effects

• Biomarker potential:

  • Phospho-S1PR1 T236 levels could serve as a biomarker to identify TNBC patients who might benefit from targeted therapies like FTY720

  • The ratio of phospho-S1PR1 T236 to total S1PR1 may provide a more accurate indicator of disease progression than either marker alone

These findings suggest that therapeutic strategies targeting the AKT-S1PR1 T236 phosphorylation axis could be particularly effective for TNBC patients with elevated phospho-S1PR1 T236 levels, potentially repurposing existing FDA-approved drugs like FTY720 for TNBC treatment .

How do the mechanisms of S1PR1 phosphorylation at T236 differ from those at Y143, and what are the implications for different disease models?

The mechanisms and implications of S1PR1 phosphorylation differ significantly between T236 and Y143 sites, with distinct consequences for different disease models:

• Mechanistic differences:

  T236 phosphorylation:

  • Mediated by AKT kinase in TNBC cells

  • Appears to be a constitutive modification in cancer cells rather than a rapidly cycling regulatory mechanism

  • Not significantly affected by S1P stimulation in the documented studies

  • Associated with pathological states, particularly cancer progression

  Y143 phosphorylation:

  • Rapidly induced by S1P stimulation (within 5 minutes)

  • Functions as a physiological regulatory mechanism in endothelial cells

  • Shows a distinct temporal pattern: phosphorylation increases within 5 minutes, peaks around 15 minutes, followed by dephosphorylation and receptor recycling by 60 minutes

  • Plays a role in normal endothelial barrier function regulation

• Functional consequences:

  T236 phosphorylation:

  • Promotes cancer cell migration and invasion

  • Does not appear to significantly alter receptor internalization or degradation

  • Sustains pathological signaling that drives disease progression

  • Serves as a therapeutic target in TNBC

  Y143 phosphorylation:

  • Required for rapid (within 20 minutes) internalization of the receptor

  • Controls receptor responsiveness to S1P by regulating cell surface expression

  • Dephosphorylation of Y143 correlates with receptor recycling to the cell surface

  • Regulates endothelial barrier function in a cyclical manner

• Disease model implications:

  T236 phosphorylation in cancer:

  • Critical biomarker and therapeutic target in TNBC

  • Correlates with disease progression and invasiveness

  • Predicts sensitivity to FTY720-induced cytotoxicity

  • May identify patients who would benefit from AKT inhibitors or S1PR1 antagonists

  Y143 phosphorylation in vascular disorders:

  • Potentially important in vascular leak syndromes and endothelial dysfunction

  • Regulates endothelial barrier integrity through S1P responsiveness

  • Disruption of normal Y143 phosphorylation/dephosphorylation cycling could contribute to vascular pathologies

  • May represent a distinct therapeutic target for vascular diseases

These mechanistic differences highlight the context-specific regulation of S1PR1 and suggest that different phosphorylation sites may be targeted depending on the disease context: T236 for cancer therapeutics and Y143 potentially for vascular disorders .

What are common technical challenges when working with Phospho-S1PR1 (T236) antibody and how can researchers overcome them?

Researchers working with Phospho-S1PR1 (T236) antibody may encounter several technical challenges that can be addressed with the following approaches:

• Low signal intensity in Western blots:

  • Challenge: Phosphorylation-specific antibodies often produce weaker signals than total protein antibodies.

  • Solutions:

    • Increase protein loading (50-80 μg per lane)

    • Optimize antibody concentration (try 1:500 instead of 1:2000)

    • Use enhanced chemiluminescence substrates specifically designed for phospho-proteins

    • Incorporate phosphatase inhibitors (e.g., sodium orthovanadate, sodium fluoride) in all buffers

    • Consider using PVDF membranes which may retain phospho-proteins better than nitrocellulose

• Specificity concerns:

  • Challenge: Ensuring the antibody only detects S1PR1 when phosphorylated at T236.

  • Solutions:

    • Include S1PR1 T236A mutant-expressing cells as a negative control

    • Perform peptide competition assays with phospho-T236 peptide

    • Use phosphatase treatment of duplicate samples to confirm phospho-specificity

    • Compare with other commercially available phospho-S1PR1 T236 antibodies if possible

• Inconsistent phosphorylation levels:

  • Challenge: Phosphorylation states can rapidly change during sample handling.

  • Solutions:

    • Harvest cells directly into hot SDS sample buffer to instantly denature phosphatases

    • Add phosphatase inhibitor cocktails to all buffers

    • Keep samples cold throughout processing

    • Standardize time between cell harvesting and sample denaturation

    • Consider chemical stimulation (e.g., with phosphatase inhibitors) to maximize phosphorylation before analysis

• Background in immunofluorescence:

  • Challenge: High background can obscure specific phospho-S1PR1 T236 signal.

