STRADA Antibody

What is STRADA protein and what cellular pathways does it regulate?

STRADA (also known as LYK5, PMSE, STRAD alpha) is a pseudokinase that functions as an upstream regulator of the mTORC1 signaling pathway . STRADA forms a complex with LKB1 and MO25, thereby activating LKB1 kinase activity . When activated, LKB1 phosphorylates and activates adenosine monophosphate-activated kinase (AMPK), which subsequently activates the tuberous sclerosis 1/2 complex (TSC1/TSC2), an inhibitor of mTORC1 . This signaling cascade is crucial for cell growth regulation, energy metabolism, and neural development. Loss of STRADA function results in disinhibition of mTORC1, leading to abnormal cell growth and potential pathological outcomes .

What applications are STRADA antibodies most commonly used for in research?

STRADA antibodies are primarily utilized in Western blot (WB) applications to detect expression levels and post-translational modifications of STRADA protein . They are also validated for use in enzyme-linked immunosorbent assays (ELISA) and immunohistochemistry on paraffin-embedded tissues (IHC-P) . These antibodies serve as valuable tools in research examining cell signaling pathways, particularly those involving the MAPK and mTOR pathways . They enable researchers to investigate STRADA expression in various cell types, especially in studies exploring neural development, cancer biology, and metabolic regulation .

What are the key considerations for selecting an appropriate STRADA antibody?

When selecting a STRADA antibody, researchers should consider:

• Target specificity: Choose antibodies validated against knockout (KO) samples to ensure specific binding to STRADA protein without cross-reactivity .

• Epitope recognition: Consider which region of STRADA the antibody recognizes. For example, some antibodies target amino acids 25-210 of human STRADA (NP_699166.2) .

• Species reactivity: Verify the antibody's reactivity with your experimental species. Available antibodies demonstrate reactivity with human, mouse, and rat samples .

• Application compatibility: Confirm validation for your intended application (WB, ELISA, IHC-P) .

• Isotype and host species: Most STRADA antibodies are rabbit polyclonal IgG, which influences secondary antibody selection and potential cross-reactivity issues .

How can I optimize Western blot protocols when using STRADA antibodies?

To optimize Western blot protocols with STRADA antibodies:

• Sample preparation: For cellular samples, use RIPA buffer supplemented with protease and phosphatase inhibitors, as STRADA undergoes phosphorylation events within signaling cascades.

• Protein loading: Load 20-40μg of total protein per lane to ensure sufficient detection of STRADA protein.

• Dilution optimization: Start with the manufacturer's recommended dilution (typically 1:1000 - 1:2000 for Western blot) and adjust based on signal-to-noise ratio.

• Blocking conditions: Use 5% non-fat dry milk or 3-5% BSA in TBST for 1 hour at room temperature.

• Primary antibody incubation: Incubate with diluted STRADA antibody overnight at 4°C for optimal binding and specificity.

• Positive control selection: Include validated positive controls such as HeLa cell lysates, which are known to express STRADA protein .

• Visualization method: Both chemiluminescence and fluorescence-based detection systems are compatible with STRADA antibodies, though chemiluminescence may provide greater sensitivity for low abundance samples.

What methods should I use to validate the specificity of my STRADA antibody?

To validate STRADA antibody specificity:

• Knockout/knockdown validation: Compare samples with and without STRADA expression using CRISPR/Cas9 knockout or siRNA knockdown models to confirm signal specificity .

• Peptide competition assay: Pre-incubate the antibody with excess immunogenic peptide (corresponding to amino acids 25-210 of human STRADA) before application to verify signal suppression.

• Cross-reactivity assessment: Test the antibody against related proteins (particularly other pseudokinases) to ensure it doesn't recognize unintended targets.

• Multiple antibody validation: Use antibodies targeting different epitopes of STRADA to confirm consistent detection patterns.

• Immunoprecipitation followed by mass spectrometry: This approach can verify that the antibody is capturing the intended protein rather than cross-reactive species.

How should I design experiments to investigate STRADA's interaction with LKB1 and MO25?

When investigating STRADA's interaction with LKB1 and MO25:

• Co-immunoprecipitation (Co-IP): Use STRADA antibodies to pull down the protein complex, followed by Western blot analysis for LKB1 and MO25. This approach requires careful buffer optimization to preserve native protein interactions.

• Proximity ligation assay (PLA): This technique can visualize protein-protein interactions within cells using antibodies against STRADA and its binding partners LKB1 or MO25.

• Bimolecular fluorescence complementation (BiFC): By tagging STRADA and its interaction partners with complementary fragments of fluorescent proteins, researchers can visualize complex formation in living cells.

• FRET analysis: Fluorescently labeled STRADA and binding partners can be analyzed for energy transfer, indicating close proximity consistent with protein-protein interaction.

• Sequential immunoprecipitation: First immunoprecipitate with STRADA antibody, then elute and perform a second immunoprecipitation with LKB1 or MO25 antibodies to isolate the trimeric complex specifically.

