STK38 Antibody

What tissue/cell types express STK38 and can be detected with STK38 antibodies?

STK38 is widely expressed across multiple cell types and tissues. STK38 antibodies have been validated for detection in various cell lines including HEK-293, HeLa, HepG2, Jurkat, and MCF-7 . In tissue samples, STK38 antibody has been validated for immunohistochemistry in mouse cerebellum tissue .

For researchers investigating STK38 in different experimental models, it's important to note that STK38 has been studied in various contexts, including:

• Cancer cell lines (U2OS, MDA-MB-231, VAL lymphoma cells, and Jurkat T-cell lymphoma)

• Primary cardiomyocytes isolated from neonatal mouse heart

• B cells in lymphoma research models

When establishing STK38 expression in a new cell type or tissue, validation using positive controls from these established models is recommended.

What are the recommended dilutions for STK38 antibody in different applications?

The optimal dilution for STK38 antibody varies by application and should be determined experimentally for each specific research context. Based on available data, the following dilutions are recommended as starting points:

It's essential to include appropriate controls and perform antibody titration to determine optimal concentration for your specific experimental system .

What are the most reliable methods for validating STK38 antibody specificity?

Validating antibody specificity is crucial for reliable STK38 research. Multiple complementary approaches should be used:

• Genetic knockdown validation: Compare STK38 antibody signal in control and STK38 knockdown samples. This approach has been documented in several studies, where shRNA targeting STK38 resulted in reduced antibody signal in both Western blot and immunofluorescence applications .

• Multiple antibody validation: Use different antibodies targeting distinct epitopes of STK38 to confirm consistent results.

• Immunoprecipitation followed by mass spectrometry: Confirm that the immunoprecipitated protein is indeed STK38.

• Negative controls: Include samples from tissues or cell lines with minimal STK38 expression or use isotype control antibodies to establish background signal levels.

The literature shows successful STK38 knockdown validation in multiple cell types, including VAL lymphoma cells, HL-1 cells, and primary cardiomyocytes , making these potential positive controls for antibody validation experiments.

How can STK38 antibodies be used to investigate its kinase-dependent versus kinase-independent functions?

STK38 exhibits both kinase-dependent and kinase-independent functions in different cellular contexts. To differentiate between these functions using antibodies:

• Co-immunoprecipitation studies: STK38 antibodies can be used to immunoprecipitate STK38 and analyze its binding partners in different contexts. For example, STK38 has been shown to associate with ubiquitin E3 ligase Smurf1 in TLR9 signaling and interacts with MYC through distinct domains .

• Complementation experiments: Compare wild-type versus kinase-dead mutant STK38 in rescue experiments after endogenous STK38 knockdown. Research has shown that STK38's role in promoting ATM activation is kinase-independent , while its regulation of MYC protein stability is kinase-activity-dependent .

• Phospho-specific antibodies: Use in conjunction with STK38 antibodies to detect active (phosphorylated) versus inactive forms of STK38, particularly when investigating its kinase-dependent functions.

• Inhibitor studies: Compare STK38 antibody staining patterns and co-immunoprecipitation results in the presence or absence of kinase inhibitors to distinguish between kinase-dependent and independent functions.

The literature reveals that STK38 contains a UFM1 binding motif that is critical for its interaction with ufmylated H4 and promotion of ATM activation , providing a specific interaction domain that can be targeted in structure-function studies.

What are the key domains of STK38 that researchers should target with domain-specific antibodies?

Based on functional studies, several key domains of STK38 are particularly relevant for research:

• UFM1 binding motif: STK38 contains a UFM1 binding motif that recognizes ufmylated H4. Mutation of conserved amino acids in this motif abolishes interaction with ufmylated H4 . Domain-specific antibodies targeting this region could help investigate STK38's role in DNA damage response.

• Kinase domain: STK38's kinase function is important for certain activities, such as MYC protein stability regulation . Antibodies recognizing the kinase domain, particularly in active versus inactive conformations, would be valuable.

• MYC interaction domains: STK38 forms complexes with distinct MYC domains, affecting MYC protein turnover . Antibodies targeting these interaction interfaces could help elucidate the STK38-MYC regulatory axis.

• Phosphorylation sites: Antibodies detecting specific phosphorylation states of STK38 would be useful, particularly for studying its activation in different signaling pathways.

When designing experiments, researchers should consider that STK38 4A mutant (with mutations in the UFM1 binding motif) fails to restore radiosensitivity in STK38 knockdown cells, highlighting the functional importance of this domain .