  • Solutions:

    • Optimize blocking conditions (try 5% BSA instead of serum)

    • Extend blocking time to 2 hours or overnight

    • Use phospho-blocking reagents specifically designed for phospho-epitopes

    • Increase washing steps (5 x 5 minutes instead of 3 x 5 minutes)

    • Try fluorophore-conjugated F(ab')2 fragments instead of whole IgG secondary antibodies

• Antibody cross-reactivity:

  • Challenge: Polyclonal antibodies may recognize similar phospho-epitopes on other proteins.

  • Solutions:

    • Validate with siRNA knockdown of S1PR1

    • Compare signal patterns between phospho-S1PR1 T236 and total S1PR1 antibodies

    • Confirm results with alternative techniques (e.g., mass spectrometry)

    • Use S1PR1-null cell lines as negative controls

These troubleshooting approaches will help researchers obtain reliable and reproducible results when working with Phospho-S1PR1 (T236) antibody across various experimental applications .

How can researchers quantitatively analyze phospho-S1PR1 T236 levels in relation to total S1PR1 and correlate with functional outcomes?

Proper quantitative analysis of phospho-S1PR1 T236 levels requires rigorous methodological approaches to establish meaningful correlations with functional outcomes:

• Quantification approaches for Western blots:

  • Normalization strategy: Calculate the ratio of phospho-S1PR1 T236 to total S1PR1 after normalizing each to loading controls (e.g., ACTIN)

  • Densitometry software: Use ImageJ or similar software with background subtraction

  • Multiple exposure times: Capture images at different exposure times to ensure signals are within linear range

  • Standard curve: Consider including a dilution series of a positive control sample to ensure quantification is in the linear range

  • Statistical analysis: Perform at least three independent experiments and use appropriate statistical tests (e.g., t-test, ANOVA) to determine significance

• Correlating phosphorylation with receptor function:

  • Surface expression: Use cell surface biotinylation or flow cytometry to quantify membrane-localized S1PR1 and correlate with phosphorylation status

  • Internalization kinetics: Compare internalization rates between wild-type S1PR1 and T236A mutants using antibody feeding assays or live-cell imaging

  • Signaling output: Measure downstream signaling (e.g., ERK, AKT activation) in response to S1P stimulation and correlate with phospho-T236 levels

  • Time-course experiments: Track changes in phosphorylation and associated functions over time following stimulation or drug treatment

• Multi-parameter analysis in cancer models:

  • Migration-phosphorylation correlation: Quantify wound closure rates or transwell migration and plot against phospho-S1PR1 T236/total S1PR1 ratio

  • Invasion index: Calculate invasion index in 3D models or zebrafish xenografts and correlate with phosphorylation levels

  • Drug sensitivity profiling: Plot dose-response curves for FTY720 or MK2206 and correlate IC50 values with phospho-S1PR1 T236 levels

  • Multivariate analysis: Consider phospho-AKT levels, phospho-S1PR1 T236, and total S1PR1 in multivariate models to predict invasion potential

• Advanced imaging-based quantification:

  • Phospho-specific immunofluorescence: Perform double immunofluorescence with phospho-S1PR1 T236 and total S1PR1 antibodies, then calculate intensity ratios at single-cell level

  • Subcellular localization: Quantify the distribution of phospho-S1PR1 T236 between membrane, cytoplasmic, and endosomal compartments using confocal microscopy

  • FRET-based sensors: Consider developing FRET-based S1PR1 phosphorylation sensors for live-cell imaging of phosphorylation dynamics

  • High-content imaging: Apply automated image analysis to quantify phospho-S1PR1 T236 levels across large cell populations and correlate with phenotypic outcomes

• Validation in clinical samples:

  • Tissue microarrays: Analyze phospho-S1PR1 T236 levels in TNBC versus non-TNBC tissue microarrays

  • Correlation with patient outcomes: Associate phospho-S1PR1 T236/total S1PR1 ratio with clinical parameters like tumor grade, metastatic potential, and patient survival

  • Multimarker panels: Evaluate phospho-S1PR1 T236 alongside other markers (e.g., phospho-AKT, SPHK1) as a prognostic signature

  • Receiver operating characteristic (ROC) analysis: Determine optimal cutoff values for phospho-S1PR1 T236 levels that predict clinical outcomes or drug responses

These quantitative approaches enable researchers to establish robust correlations between S1PR1 T236 phosphorylation and functional outcomes, providing a foundation for developing phospho-S1PR1 T236 as a biomarker and therapeutic target in diseases like TNBC .