How can STRADA antibodies be used to investigate mTORC1 signaling dysregulation in pathological conditions?

STRADA antibodies can be used to investigate mTORC1 signaling dysregulation through:

• Comparative expression analysis: Quantify STRADA expression levels in pathological versus normal tissues using Western blot or immunohistochemistry with STRADA antibodies .

• Phosphoproteomic analysis: Use STRADA antibodies in immunoprecipitation followed by mass spectrometry to identify changes in phosphorylation patterns within the STRADA-LKB1-AMPK-mTORC1 pathway.

• Tissue microarray analysis: Apply STRADA antibodies to tissue microarrays to assess expression patterns across multiple patient samples or disease states.

• Correlation with downstream markers: Combine STRADA antibody staining with detection of phosphorylated S6 kinase1, phosphorylated S6 (pS6), and c-Myc proteins to assess mTORC1 hyperactivation status .

• In vitro manipulation models: Use STRADA antibodies to confirm successful knockdown or overexpression in cellular models designed to study mTORC1 dysregulation.

• Patient-derived organoid analysis: Apply STRADA antibodies in immunofluorescence studies of organoids to connect altered STRADA expression to structural and functional abnormalities in 3D tissue models .

What approaches can be used to study STRADA's role in neural stem cell regulation using specific antibodies?

To study STRADA's role in neural stem cell regulation:

• Immunofluorescence in neural organoids: Use STRADA antibodies for spatial and temporal expression analysis in human cortical organoids, which can model developmental processes more accurately than monolayer cultures .

• Co-localization studies: Combine STRADA antibodies with neural stem cell markers (NESTIN, SOX2) and differentiation markers (TUJ1, MAP2) to track STRADA expression during neurogenesis.

• FACS-based analyses: Use STRADA antibodies in flow cytometry to sort neural progenitor populations based on STRADA expression levels, allowing further characterization of subpopulations.

• Time-course experiments: Apply STRADA antibodies in temporal studies to track expression changes during neural differentiation of induced pluripotent stem cells (iPSCs) .

• Chromatin immunoprecipitation (ChIP): Use STRADA antibodies in ChIP experiments to identify potential transcriptional regulatory mechanisms if STRADA exhibits nuclear localization .

• Cellular fractionation studies: Use STRADA antibodies to monitor subcellular distribution between cytoplasm and nucleus during neural development .

How can STRADA antibodies be utilized in investigating PMSE (Polyhydramnios, Megalencephaly, and Symptomatic Epilepsy) pathophysiology?

For investigating PMSE pathophysiology:

• Patient-derived iPSC models: Use STRADA antibodies to confirm loss of STRADA expression in iPSCs derived from PMSE patients, validating disease models .

• Cerebral organoid analysis: Apply STRADA antibodies in immunostaining of cerebral organoids derived from patient iPSCs to examine developmental abnormalities in 3D culture systems .

• Comparative phenotyping: Use STRADA antibodies along with markers for neural progenitors and mature neurons to compare cell fate determination defects between control and PMSE models .

• Rescue experiments: After genetic or pharmacological intervention to restore STRADA function, use STRADA antibodies to confirm successful restoration and correlate with phenotypic improvements.

• Developmental time-course studies: Apply STRADA antibodies to track expression patterns throughout neural development in patient-derived versus control neural precursors .

• Correlation with clinical features: Use immunohistochemistry with STRADA antibodies on autopsy specimens to correlate STRADA loss with cytomegalic neurons and heterotopic neurons in subcortical white matter observed in PMSE patients .

What are common issues when using STRADA antibodies and how can they be resolved?

Common issues with STRADA antibodies include:

• High background signal:

  • Solution: Optimize blocking conditions (try 5% BSA instead of milk)

  • Increase washing steps and duration

  • Try a higher dilution of primary antibody (1:2000 instead of 1:1000)

  • Use fresher blocking agents and buffers

• Weak or absent signal:

  • Solution: Increase protein loading (50-75μg)

  • Reduce primary antibody dilution (1:500 instead of 1:1000)

  • Extend primary antibody incubation time (overnight at 4°C)

  • Use enhanced chemiluminescence substrates

  • Verify STRADA expression in your sample type with literature

• Multiple bands:

  • Solution: Validate bands using positive control (HeLa cells)

  • Compare band pattern with expected molecular weight (approximately 48 kDa)

  • Consider the possibility of splice variants, post-translational modifications, or degradation products

  • Perform peptide competition assays to identify specific band

• Inconsistent results between experiments:

  • Solution: Standardize protocols rigorously

  • Use the same lot number of antibody when possible

  • Prepare fresh samples for each experiment

  • Include internal loading controls and positive controls consistently

How should I interpret differences in STRADA staining patterns between cytoplasmic and nuclear compartments?