How can STK38 antibodies be used to investigate its role in ATM activation and DNA damage response?

STK38 functions as a reader of histone H4 ufmylation to promote ATM activation in DNA damage response. To investigate this role using antibodies:

• Chromatin immunoprecipitation (ChIP): Use STK38 antibodies to perform ChIP assays before and after DNA damage induction to analyze STK38 recruitment to double-strand breaks (DSBs).

• Co-immunoprecipitation: STK38 antibodies can be used to investigate interactions with other DNA damage response proteins, particularly after irradiation. Research has shown that STK38 recruits SUV39H1 to DSBs, resulting in H3K9 trimethylation and Tip60 activation .

• Immunofluorescence analysis of STK38 foci: Compare STK38 localization before and after DNA damage induction using STK38 antibodies in immunofluorescence assays.

• Sequential ChIP (re-ChIP): Combine STK38 antibodies with antibodies against H4K31-ufmylation to investigate their co-localization at damage sites.

When investigating STK38's role in ATM activation, it's important to note that this function is kinase-independent but requires the UFM1 binding motif . Proper experimental controls should include the STK38 4A mutant, which has disrupted UFM1 binding capability.

What are the recommended controls when studying STK38's influence on cellular radiosensitivity?

When studying STK38's impact on radiation sensitivity, several controls are crucial:

• Knockdown validation: Confirm STK38 knockdown efficiency by Western blot before radiation experiments to ensure adequate protein reduction.

• ATM inhibitor controls: Include ATM inhibitor (e.g., Ku55933) treatment groups to confirm that STK38's effect on radiosensitivity operates through ATM. Research has shown that knockdown of STK38 did not further sensitize cells to irradiation in ATM knockdown cells .

• Genetic complementation: Include rescue experiments with:

  • Wild-type STK38

  • STK38 4A mutant (defective in UFM1 binding)

  • Kinase-dead STK38 mutant

  Research shows that reintroduction of wild-type STK38, but not the STK38 4A mutant, reversed radiosensitivity caused by STK38 knockdown .

• Cell cycle analysis: As STK38 knockdown affects the G2/M checkpoint but not general cell cycle distribution , include cell cycle profiling as a control in radiation experiments.

• ATM acetylation mutants: Consider using the ATM K3016Q mutant (acetylation mimic) as research shows this mutant reversed radiosensitivity caused by loss of STK38 .

Colony formation assays have been successfully used to measure radiosensitivity in STK38 knockdown cells, with significant reduction in survival observed at various radiation doses .

How should STK38 antibodies be used to investigate its role in MYC-dependent tumor growth?

STK38 regulates MYC protein stability and function, making it relevant for cancer research, particularly in MYC-dependent tumors. To investigate this relationship:

• Xenograft tumor models: STK38 antibodies can be used for immunohistochemical analysis of tumor sections from xenograft models with conditional STK38 knockdown. Research has shown that STK38 knockdown suppresses tumor growth in MYC-dependent lymphoma xenografts .

• Multiplex immunohistochemistry: Combine STK38 antibodies with markers for:

  • Proliferation (Ki-67)

  • Apoptosis (cleaved caspase-3)

  • MYC expression levels

  This approach can correlate STK38 expression with these phenotypes in tumor samples.

• Protein stability assays: Use STK38 antibodies alongside MYC antibodies in cycloheximide chase experiments to analyze how STK38 affects MYC protein turnover.

• Co-immunoprecipitation: STK38 antibodies can identify MYC-STK38 protein complexes and how these might be altered in cancer contexts.

Experimental models should consider that STK38 knockdown in VAL and Jurkat lymphoma cell lines results in decreased proliferation (measured by Ki-67) and increased apoptosis (measured by cleaved caspase-3) , providing useful positive controls.

What are the methodological considerations when using STK38 antibodies in different cancer types?

STK38's role appears context-dependent across cancer types, requiring specific methodological considerations:

• Cancer-type specificity: STK38 shows varying expression patterns across cancer types. It's upregulated in progressive breast ductal carcinoma and melanoma, but downregulated in gastric cancer and B-cell lymphoma compared to normal tissues . When using STK38 antibodies, include appropriate tissue-matched controls.

• Antibody validation in specific cancer contexts: Validate STK38 antibody performance in each cancer type under investigation, as protein modifications or interactions might affect epitope accessibility.

• Correlation with clinical outcomes: When analyzing STK38 expression in clinical samples, correlate with:

  • MYC expression levels and stability

  • Patient survival data

  • Treatment response metrics

• Interaction partner analysis: In different cancer contexts, STK38 may interact with different partners. Use:

  • Co-immunoprecipitation followed by mass spectrometry

  • Proximity ligation assays

  • FRET-based interaction studies

• Phosphorylation status: Consider how STK38 phosphorylation status varies across cancer types and how this affects antibody recognition.

Research models should be carefully selected based on STK38 expression. MYC-dependent cell lines such as VAL (with MYC translocation) and Jurkat T-cell lymphoma have been successfully used to study STK38 function in cancer contexts .

How can STK38 antibodies be used to investigate its role in TLR9-mediated immune responses?

STK38 negatively regulates TLR9-mediated immune responses in macrophages. To investigate this function:

• Co-immunoprecipitation with immune signaling components: Use STK38 antibodies to study its interaction with:

  • Smurf1 (ubiquitin E3 ligase)

  • MEKK2 (which STK38 and Smurf1 target for degradation)

  • Other TLR9 signaling components

  Research shows STK38 constitutively associates with Smurf1 and facilitates Smurf1-mediated MEKK2 ubiquitination and degradation .

• Phospho-ERK1/2 analysis: Use STK38 antibodies alongside phospho-ERK1/2 antibodies to investigate how STK38 levels affect ERK1/2 activation following CpG stimulation.

• Cytokine production assays: Correlate STK38 levels (detected by antibodies) with TNF-α and IL-6 production in response to CpG stimulation.

• Comparative pathway analysis: Use STK38 antibodies to analyze its role in TLR9 versus other TLR pathways (e.g., TLR4/LPS), as research shows STK38 deficiency increases CpG-induced cytokine production without significantly affecting LPS-induced cytokine production .

When designing experiments, consider that STK38-deficient mice produce more TNF-α and IL-6 and display increased lethality upon E. coli infection compared to wild-type mice , providing an important in vivo model for validation.

What controls should be included when using STK38 antibodies to study inflammatory cytokine regulation?

When investigating STK38's role in inflammatory cytokine regulation:

• Pathway-specific stimulation controls: Include multiple TLR ligands as STK38 preferentially inhibits TLR9 (CpG)-activated pathways but not TLR4 (LPS)-activated pathways . This specificity should be reflected in experimental design:

  • CpG oligodeoxynucleotide (TLR9 ligand)

  • LPS (TLR4 ligand)

  • Other TLR ligands as negative controls

• Time-course analysis: Include multiple time points when analyzing STK38's effect on cytokine production, as regulatory effects may vary over time.

• Genetic controls:

  • STK38 knockdown/knockout

  • MEKK2 knockdown/knockout (as MEKK2 is required for CpG-induced ERK1/2 activation and cytokine production)

  • Smurf1 knockdown/knockout (STK38's partner in regulating MEKK2)

• In vivo infection models: When possible, complement in vitro findings with in vivo models:

  • E. coli infection model

  • CLP (cecal ligation and puncture)-induced sepsis model

  Both models show increased susceptibility in STK38-deficient mice .

• Cytokine measurement standardization: Include recombinant cytokine standards when measuring TNF-α and IL-6 production to ensure accurate quantification across experiments.

Include appropriate cell types for these studies, as research has been conducted in macrophages where STK38's role in TLR9 signaling was established .

What methodological approaches can overcome challenges in detecting STK38 post-translational modifications?

STK38 function is regulated by post-translational modifications, which can be challenging to detect. Advanced methodological approaches include:

• Phospho-specific antibodies: Generate or obtain antibodies specific to key STK38 phosphorylation sites to directly monitor its activation state.

• Mass spectrometry-based approaches:

  • Immunoprecipitate STK38 using validated antibodies followed by mass spectrometry

  • Employ targeted proteomics approaches (SRM/MRM) to quantify specific modified peptides

  • Use SILAC or TMT labeling to compare modification levels under different conditions

• Proximity ligation assays (PLA): Combine STK38 antibodies with antibodies against modification-specific markers (phospho, ubiquitin, UFM1) to visualize modified STK38 in situ.

• 2D gel electrophoresis: Separate STK38 isoforms based on charge (reflecting phosphorylation status) before Western blotting.

• Phos-tag gels: Use Phos-tag acrylamide gels to enhance separation of phosphorylated from non-phosphorylated forms of STK38.

Research has shown that STK38 contains a UFM1 binding motif important for its function , and phosphorylation of STK38 may regulate its kinase activity, making these modifications particularly important to investigate.