When interpreting differential subcellular localization of STRADA:

• Physiological significance: STRADA has been reported to localize to both cytoplasm and nucleus , with potential functions in each compartment. Nuclear localization may indicate roles in transcriptional regulation, while cytoplasmic localization aligns with its known function in the LKB1-AMPK pathway.

• Quantification approach: Perform quantitative analysis of nuclear-to-cytoplasmic ratio using digital image analysis with software like ImageJ.

• Context-dependent interpretation:

  • In neural progenitors, changes in STRADA localization may correlate with differentiation state or cell cycle phase

  • In pathological contexts, aberrant nuclear localization might suggest dysregulated signaling

• Controls for compartment-specific staining: Include nuclear (DAPI, lamin) and cytoplasmic (tubulin, GAPDH) markers to validate subcellular fractionation.

• Validation methods: Confirm immunofluorescence findings with biochemical fractionation followed by Western blot analysis using STRADA antibodies.

• Dynamic regulation: Consider whether shuttling between compartments occurs in response to specific stimuli, which would require time-course experiments following treatment.

How can I distinguish between specific and non-specific binding in STRADA antibody applications?

To distinguish between specific and non-specific binding:

• Knockout/knockdown validation: The gold standard approach is comparing staining between wild-type and STRADA-depleted samples. Knockout-validated antibodies offer the highest confidence in specificity .

• Peptide competition: Pre-incubating the antibody with the immunogenic peptide (amino acids 25-210 of human STRADA) should eliminate specific binding while leaving non-specific interactions intact.

• Multiple antibody approach: Use several antibodies targeting different epitopes of STRADA and compare staining patterns.

• Isotype control: Include a control using non-specific IgG from the same species at the same concentration to assess background binding.

• Signal intensity gradient: In systems with variable STRADA expression, specific binding should correlate with expected expression patterns, while non-specific binding typically shows random distribution.

• Correlation with mRNA expression: Compare protein detection patterns with STRADA mRNA expression data from RT-PCR or in situ hybridization to confirm concordance.

How can I implement advanced imaging techniques with STRADA antibodies for high-resolution analysis?

Advanced imaging with STRADA antibodies can be implemented through:

• Super-resolution microscopy: Techniques such as STORM, PALM, or STED microscopy can resolve STRADA localization at nanoscale resolution, revealing previously undetectable organizational details.

• Expansion microscopy: Physical expansion of specimens combined with STRADA immunolabeling can achieve super-resolution imaging on conventional microscopes.

• Multiplexed imaging: Combine STRADA antibodies with sequential staining or spectral unmixing to simultaneously visualize multiple proteins in the mTOR pathway.

• Live-cell imaging: Although conventional antibodies cannot be used in living cells, nanobody or scFv derivatives of STRADA antibodies could potentially be developed for live-cell applications.

• Correlative light and electron microscopy (CLEM): STRADA antibody labeling can be combined with electron microscopy to correlate protein localization with ultrastructural features.

• Volumetric imaging: Techniques like tissue clearing combined with light-sheet microscopy can enable whole-organ imaging of STRADA expression in intact neural tissues.

What emerging methodologies can enhance the specificity and utility of STRADA antibodies in research?

Emerging methodologies to enhance STRADA antibody utility include:

• Single-domain antibodies (nanobodies): Development of STRADA-specific nanobodies could offer improved penetration in tissue sections, reduced background, and potential for live-cell applications.

• Proximity-dependent labeling: Conjugating STRADA antibodies with enzymes like APEX2 or BioID can identify proximal proteins in the native cellular context.

• Antibody engineering: Site-specific conjugation of fluorophores or other functional moieties can improve signal-to-noise ratio and enable multiplexed detection.

• Degradation targeting chimeras: STRADA antibody-based molecules can be designed to induce targeted protein degradation for functional studies.

• Microfluidic antibody screening: High-throughput screening platforms can identify optimal antibody clones and conditions for specific applications.

• Spatial transcriptomics integration: Combining STRADA protein detection with spatial transcriptomics can correlate protein levels with gene expression patterns in tissue contexts.

How might STRADA antibodies contribute to therapeutic development for mTORC1-related disorders?

STRADA antibodies may contribute to therapeutic development through:

• Target validation: Using STRADA antibodies to confirm target engagement in drug development programs targeting the STRADA-LKB1-AMPK-mTORC1 pathway.

• Biomarker development: STRADA antibodies could be useful in developing immunoassays to monitor treatment efficacy in clinical trials for PMSE and other mTOR-related disorders .

• Patient stratification: Immunohistochemistry with STRADA antibodies might identify patient subgroups most likely to benefit from specific therapeutic approaches.

• Antibody-drug conjugates: While not directly therapeutic, the epitope recognition properties of STRADA antibodies could inform the development of targeted therapeutic modalities.

• Functional screening assays: STRADA antibodies can be used in high-throughput screening to identify compounds that restore normal STRADA levels or function in disease models.

• Direct therapeutic targeting: Understanding STRADA's structural properties, facilitated by antibody-based studies, could enable small molecule development to modulate its function or stability.