How can researchers resolve contradictory findings when using different STK38 antibodies?

Contradictory findings with different STK38 antibodies require systematic troubleshooting:

• Epitope mapping and antibody validation:

  • Determine the exact epitopes recognized by different antibodies

  • Validate each antibody using STK38 knockout/knockdown controls

  • Test antibodies on recombinant STK38 protein fragments

• Context-dependent protein interactions:

  • STK38 functions differ across cell types and contexts (DNA damage response , immune regulation , cancer , sarcomere assembly )

  • Certain protein interactions may mask antibody epitopes in context-specific manner

  • Use multiple lysis conditions to disrupt different protein interactions

• Post-translational modifications:

  • Different antibodies may have varying sensitivity to STK38 modifications

  • Use phosphatase or deubiquitinase treatment of samples before antibody application

  • Compare results in basal versus stimulated conditions

• Isoform specificity:

  • Confirm which STK38 isoforms each antibody recognizes

  • Use isoform-specific primers for qPCR correlation with protein levels

• Methodological cross-validation:

  • Apply multiple detection methods (Western blot, immunofluorescence, flow cytometry)

  • Use tagged STK38 constructs as positive controls

  • Consider native versus denatured conditions for epitope accessibility

When contradictory results persist, consider that STK38's context-dependent functions may explain real biological differences rather than technical artifacts .

What are the optimal methods for using STK38 antibodies to study sarcomere assembly in cardiomyocytes?

STK38 modulates Rbm24 protein stability to regulate sarcomere assembly in cardiomyocytes. For investigating this specialized function:

• Co-immunofluorescence analysis:

  • Use STK38 antibodies alongside sarcomere markers (Actn2/α-actinin)

  • Quantify sarcomere number per cell and sarcomere alignment

  • Compare control versus STK38 knockdown conditions

  Research shows STK38 knockdown disrupts Actn2 distribution and reduces sarcomere number per cell in primary cardiomyocytes .

• Co-immunoprecipitation of Rbm24:

  • Use STK38 antibodies to co-immunoprecipitate Rbm24

  • Analyze phosphorylation of Rbm24 by STK38

  • Investigate how this interaction affects Rbm24 protein stability

• Rescue experiments:

  • Combine STK38 antibody staining with rescue experiments

  • Compare sarcomere structure after reintroduction of wild-type versus mutant STK38

  • Include Rbm24 overexpression in STK38 knockdown cells

  Research shows Rbm24 overexpression rescues the disturbed sarcomere distribution resulting from STK38 deletion .

• Live cell imaging:

  • Use STK38 antibodies for immunofluorescence at different stages of cardiomyocyte differentiation

  • Correlate with sarcomere assembly dynamics

Primary cardiomyocytes isolated from neonatal mouse heart and the HL-1 cardiac cell line have been successfully used as models to study STK38's role in sarcomere organization .

How can STK38 antibodies be used in combination with other tools to study its multiple cellular functions?

STK38 participates in diverse cellular processes including DNA damage response , immune regulation , MYC regulation , and sarcomere assembly . To study these multiple functions simultaneously:

• Multiplex immunofluorescence/immunohistochemistry:

  • Combine STK38 antibodies with markers for different pathways

  • Use spectral unmixing to resolve multiple fluorophores

  • Quantify co-localization coefficients in different cellular compartments

• Temporal analysis of STK38 interactions:

  • Use inducible systems to trigger specific pathways

  • Apply STK38 antibodies at defined time points to track dynamic changes in:

    • Protein interactions (co-immunoprecipitation)

    • Subcellular localization

    • Post-translational modifications

• Interactome analysis:

  • Use STK38 antibodies for BioID or APEX proximity labeling

  • Compare STK38 interaction partners across different cellular contexts

  • Validate key interactions with co-immunoprecipitation

• Combined genetic approaches:

  • Use CRISPR/Cas9 to generate domain-specific STK38 mutants

  • Apply STK38 antibodies to analyze how specific mutations affect different functions

  • Create cell lines with fluorescently tagged endogenous STK38 for live imaging

• Tissue-specific analysis:

  • Compare STK38 antibody staining patterns across tissues with different STK38 functions

  • Correlate with tissue-specific interaction partners

When designing multiplexed experiments, consider that STK38 has been studied in diverse contexts including cancer cells , immune cells , and cardiomyocytes , requiring careful optimization of experimental conditions for each cell type.